What does the Aux battery (in rear storage area) power?

[RJT895]

My 2020 Hybrid is in getting a "Service Charging System Soon" error that ended up being a blown fuse protecting the Auxiliary battery (motorcycle sized) in the rear of the truck. Anybody know what it powers? I've had the error for a while but the engine starts and restarts normally and all the electrical accessories are normal.

Very confused, the Service Writer at the dealership didn't know the battery was there, and the Owners Manual is silent too...

 

[peterk9]

Perhaps it is this. From the Owner's Manual.

Peter

 

[MikeHTally]

Is it a last-ditch effort to start the motor?

 

[peterk9]

Is it a last-ditch effort to start the motor?

The only mention of a battery other than the high voltage and 12 volt one is what I posted above and that is just speculation.

Peter

 

[MikeHTally]

The only mention of a battery other than the high voltage and 12 volt one is what I posted above and that is just speculation.

Peter

That's weird. I'd think the trailer battery would only charge off the seven-pin connector. My lil' ol' utility trailer ain't got no batt'ry.

 

[bcarlson]

I’m not sure about the Explorer, but most hybrids have a 2nd battery that is tied into the hybrid drivetrain . It might be a 48 volt battery, and it’s not used to power other vehicle accessories.

Even my 2021 BMW M340i, which is called a mild hybrid, has a 2nd battery and a special alternator to work with the regenerative braking system and the automatic start-stop.

 

[Dale5403]

I’m not sure about the Explorer, but most hybrids have a 2nd battery that is tied into the hybrid drivetrain . It might be a 48 volt battery, and it’s not used to power other vehicle accessories.

Even my 2021 BMW M340i, which is called a mild hybrid, has a 2nd battery and a special alternator to work with the regenerative braking system and the automatic start-stop.

The Explorer hybrid does have a second battery for the drive line. That is located under the 2nd row seats from what I've seen. Not sure of what the voltage is. I haven't seen any thing about a battery in the cargo area. Maybe the OP could post a picture of it.

 

[RJT895]

I got an answer from the service department:
The under-hood 12V battery is the normal start/run battery
The 450V Hybrid battery lives under the R middle passenger seat to power the hybrid motor
Rear mini 12V battery in the rear storage area on the left side under the cupholder/storage bin is, per the dealer, a float battery to keep accessory power at 12V even when the engine is being started so it runs in parallel.