Batteries not charging while driving?

DavidH · 10-31-2017, 12:13 AM

My coach batteries are fairly new and seen to hold a charge ok if I charge them from shore power or with the generator. But I don't think they are getting charged while I'm driving. Is there a switch or fuse somewhere that I should be checking?

Bluepill · 10-31-2017, 01:43 AM

Make, model, year of your RV please.

KansasFR3 · 10-31-2017, 07:03 AM

Quote:

Originally Posted by DavidH

My coach batteries are fairly new and seen to hold a charge ok if I charge them from shore power or with the generator. But I don't think they are getting charged while I'm driving. Is there a switch or fuse somewhere that I should be checking?

I think if your driving around with the coach power disconnect switch disconnected, it might not charge while your driving. Otherwise, get a voltmeter and check your battery voltage with the engine running and see if its above 13vdc. Then you'll know if your getting a charge. I know it does charge with the coach batteries connected, but not sure what sort of current that we'd see from the engine alternator. You may not being getting the amount of current you think you're getting.

DavidH · 10-31-2017, 08:51 AM

Quote:

Originally Posted by bluepill

make, model, year of your rv please.

2013 fr3 30d

DavidH · 10-31-2017, 12:27 PM

Coach disconnect switch is set "on"... that is, NOT disconnected.

I just double-checked to make sure.

tomrob1161 · 10-31-2017, 01:51 PM

If your RV is a trailer, be sure your positive fuse going to your 7 plug isn't blown.

wogden · 10-31-2017, 02:24 PM

typically the engine alternator will not charge the storage batteries until the voltage in the units dip to around 12.27 + -. Best to check your batteries with a meter and see what you have there. Then if below the threshold you can see if the engine alternator is charging them. The alternator should be around 14.5 but you can check that on the engine for your baseline. A fully charged storage battery should be in the vicinity of 13.40 + -.
On my 3300s FR MH there is a control panel that apparently works with my Afco convertor right next to my storage batteries. The control module, relay, and the isolation unit are located there. Don't know where they may be in a FR3.

camaraderie · 10-31-2017, 02:29 PM

David...as suggested by K-FR3..with the engine running ...put a voltmeter on your battery terminals. Anything over 13.2V means the alternator is charging your batteries.
If it isn't..also check the voltage to your engine battery. If neither is over 13V you have an alternator issue...If only the engine battery is 13+V then there is a wiring or inline fuse issue on the alternator aux charge line.

John bodey · 10-31-2017, 03:04 PM

What are you towing with, f115 has fuses in the glove compartment that need to go into your fuse box in the truck.

A32Deuce · 10-31-2017, 04:08 PM

Quote:

Originally Posted by John bodey

What are you towing with, f115 has fuses in the glove compartment that need to go into your fuse box in the truck.

Class A. Not towing.

CedarCreekWoody · 10-31-2017, 04:11 PM

Quote:

Originally Posted by tomrob1161

If your RV is a trailer, be sure your positive fuse going to your 7 plug isn't blown.

This is a motorhome, not a trailer.

DavidH · 11-04-2017, 04:27 PM

Final outcome:. There is a relay that trips when the engine is running and house batteries drop below 12 v. The relay isn't working and I've ordered a new one. On the FR3, this relay is in the black box in the battery compartment.

bubbles · 11-04-2017, 06:24 PM

Quote:

Originally Posted by DavidH

Final outcome:. There is a relay that trips when the engine is running and house batteries drop below 12 v. The relay isn't working and I've ordered a new one. On the FR3, this relay is in the black box in the battery compartment.

The relay may be bad but it is not controlled by the coach battery level when being charged by the engine alternator. It is the level of the chassis side voltage on the switching line. When connected to shore power just the opposite is true. In other words chassis battery has priority while driving and coach battery has priority when on shore power.

bubbles · 11-04-2017, 07:18 PM

Additionally, if that black box is the battery control center that relay is the interconnect relay and is the same one energized for the emergency (aux) start function.

DavidH · 11-04-2017, 07:26 PM

Quote:

Originally Posted by bubbles

Additionally, if that black box is the battery control center that relay is the interconnect relay and is the same one energized for the emergency (aux) start function.

That makes sense. I'm sure that the emergency start function isn't working either. I'll report back after the new relay is installed.

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