Hi Everyone,
I think I might have an issue with charging my Ford factory auxiliary battery. The one mounted on the passenger frame rail. I need to know what the voltage should be coming from the factory isolator to the aux battery? It was just replaced with a Group 65 AGM last week. As part of the replacement all my wheelchair equipment in the van was attached to it. Previously there was nothing attached to the aux battery so I don't know what the condition of the old battery was.

The symptom I have it that my wheelchair lift is getting very slow while lifting me into the van. After traveling almost to the top it threatens to stop. Also the power sliding door is taking longer to open/close.

I am taking it back to the mechanic that did the work tomorrow afternoon so I hope to get a quick answer. I have a 5.4 with the stock alternator. Any help would be greatly appreciated.
Thanks in advance.
Cheers
Darryl

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2006 Ford E250 RB 5.4L gas
Clydesdale 4WD Conversion
SCT Livewire TS+ with 8 5Star custom tunes
4.10 gears, Dana 44 TTB open carrier
VA7DTP

First step is determine if the battery is charging. Should be 14v plus or minus with the engine running.

^What he said

If there's never been anything attached to it, the "transit" plug may still be installed. If you pop the hood and see a round 4-pin connector attached to the cowl above the heater blower, with a dummy plug with a single wire loop, thats a transit plug. It has to be removed, the the other end plugged in to activate the aux battery. This is because when the aux battery is connected there is always voltage present in some circuits, even if the primary battery is disconnected.

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2000 E450 dually V10 wagon

Thank you for the replies.

Carringb, Well I just looked and I could not see any connector like you described. Any chance you could snap a quick pic of the connector and location? That way I will know what I am looking for.

Anyway, today I was back at the mechanics and the aux battery is definitely not charging. It was down to 10.2 volts and was not seeing anything from the alternator. The starting battery and house battery were seeing 13.45 volts.

3 questions:
Where is the the factory relay located (is it under the starting battery)?
What would be a good replacement for it (possibly Sure Power Isolator)?
What will fit in the factory location?

I take it that I will have to confirm that the 4-pin connector is correctly connected so that the factory wiring will work regardless if I swap out the existing isolator?

I really appreciate the help.
Cheers
Darryl

__________________
2006 Ford E250 RB 5.4L gas
Clydesdale 4WD Conversion
SCT Livewire TS+ with 8 5Star custom tunes
4.10 gears, Dana 44 TTB open carrier
VA7DTP

Please excuse iPhone formatting....

White connector is the aux battery connection. Also pictured is the transit plug (I kept it in case I ever have issues with the setup). Also attached is a pic of the relay, which is on the inner fender below the main battery. Mine currently is hooked in parallel because a bad terminal on the aux battery gave me trailer running light problems, and I never switched it back after fixing the terminal.

Attached Thumbnails

     

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2000 E450 dually V10 wagon

Also, I think activating the aux battery charge requires installing the trailer charge relay in the power distribution box.

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2000 E450 dually V10 wagon

Wow, a picture is worth a thousand words! That is perfect. Thanks.

I just looked at it and my plug looks like yours. It has 3 wires coming out of it. So that eliminates a transport plug as the issue. As for the trailer charge relay, I have the factory tow package with a Prodigy p3 connected, so I don't that could be it. I assume that the aux battery relay is the next thing to check, correct?

Thanks
Darryl

__________________
2006 Ford E250 RB 5.4L gas
Clydesdale 4WD Conversion
SCT Livewire TS+ with 8 5Star custom tunes
4.10 gears, Dana 44 TTB open carrier
VA7DTP

Trailer brake controller is not on the same circuit as the trailer battery charge relay. Have you ever verified charging voltage at your trailer?

This relay is supposed to be installed by the selling dealer, and even comes in a baggy with the owners manual, like many Ford trucks and SUVs. However, I've only once seen it come installed like the dealer is supposed to do.

But once you verify the trailer charge circuit works, then the aux battery relay should be checked next.

PS - thinking about it harder, I'm certain the trailer charge relay is required to activate the aux battery, because the trailer gets all power from the aux battery when the ignition is off.

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2000 E450 dually V10 wagon

Based off my 2004 documentation I gather this is how the circuit works. The Transit Plug is actually before and after the the relay , part of the output of the aux relay can feed trailer tow relay, if you have the aux battery.




I would expect that F2.12 would read 12 volts (or main battery voltage)
F1.20 will read 12 volts (or main battery voltage when in Run)

F1.8 would read (aux Battery Voltage when not in Run), when in Run it should measure the same as the main Battery voltage

This give you points to read that are all Battery Junction box.

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-greg
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"Goldilocks" 2020 Ford Transit High Roof Extended 3.5 EcoBoost AWD Homebuilt

I can finally report that the problem was found and fixed! It came down to the relay under the battery being the problem. It wasn't working. I have to say What A PITA to CHANGE!!! There is no room in there. Out was bad enough but in was dam near impossible. Some colorful language was uttered during that exercise. Anyway thanks for all the help. I really appreciate it.
Cheers
Darryl

__________________
2006 Ford E250 RB 5.4L gas
Clydesdale 4WD Conversion
SCT Livewire TS+ with 8 5Star custom tunes
4.10 gears, Dana 44 TTB open carrier
VA7DTP