question

Hi @Richie Gorrod

I don't envy you. I once had 6x parallel strings of Pb's and it was a nightmare. And you have 24. What happens is that each string develops a different resistance, and they charge up at different rates. Might be ok in a UPS setup, as they have time to equalize and balance. But daily cycling (say from solar) won't let this happen.

You mention it changed when charging with a Multi. What I'd try is lowering the charge V there and give them time. Like cutting out Absorb phase and charging with only Float V. They'll still charge, but more slowly. This may not suit if you're using a genset, but it's an option to experiment with.

Might also be possible that they're starting to fail with age, and you're seeing weak cells. The Victron balancer alarms are designed to show this of course, and all you can do there is remove the offenders. That probably means getting down'n'dirty with a multimeter. Temperature will usually go higher on doubtful batts, and that can be noticed by a touch test. A temp gun would be useful if you have access to one.

Many thanks John. WB Solar.JPG

I am charging with Solar and Mutli over nite if the dont get up to charge with the Solar (The Summer was fine).

I have grid into the multi using ESS. I has been fantastic over the summer and completely off grid :-)

I think I have a bunch Batteries dragging the rest down. I think i am going to bite the bullet and dismantle the bank and test the batteries.

I am not to sure how to do this. I guess just meter their voltage.

I have done this with the top bank of 16. I have 10 sitting around 13v and 4 x around 11.8 and 2 at 10.8.

The bit i don't understand is that the 8 that are on the negative bus bar are ok and the offenders are on the positive rail (I have them sitting in 2 row of 8 with a bus bar on the negative and positive on the outer side and series links in the middle. I also have the centre terminals linked together for the balancer.)

I have victron Smart 12v 30a charger and will get them all up to float individually with that. Would be worth putting a 30a load on with them and testing their capacity.?

I would just like to add that the victron gear is amazing and has been performing great through out the summer.

Many thanks for taking the time to read this.

Rich

@Richie Gorrod

Pb batts can be strange things. Plates can fail or they might be just sulphated. I'd pull out the ones that won't hold good V overnight and set the remainder up so you can still use them.

Then test the baddies. Anything that gets hot under a charge of (say) 14.4V is probably a goner. Sulphated ones mightn't get hot, but won't accept a heavy charge. Until you leave them for weeks under charge and they recover and go on to give good long service. So it's hard to say, but after you've come through testing a few you should get a feel for it.

The man at the battery shop might test them under load and conclude they're done for, but they may not be. I think they need 'exercising', and many swear by Equalising. I don't, but then mine get a cycle down to ~80% every day. Coming off ups service, you could hope and pray that it's just lack of fitness.. :)