How to Series Connect 12v LiFePO4 Batteries, and Top Balance 

Thanks for watching LithiumSolar.

Thanks for watching Bobby. Happy new year to you. I hope this video helps your friend out.

Happy new year to you too.

Your welcome. Best of luck on your build.

Your welcome. Remember, the best thing is to buy a 48V battery from the start. This video is more for people with an existing 12V system, who want to re-configure their existing batteries to 48V. Since you are starting new, please consider buying 48V batteries. Here is are some affiliate links to consider: 48V waterproof battery (good for Vans, RVs.) On sale right now: signaturesolar.com/eg4-wp-lithium-battery-48v-100ah?ref=4_rHcgZ9x-TiF-

Hey Bruce, Fellow Aussie here in the same situation, how did you'd go? did is it holding up? Just bought a pair of the same type also wanting to hook em up in series but just noticed the manufacturer warning against using em in series. Unsure what to do atm. 🤔. I thought they were a bargain when I saw em but now not so sure.

Haha, thanks.

Thanks. Yeah, about the drawings... I'm not great with computers.

Thanks. I tried making those graphics on my computer, but I'm just not very good with it. So I drew them out.

Same here, I have 106.2kwh of them, they are simple and trouble free. Yes they weigh 8000lbs, but they are fine.

@@camarocraig7060 trouble free? who are you trying to kid?

I glad to help you solve the problem. With 200ah packs you might want a larger charger, otherwise it will take awhile.

How would the 12v battery's internal bms know / suffer if it's part of a 48v battery?

Your welcome. Thanks for watching.

How exactly does this play out? I'm using 4x12v in series, each of which say not to go higher than 24v, and they still work fine. I'm not saying you're wrong, I just don't understand the risk.

@@jimmybrad156 Nothing will happen unless one of the BMSs decides to disconnect. Then (as per your other question) it'll suddenly know how many batteries are in series with it,. Have they been fine over the three intervening years?

Yes, I was recently in communication with a Chinese company that uses CATL cells in their products. The advice was to keep the pack between 20-80% but if you want maximum cycles then 50-80% with a >6000 cycle life is what they claim. Obviously the latter would involve buying a larger battery than you might otherwise need... perhaps a marketing ploy? I guess we will find out who was right in 20 years but my guess for best practice is to keep the pack out of the steep part of the charge/ discharge curve and let an active balancer keep the cells within a certain limit of each other.

What was the voltage output of the charger that was used to charge all four in parallel? A voltage output of 12V won't charge 12v lithium batteries, I believe it would have to output somewhere around 14.8v if I'm not mistaken.

there are 12v balancers on the market if you are concerned about it

Hello I have 4 nos 12 vbattery it have individual bms can i connect in series

@@afgamer322 The video is showing four LiFePO4 batteries with individual BMS built in. So what he is doing is what you should do as well.

I think that I understand what you are saying. Even though each ready-made battery has a dedicated BMS that monitors the overall health of the battery pack in each ready-made battery, there is no real way of telling what the health of each cell is that makes up that battery pack. Essentially, the only way of telling what the health of each cell is in the pack is to hope that the battery BMS has the capability to tell you the health of each cell. Otherwise, the only other way is to tear the battery apart and test each individual cell in the pack. Honestly, I don't ever recall any of the channels or books that I have read say that there are ready-made batteries that can tell what the health of each individual cell is that makes up the battery pack in a ready-made battery. On the other hand, all ready-made battery packs in ready-made batteries that I have seen and/or read about do have BMS protection. I would bet that manufacturers don't want ordinary battery owners to have the ability to diagnose and replace battery cells in a battery pack. Will Prouse does indicate that this is OK and has done so himself, but I bet that a person takes on a certain amount of liability by replacing individual cells. Personally, I see not being able to monitor the cells in a ready-made battery as a problem, so I have decided to use individual 32650 cells to build battery packs and then monitor the health of each individual parallel group in those packs with a BMS that is able to do so. In my mind, if I can see that a group is underperforming and is readily accessible, then I can quickly do a visual inspection and/or test each cell in the group and isolate any problem cells. The only part that truly concerns me is the thousands of welds that I have to make to construct a pack of any size. I still get the "willys" just thinking about welding on a lithium cell.

@@westking7746 good job explaining your point

You are right, and it's a good point. Maybe I edited out that clip, It took me 3 days to edit this video and some stuff gets cut for time. I could parallel mine because they were 0.02v delta. When people ask me about paralleling I tell them to be within 0.10 volt delta to keep the amps low.

@DavidPoz I completely understand during edit LOL. I have heard you say that in other videos!

I've never tested a Pecron E2000, so I just looked up the specs on it. Looks like you can add an expansion battery (EB3000). I assume you are trying to make your own expansion battery? If that's the case, then try to match the specs of the expansion battery. It is a 25.6V battery (usually called 24V, but in LiFePO4). Sorry I can't be more help, but I haven't tried making an expansion battery for a pre-built portable power station.

I think once a year is good practice.

Higher internal resistance does NOT matter. Battery cell wih higher internal resistance will still recieve the same amount of electricity (Amp*hours) except at slightly different voltage. The real problem is uneven colombus efficiency or self-discharge. Lithium batteries are also very special in a following way: cells with poor colombus efiiciency (

Thanks for sharing a tip from the marine world

I think that would actually be a more ideal solution. Unfortunately I haven't seen solar chargers with that configuration. Perhaps some sort of external balancer could be used instead to achieve a similar effect.

Could you please explain how you were able to do this?

So this pow Mr when put on 4 12v lifepo4 will balance the batteries and that all you have to do?

I guess in a single 48v the bms will take care of the balancing? But wouldn't that be of a reduced capacity as compared to bigger batteries in series? Also why not use a bms for the series connected batteries? Total noob here 😀 I need to replace lead acid batteries 12x8 Have a 96v inverter

I use solar MPPT charge controllers. Currently I'm using a Victron one, but most MPPT controllers can be programmed. However, if you are asking about a wall charger, then I use this one: signaturesolar.com/eg4-chargeverter-battery-charger-48v-100a-5120w-output-240/120v-input?ref=4_rHcgZ9x-TiF-

I once tested some active balancers (for single cells) and found it made my pack worse. Since then, I've steered away from them. That being said, I've never tested the 12V balancers made for 4x 12V batteries in series. They might work well, but I don't think they are necessary. If all 4 of your batteries in series are the same type, same age, then they should stay balanced well over time assuming you top balance them together.

The short answer is yes, Bus bars with equal length cables are the way to go. However, we could do a little math and get into that in more details. There are a few different configurations that can work if you are trying to tidy up all the long cables, or something.

This one too: lddy.no/tczy

Lithium iron phosphate would work well though you might need another charger and BMS but they would likely take up too much room as 12v batteries. You could get individual cells but remember in the lead acid you only discharge about 50% of their power and these can provide at least 80% of their power. They also weigh about half as much. It might be difficult to find 20ah or less cells to make a pack for that scooter that would fit in it and larger cells would also be pretty expensive. Are u SURE the cells are in series and not parallel? Check ali express for cells and make sure and note their size and whether or not they come with busbars and terminal screws .You would need 20 individual cells in series and a BMS and a comparable charger though the one currently used might work as long as you use a BMS.

Sure. Alt-E sells one made for this purpose. I linked to it in the description.

@@DavidPozEnergy sorry, must have missed it. Keep up the good work!

I was wondering if there was such a device. Do you have a link to the product?

@@judo-rob5197 www.ebay.com/itm/333113199150 www.amazon.com/KRXNY-Battery-Equalizer-Batteries-Balancer/dp/B07FD1R6Q1

The first one. Top balance the cells. Then arrange them into 1p16s using one BMS rated for 16s. It's always best to build a battery to the voltage you want.

@@DavidPozEnergy Thank you!

@@DavidPozEnergy What would you recommend for a good BMS! I was looking at getting an Overkill.

I've never used Overkill brand, but they seem good. I have no reason to think it wouldn't work well. I have used the BMS's from Battery Hookup and they work well. My discount code with Battery Hookup is "DAVIDPOZ" which helps the channel through the affiliate program.

Each BMS needs it's own Bluetooth dongle. Then inside the App you will see the different serial numbers and you select which one to open. I have about 8 batteries in my garage now all with bluetooth.

@@DavidPozEnergy Thanks for the info...regards keep up the good video's

Yes, you can do that too.

@@DavidPozEnergy Thank you so much for replying. I’m new to the Solar world 🌎. I just bought 16 100 amp hour Battle Born Batteries 🔋 with the Victron inverter that battle born recommended for my 48 volt set up. I also bought 8 Solaria 400 watt solar panels. I’m excited to learn. I’m learning from you & Will Prowse of DIY Solar. You two are the best teachers in my humble opinion. I’m putting my system inside of an all aluminum cargo trailer so I can have portable power & an option of a toy hauler too. Thank You again. I’m a brand new Subscriber to your channel too. Please stay Safe & Stay Free 🍻 🇺🇸

This one: lddy.no/tczy

@@DavidPozEnergy I love alt e utube videos. This looks like what I need. Many thanks.