I have a 2015 Jayco Pinnacle with a residential fridge. When I am plugged in to shore power and have fully charged batteries (two of the biggest Trojan 6 volts that I could fit in the battery cases) my voltage readout is 13.2/ 13.3. After driving for 4 to 5 hours my readout has dropped to around 12.3 to 12.4 volts. I thought that it should at least maintain my full charge running off my truck charging system. When we then dry camp overnight my LOW voltage alarm starts to beep usually around 5 am and of course wakes me up. I did not spend 100K to have a very fancy alarm clock. Any suggestions would be appreciated. Thanks .

Sounds to me like too much draw and not a big enough reserve for dry camping and towing. Depending on the draw (residential fridge) don't expect your trucks stock charging system to keep up.

Read voltage at the truck battery and then at the RV battery when this occurs. Very likely that the wire gauge is too small to allow full voltage/amperage to reach the RV battery.Unless you are running a lot of heavy electrical loads in your truck, your alternator should be able to keep up with an inverter powering a residential refrigerator.

need to know amp hour ratings of batteries or the model number so we can look it up on the charts.draw of fridge and duty cycle. Are you expecting fridge to cool from ambient temp down to proper temp or are you precooling fridge on shore power?Do not make the mistake of thinking that FOR EXAMPLE 2 six volt 250 AH batteries means you have 500 AH at 12 volts.you have 250 AH at 12 volts.So get the figures and repost here

The 'charge line' from truck to 5vr via 7 pin connection is NOT large enough to recharge those batteries and keep up with the demand.The OEM charge line is barely large enough gauge wire to maintain battery.You need to run a larger gauge wire on truck to 7 pin to use for charge line

bc canuck wrote:I have a 2015 Jayco Pinnacle with a residential fridge. When I am plugged in to shore power and have fully charged batteries (two of the biggest Trojan 6 volts that I could fit in the battery cases) my voltage readout is 13.2/ 13.3. After driving for 4 to 5 hours my readout has dropped to around 12.3 to 12.4 volts. I thought that it should at least maintain my full charge running off my truck charging system. When we then dry camp overnight my LOW voltage alarm starts to beep usually around 5 am and of course wakes me up. I did not spend 100K to have a very fancy alarm clock. Any suggestions would be appreciated. Thanks .I would check the 12V current being drawn. It sounds like you are drawing more current than the truck can put supply. With a long 12V wire from the front of the truck back to the RV, you will be lucky to supply 8 amps. You could be drawing more than that if running the refrig on 12V. Sometimes the 12V wire isn't even connected in the truck or RV, even though the pin is in the connector. Might check that.The only other thing I can think of is installing a much heavier gauge 12V wire in both the truck and RV. Even if it's a 12 gauge, it may not supply enough current for your situation.

Battery voltage drops!!! | Good Sam Community

Old-Biscuit
Explorer III
Oct 21, 2015
The 'charge line' from truck to 5vr via 7 pin connection is NOT large enough to recharge those batteries and keep up with the demand.

The OEM charge line is barely large enough gauge wire to maintain battery.

You need to run a larger gauge wire on truck to 7 pin to use for charge line
darsben
Explorer II
Oct 21, 2015
need to know amp hour ratings of batteries or the model number so we can look it up on the charts.
draw of fridge and duty cycle. Are you expecting fridge to cool from ambient temp down to proper temp or are you precooling fridge on shore power?
Do not make the mistake of thinking that FOR EXAMPLE 2 six volt 250 AH batteries means you have 500 AH at 12 volts.you have 250 AH at 12 volts.
So get the figures and repost here
wolfe10
Explorer
Oct 21, 2015
Read voltage at the truck battery and then at the RV battery when this occurs. Very likely that the wire gauge is too small to allow full voltage/amperage to reach the RV battery.

Unless you are running a lot of heavy electrical loads in your truck, your alternator should be able to keep up with an inverter powering a residential refrigerator.
DavidP
Explorer
Oct 21, 2015
Sounds to me like too much draw and not a big enough reserve for dry camping and towing. Depending on the draw (residential fridge) don't expect your trucks stock charging system to keep up.

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