House battery charging issues

[Timdog]

I was boondocking last week in 2021 Seneca and had some issues with charging house batterys from generator. Sometimes it would charge up to 14.2 volts then the next time it would only go up to 13.4 causing generator to run a long time since i have the ags set to 13.6 shut off.Cleaned all connections on batterys.load tested batterys when i got home and they seem good.Ground by generator is been cleaned. Could I have a bad B.I.M.?

[Timdog]

Also when the generator would shut off at 13.6 volts the firefly screen would show the voltage drop to around 12.9 right away and then I could live on the batterys for about 3 hours before generator would need to start again at 12.2 .

[JimD]

The converter will pick the voltage required for a particular battery condition. When in the 14 volt range it is considered a "boost" condition. Not sure how long it stays there.

If by chance you have an Inteli-power converter, you can buy a little gadget that allows you to override your current charge level. I bought one but haven't used it to change anything.

[Robbbyr]

In your scenario of charging the house batteries from the generator your BIM does not come into play. The converter (part of your power center) takes 120-volts AC from the genny, "converts" it to DC, and then there is a large wire that takes it from the converter forward to your battery area where it passes through a breaker to the house batteries.

The BIM is a "bridge" between your house and chassis batteries, If the BIM is malfunctioning you might see reduced or no charging of your CHASSIS batteries when plugged in or running generator; OR when driving you have reduced or no charging of your HOUSE batteries.

[Robbbyr]

Does your rig have these electrical devices in the compartment just to the rear of the batteries? Might have to remove a cover to see the components if you do.

If you have it, remove cover and check all the connections. A couple of folks with similar rigs have found loose connections causing them trouble.

[Timdog]

I think it might be the B.i.m. when I'm plugged in or gunny the house charges but it seems the chassis is not. The chassis is always around 12.7 volts.

[Robbbyr]

Originally Posted by Timdog

I think it might be the B.i.m. when I'm plugged in or gunny the house charges but it seems the chassis is not. The chassis is always around 12.7 volts.

12.7 volts is fully charged for the traditional lead-acid starting batteries. The BIM will cutoff charging when it senses those batteries are charged.

Here's a link to BIM troubleshooting that might help, the picture of the BIM is the old style but the operation is the same.

http://precisioncircuitsinc.com/wp-c...e-Shooting.pdf

[Timdog]

Thanks Rob that clears up a few things I've been wondering about.