Generator Battery not charging

[Nater Potater]

The first link posted is only a 100 amp unit. A proper "starting" battery test involves bringing the battery to full charge, letting it sit for at least an hour or two and then load testing with a tester that will pull 200 amps for 10 seconds. The battery should not drop below 10 volts and bounce back fairly quickly depending on cranking amp rating.

As to the second link. You really need to spend a lot more than that to get a good electronic digital battery tester.
Note: lead acid, agm, gell, and others all have different charge and testing equipment, specs. and requirements.

I won't argue that it's best to pull a higher load than 100 amps, but, even so, that one will weed out a bad battery fairly quickly. I suggested it as a usable tester that wasn't too expensive. However, if so inclined, one could go with their carbon pile load tester. Good for 500 amps. Protocol says to pull 1/2 of the rated CCA for 15 seconds without dropping below 9.6 volts. Probably what I'll do in the near future, as my batch-o-batteries continues to grow. Two in the RV, two in the truck, three in the boat...

 

[ttmott]

You guys are making too much out of this. Put a known good battery like from the engine there and if the generator starts it's a bad battery end of story. If the generator's alternator is charging, then if the charger is charging go buy a new battery... Clean up the area, install the battery, and go have a good time.

 

[Mig22]

Previously had a Westerbeke on a 340, battery would not charge and kept losing its charge over the season. Took a while but tracked it down to a failed Bridge Rectifier that’s a component of the generator charging system.

 

[Bartlett Bob]

Ok, as always when I get on this site with an issue, I learn something. I agree the load test is the only way to really understand weather a bwattery is good or bad.

What I didn't know is that the E Start switch would also connect the generator. Bill Collector, did I understand that correctly. This is good to know!

 

[km1125]

Ok, as always when I get on this site with an issue, I learn something. I agree the load test is the only way to really understand weather a bwattery is good or bad.

What I didn't know is that the E Start switch would also connect the generator. Bill Collector, did I understand that correctly. This is good to know!

It does not, if that schematic posted earlier was accurate to the situation. There is no connection there between the emergency start solenoid and the generator battery/starter system.

 

[Bartlett Bob]

On the DB 400 the E Start switch for inconnecting the batteries to starts the Cats is on the bridge and the start button for the genset is in the electrical panel in the salon so unless your arms are really really long there is no way to push both at the same time. I agree the E Start does not connect the generator battery to the engine batteries. I did get the jumper cables and connect the genset batt to one of the CAT batts, fired right up as I expected, bought new battery for the generator, no more issues, voltmeter indicates battery maintainer is charging the generator battery and I now know that a thermal breakers for the charger is hidden behing the battery. Thanks to everyone for the advice.