camper battery charging question

[iwon415]

I found a trailer tow battery fuse blown on my Ford. I was checking as it didn't seem as if alternator was charging the camper battery anymore.
Can someone refresh my memory on what meter readings I should see on the camper battery, both with the truck running and when plugged into shore power. Would those readings be significantly different?

I'm getting 13.1 without truck running and batteries charged.
13.3 with the truck running, and 14.1 when on shore power. Could this mean the truck still isn't charging the camper properly? Thanks for any suggestions.

TimH

[YC_1]

With the truck off and not connected to shoreline turn several lights on inside to put a load on the battery. If it is cold turn the heater on and the fan will draw quite a bit of current.

Now take your voltage readings after ten minutes. Then start the truck and check again.

Those 13 + volts are surface charges of recently fully charged batteries. Doing the above test will give you some good insight.

[DWeikert]

pcoplin wrote:
You'll get more than 14 when the truck is running and the battery charged. Below 13 when on battery only.

Fixed it for you. If the battery is still charging you may read below 14v depending on the length and gauge of wire between the battery and alternator.

[GordonThree]

dont forget voltage drop. the stock charge line is a tiny wire, if it's hooked to a low battery, it will read the voltage of the low battery at one end, and alternator voltage at the other. measure the open-circuit voltage (trailer battery disconnected) at both ends to confirm.

[Kayteg1]

Proper charging is 13.5+ V
Battery right after charge might show 13V, but anything above 12.5V is good.
Lower than 12.5V means battery is getting discharged.
Those are rules of thumbs as converting chemical reaction to electrical current do have lot of hard to understand details.

[pcoplin]

You'll get more than 14 when the truck is running. Below 13 when on battery only.