Hi 

There's so many videos demonstrating how to balance your battery when introducing a new unit to your system it kinda makes you believe that you have to do it in order for your system to work , and I did.

However this time arround I decided not to balance my batteries when I added another 2 units to my system yesterday afternoon just to see what happens.Thinking I can always balance it later if need be.

When I checked this morning (about 18hours later) the batteies are all within 1%. 

So ,do you really need to balance your new battery to your system or do you trust the BMS in the battery to do what its suppose to?

 

Edited March 25, 20224 yr by Piper

I also did the same and came to the conclusion that its not necessary at least not with Pylontech batteries.

5 hours ago, Piper said:

So ,do you really need to balance your new battery to your system or do you trust the BMS in the battery to do what its suppose to?

The BMS will do absolutely nothing except inform you. The packs will equalize themselves by the means of common terminal voltage. The best you can do is to make sure that the new pack has almost the same SOC (same terminal voltage) as the existing ones before you connect it.

I added new packs in 2 steps with no problem. However some differences in internal resistance (Ri) remain which results in differences in charging and discharging currents. There is nothing one can do about it. But when reaching 100% SOC they equalize.