Originally Posted by Pete7
Perhaps one duff cell in one of the batteries, which because they are now all wired together .................
Yes, Pete, you got it in one. They are not
all wired together, because the interconnect switch is off when I'm on shore power
. But never mind.
As it turns out -- I couldn't figure it out because I was assuming that all the batteries were new. In fact I was cheated by the brokerage who were supposed to replace every battery on the boat (it's even in the contract). They chose four out of the old batteries which seemed to more or less work, and left those as the house bank. They all looked new since they were in protected battery boxes, but they were not. There were two dead cells in two of the batteries. The charger
falsely sensed that the batteries were down and pumped in current to bring them back up. Since there is no temperature sensor, the charger
couldn't tell that it was just burning up the batteries. Problem located.
I installed four new batteries to the house bank and voila everything works fine. I just got back from a three-day cruise
with no shore power
anywhere. Without activating the interconnect switch, the new house bank of 4x 110Ah 12v batteries wired to provide 220Ah at 24v were quite sufficient for 12 to 15 hours between charging
(admittedly we were not using much cabin lighting
because it was so light out), but we had instruments working (for anchor alarm
purposes), a 25 watt anchor
light burning, stereo working, and refrigeration
going full blast in the heat.
I also got a note back from Driftgate saying that categorically, positively, there will be no harm to the splitter from leaving the banks interconnected while charging
and no feedback or other problems.
The Newmar battery charger manual also says categorically, positively, that there is no harm in having the charger on while the engine
is running and charging through the alternator
So it looks like problem solved
(other than the coming show-down with the cheating boat brokers). I don't regret the interconnection switch, because that will let me double power capacity if I need it for some reason.
Only thing missing now from my setup is the Victron charger-inverter which will allow me to (a) charge faster from the generator
, (b) use AC power for short periods without cranking the genset; and (c) will prevent my flipping the isolation transformer breaker all the time, by strictly limiting AC power consumed, supplementing it with inverter
power when necessary.
Oh, and figuring out how to make the battery monitor
work. But as long as the interconnection switch is not used, the monitor
works as normal, and I'm finding it to be extremely useful.