A great video as usual. If I may, I'd like to point out that Andrew provides these videos free of charge on You Tube, but if you feel that you get valuable information, then it would be a really decent thing to contribute on his Patreon account. I'm certainly going to. (P.S. I'm in no way connected to Andrew, I just love the videos)
and if like me you can't afford to donate, at least watch the ads on this channel in full and don't skip them. It doesn't cost a cent but helps the channel and the more people who do it, the more it helps.
Unfortunately he's anthropomorphised the batteries behaviour so much he's lost the facts. Dumb alternators, such as the one he is exhibiting will do the job as well or better than the DC-DC chargers in most situations, esp when the battery is in a low SOC. Forget the hype lads.
I am done with double battery systems and killed too many batteries after too much discharging. Now I have only one standard battery to start the car and a separate lithium battery from Goalzero (3000x) to charge anything else: fridge, lights, phones, coffee machine etc. Charged by either solarpanel, DC or 12v car charging depending on what is available. Works excellent for me and is very flexible as nothing is fixed in the car. I can remove the battery and take it to the boat or use it as a backup in the house.
I have a 1984 Landcruiser 60s with a factory fitted dual Battery system- mechanical solenoid! I've owned it for over 10yrs lots of traveling running large fridges, lights,winch and many other 12v items! Never had any problems keeping batteries charged at all!!
Please bear with me on this, I’ve spent a long time researching specifically for this post and it also draws on my own experience. I don’t wish to rubbish everything you say - it’s a topic that far too many people jump in to without actually thinking and anything to encourage people to think is good. However, I think you make a number of mistakes. 6:40 "when you connect the auxiliary battery directly to the car battery they do not instantly equalise". They don't equalise state of charge, but they should, near as makes no difference, equalise in voltage. If they aren't then the cabling isn't good enough. You absolutely do not need a DC/DC charger to properly charge a second lead acid battery with the majority of vehicles that have properly working dumb alternators. The exception is a modern vehicle that does fancy stuff with regen but we're not talking about that here, we're talking about a dumb alternator that puts out ~14-14.4V constant. When I've run my auxiliary battery down to about 60% state of charge (measured using an integrating state of charge meter) it will charge at a rate of around about 35A, plus whatever load the fridge is drawing. The voltage difference between the two batteries is approximately 0.05V because the cabling is good. In many cases, a DC/DC converter will slow down the charge process because they are current limited to 25A or so. That's for both charging and running your fridge and other electrics. You can get bigger ones, but you pay more for them. My battery doesn't drop to 25A charge rate until it's well over 90% full. That’s a fact borne out by datasheets of a great many batteries, the charge current stays high until that last little bit. 7:29: "deep cycle batteries require a different charging profile than high cycling batteries". There are some issues with what you're saying here. Thing 1, deep cycle lead acid batteries do exist: they're used to power submarines, forklifts, phone masts and that sort of thing but those banks tend to be made up of individual 2V cells. The vast majority of so called leisure batteries on the market are just rebadged starting batteries. I can't find a data sheet for the AC Delco battery you've got there but I'd be extremely surprised if it was a true cycling battery because they aren't generally made for our application. That then brings us on to thing 2, which is that deep cycle lead acid batteries use the same chemistry and innards as starting batteries, so actually use the same curve. The difference is that deep cycle batteries have much thicker plates. Talking of curves, thing 3 is that an alternator has no curve, it's just a constant voltage (we'll come to that later). AGM Batteries: it is fair to say that some brands of AGM battery desire a slightly higher charge voltage than a flooded battery. It is very difficult to find proper data sheets from most manufacturers of consumer grade batteries. However, if we take the datasheet for a Yuasa NP series 12V AGM battery (the sort that are commonly used for backup applications, UPS use, etc.) we find that it says "Charging at constant voltage is the most suitable and commonly used method for charging valve regulated lead acid batteries. " The datasheet then goes on to display a load of graphs with different charge voltages from 13.6 up to 15V and they all get to 100% charge eventually with higher voltages getting there quicker. Everything is a compromise, the quicker you charge a battery the harder it is on the battery, the more it gasses, the less efficient it is (i.e. you're creating more heat). 14.2-14.4V is a reasonable compromise for both flooded and AGM batteries. For long term float use, you reduce the voltage a little. And back to the video. At around 3 minutes you claim that the second battery you have is a deep cycle type. 7:40 you then state that you have high cycling batteries in both positions (which I take to mean a starting battery - this is a bit unclear as lots of cycling is actually what a deep cycle battery is designed for), before going back to referring to your fridge battery as a deep cycle. It is almost certainly correct to say that you have starter batteries in both positions for the reasons mentioned above, at which point a relay/solenoid/contactor based charging system is fine. I don't know how close to Cairo you are but over the course of about 10 hours at 14V ish it will get fully charged. Claiming that one battery will take precedent over the other is misrepresenting what the alternator is doing. The alternator is not doing anything smart, it’s not switching to a float or storage mode, it’s just maintaining a constant voltage. The batteries are in parallel so they will be charged as equals. The second battery will start at a lower state of charge, it will then charge at a higher current (at the same voltage) and will eventually reach the same state of charge as the primary battery. I can monitor, in real time, the current going in to my auxiliary battery as I drive and as I’m a geek, I do sometimes. Depending on how far I’ve discharged it, after an hour or two of driving my meter will be showing that it’s full and the charge current will be reading about 0.5A. After another couple of hours the absorption charge will be finished (so it really is at 100%) and it will stay sat at 0.5A for as long as the engine is running or I have a charger connected to it at 14.4V (it’s quite a lot lower when in float or storage mode on my charger). Again, if the battery in your application is not doing something very similar to this then the wiring is inadequate, not that there is anything fundamentally wrong with using that method of charging. Around the 9:20 mark you seem to be saying that the primary battery is controlling the charge of the secondary battery. It can’t do that because they’re in parallel. Either both batteries are flat, you’ve got all the lights and the winch running and the alternator can’t cope in which case the entire system voltage will drop; or the alternator is within its capacity and the batteries will independently charge at the rate they require. Lead Crystal. Lead Crystal is a brand, i.e. it’s not a technology like lead acid or lithium ion. Thankfully, I’ve found some datasheets for them. They’re quite happy charging at 14.4V same as your starter battery, or you can charge them a bit quicker at 14.7V same as an AGM. They cycle very well too, as good as top brands of AGM battery. The charge curves are also indistinguishable from AGM curves. They require the same amount of time at the same voltage to reach the same state of charge. Sadly the datasheet fairly quickly descends in to marketing but I think the reason that AGM batteries and Lead Crytal batteries have similar performance is that the Lead Crystal battery is an AGM battery. For instance, it claims to have “composite SiO2 electrolyte” in between the plates. An AGM battery uses a composite of a glass mat (silicon dioxide) with the acid electrolyte to separate the plates. That’s the same thing. The more I read, the more I come to conclusion that they’ve just given an AGM battery to someone that’s good at marketing and told them to come up with a way of selling it. One of their pamphlets states that they use “Technology: A unique micro-porous high absorbent mat (AGM)”. Either way, they handily provide a chart showing the chemical reaction that’s taking place which is just the standard lead acid cycle. The REDARC BCDC 1240, I’ve just read the datasheet for it (yay). It uses the same charge profile for flooded and AGM batteries installed in the engine bay, if they’re installed somewhere cooler then it can be set to charge the battery at a slightly higher voltage. As discussed before, that can speed up charging a bit. Where something like that really shines is when you have a long cable run between the starter battery and the auxiliary battery because that creates a voltage drop. If the two batteries are next door to each other with decent cables then it will make no difference at all. CTek will even sell you a kit that bypasses their DC/DC charger to speed up the bulk charge. Note that both flooded and AGM batteries can be charged at 14.7V, they’ll both charge quicker but it’s harder on the battery so people don’t. In industrial use, you’ll often be charging AGM batteries around 13.5V to extend their life. What DC/DC chargers do not do is tell the alternator anything. They can’t do, they appear as a load to the system just like if you were to turn on your headlights. 13:15 “The module is not interested in the voltage of this [starter] battery; it’s interested in the voltage coming out of the alternator”. If the cabling is up to scratch from the alternator to the battery, these are near enough the same. If they weren’t, the starter battery would never get charged. The module is also not paying any attention to the alternator, they are connected as a load to the starter battery. That’s how they wiring diagrams specify for everything that I’ve seen on the market.
13:35 Lithium. “If you attach the lithium to this [relay], you would have exactly the same problem”. Victron Energy make good products with good datasheets and they provide one for their lithium iron phosphate (LFP) batteries. It states “Charge voltage: Between 14V/28V and 14,4V/28,8V (14,2V/28,4V recommended). That’s the same as you’d charge all the other batteries we’re talking about. They will also sell you a relay specifically intended for the case of a lead acid starter battery and an LFP auxiliary battery: “The Cyrix-Li-ct will parallel connect a lead acid starter battery and a LiFePO4 battery”. They have nothing to gain by selling you something that doesn’t work, they sell AGM batteries, DC/DC chargers and all the other battery stuff you could ever want. If you needed a DC/DC charger in that application they wouldn’t have something that specifically isn’t one. 16:05 “How much of that is actually usable” - it really depends on how long you want your batteries to last for. You’ll get a life of about 300 cycles to a 100% DOD - compared to a flooded battery that’s really good, but it’s still a lot shorter than if you’re kind to your batteries. Discharging to 50% will get you nearly 1800 cycles. Compare that to an LFP battery which will cycle 5000 times to 50% or 2500 to 80% DOD. I’m sorry to say that your conclusion that people don’t understand the systems properly applies to you as well. Connecting the two batteries in parallel has some serious advantages - but they do rely on good cabling between the batteries. I have wired my system in that way because I get a faster charge (my battery will take more charge than any mainstream DC/DC charger, and it’s not a fancy battery); because it allows me to run my compressor at full speed from my auxiliary battery whilst the engine is running or run it from the auxiliary battery with the engine off; and because it allow me to combine the two batteries easily for winching or jump starting. I’d be very happy to discuss this further with you. You have my details through Patreon and through your pre-Patreon website. Sources: Lead Crystal docs-emea.rs-online.com/webdocs/159b/0900766b8159b4c1.pdf Also LC docs-emea.rs-online.com/webdocs/1316/0900766b81316a6d.pdf AGM docs-emea.rs-online.com/webdocs/0385/0900766b80385807.pdf Lithium www.victronenergy.com/upload/documents/Datasheet-12,8-&-25,6-Volt-lithium-iron-phosphate-batteries-Smart-EN.pdf Other battery stuff: batteryuniversity.com And a degree in electronic engineering, plenty of professional experience with large UPS systems, an off grid home in planning and a 4x4 with far more than its fair share of good battery monitoring kit because I like that sort of thing.
Tom - I totally agree with what you have said. I am an electronics engineer, involved in remote solar powered weather stations and lead acid battery charging is an essential part of the business obviously. The mistake Andrew made is trying to dumb it down too much , and you cant dumb down a complex subject, which this is. Battery life is all about charge rate, how often they are cycled ( tell my wife that when she leaves the lights on), battery temperature and vibration. All of these are at their worst in the engine bay! Telecos in the old days used to have their glass cells on a concrete floor (low temperature, no vibration), didn't deep cycle them, and used a slightly lower terminal voltage and --got a battery life of tens of years. I wonder why? In your 2nd para you said that the terminal voltage will equalize straight away, but of course if the cable is a few milli-ohms, the distant battery will see less headroom and will charge at a lower rate. As you correctly stated - the connecting cable AND the relay, SS switch or whatever must have low resistance.
Hi Tony, I don't drive a 15 year old rust bucket, I drive a 7 year old non rusty vehicle. The vehicle Andrew is waving at in this video is a recent Land Cruiser from Techpro Safari. It uses the same system. Something like the current generation Ford Ranger I believe uses the newer system which doesn't charge the main battery properly and that is a different kettle of fish. Some people swear at it, some people say it's no issue, I don't have any experience with it to be able to tell.
@Simon Franklin I did spend a long time writing it I have to say. It's certainly not meant as an attack on Andrew, I appreciate what he does and wanted to add something from a technical angle. As you correctly point out, I made a mistake. The batteries will charge at different rates, depending on their condition etc. but from the perspective of the alternator they will have the opportunity to charge as equals should they so desire. One is not treated preferentially, there is no discrimination, but may not accept the resources offered to it.
Hey Andrew we should get together and run through some electrical principles. And maybe a camping mission using my fridge to chill the beer followed by a demonstration and explanation of how a relay direct from the alternator can dump more current into a battery than what a DC-DC converter can.
Thanks, I had to see this twice. The first one I did not understand but I left with questions (the right ones by the way)... then I went out to review and design, read and go into detail of what CTECK or Redarc does in detail ... modes and diagrams... (for example). Now saw it for the second time after a year and is crystal clear for me! My set up: CTECK + 1 deep cycle (solar) AGM and two identical led acid batteries to support winch and other high demands when normal driving (lights, etc)
Mostly agree but would like to add something. The sensor Andrew speaks of with modern alternators is a Hall effect dc current sensor usually located on the start bat negative lead. As the start bat charge state increases, it accepts less current, which the sensor detects and tells the alternator to reduce voltage. If you connect your negative terminal from your aux bat to the chassis or body, it will not work well as Andrew states. However, if you connect the aux negative to the start bat negative, upstream of that sensor, it will measure the current both batteries are pulling in as they charge. This means whilst the aux bat is still asking for it, the sensor will see that and provide a higher voltage from the alternator for longer. This is like measuring flow rate in a pipe, where 2 pipes come together into a tee piece. You need to measure that flow downstream of the tee piece where the flow has combined. This will mitigate some of the issues mentioned here greatly, BUT will still not be as good as a proper dcdc charger.
I have no idea this has turned out to be so interesting a topic. This clip is so full of information and explained so clearly. I'm absorbing this info just like the lead battery. On the lighter end of things, the presenter is so emphatic in the subject, the presentation is so intense. I was all tensed up watching, but since the info is so interesting, I watched till the end.
I agree with all you say Andrew BUT, a switching system with a 105AMP deep cycle is a less than 250$ option that will allow you to run you fridge at night + some camping light. Not in the most efficient way but still. A BCDC alone start at 350-500 depending the AMP, solar ready ETC... What I mean is the switching system with deep cycle is a working solution at low price for day or weekend out. BTW I'm a massive fan of you and love all your video. John
The major reason you should use a dcdc charger with lithium is so you don't burn up your alternator due to the huge draw they can create. The DCDC module limits the current the lithium batteries can draw from the alternator. The switching system can work with lithium, and charge it faster, but got to be sure that the alternator is able to handle the high amp draw.
Andrew, your points are well taken, however you also clearly make the argument why a POWER-GATE Dual Rectifier is a far better solution to multi-battery charging verses the relay (solenoid) method. With dual MOSFET arrays, each battery is able to absorb whatever level of current it requires based upon its respective health, chemistry, state of charge, and load...and it does this without causing the batteries to equalize, and it does this with no moving parts and a miniscule voltage drop. In "Andrew" parlance, think two huge pipes running from the alternator to each battery, each pipe able to treat each battery as its own entity. You really should consider learning about Perfect Switch MOSFET-based battery isolation products. The technology and performance make Perfect Switch dual battery isolators a very compelling option where performance, longevity, and reliability are paramount.
Andrew - you appear to confuse "amps" with "ampere-hour" - Several times you said amps, when you meant AHr, which would be confusing for some. Simply put - the deep cycle house battery needs a higher terminal voltage than the lead acid starting battery, and the alternator sensing is influenced by the truck battery terminal voltage and not the house battery terminal voltage. I don't run a fridge, I use LED lighting, and I use two traction batteries, with a decent sized cable between the batteries( with a solenoid obviously), and provided the trips are an hour or so, there is never an issue. The problem only arises when you try and mix two battery types with a single charging system. You didn't talk about solar charging, with a separate solar regulator.
"It seems to work fine whether or not it's optimal." Thank you for backing up exactly what I was saying. Which is, why have something that seems to work when for the same cost something optimal can be had?
THanks for that explanation .. I, like others, thought I knew alot about batteries and connecting them. Your explanation of different types of batteries connected together not working makes perfect sense. I use the Optima yellow top series because I have a winch .. if I was going to connect another battery it would be the same yellow top .. for some reason I knew in the back of my mind that you shouldn't mix batteries. I easily could have made the mistake though.
Thanks a lot again Andrew...... now i know why my system isnt giving me what i expect and has let me down already a few times in the middle of the no where, i guess now i need to upgrade my system, Thank you so much
You remind me of the great Julius Sumner Miller. Excellent presentation that creates interest, and for some reason, causes retention of information! Thank you Andrew.
Dear Andrew, An alternator will charge any lead acid battery very well if you wire it very well. Simply put the habitation battery first and sense from the starter battery and use 35mm² or greater. The alternator is not the problem it's conventional installation. I pull 1kW to my FLA golf cart service battery at 50% DOD. They accept current fine once I convince the alternator to deliver it. It does work I have data, happy to show it. If I used a DC - DC charger I would lose power. The only reason you can't fully charge a traction battery from the alternator is either runtime or installation. Lead crystal is not new but is extremely brittle.
I don't use a relay I use a magnetic latching contactor. Albright SW-80. The contact resistance of feeble little over-rated relays is another culprit for poor charge.
you forgot that todays cars are equipped with smart charging systems which sense the main battery's current/voltage to decide if any charging is needed. this is due to energy saving regulations imposed on car makers around the world.
How can we not respect your words. You go out into the bush and with all your filming equipment on top of the normal camping gear use more electricity than probable anyone. Thank you for your clear explanation, it wasn't a rant, it is how people used to speak, straight talking. "This is the truth, this is bollocks." No grey area's. If anyone wants to argue please state using the laws of physics why. Lovely to see a 1HZ again, I sure it feels under powered after the V8 but to my eyes it is beautiful because I can see what is going on!
I am super excited I found this video. I wanted to put a switch isolator in my overland travel rig, but there are way to many options. I found a Renogy 200A Battery Isolator that I hope will do as you suggested if I get the right battery. Thank you so much for making this video! Cheers!
Wow, you saved me a ton of effort here. I thought I kinda knew how to build a dual battery system, but now I need to read a lot more. Is there room out there for a lower budget setup with high cycle batteries just to get one offline to run some basic stuff? (12v fridge for example). I always just pictured the two "buckets" just refilling eachother and leveling out when the 'smart realy' closed the circuit. If your batteries are dissimilar, I get it, you need to work that out, but what if they match and are both 'high cycle' batteries?
as he said the most efficient and cheap solution is 2 matching cold start batteries with a solenoid between. You will certainly kill the one thats in aux in a few years at best, if you have it running 2ndary systems regularly. If you dont and are just going on the occasional trip (once a month or less) then you CAN certainly get a good deal of life out of a CCA Battery, they wont have as much amp-hour potential as a same weight/size Deep cycle but that depends on your personal needs of the system, what fridge youre running ,how many personal electrics are you charging off-grid etc. And you can further help yourself by removing the aux battery when not on trips (this also save on fuel, less weight and less work for the alternator to do) and keeping said aux battery at home, in an ideal storAge place (somewhere that has the least amount of temperature and humidity change on the property, on a surface that has minimal leaching potential so avoid concrete and metal based surfaces like the plaque and hook it up to a smart charger NOT a common cheap charger, a SMART charger as these actively interrogate the battery constantly and alter their charging profile and type based on the state of the battery. I have a genius charger which i think works really well.)
Matthew Ray: Using a Cranking Battery For Aux, is really best for "hardcore" 4x4'ers where they need lots of reliability running winches during heavy recovery... Just make sure the cables parallelling the 2 batteries (and solenoid) are rated to current of 300-500Amps. [The "100 Amps" that Andrew said is used during cranking (or winching) can often be far more than 100A, like 3-5 times..] Cranking Batteries really shouldn't be used for running any constant loads (ie a fridge, 2 Amps for 12-15 hours, will kill a cranking battery in a lot less than we may think, if used very often, so for occasional use only.) BTW. typos are funny and suck at the same time, "plague", also modern batteries with PolyPropylene aren't (AFAIK) affected by Concrete during storage like the old "Rubber" based battery cases - to be accurate of course we must say "as much".
The best way IMHO, is to use a deep cycle battery either under bonnet, rear compartment or in trailer and charge it with an small DC to DC charger, even 10 amp is enough and mount it close to said battery with secure permanent connection. The supply line to this charger comes from start battery via a voltage sensitive relay under bonnet so it doesn't get discharged at all because the supply line is disconnected shortly after engine shut down. Also wire it so the fridge etc is drawing from the cars alternator when traveling and the aux battery is disconnected using a 30amp 3 way switch where up is car supply and down is aux supply. Off in the middle. Just got to remember to switch to aux when pulled up for the night. Also put 240v smart charger when power available. One more thing all chargers have whats call paracitic draw so it's a good idea to use a large battery isolator master switch to disconnect these for lay up periods. Good luck.
Brilliant vid. I have had this argument with many 4x4 enthusiast regarding exactly this and many are convinced that their solenoid system is the best and that it works well until their aux. Battery fails after about 2 yrs. My explanation is that even if you drive the vehicle all day the aux battery only gets to approx. 85% state of charge and that the top 15% is what is needed when remote camping. Personally, I keep the OME battery just for starting the diesel and use a voltage sensitive relay to provide power to an off road camper only when engine is running, including charging the aux battery via a DC to DC multi stage charger. The only other way to fully charge these deep cycle is via a solar panel and micro processor regulator or a portable 2 hp petrol powered alternator thats also regulated. Connection of two batteries is just silly, not only for the lack of charging but I like to keep the start battery just for that. Starting a diesel when remote camping is impossible on the modern Ecu start sequence systems with a flat start battery. If your by yourself and no jump start vehicle..... well your in some shit!
Thank you for a great video Andrew! I should have had this knowledge about seven years ago when I changed my altenator because I thougth i was broken. It couldnt charge my aux-battery :) now running a DC.DC charger and it works great!
I think Andrew is spot on the fact that you should use DC-DC chargers if using mis matched batteries however I don't think your explanations for this is factually accurate a lot of what you said regarding to how charging happens is incorrect and slightly miss leading. Your conclusions are spot tho.
Surprised you haven’t tried the Intervolt DCC pro system built just down the road from you in Perth, I imported one excellent results and amazing customer service.
Here in the States there are folks that have HUGE stereo systems in their vehicles that use MASSIVE amounts of power for their amplifiers. They may have 5 alternators working together to produce enough power for the system. They use capacitors instead of batteries. Electricly speaking HUGE capacitors measured not in micro-farads but in farads. Hundreds of farads. As you may know, capacitors take and release power VERY quickly. Have you ever researched capacitors for this type of application? Nice video.
problem is Andrew just because charge separately doesn't mean those batteries are electrically isolated you are likely drawing current from both all the time.. regardless of what general capacity you use the in..
On the lead acid deep cycle batteries you should only pull 50% of the rated amps unless you want to risk damage. I laugh at people who put the latest battery types in their vehicle while keeping the old alternator to charge it... Foolish. As you said, they all have a different charging profiles and need different levels of volts and amps at different times and a 20 year old alternator won't do them all.
Reading the comments has been useful, however, I will go with the man with the experience of this and understands the practicalities and forgo those who have read a manual !! It seems most of those who 'have a point to make' have missed the main point of this guy. He clearly states 'yes, it does work to a point, but it could and should be so much better by those who prepare these vehicles , and should understand it better ! Great video. I have learn't something useful today. He explicitly relates the issue to over landing vehicles, not weather stations or other remote power supply issues. It seems people do not know how to listen these days.
Owning a PX Ford Ranger.....there is no way of fitting a second battery without using (in my case the Red Arc BC -DC charger 20 amp) as the factory set up for the alternator is a float charge system. At the first service I had the alternator reprogrammed to charge constantly after several flat batteries. The BC-DC is programmable for lead acid, gel, and deep cycle. Over the past twenty five odd years I have had quite a few 4wds and in the early days we were forced to use solenoids as none of this stuff was available, even the battery options were lead acid. The alternators in those days were ",compared to today's units" ....minuscule most were around the 40 amp mark.Nearly all the diesel alternators were designed to drive the vacuum pump and were low output. We had stators rewound and were able to get a few more amps out of them. With the new alternators they now have well over 100 amp output and beyond due to higher demand from electrical components. Now this is where the motorists get confused, they think you can jamb the high current straight back into the battery, they don't realise a battery acts as a very large resistor. On the point of Toyota warranties, I worked for a company that sold Auto Electrical parts amongst other things. We were supplying a couple of places out in the bush that were running V8 landcruiser diesels in the mines. The factory alternators were failing at an amazingly fast rate, we supplied an upgraded corrosion resistant unit that lasted quite a bit longer than the factory Denso unit.
amazing as allways. just briliant info there. i have second normal battery in my car and i was thinking to c onnect it via switch solenoid, so now i know it will work well.
I've got a 2005 RAV4 which I take into remote areas and I have a portable deep cycle battery which I plug into the Anderson plug in the rear cabin. It's got the Voltage Sensitive Relay, so once the present start battery voltage is reached (which is very fast) it feeds into the auxillary battery at the same rate of charge, just over 14v. So I've read from about 2006 most car manufacturers had smarter charging systems that would sense your batteries voltage and drop the rate of charge. My vehicle doesn't have this type of system and so I get the charge I need to both batteries.
Very good vid Andrew. The Language the different batteries speaks are calles in german "Kennlinien" (characteristic curves). The way the battery want to e charged. A lot of solarswitches get special switches for different batterytypes. But good to remeber the solonoid-switch. ;-)
I dont even need to watch a video of yours before I already hit the "like" button. I know your info is all trustworthy based on experience. Cheers for the info! I wish you could only do things to things other than Landcruisers haha
Thanks for the great advice, would having a dual battery system for normal 4x4ing like winching and other battery heavy tasks, and then having a lesuire battery system for the camper that is all independent form the other system
I am very interested in watching developments in lithium batteries as 'house batteries'. The are more complex to run but they look like being a real game changer in terms of longevity and less weight.
Not really related, but I'll share it. It's good to know a little about paralleling batt.'s. I had what the locals would consider a car engine in my motorcycle. It was a lead acid and failed a little earlier than I expected - probably due to vibration and heat. the only batteries they had were for moped size engines. I probably could have used two or maybe three batt.'s (no need for CCA in the tropics) in parallel, but bomb started for a few mornings until I got to a major city.
Thanks for explaining this. I have had this exact problem with my National Luna 2 battery system in My FJCruiser. I have tried different batteries and spare would never achieve full charge.
This video couldn't have come at a better time. I am currently considering a dual-battery system and I questioned these solenoid systems. Then, this video was recommended on the RU-vid home page and I immediately clicked to watch it. I thought it was one of your older videos, but then I saw that it was just posted. So, thank you very much for the advice and answers. It is deeply appreciated.
floating voltages is different in the batteries as well, so the alternator can not reach the higher floating voltage as it is set for 12.7/// 14.4 , make your choice you can only have 12.7 or the higher voltage by changing the voltage regulator on the alternator, or run a piggy back alternator with a dual output for 2 batteries with different voltages,,,or use a special charger made for the spare battery, if you dont you are screwed !
Sorry I couldn't make it to the end of this rant. I'm thinking of using a Marine industry solution and using a DC charger that I can run off the main battery. I'm also going to switch it so I can disconnect it when the truck is off. I'm using a Keyed switch like Andrew uses in one of his earlier videos.
Agree about the charging system. Way better to use a good charger for second battery. Compared Lead Crystal and Lithium for the system, and found the Lead Crystal is good, but too heavy. 100Ah is 33Kg for Lead Crystal and our Lithium 100Ah is 12.7Kg Redarc charger for ours and works excellent.
Lead crystal is about the same weight as lead acid. They are excellent at cold cranking, and can take deep discharge and rapid charging without damage. I think lead crystal is the future. IMHO
Fair enough. We chose Lithium to be better than AGM etc and to minimize the added weight and battery size in the canopy of the 79 series. Works excellent. How are your GVM running?
yes think so to they are awesome does lead crystal battery ,, im grea what you where telling ,, I have a dual system dcdc to get the battery better charged with the alternator in my trailer ,, he protect the start battery thnx Andrew
Andrew, love all of your other videos, but there are a few incorrect statements here.. ‘Charging profiles’ in the common meaning of the word are not based on deep cycle or starting battery, but based about battery chemistry type, PB, AGM, Gel, Lithium etc. this differs by Charing state and voltage not about the amps that the battery can draw, Once batteries are connected to the together they all become part of the circuit voltage will equalise fairly quickly if the distance is small and sufficient cables used, the alternator doesn’t differentiate between them, batteries between deep cycle and starter battery will pull larger or smaller amount of current but that won’t make a huge difference to charging it while driving, the only way that the Aux battery won’t hit 100% if there is too much resistance in the cabling and has voltage drop, even if it doesn’t hit 100% because of internal resistance it will get fairly close( generally speaking both battery’s won’t get to 100% charge exactly by using an alternator), (which is fixed by using a dcdc charger wired close to the aux battery). Alternators (non smart ones) just dump higher voltage above 14v and any amps can be drawn as per the battery. Every deep cycle battery’s will accept charge of 30amps or more, when you have a 140amp alternator and running all of the cars electrics there it’s probably only about 80amps left to charge any batteries so this is 40amps per battery anyway
All good in theory Dean. So then why don't these charging systems work in the real world? They are a grossly overpriced, under-performing kit, promoted with marketing lies. Irresponsible? I call it challenging common beliefs with real world experience.
4xoverland don’t get me wrong, I also dcdc chargers for dual batteries for 2 reasons. 1. It has a proper multi stage charging profile for the battery chemistry type. Not just dumping 14+ volts like an alternator. 2. Deals with voltage drop in my batteries in my camper and rear of the car. 3. Can work instead voltage sensitive relay if installed correctly. 4. Accepts solar input. I have fully installed myself and setup a RedArc Manager 30+TVMS in my camper and multiple DCDC/BC in my vehicles. They are absolutely awesome. My comments were my triggered when you indicated that the alternator can work out what battery is which and treat them differently when they are on the same circuit in parallel. Maybe my points were more in theory and I suppose there are also a lot of variables that can differ results. I just got a new Ranger wild track and connecting over the OBD port I notice it has has options for dual batteries charge percentage ie. 75,85,95,100% which is interesting. Btw I absolute love your videos please keep them up! I’m a big fan..
GREAT video!An example...60ah - 12v HIGH cicle battery for starting car ,and 3 more the same type in caravan treiler conected parallel...For an electric divice that consumes 1000watt in 220volt power grid , how many hours will it run? (For the 3 batteries fully charged with 2000watt inverter.)
andrew, I have to disagree to a certain degree. I am into charging stuff as well, and pretty deep. You are correct, an ordinary alternator is not able to charge a deep cycle battery completely, cause it's charging characteristics (simple IUoU) are not matched to it. BUT: any battery will TAKE the current it needs, simply due to it's inner resistance. if two batteries are connected in parallel, and one is deeply discharged, hence has a low inner resistance, it takes more current than the one with higher resistance. only downside, or obstacle, is the voltage which does not match. but just as an example. from my battery monitor of my 90Ah aux battery I can read a current pull of some 30A at a discharge state of about 30% (70% charge remaining) in the mornings. it works. but an alternator will never charge a deep cycle battery to a 100%. that's what the 110W solar panel and MPPT charger is for ;-) (maybe this picture helps the audience, to get the connection between current and voltage: voltage is the pump. current is the pipe diameter.)
Great video, but this is more to do with smart Alternators. My 2006 TD42Ti Patrol, is old school. Plus I have a Delco calcium battery that is deep cycle AND a starter battery in one. DCDC chargers are for smart alternator.Oh and I use a smart charger at home to keep both batteries in top condition. I run a CFX 65, I plug in a 120 AMP good quality solar panel when camping stationary. If I drive home for 5 hours or more, when I plug in a CTEK smart charger both batteries are fully charged. If less than that, the CTECK will say the 2nd battery is 90 percent and it will top it up.
This video has provoked a lot of comment and one is hesitant to stick one's head above the parapet for fear of upsetting someone. Andrew has highlighted a problem with some charging set ups but IMO there's a bit too much rant (his word) and too little fact to make this a great video. However a number of the commentators have tried to clarify some of the points raised in this video. It needn't cost a fortune to have a good dual battery system, at least not in an older vehicle with no electronics. In my 27 year old Defender I have an external charge controller (Driftgate) set at 14.4V boost / 14.0V float, a solid state splitter (Driftgate) and battery sensing to the auxiliary batteries. I am also experimenting with a de-sulphurator to keep the plates of the auxiliary batteries clean. This set up isn't sophisticated or high tech but works well. After a longish overnight stop (say 15-18 hrs) with fair usage the auxiliary batteries will typically draw up to 30A initially (it has been known to exceed 50A total charge to all batteries) which reduces to around 20A within less than 30 mins. It can take several hours to get to the float charge of c. 3A. For longer stops I must use solar panels or an electrical hook up to a permanently installed smart charger (Sealey) if there's no sun. This seems to be a good set up and I doubt if an expensive DC-DC charger would be any better.
G'day Andrew. this is a very good video & it starts the grey matter firing + you explained it quite well. As a result, I have a request for a little guidance please, if you can spare the time as I am sure you are quite busy mate. I am just starting to build our truck & want to get it reasonably right first off, The setup at present is 24V & as follows, A single sealed Alternater delivering 150Amps to the twin 260Amp starter batteries, the start batteries then connect to a REDARC SBI224D which in turn supplies four 300Amp AGM house batteries. All the electcical wiring,, fuses & terminals are above standard & finally solar power is also supplied to the batteries as follows 1 X200W pannel to the start batteries & 3 X 200W panels to the house batteries.............Finally, after the long story my question is, have I messed up by fitting the REDARC SBI224 which had been highly recommended at the time by the stores electronics GURU. Just as a side note & not a boast or anything the batteries & inverters weigh in at 565 kg give or take 3 kg Your thoughts would be greatly appreciated mate, Steve.
I love your passion in these videos Andrew... great information. The question i pose with these new technology batteries is are they able to handle the vibrations and rigors of off-roading? Maybe something to bring to the viewers in a future follow up video. Cheers, Wes.
Oh god now I’m confused - before I waste money - what do I need? Not long trips but for a fridge some lights and a water pump (not shower) for use for a weekend - 7 days max - green lane and camping
Biggest issue is that an alternator is not a "smart charger" and so will charge the cranking battery to maybe 75% of its total possible charge. This doesn't matter because once the engine is started, the alternator delivers the power to your lights/stereo etc and the cranking battery remains at "full charge". So to have an aux battery in parallel will also only be charged to 75%. Which means your lovely 100AHr battery is really only 75AHr. So the BCDC smart chargers are definitely the way to go as Andrew says.
Bullshit. 75% is a number you have plucked out of the air. The alternator will continue to charge as long as a battery will accept it. Bottom line is you will have to drive for a week to fully charge a battery on alternator OR DC-DC. Alternator because the last 5% will take that long, DC-DC because its only chucking 20amps at the battery in the first place. If you want the best charge of a low SOC battery within 1-2hrs the (dumb) alternator will do the job better
very detailed answers there. Im starting to look into Lithium Batteries for my 200 next, ill be making a video about which ones and why i chose them, still abit down the track because of how much the batteries cost
I appreciate your passion and frustrations Andrew. Electrical systems continue to elude my current understanding (although I'm working on that) so your explanation an presentation was helpful. Thank you.
Hi Andrew love your videos but you're wrong sorry, Batteries have an internal resistance a flat one is low a charged one is high at a given voltage resistance controls current you can observe this with a battery charger as the charge builds up so does the resistance and the current goes down, if 2 batteries are put in parallel each may take different current depending on state of charge. Just the same as a headlight and sidelight bulb in parallel take different current . Alternators are fantastic for charging, regulated voltage and more spare amps than you can throw a stick at, the regulator only senses voltage, a battery is a load the same as a bulb if voltage drops it allows more current to the rotor which strengthens the magnetic field hence more output to maintain voltage and vice versa so nothing wrong with split charge relay. The only problem is charging time they only work with the engine running ,time is one of the most important factors the holy grail is to reduce it however peukerts law applies people forget its a chemical process its not just an exercise in ohms law, peukert says you have to take into account battery discharge and recharge efficiency about 95% and as low as 50% for a lead acid so if you take out 10 ah you have to put back 15/20 ah do not base calculations on 100% efficiency or you will be disappointed. There is no scientific proof that going over 14.5 volts reduces charge time you may waste 10 amp just getting the battery hot, So time time time the 20 hour rate is the most realistic 5% average for 20 hour I work on 15 hour charge time I never discharge fully , I only use a relay so being realistic to get 15 hours it takes me 5 days but I have 7 days of capacity so my system it robust, basically you have 3 options increase charge time with solar , increase capacity ( both involve weight) or reduce load, forget dc - dc charges, even a good lawyer cant change the laws of physics, mathematics fun for all the family, there that's my little rant ha ha Roy.
Hi Tom thank you for your reply, please check out peukerts law on Wikipedia and read the external links at the bottom, smart gauge give a better explanation than I and see where I'm coming from, using Ohms law V=IR, R=V/I, I=V/R, I = amps, r = ohms v = volts, when you know the voltage and current calculate the battery resistance when you know that you can calculate the current at different voltages you will see the current gains are not worth the expense also take into account higher voltages can damage batteries and any circuits connected particularly electronic, my advise is stay well away from 15v or disconnect when charging including compressor fridges with digital displays, (the root of everyones problems)
Use all of your amp hours and you do it to detriment of the two deep cycle batteries reducing life. Use 50% ie 76 AH of your 152 AH and you maximize the number of available cycles for the two batteries and increase the life of the two batteries immensely.
Andrew, I've noticed you have KC gravity pro sports on your vehicle. I live in Australia, I've just purchased some after lengthy research but never seeing the lights in real life. I haven't recieve them yet but am keen to know your thoughts. Your opinion is highly valued amongst the broader 4x4 community.
Yeah, that helped a great deal. I can look at technical specs, charts and wiring diagrams all day but they way you've worded the descriptions in this video made it a lot easier for me to understand / put in perspective. I'll be saving this video for future reference for sure.
Great explanation of how the different types of batteries and charging systems work and how they can work together. Just wished I had know this many years ago, luckily for me, I had good advise on my current build and have what I believe is the best system for me. Again, great video.
