So I finally got around to checking water levels...

RandomJoe Solar Expert Posts: 472 ✭✭✭
I was getting worried - it's been at least six months since I checked the water levels in my batteries (six T-105s wired for 12V) and I figured I was headed for trouble. Just couldn't seem to find the time / desire to get out and check them. Wasn't sure what I'd find today...

So what does this mean? I added almost NO water! (Total across all 18 cells, less than 1/4 gallon.) I found a couple cells here and there that were a bit lower than the others, but nothing significant. I have a squeeze-bulb "baster" to add the water with (thin tube though, not a fat one like a regular turkey baster) and even the very lowest didn't take a full squeeze bulb. Many were still clinging to the end of the "max fill" indicator.

From what I've heard / learned here, this should indicate undercharging, right? But everything seems to be good. I'm using the voltages recommended by Trojan, they are being reset up/down by the CC based on temperature, the system hits absorb every (sunny) day and almost always drops out to float before the end of the afternoon. Not a huge load on the bank, I only take it down about 10-12% per day.

Should I worry? Adjust something? Be happy?... :p

Maybe this is a side effect of low charge rates? I only have 540W in panels right now, usually hits 30A or so which is 5%. Once everything arrives - and I get around to installing it all - I'll be doubling that - although I'm also adding two more batteries to get me to 880AH. (Wanted to get those last two so I had 8 roughly-equal-age batteries should I eventually decide to go 48V.)

I'll add that I don't regularly equalize. Think I've done it all of twice, actually. I'm going to (again - FINALLY) check SG soon as well, figured I'd let the water I just added mix in and - since the bank is currently charged - maybe even do an equalize this afternoon. (I have to turn things off to do it - many items I run directly off the bank aren't happy with 15+V! )


  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: So I finally got around to checking water levels...

    You should check the SG before you add water - only add water to fully-charged batteries (unless needed to cover plates).
    If the SG is good and water usage is low you are in 'happy battery land'. There's a number of factors that figure into battery water usage, most importantly the maximum charge Voltage (Absorb) but also the time held there; higher Voltage bubbles more, the longer it bubble the more water is used. A '12 Volt' system generally will have Absorb Voltage set around 14.2 - 14.4, and the time is variable. I like the MX 60's method of adding up how long it takes to reach Absorb and then using that as the length of time to Absorb. I have mine set to count up to the maximum 4 hours if necessary.
    Only equalize if here's a difference of more than 0.025 per cell somewhere in the bank. Then only do it for an hour, recheck, and re-equalize if needed. EQ Voltage for a '12 Volt' system would be 15 - 15.5.

    Without checking the SG, you don't know what state the batteries are in. It's a balancing act to keep the SG high and the water usage low.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: So I finally got around to checking water levels...

    i would not worry that you didn't lose much electrolyte. a 5% rate will not boil the electrolyte as vigorously as the higher rates of charges will. do keep a better eye on them regardless of your charge rates.