Hello All
I picked up a 2000 E350 with the 7.3 diesel in it the other day. It drove home after banging on the starter, so I know it needs a starter. It had been sitting over a year so the batteries are weak but my question is can I charge the second frame mounted battery through the first one under the hood? I get good voltage on the under the hood battery but when I try and start the van the volt meter reads 8 or below. Looking to see what options I have before battling that frame mounted rust box.

Also with the batteries paired together once the van is running (and charging) if the second battery is under voltage would that cause aux loads to not work? The van is an old para-transit bus with a rear heater A/C that was unresponsive. Didn't try to play with the wheel chair lift yet.

 

Welcome to the site..

7.3 needs to meet a 100 cold cranking ‘minimum’ RPM otherwise it won’t start. Warmed cranking speeds will be greater.
Batteries, generally no less than 10.8 or so for the glow system and cranking.
Problem with primary/secondary batteries or parallel connection is that if one battery is failing, it will draw from the other. I would charge the batteries uncabled and load test them individually. May be that one/both are useable, but if there’s any question as to their health, I’d replace them.. If they’re aged out, and one seems ok or tests out, and a new single battery replaced, at some point the older remaining may take its toll on the newer unit.. If your seeing 8 volts, sounds like batt capacity is weak. But if jumped, and the charging system output is spec, all the features should be working. If it suffers from some rust, corrosion, always make sure the cables and connections are clean/tight and solid....