2nd battery charging?? 2009 E350 5.4

[carringb]

Is there a chance the starting battery is low? Starting with '09 vans, the aux battery charging relay won't engage until the starting battery is fully charged.

I think the battery relay might be the same as the starter relay. It looks identical anyways.

[happycampingcouple]

Carringb,

I dont think the starting battery is low, I will check it and maybe throw a charger on it... Then then re test again...

Thanks!!

[happycampingcouple]

I charged the battery until the green light came on my charger, reinstalled the battery and it reads 12.6v While it was charging I checked it and it was 14v. Engine running 14v

I will replace he starter solenoid when it arrives and report back.

Thanks for the help!

[TomsBeast]

My 1995 ‘stock’ dual battery system has no isolator, the batteries are wired from Ford in parallel, meaning what happens to one battery, happens to both. The same with my old dual battery 2000 v10. I’m not sure about your 2009.

Performing the test I described is a good next step. Without those results, I can’t help any further. Best of luck to you

[carringb]

Did you already check the Maxi-fuse in the power distribution box?

I blew mine once because the aux battery got deeply discharged running way too big of a load on the inverter. Since then... never had it blow again.

[Scalf77]

So I believe the aux battery solenoid is under the battery tray, the starting solenoid is relatively level with the battery. They both I believe have three terminals, input, output, and coil positive. Ground is by attaching to the frame.

It will be difficult to test, because you pretty much need to remove battery to get to it. But you should at least attach some monitoring wires to the input, and to the positive coil.

You could jumper 12 volts to the positive coil, and with the input and output disconnected measure across those terminals with a ohm meter. But, as others have said you should check to make sure you are reading the start battery voltage at the input terminal.

-greg

[carringb]

Originally Posted by Scalf77

So I believe the aux battery solenoid is under the battery tray, the starting solenoid is relatively level with the battery. They both I believe have three terminals, input, output, and coil positive. Ground is by attaching to the frame.

This is all correct. Aux relay is under the starting battery.

[happycampingcouple]

Starter relay Motorcraft sw5181 arrived this morning via Amazon.

Installed it and guess what? 13.3v on my hardwired aux battery meter!

$18.00 and problem solved. Thanks all who helped with this. Loading up for our camping trip now!

[dave0718]

Does the house battery charge when on land line? Two years ago my rig would charge on land line but not from engine. Camping World said replace inverter/charger. Since they were wrong on two previous visits, I changed my isolater instead. Working fine now for two years.