So as in the previous post, I found the EVE 280Ah cells. People on https://diysolarforum.com/ have had very good experience with these, and also recommended some sellers on Alibaba to source these from.
So I went ahead and bought 4 cells for my build. The seller was able to provide me with DDP shipping (Delivery Duty Payed), so including all taxes and so on. Recommended by users of the forum was to use either boat or train as transport, since that would be much cheaper than shipping by air. Yes, it will be slower (Generally people mention 30-45 days) but that was fine for me.
In order to protect the batteries and monitor them, you need a BMS (Battery Management System). They are available in a whole bunch of options. Most of the DIY people tend to use Daly, Chargery, ANTBMS, or JBD. Some of them are sold under various other brand names, but they are the same.
I opted for the LTT Power (JBD) branded 4S LiFePO4 BMS :https://www.lithiumbatterypcb.com/product/4s-or-3s-12v-li-ion-or-lifepo4-battery-smart-bms-with-bluetooth-function-uart-and-rs485-communication-with-60a-to-120a-constant-current/
This BMS is fully adjustable, does have bluetooth and is affordable. It also can handle up to 120A, so a smaller inverter can be connected to the BMS. (In theory: any inverter <1400W, but I tent to not use a BMS above 50-60% of its rated current). So for a <800W inverter: No problem. Since my inverter is 1500W, I’ll use my inverter directly connected, only controlled by the BMS (more on that later)
– Balances the cells so they remain equally in charge
– Protecs the cells for overcharge, and overdischarge
The Daly BMS is a good option, and is easier to install (1 complete unit, unlike a more PCB-like BMS as the one I have), but its very limited. With the LTT BMS I can adjust various settings more specific. Also, it has low-temp protection, where the Daly doesn’t have it.
(LiFePO4 cells can’t be charged below 0°C / 32F)
There is a new Daly Smart BMS on the market, but there aren’t many reviews yet, and its more expensive, so I did go for the LTT BMS.
3 Replies to “DIY LiFePO4 battery – Acquiring cells and hardware”
Hi, interesting subject. The some what more expensive BMSs usually have an overvoltage and undervoltage limit that can be set per cell. Now I’m looking for a BMS where this can be set and that the BMS also stops charging or discharging when the cell voltage of one cell reaches the set value and not stops by eg 4* the set voltage with a 4S. Have you tested with your built battery whether this works? Thanks for your reaction.
Yes. I’m using the JBD BMS, also sold as eg the Overkill solar BMS. It allows fully customizable settings. As any decent BMS should do it will stop charging (or discharging) when a single cell hits its lower or upper limit (I set it to 2.5V / 3.65V for a single LFP cell)
Thx. Which JBD BMS do you have?