Help with Battery cross charging

[mtemplenc]

I just bought an older diesel pusher and I'm a little over my head on some stuff, but I'm learning... Question: Are the batteries supposed to be "cross-charging" - i.e., the coach system charges the chassis batteries when plugged in or running generator and the chassis system charges the coach batteries when running the drive motor?

Thanks in advance for your help!

Matt

[mtemplenc]

I really appreciate the responses - very helpful!

[dougrainer]

Your 2002 Newmar does Cross Charge. I also have never heard that term before. Both when driving and when parked and connected to Shore Power. You also have a small solar charger with a Dash round LED indicator for charging the chassis battery. Odds are after 16 years that solar Charger is not functioning. Doug

[time2roll]

Virtually all RVs charge the house battery when the chassis battery is charging via the alternator. Your voltmeter can verify this operation. May not be a huge charge to recover low batteries fast but still should keep them up while in transit.

Then test the opposite by shutting it down and plugging in. The house battery should be charging with a steady 13.4+ volts and then check the chassis voltage. If not you can add a combiner or discover if you have a built-in relay system that needs repair.

[Jim]

mtemplenc wrote:
I just bought an older diesel pusher and I'm a little over my head on some stuff, but I'm learning... Question: Are the batteries supposed to be "cross-charging" - i.e., the coach system charges the chassis batteries when plugged in or running generator and the chassis system charges the coach batteries when running the drive motor?

Thanks in advance for your help!

Matt

There's lots of ways to do it and older diesel pushers usually didn't make allowances for charging the chassis (starting) battery when plugged into shore power. And yet there were still many items drawing power from them. The dash radio being a good example.

The way it works on older rigs...generally...was that the alternator would send a charge to the chassis batts when the engine was running. After a minute or two to allow the starting battery to get back up to nominal voltage after a start, the BCC (Battery Control Center) would sense that and close a solenoid so that the alternator would then charge the house batteries also. So when you arrive at your destination, both sets are charged.

Then you plug into shore power, and the CONVERTER would work to supply the 12 volt house systems with enough energy to operate while keeping the house batteries charged...but generally, would not send a charge to the chasssis batts.

So most people bought an after market charging system that sent a charge to the chassis batts. Either a simple 120 volt to 12 volt Schumaker charger connected to the chassis batts, or a Trik-L-Start connected from the house batts to the chassis batts.

Some people just kluged it with jumper cables from one set to the other while deciding. Others just jumper wired something in (not recommended).

So, yes, there is some 'cross-charging' going on at certain times under the control of the BCC, other times, no. Manufacturers saved lots of money giving the least of the types of systems.

You can test all this under the various conditions with a simple digital volt meter (recommended).

[MountainAir05]

Some do , some don't. Mine does

Never heard the "cross charging before"