Battery Bafflement

[gksmith]

Coach battery bad ground is beginning to make sense to me, too. This explains why there is absolutely no activation of the genset starter solenoid when trying to start off of the coach batteries. Plus, it explains why the genset shuts down when the ACR (battery separator) switches from automatic to separated, with the genset being then only connected to the coach battery system. Then the genset would not have a good 12 volt circuit to keep it running. I am surprised, though, that it needs 12 volts to keep running, as does it not have a magneto for its own electricity? For the first minute or so, it runs fine, then dies, producing 120 volts before dying. The strange performance was noticed when I had the new batteries installed, but I observed the installation and am confident it was done correctly. (Pardon all of the verbiage, but writing this out helps me to think this out!)

So, how do I verify the possibility of a bad chassis ground? Or do I just trace the ground cable on the coach batteries back to where it is attached to the chassis? Is it likely to have more than one ground cable? I guess I need to dig more deeply into the electrical corner of the van and see what I find. I will wait until the rain stops, though!

As alway, thanks for all of the input.

[booster]

Originally Posted by gksmith

Coach battery bad ground is beginning to make sense to me, too. This explains why there is absolutely no activation of the genset starter solenoid when trying to start off of the coach batteries. Plus, it explains why the genset shuts down when the ACR (battery separator) switches from automatic to separated, with the genset being then only connected to the coach battery system. Then the genset would not have a good 12 volt circuit to keep it running. I am surprised, though, that it needs 12 volts to keep running, as does it not have a magneto for its own electricity? For the first minute or so, it runs fine, then dies, producing 120 volts before dying. The strange performance was noticed when I had the new batteries installed, but I observed the installation and am confident it was done correctly. (Pardon all of the verbiage, but writing this out helps me to think this out!)

So, how do I verify the possibility of a bad chassis ground? Or do I just trace the ground cable on the coach batteries back to where it is attached to the chassis? Is it likely to have more than one ground cable? I guess I need to dig more deeply into the electrical corner of the van and see what I find. I will wait until the rain stops, though!

As alway, thanks for all of the input.

You can do the ground check with meter most of the time. You can just check from the battery post, not terminal, to a good chassis and measure the ohms of resistance. The other way is with a fairly large 12v load running and the starting battery out of the circuit measure the voltage from the negative battery post to a good ground. You should nearly no voltage there.

[hbn7hj]

Originally Posted by gksmith

I am surprised, though, that it needs 12 volts to keep running, as does it not have a magneto for its own electricity?

Nope. The generator draws 1-2 amps from the battery while running. Just one piece of info a shunt based battery monitor will tell you. I noticed that when running the generator to charge the lithium battery with the converter off that charges the lead acid battery there was a drain on the lead acid battery.

Usually when the generator is running the converter is on and we don’t see it.

I’m a bit embarrassed we didn’t pick this up earlier. It is so obvious.

[Dlemunyan]

I am having a similar issue, though I’m in a dodge 2001 pleasure way. I’m currently plugged in at an rv park and constantly needing to run the engine as the batteries in the back are losing their charge. This is happening in just a few hours with almost nothing plugged in. I have contacted people who know more than me and we believe that the convertor is bad. I’m looking at potentially trying to replace myself. Any thoughts?

[engnrsrule]

Dlmunyon: If the batteries are being charged by the engine then their connection and ground is likely ok. If not being charged by the converter then it is quite possibly a bad converter (charger). The batteries may also be shot if they are not holding charge.

You should be able to change your converter yourself. Select a model with same power rating. If you upsize power you may have to change cabling. I replaced ours with this one.

https://www.amazon.com/dp/B000GASX9O/

It comes with a pendant (remote) that shows status of charge and allows you to override automatic levels if you want to. The cord for the pendant is short and I had to splice it to a longer RJ9 wire to locate it where I wanted it.

Any RV or car parts place will test your batteries. I changed from a single 12v at 90 ampere hours to two 6v golf cart batteries in series for 235 Ah. That made a marked improvement and I have gone 8 days on batteries with significantly power remaining. If you change battery type (like going from Lead Acid to lithium) be mindful that different chargers are required.

Lastly consider a battery monitoring system like the Victron. These require a shunt on the negative path to the coach battery and provide very accurate readings on your battery. I have one with Bluetooth to my phone which is a big plus. Installing the shunt will require some new cabling to negative side of battery. You can get appropriate length battery cables with terminals from amazon. The cabling goes from battery negative to one side of shunt, and ground, charging and service connections all move from the negative post to other side of shunt.