question

Even though your batteries are not new, installing a battery balancer may prolong their life. The longer they are in use, the wider an inballance between them may get. The issue I can see is that the balancer you referenced is designed for 2 batteries in series and not 4. If you used 2 of them between 2 series sets, you would still not be balancing between the sets. I am not very familiar with the victron balancers and wether they can talk to each other in order to properly balance the entire series string. If that is not a feature that they are capable of, then you need to find a balancer that is designed for a 4s application. You should be able to find something on the fleabay or the jungle website.

Hi @AKO

The need for a balancer is somewhat subjective. I use 8x 6V batts as 48V, so I'd need 3x balancers. But I chose to go with a Smartshunt and use the midpoint monitoring. If I found deviation enough to require balancing then I'd know I had a serious issue anyway. And the balancers mightn't be so useful with a dud cell anyway. This is what I see on a normal day..

A little imbalance under charge, but all settles down. At worst ~0.1V, and these are >5yo fla's. From previous posts I see you have all the options to have VRM, and I suggest you could consider doing the same. All the alarms etc available just to monitor rather than actively balance. And the day I see the alarm at least one cell will be a goner. Balancers can't fix that.