Battery charging

[Justin B.]

Question for the brain trust. I am heading up to our cabin next week to wire the rest of my solar panels together (6 100 W Renogy) and re-wire my battery bank ( 6 100 Ah AGM in parallel) with two buss bars and equal length cables from buss bar to each battery terminal. I have bought an IOTA DLS 45 charger to help top off the battery bank when it's cloudy and to top it off before we head back home. I am also wiring in a DROK Battery monitor/tester module - https://smile.amazon.com/gp/product/B07759SLYP.

I don't feel I've been getting a very good charge on them so I was wondering if I should initially charge each battery with my 12 amp smart charger or if it would be OK to just hook everything to the buss bar and turn the IOTA charger loose on them?

Thanks,

Justin B.

[PNjunction]

YES - definitely charge each on up individually first with the Iota, THEN buss them all together and treat as a bank.

This is one of the reasons why one shouldn't parallel so many batteries together - it is *much* easier for a cell or cells to become undercharged, or have other problems, and hide that fact pretty easily because there are so many of them, leading to poor performance. The more cells you have, the easier it is for the problem cells to hide.

Next time strive to use larger amperage batteries to cut down on the cell count.

But for now, by all means charge each individually before wiring up as a bank. Consider doing that as a preventative maintenance measure from time to time, especially with AGM's, where you can't monitor cell health easily.

This is the first mistake many make when putting the bank together initially, so I'm glad you asked!

[Sunking]

I don't feel I've been getting a very good charge on them so I was wondering if I should initially charge each battery with my 12 amp smart charger or if it would be OK to just hook everything to the buss bar and turn the IOTA charger loose on them?.

First lesson is never ever parallel batterries. There is no need to do so and just causes all kinds of problems.

However this is a part time system, and you can get away with parallel batteries because you have many days or even weeks before being cycled, thus have time to equalize fully. So just hook up the IOTA and forgo the buss work. Now next year when the batteries need replaced is if you need 600 AH batteries, buy 600 AH batteries. Not 6 x 100 AH batteries wired in parallel.

[Justin B.]

Well, buss bars were installed and it actually helped me clean up my wiring somewhat. My 24V inverter is on the way so next trip (in a couple of weeks) I will re-wire in series parallel and add two more 100 watt panels which I already have. This will have to do until I save up a few more SS checks! When the batteries give up the ghost I'll likely replace them with a string of 6V "wet" batteries.

When we go up to the cabin we usually spend at least a week as it's about a 300 mile drive. The last trip we stayed 11 days until it got so hot we couldn't deal with it anymore. I am seriously thinking about taking up an air conditioner this next trip and working the generator to death!