Balancer

A very important thing to watch is the voltage of each pack. All packs should have the same voltage. The balancer takes care of this when an unbalance pops up. When one pack is a few milivolt higher, it transfers the energy to the pack with the lowest energy. I want to mention again the importance of making well balanced packs. When made properly, the balancer will sit idle most of the time. Next to the balancer I installed a little switch. When the packs are balanced, I can switch off the unit. The balance wires are located in the white cable trays. A BMS I hear you asking......there's no BMS. I will explain why I don't use a proper hardware BMS.

Around the pack I mounted the cable trays with a few screws. The trays only house the balance wires. All wires have the same length.

Drilled a large hole to guide the wires to the bottem of shelf. The balancer is installed on the other side.

The balancer can balance up to 24 batteries. The hardware is designed for Li-ion and lifepo4.

The balancer comes with 2 leads. In this setup I only need 14 wires. You have to connect pin24 with the positive side of the pack (48v)

The balancer has a bluetooth module. The install is straightfoward and went very smoothly. You can see the voltage of the pack and all cells. There's room for improvement with some translations in the app, but it's pretty clear what the meaning is for each word.

You can activate the balancing function by sliding the button to right. The function is disabled most of the time. It's now off for a few months and packs stay all within 0.02V.

The function of a BMS in large packs is to protect your packs from under voltage, over voltage and to cutt-off charge when it's freezing. Overcharge is not possible, because it's limited in the software from the PCM60X, it's set to save voltage of 4.02V/pack, so there is some margin. Undervoltage is protected by the inverter. When voltage of the pack is to low, the inverter will shut off. In my case, a manual restart is needed. So I bought a 100$ balancer (which sits idle most of the time) and kept 900$ on my bank account.

I recommend a BMS when using smaller systems with a few batteries in series and a few ones in parallell. This will protect your pack from over and under voltage. Don't think that over discharge wont happen to you. It will and you will regret you didn't had that board installed. With smaller packs, making well balanced packs becomes even more important. Don't count on the balancing function these boards offer. It's so called top balancing. Balancing kicks in when cell reaches 4.2V and balancing current is only 20ma.