Do battery balancers work?

Re: Do battery balancers work?

tonygcan wrote: »

I have a friend near my farm who recently added PV panels and 8 more batteries to his existing 2 year old batteries. Same brand and Ah ratings.

His installer/integrator installed "battery balancers" to every string of his batteries in order to balance out the batteries against each other.

I haven't seen ithe add-ons yet but I was wondering if anyone has had the experience of installing battery balancers when they add batteries. He now has 5 strings of 200 Ah, 48 volts of batteries.

Folks that homebrew electric vehicles frequently use battery balancers. They can add years to your pack life and improve performance of the batteries as they get older.

Thre basic types of balancers, one type works by keeping the highest charged batteries from over charging (shunt types, etc.) another type works by boosting the low batteries, the third does both.
Charge shuttle or bucket brigade types do both at the same time, take some charge from the higher voltage battery in a pair and send it to the lowest. Since every battery has two buddies (one above and one below it in the string) they can send a charge from one end of your pack to the other.

Shunt types are simple and usually fairly cheap, can be as simple as a pair of diodes and a lamp, or up to $20-$30 for each battery.

I'm building a "Lee Hart" balancer for the next pack I put in my EV. This is a central balancer that works by propping up the low batteries. Normally these use a DC-DC converter that runs on pack voltage for the input and the output is connected to whichever battery has the lowest voltage. I'm thinking that I'll use a PV panel instead of the DC-DC that way I'll get a little extra charge in while I'm at work as well as keeping the pack in balance.