2005 Dodge Ram, Smart charging through trailer plug???

[Diesel_Camper]

So while on a road trip with our 5er, I had a rider in the back periodically let me know what the volt meter read. During the trip it seemed to climb from around 14v to about 14.25. The next reading was 13.8 with no electrical changes in the trailer. I also noticed on my digital readout in the cab that the commanded alternator voltage went from 15 to 14.9. I know that's not a big jump, but it confused me a bit until I thought about the possibility of Dodge writing in a smart charging program for the trailer lead. Seams totally possible to me and never considered auto makers might do this...

[Me_Again]

Nothing smart in the trailer charge circuit OEM.

There are marine devices like the Echo Charger that will do smart things.

However, with the length of the wiring it would be hard for the truck to over charge the trailer batteries.

Chris

[path1]

sfpcservice wrote:
So while on a road trip with our 5er, I had a rider in the back periodically let me know what the volt meter read. During the trip it seemed to climb from around 14v to about 14.25. The next reading was 13.8 with no electrical changes in the trailer. I also noticed on my digital readout in the cab that the commanded alternator voltage went from 15 to 14.9. I know that's not a big jump, but it confused me a bit until I thought about the possibility of Dodge writing in a smart charging program for the trailer lead. Seams totally possible to me and never considered auto makers might do this...

That's almost "normal" on my cheap device that plugs into power port. Although mine most I've seen is 14.75 max. Flip your a/c on and off couple times and watch read out. Surprised me.

[Sam_Spade]

There must be some "intelligence" between the truck alternator and the trailer.

Those readings sound fine to me. Indicates that the electronics has determined that the trailer battery is getting full and is cutting back the voltage to it.

I've noticed that my truck voltage stays up around 15 much of the time too but haven't paid real close attention. I would think it too should drop back to about 14 if that battery comes up near full.

This post just reminded me that I need to check the water in the truck battery before going out again.

[thomasmnile]

sfpcservice wrote:
So while on a road trip with our 5er, I had a rider in the back periodically let me know what the volt meter read. During the trip it seemed to climb from around 14v to about 14.25. The next reading was 13.8 with no electrical changes in the trailer. I also noticed on my digital readout in the cab that the commanded alternator voltage went from 15 to 14.9. I know that's not a big jump, but it confused me a bit until I thought about the possibility of Dodge writing in a smart charging program for the trailer lead. Seams totally possible to me and never considered auto makers might do this...

Truck air conditioning on and cycling? Engine cooling fan clutch engaging/disengaging? It is an electronic clutch, and as I found out, can cause a noticeable drop in alternator output voltage that fluctuates low to high when it fails.