Good stuff. A couple more things to chew on. (As Les commented) With a 24V setup, you'll also need a buck converter to step down to 12V to power your house DC circuits. Adding to your point on solar, you potentially will save a bunch-o-$$$ with 24V, assuming you're maxing out your solar. Since you're generating less current solar charging a 24V battery bank, you can use MPPT solar charge controller(s) with a lower output amp rating (less expensive). The higher rated controllers really get expensive. Hope that makes sense 🙂
I am running a 24 v system with 600 watts of solar panels with 2 lithium batteries in series for 4 years now. I run a step down transformer 24 to 12 volts that runs all my 12 volt system at 13.6 - 13.7 volts . I've been very happy with it so far.
Any difference in discharging the batteries? Because I have two 12v 200ah lithium batteries blue carbon, it's looks like those batteries were not make it to work in series, when get 27.5 the BMS start cutting the power... Horrible...., so I'm thinking to put them in parallel buying a new 12v inverter.
@@Fincabaracoa I have SOK batteries, I monitor them with a Victron shunt and the voltage has stayed very close to each other. I don't know why your BMS cuts power, you should be able to go to 28.8 volts.Sounds more like an issue with the solar charger.
@@mkroach59 thank for reply, after running my investigation and watching more than 15 videos, yes it's the cheap BMS in blue carbon battery, a lot of people complaining about the bms, they even change the bms for one of 24v for two 12v batteries.
Another benefit, and the main reason I chose 24v for my very large dual 5k inverter setup, is the efficiency. Charging and consuming power at 24v is more efficient than 12v by a few percentage points at least (48v is even better). You have lower current through conductors, so lower transmission losses, and better conversion efficiency in charge controllers and inverters. I do have native 24v batteries in my system so I do not have to balance upper and lower stacked 12v batteries - definitely they way I would recommend going about a 24v (or 48v) system - native voltage batteries. I am not a fan of running batteries in series personally. Now 24v does require some DC-DC converters for your house 12v DC loads and those will have a conversion loss as well. For me it came down to "where is most of my power getting used?" 12v DC or 120v AC. For me it was the 120v AC so I prioritized higher efficiency there (my inverters) vs worrying about the 12v conversion loss.
Yep my buddy installed a 24 volt system, unfortunately his charge controller failed and sent 24 volts through his 12 volt appliances. It cost him thousands to replace everything.
Need your expert opinion. These days people are commonly using a 12v DC setup where battery is charged by a MPPT charge controller while the load is put parallel to the battery (MPPT chargers here don't have a load/output option) via a PWM controller ( to avoid over discharge). In my view the charger will be over charging the battery as the load running is in parallel. Your view please.
LOVE YOUR VIDEOS, I'm getting a 2023 motor coach. It has 1 200 watt solar panel, a 1000 watt inverter , a dual controller what ever that is and 2 100 AH AGM batteries. I plan to up grade the inverter to 2000 or 3000 but initially would like to upgrade to a 200 or 300 AH lithium battery, can I just drop a lithium in with my current equipment ?
is there an advantage on going with 48v system (EG4 48v 6.5kw all in one inverter) with 2 - 100amp batteries vs 12 or 24 volt with 200-400amp battery bank? Would the 48v need a step down transformer as well or is it contained in that system? Would I even need that size system on 45' toyhauler? Would like to add 600-1000 watts of solar panels to roof.
What about the energy density of the batteries between 12v, 24v and 48v? I am looking at a system using a 48v system party due to the price/kW hour for the batteries AND the fact you can dump a ton of solar into a 48V system.
So to understand your question, I think you are asking total watts and size of battery in 12v vs 24 vs 48 Energy density is calculated by the actual substance providing the energy in relation to volume. The specs of my batteries can be found here. www.bigbeardbatteries.com/online-store
For the same battery chemistry the energy density / capacity (in watt-hours) is the same regardless of the battery voltage. E.g. 200Ah 12V battery vs 100Ah 24V battery vs 50Ah 48V battery ... all three batteries will weigh and have the same dimensions and capacity, roughly. The internal topologies of the batteries are the only difference. e.g. 4s4p (16 cells) vs 8s2p (16 cells) vs 16s1p (16 cells). For example. NOTE: For 48V LiFePO4, always get 16s (16 series internal) "48V", which is 51.2V nominal. Don't get 15s batteries that are also marketed as "48V". In anycase, if you have the choice, go with 48V, it is hands-down the best choice for many reasons, not just wiring. Amperages are far lower, heat is far lower, efficiencies are far higher, charge controllers (as you noted) can push far more solar power. A 48V system has 1/16th the wire losses that a 12V system has. 48V is massively expandable even when starting small. On the charge controllers. For example, a cheap Victron 100/20 charge controller can push 256W of solar to a 12V battery system, and the same charge controller can push 1024W of solar to a 48V battery system. Its night and day. EDIT EDIT EDIT: I previously used the Victron 75/15 as an example but that charge controller cannot actually do 48V battery systems, so I updated my example to using the Victron 100/20 which can. There are other discussions that can be had regarding equipment. 12V legacy equipment is certainly an issue but I would also say that when putting together a new system all the heavy hitters have native 48V options. And things like POE+ (power over ethernet), including Starlink, can be directly powered on 48V 16s LiFePO4 (51.2V nominal) battery architectures. -Matt
@@markk171 One last thing I should mention is that with a 48V system voltage, the solar inputs for most charge controllers have to having operating voltages of 60V+. Which means the minimum panel configuration is something like 3 x 100W panels in series. Or for example two 320W 40V residential panels in series. That's the only real issue and most people putting together systems and looking to expand have at least that in solar panels already. In anycase, it is still possible to use cheap charge controllers. The Victron 100/20 is a good fit. The Victron 75/15 which I improperly used as an example in my first posting actually only does 12 or 24V batteries. So the minimum charge controller for a Victron is the 100/20. Always double check voltages. -Matt
@@junkerzn7312 yep...the Growatt 3000w inverter/charger solar input is 60v and the EG4 all in one 3000w inverter/charger requires 120v. My initial build will not include solar...these are for later.
My issues are how many 200 w panels can I have with a 30a solar controller and how many 100a batteries can I have/get. Note: I have 2 panels, 2 100a batteries and a 30a controller
So a 30 amp solar controller going into a 12v battery is pushing a maximum of 360 watts. (30x12). So 2 to 3 panels is a good match. Any more and you are just taking up valuable space on the roof and never getting more than 360 watts of charge. At 24 volts then you can charge up to 720 watts.
I watch and enjoy your videos but this one i feel compelled to comment. I don’t think saying “by going 24v that you can double amount of panels”. Don’t you have to consider panel voltage/wattage and series/parallel? Thanks for all you do.
Absolutely. But let me sow you. 300 watt panels 40 voc 10 amps. (Edit the fat finger) On a 12volt system with a solar controller 150/100 I could put 4 in series/parallel ending with 80voc 20 amps 1200 watts. The solar controller is maxed at 100 amps regardless. 100 amps at 12 volts, limited to 1200 watts. In a 24volt configuration. I could do 4 strings of 2 in series. I would be at 80 volts abd 40 amps. The solar controller pushing 24 volts at 100 amps max gives a potential of 2400 watts.
Thanks but I’m not following your math of 40voc/20a = 300watt per panel. If you could please let give me example of a panel w those specs, I can pull data sheet n figure it out. Also, in 12v example, if (4) were in series/parallel wouldn’t output be 2xVolts and 2xAmps of panel rating? For my small 2S/2P of 4x100, I get ~40v @ 10a. Just trying to learn so I appreciate your time
