battery issue

[alan1]

Strange thing happened while boondocking on our one night on the road to our winter place. While on our batteries the voltage was slowly going down as would be expected. At about 12.3 it would suddenly drop to mid 11 or so and the AGS would start the generator as it is set for 12.1. This happened several time and I ended up leaving the generator going all night. Any thoughts as what would cause the sudden drop? I am going to remove the batteries and test them to see if I might have a bad one. As I remember, due to the inverter, I start with the ground side first after cutting off all power.

[richpatty]

Could it be something turning on that momentarily drops the voltage down?

[Sealyn]

When disconnecting batt. remove inverter positive first.

[bs077331]

It's probably a heavy load, such as the refrigerator. That will drop voltage quickly when it starts up.

[UMXHAULER]

I concur on these comments. 12.1 volts is too high of a setting for the AGS. I think they suggest something like 11.7 volts. Anytime something turns on or is drawing power off the batteries the voltage will drop and then come back up after the demand is removed. The 50% draw down figure for a lead acid battery at 12 volts is a voltage taken on the batteries at a "resting" state for like 30 minutes with no draw on them. That never occurs in an RV, thus we can only approximate where a 50% draw down is actually occurring. A high demand load such a refrigerator compressor starting or turning on the microwave can have a huge drawdown in battery voltage temporarily and will often produce an AGS false start if the voltage is set too high.

[alan1]

Originally Posted by Sealyn

When disconnecting batt. remove inverter positive first.

Thanks I stand corrected, I knew due to the inverter things were done different.