Batteries: Factors that influence life


Hello, Our SM#269 is 5 years old. We live on board 9 months per year, these last 4 months at anchor. We have a bank of 8 Trojan SCS 200 batteries that are 1 year old. We have a Link 10 battery monitor exactly like the original monitor that I destroyed with a short-circuit while installing these "new" batteries. We have two 50-amp Mastervolt battery chargers, 3 yrs. old. We have always run the diesel generator twice daily, depending on the "percent used" and the negative "amp hours". We do use a great deal of DC current for a sailboat, but that is the way the boat is designed.
In the last few month, we have been accumulating negative ampere-hours. We charge with the generator twice daily, and it starts with input 100-104 amps at 26.5 volts. We stop charging when it gets to 20-25 amps and 28.4 volts. But each day the amount of amp-hours remaining increases a little, and the amount of "time remaining on the batteries" decreases a little. Eventually I just reset the monitor to 0 amp-hours, which resets the time remaining (per cent). The Link-10 manual says that to accumulate negative amp-hours, "the charge parameters are wrong" and should be reset. This includes the 460 amp-hours and a Peukert equation.
The batteries seem to hold their charge well, as we've always had to run the generator twice daily in the tropics.

1. Is my method of charging, stopping at 20-25 amp input, correct?

2. Is there anything that I can do to make the monitor more accurate?

Thank you very much.
Bill Atz
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