We have been having some battery
issues for about a week. The house bank didn't seem to be holding a charge well and could only run the Lectra San (which draws about 30 amps for a couple minutes) when fully charged.
This morning we started charging
using an Iota
75 amp charger
and within minutes smelled an acrid smell and saw a small amount of smoke coming from the main house bank ground wire which had become hot enough to melt the rubber/plastic coating. The charger
was putting out about 65 amps at the time.
The ground wire is about three feet long and runs form the battery
negative post to a shunt for the battery monitor
. This piece of wire was a 6 gauge wire at least 20 years old. The ground wire from the other side of the shunt to the engine
block is a 1/0 gauge wire.
I replaced the hot 3 foot piece of 6 guage ground wire with a similar length 1/0 gauge ground wire and we started charging
again, this time using the engine alternator
which only puts out about 35 amps. Quite frankly, I was a bit spooked by the hot wire and concerned the the Iota
was putting out too much amps for this set of batteries.
We have been charging now for about 3 hours starting at 35 amps decreasing slowly to 13 amps with no problem. No hot ground wire. No acrid battery smell. Batteries are warm, but not hot. They are in the engine compartment so some warmth is normal. Batteries were filled with water
a week ago. None of the cells were unusually low.
The battery bank is a 440 hour bank made up of 4 Trojan T-105 6 volt golf cart batteries wired in series/parallell to make up a 12 volt bank. Two of them are about 4 years old and the other two are about 2 years old. One set of two have cases that bulge somewhat. We have been using this arrangement for two years and living aboard
for the past 6 months, mostly on the hook. We've been charging the battery bank about twice a week with the Iota charger running off either a Honka 2kw generator
or on shore power
. Added the Lectra San about 4 months ago and it was working fine until a few days ago.
Sorry for the long post, but my concern is that even though the problem seems to be fixed, maybe there is some other issue besides the too small ground wire.
Is it possible that the ground wire has been undersized for the last couple years and did what it could for as long as it could, then finally just gave up?
Or was the hot ground wire just a symptom and I should be looking for something else that caused the problem?
All thoughts are welcome.