Battery under barn doors on e350 v10 - but van is empty inside

[gac1222]

Hey guys, I have a fairly stock ford e350 with a ujoint 4x4 conversion. I noticed there is an aux battery mounted under the barn doors right under the frame that looks almost factory. This particular van is just a cargo so its basically empty inside so I cant figure out what the battery is powering. Is this something that typically comes stock in ford e350 gassers? I know diesels have 2 starters, but this is a gas van.

[Scalf77]

This is probably the factory aux battery. If you have a trailer package it may be tied to that. Here a snap shot of where the aux battery relay is.

[gac1222]

It does have the trailer package! This is excellent, thank you!

[dhally]

My 2009 gas E250 had a 2nd battery in that location. It came with the rear AC option and maybe the trailer package. It has a relay that disconnects it when the motor is off. Then the trailer lights use that battery so it doesn't drain the main battery.

The battery, fuse,, relay, and wiring wasn't big enough to use for my house system. So I removed it. I did use the relay to power the 12v mode on my absorption frig

[deserteagle56]

Yup, that's the standard location for the auxiliary battery available from Ford. My 2007 E350 has one mounted there and it is listed on the build sheet.

Wait till you see how much fun it is changing it out in that location......

[carringb]

It’s a nice option. Besides trailer lights, I also use mine to run the inverter.

Note - the harness for that batter comes with a dummy plug from the factory, and it’s supposed to be connected by the original dealer doing delivery prep. Mine was not connected. Took me a while to figure out why the battery was always dead.

Anyways the connector is just above the blower compartment under the hood.

[1der]

Originally Posted by deserteagle56

......
Wait till you see how much fun it is changing it out in that location......

It actually is pretty easy to drop and install that battery. There are four bolts holding the box to the frame rail, three bolts just have to be loosened but stay threaded, the fourth has to be removed. The battery box then slides off the three bolts. The restraining cables on each end are there to hold the battery box and allow the box to be tipped over to 90 or so degrees to remove the plastic top and battery.

The plastic top (if present) comes off with two bolts. The battery is held in place by a long bolt and a wedge. The battery terminals are pretty standard.

[Big_ern_101]

The under-frame batteries are literally one of the best things about these vehicles. Frees up so much room in the engine bay. Not a big deal to change either - takes a few extra minutes tops. If you have a gasser with a single under-frame battery, there are factory parts to add a second battery from the 6.0 parts catalog.

[gac1222]

Originally Posted by 1der

It actually is pretty easy to drop and install that battery. There are four bolts holding the box to the frame rail, three bolts just have to be loosened but stay threaded, the fourth has to be removed. The battery box then slides off the three bolts. The restraining cables on each end are there to hold the battery box and allow the box to be tipped over to 90 or so degrees to remove the plastic top and battery.

The plastic top (if present) comes off with two bolts. The battery is held in place by a long bolt and a wedge. The battery terminals are pretty standard.

I just wanted to come back here and tell you this was incredibly helpful information in helping me drop and change that battery.

For anyone wondering, here is what I was able to find out. In the v10 e350, the two batteries are directly linked in parallel. My batteries did NOT have a isolator, despite there being conflicting evidence that there was. I tracked the entire line and it went directly from one battery to the other. I noticed this when the aux battery under the barn doors died and used an amp clamp and saw it was pulling almost 15 amps from the main engine compartment battery trying to charge it, despite the engine being off.

I did a bit of searching on this forum and found some old threads, but hopefully this is useful to someone.

[jeff.depaul]

Big_ern,
Possible you could post details (links/part #) for the 6.0 battery mounts? I have a v10 gasser but would really like to install.