I am the second owner of a 1993 E-250. My employer was the first owner and the van had a 12V pump mounted in the rear- the pump and wiring were removed 15 years ago.



The van has a factory installed dual battery system.




It is time for a new battery- but should I buy one or two? I normally would think two- But, the auxiliary battery doesn't appear to power anything, or receive a charge... The positive wire runs to a relay under the main battery.
When I check voltage at the battery, it doesn't change when the engine is off or running. It isn't in parallel with the main battery... I unhooked it and everything still works..
I only use the van occasionally. So, I may just replace the main battery and cap the positive wire than runs to the auxiliary battery.
Any advice or a better explanation of this dual battery system would be appreciated.

 

If its not a diesel and you're not using the auxilary battery, you might as well save some money and skip the other battery.

 

It is not a diesel. Thanks for confirming my thinking. I' can save money and "dead" weight.

 

My van is a 2007 with the dual battery set up. I capped off the auxiliary battery cables and the only side effect was that my trailer lights didn't work when I was towing. More specifically – the running lights on the trailer did not work. The brake lights and turn signals work just fine.

 

That makes some sense to me. That would allow you to run an auxiliary unit without pulling down the main battery. Ill check mine. But, since my trailer wiring is aftermarket, I might be okay. Thanks for the info!