Off Grid Home Forums Technical Discussion Insane battery system need help Re: Insane battery system need help


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.