I left my boat for two weeks, and one of the bilge
pumps got into a feedback loop situation endlessly pumping and repumping a small amount of water
which kept flowing back into the bilge
from the large diameter pipe the bilge pump
The batteries were completely dead. Eight 110 amp-hour Varta leisure batteries arranged as two interconnected 24 volt banks (220 amp hours * 24v each).
The batteries were fairly new -- four of them 18 months old, and four of them less than a year old.
The boat is not in a marina, so I've got no shore power
for a continuous long charge to bring the batteries back up. I did manage to get in two overnight charges when I happened to be in a port with shore power
. And I have done a couple of equalization
charges with my Victron charger
But although I am able to get the voltage up, and the battery charger
switches into float mode, I have not been able to get the specific gravity of the batteries up to fully charged level, and the batteries have very little capacity. And a couple of cells in a couple of batteries show lower specific gravity than the others -- possibly dead cells.
What to do? My Victron charger has a way to force absorption charging
for a set period of time -- maybe I need to do that a few times in order to get the specific gravity up?
Will a battery
not survive even one such incident? I thought you could bring them back to life after even a few incidents like this -- didn't think you could kill the whole bank in one shot.
Why don't we have switches in our systems which shut off the batteries when they are, say 80% discharged, in order to prevent this kind of damage? Our cell phones shut off automatically before the batteries get down that low. Why not our boats?