Insane battery system need help

hi i think you may be overstating the amp hours of the battery bank

96000 sounds way to high.

elnav may be able to chime in but if it were me the first thing i would do would be to bring the system up to full charge that will probably mean running your generator for a while to get it up fully.most likely you have been running at a low charge rate for a long time only running the generator

to top up most likely never to full charge.

if you have been running low for a long time you may have a battery sulphite problem do a search for the cure to this.my cure is low tech and probably

not the best idea for a learner but i also dont think you need to pay out the big buck for a battery desulphite gadget.

so you need to research learn and decide what is best for you

what is the amp hour rating of each cell? because this is the rating of your

whole system.(because its a series system) i could not imagine the size of a cell to provide 96000 amp hours

Dustoffer, I will be the first to admit desulfators are not a magic solution.

However I have also had sucess in some cases.

The original poster has a very unique problem. The battery bank is way too big for the available charge source. What the battery manufacturers are not telling us is there is a minimum limit as well as a maximum charge current limit. Joe’s problem is he cannot accumulate enough charge in a day to bring the battery bank up enough with the available solar panels. Consequently the bank is constantly under charged. circumstances beyond his control or even his knowledge compounted the situation.

You are right, adding one good cell into a bank of older batteries is not good. Its worse when the batteries are in parallel. With care it could sometimes be done when the cells are wired in series.

When I first had to deal with this kind of problem I always yanked the whole bank. After testing and recharging the batteries I kept the good ones for single battery use, and junked the rest. Prior to that we were lucky to get 18 months from a bank of mixed new and old. Things improved after that. Unfortunately company policy dictated I use size 8D because this was what we could buy at a resonable price from the wholesalers. These are not the best choice for deep cycling. The banks were typically made up of 3 – 6 of these 8D wired in parallel to power 2500 watt inverters in a rental fleet. We had a dozen charters and I was forever changing batteries. Now I know better and would argue the point with the boss because such a practice was not cost effective. But this happened 20 years ago and the industry has learned a lot since then.

Are you saying the average voltage is 1.1V or the specific gravity reading is 1.1?

Either case indicates way too low a reading indicating severe sulfation problems.

I have rejuvenated batteries that have been left unused for two years and showed low readings but never ones with such high capacity.

The issue with sulfation is you need to not only deliver a voltage sufficiently high but also at a charging current that brings up the plates to a usable level.

For two volt individual cells this requires a power source where you can adjust the voltage and current independently while monitoring the internal battery temperature. I speak from hard learned experience trying to salvage battery packs from telecom installations. Yes it can be done but preferably using lab grade adjustable power supplies and grid power so you can run tests continuously. Sometimes you need to be able to run the charge equalization cycle for several days at low currents. The voltage typically has to be adjusted every few hours.

you have bigger problems than was first apparent. Your original post indicated your daily use was 75 -100 amp hour. The comment that you only need to run genset every few days suggest the existing solar panels are choking on the over sized battery bank. It would be far better to have a much smaller battery bank that the solar panels can cope with. I have seen the exact same problem on sailboats where the owner spend thousands on a huge battery bank then proudly announce to eveyone that they only have to charge the bank once every two weeks. Within two years this oversized battery bank is reduced to a pile of useless lead sulfate because the lead sulfate formed in the first few hours of use is then left sitting until charging is finally done. By that time its very hard to convert back to lead oxide and sulphuric acid. Every battery maker has fine print saying recharge immediately after using. By that they do not mean tomorrow or next week they mean right now this same day. They also know most people ignore the advice so they will soon be back buying new battery replacements.

For off-grid applications a nickel iron ( NiFe) battery would make more sense but most people are put off by the higher initial unit cost. Brandon who owns a company providing such batteries can maybe chime in here with more data. He did post something about six months ago.

My own calculations suggest that by making best use of NiFe characteristics you will get better and more reliable service and the price premium is nowhere near as high over a 10 year period compared to lead acid. Critics will argue that NiFe is less efficient but ignore that once purchased solar cells provide power at virtually zero cost. NiFe became unpopular when we still used generators to charge off-grid banks so cost of fuel was a significant factor.