Low Battery Voltage!

**fam5mel** · 05-16-2022, 04:33 PM

Drove 6 hours today and when went to level trailer had low voltage of 10.6 volts. Have 13.2 volts plugged into shore power and 13.2 volts plugged into truck. Do I have a bad battery? If I remove battery to have checked can we still run electrical systems in trailer? In the 90s here in KY and doggie needs her AC.

**stroguy** · 05-16-2022, 04:37 PM

Shore power will run the AC.

Disconnect the battery black lead and verify the battery isolated is low. Could be a partially shorted DC device is draining you.

Sounds like a bad cell or two.

**xrated** · 05-16-2022, 04:42 PM

Originally Posted by fam5mel

Drove 6 hours today and when went to level trailer had low voltage of 10.6 volts. Have 13.2 volts plugged into shore power and 13.2 volts plugged into truck. Do I have a bad battery? If I remove battery to have checked can we still run electrical systems in trailer? In the 90s here in KY and doggie needs her AC.

13.2V when plugged into shore power is the voltage from the converter/charger.....not battery voltage. And to further that voltage number, 13.2 is float voltage, not charging voltage. Full charging voltage is going to be around 14.4V, then it should drop down to around 13.6 absorption voltage, then float is at 13.2. Unplug from the shore power and take a reading from the battery, anything less than around 12.7 to 12.8 is under a full charge.

**traveldawg** · 05-16-2022, 04:45 PM

Originally Posted by fam5mel

Drove 6 hours today and when went to level trailer had low voltage of 10.6 volts. Have 13.2 volts plugged into shore power and 13.2 volts plugged into truck. Do I have a bad battery? If I remove battery to have checked can we still run electrical systems in trailer? In the 90s here in KY and doggie needs her AC.

Yes. You can remove it and take the battery get it tested.

**huntr70** · 05-17-2022, 06:35 AM

Did you drive with the battery disconnect key in the "on" position?

Battery won't charge if the disconnect is turned "off" in any situation.

**fam5mel** · 05-18-2022, 05:57 PM

Battery disconnect key is in the ON position.

**FlyStar** · 05-18-2022, 06:18 PM

Assume you have a flooded lead acid battery. With tender loving care they can last 5 years or more. The loving care part is mostly about not running them below 50% charge which is 11.9 or 12 volts, keeping the water at proper level and using a battery tender when in storage.

No problem disconnecting them whilst on shore power.

Sent from my iPhone using Tapatalk

**Jerryr** · 05-18-2022, 08:42 PM

10.6 volts after being charged typically indicates a dead cell. A 12v lead acid battery has 6 cells in series. Each cell puts out about 2.1 volts. 6x2.1=12.6volts. With a dead cell you gave 5x2.1v=10.5 volts.

What voltage reading do you get at the battery a few minutes after removed from shore power? If it reads 10.6-11.0 volts you have a dead cell in the battery and the battery is toast.

**fam5mel** · 05-26-2022, 09:05 AM

Sorry late getting back. I had a bad battery. One bad cell. Thanks for replies and advice. Decided to add a battery disconnect swith and maybe a second battery.

**traveldawg** · 05-26-2022, 09:16 AM

Originally Posted by fam5mel

Sorry late getting back. I had a bad battery. One bad cell. Thanks for replies and advice. Decided to add a battery disconnect swith and maybe a second battery.

@fam5mel
Please know that there are likely 12v devices (like the brakes, breakaway switch and maybe LP gas detector that are wired directly to the battery and are not disconnected with a switch on the positive side. Actually, I'm surprised you don't already have a disconnect switch.

If you install a disconnect switch consider putting it on the negative side. That way everything is disconnect when you turn the switch off.