One set Batteries NOT charging

[Paul Lagasse]

Here is the scenario — I have a 1998 Tiara 35 Open powered with 2 Cummins 6BTA engines (remanufactured by Cummins with 250 hours on each). I have 2 Optima batteries for start/running and 3 house batteries. The Balmar controllers are new (ARS-5) as are the two alternators (7102NKBW – Tuff Stuff) high amp output (140 amp).

The house side(starboard) does a great job of charging the 3 house batteries and using my new voltmeter the Balmar Smartgauge Monitor typically is charging the house batteries at 13.45v or in that range from idle all the way to full RPM. The VDO mechanical gauge confirms that reading. The problem is the engine starter side(port). It will initially begin to charge at just a tad over 12V but then drops like rock to < 9V as measured by both the VDO gauge and the Monitor (position 2). Sometimes moving the RPM up will initiate another brief > 12V charging but it then drops back within minutes. I have checked all the wiring more than twice and am bamboozled at this point. I even replace the alternator once just in case the one I got was bad. Why won’t the same alternator/regulator combination on one side work identically to the other? Why won’t the port side batteries get charged? I am about to to to a alternator that requires NO external regulation at this point but thought I’d get some expert opinions….

Thanks

Topic

[Tony Athens]

DCV Issues

For me to help ( or anyone to do this realistically) from afar, I need DC power distribution diagram showing how the engines are wired to the starting batteries and exactly how the house is connected…………

You do have a common NEG ground (like 1/0 or 2/0 ga cable ) between all batteries, and the engines correct?

Also, and important– You need to be sure you have the grid / air heater circuit disconnected during any troubling shooting..That circuit alone can play havoc with the batteries and DCV readings

Tony

[Author]

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