Two batteries, $275; New Charger $400, maybe it's the isolator

Timvail said:
On the topic of charging could someone confirm my thoughts on the following. Have just purchased a 1990 350 with a converter/charger on board. The manual says the charger puts out 35 amps for charging and the converter 20 amps for operating all 12 volt acces. Am I correct that when the converter/charger is operating all 12 volt acces are being supplied by the converter and not the battery bank? And the charger is charging the batteries with no draw down from the 12 volt acces.
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One is the same - the converter can both charge and operate the boat's systems up to 35 amps. If, for example the boat's systems demand 50 amps then both the battery and converter/charger contribute until the battery is depleted. If the boat's systems are demanding 25 amps and the battery is demanding another 30 amps in bulk charging then the converter charger will only provide bulk charging at 10 amps.
 
ttmott said:
One is the same - the converter can both charge and operate the boat's systems up to 35 amps. If, for example the boat's systems demand 50 amps then both the battery and converter/charger contribute until the battery is depleted. If the boat's systems are demanding 25 amps and the battery is demanding another 30 amps in bulk charging then the converter charger will only provide bulk charging at 10 amps.
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So if I understand correctly, running the 8kw genny on the hook would provide me with infinite power then .
 
I just went through a similar problem on my 400SB.

Replaced all batteries. Every time I took the boat out to anchorage, when I went to restart, starboard ignition was dead, had to do an emergency start and put something under the emergency switch to keep it engaged, or the engine would quit. Back at the dock I checked voltage at the STRBD ignition switch and had 12+volts, but when I engaged the switch volts dropped to zero.

Next day in the dock, everything back to normal.

I took everything in my system apart Sunday. First thing I noticed, when I removed the starboard batteries from the system, I still had voltage showing on the electrical panel, and my radio was still playing (cabin systems, starboard).

I checked all cables, using multi meter I found no resistance so they were good. But strangely, when I checked continuity between port and starboard battery terminals I got a short.

I literally disconnected every cable and checked each one individually up to the emergency solenoid. All cables good.

I found the isolator was flaky. I also found some corrosion on the inside of the starboard battery terminal.

So in conclusion, this is what was happening: the corrosion inside the strbd cable connector was reducing starting amps. The backfeed through the isolator to the strbd pos terminal was providing 12 volts, but few amps. Thus why the strbd ignition was dying.

Solution? Cleaned ALL battery connections religiously. Removed battery isolator from system, so now my strbd and port systems are indeed separate, and can be joined by emergency start solenoid.
 
Timvail said:
So if I understand correctly, running the 8kw genny on the hook would provide me with infinite power then .
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12V? No - Generator fuel aside you have "infinite" up to around the maximum capability of the charger/converter; in excess of that the batteries supplement until they are depleted then you are back to what the charger / converter can provide.
 
ttmott said:
Nope - there are circuit breakers behind the main 12V circuit breaker panel on the Port side of the cockpit of the boat. If the OP simply connected the existing wires to the new charger those wires run directly to three 50 amp circuit breakers (engine, engine, generator) then are routed to the battery side of the disconnect switches. Unscrew and tilt the circuit breaker panel downward and you will see the breakers... This is a pic from my old 400DA.
View attachment 91554View attachment 91555
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I did this same upgrade on my 400 last summer. Did a direct replacement using the same wiring. I accidentally tripped one of those breakers @ttmott is describing. Had to track that down to get everything to work.
 
ttmott said:
One is the same - the converter can both charge and operate the boat's systems up to 35 amps. If, for example the boat's systems demand 50 amps then both the battery and converter/charger contribute until the battery is depleted. If the boat's systems are demanding 25 amps and the battery is demanding another 30 amps in bulk charging then the converter charger will only provide bulk charging at 10 amps.
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If both battery banks are fully discharged does inverter/ charger provide 12v power to operate systems such as engine hatch?
 
Well my problem turned out to be different. Went back to the boat after work yesterday to start tracing. Turns out these switches can go bad. The center one is my stbd bank. I have no continuity between the 2 lugs while in the on position. Everything is tight and the connections look good to me, so I went ahead and ordered a new one this morning. Guest 2304 extra-duty in case anyone is ever looking. Thanks, and good luck tracking down your drain issue.
20200915_175333.jpg
 
Boca_Vincent said:
Well my problem turned out to be different. Went back to the boat after work yesterday to start tracing. Turns out these switches can go bad. The center one is my stbd bank. I have no continuity between the 2 lugs while in the on position. Everything is tight and the connections look good to me, so I went ahead and ordered a new one this morning. Guest 2304 extra-duty in case anyone is ever looking. Thanks, and good luck tracking down your drain issue. View attachment 92287
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If you want, you can take that switch out, and disassemble it. They are really simple designs, and you can take a piece of sandpaper and clean up the contacts inside of the switch.

The contacts will corrode over time and cause the problem.

Also, there is quite a bit of corrosion on those terminal ends. Clean them as well.
 
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