Hawk battery discharge question

[Yonder37]

Have new FWC Hawk, with the dual 6V batteries and a 12V DC voltmeter. Have the 160W solar panel plus the 130W portable solar panel for charging. Primary electrical appliances are an 85-liter compressor fridge, two roof fans, and the reefer fan.

Was boondocking over the weekend, it was hot. Batteries were well charged during the day. Ran the fridge at a high setting overnight, plus the fans. In the early morning (before any solar energy was coming through), I glanced at the voltmeter and it was like 12.30V. That seemed OK, since the FWC manual says:

"Never let a 12-volt deep cycle camper battery, or your Dual 6 Volt Batteries, discharge below 12.2 volts."

Then the fridge cycled on, and suddenly the voltmeter dropped to like 12.15V. Uh-oh. Turned off the fridge and the voltmeter went back up to around 12.3V.

Can I assume that the 12.2V discharge guideline means *resting* voltage? Is it OK to dip below that level if the batteries are under load, and then recover above that level when the load is removed?

 

[Vic Harder]

Yes. Under load, voltage does drop. 12.2V is said to be 50% SOC, and is the recommended amount to drain an AGM battery without unduly stressing it.

You can take an AGM lower. If it goes lower than 50% often, it will die sooner.

 

[heinphoto]

It is also a good idea to try and recharge the batteries fully after a deep discharge with the full charge cycle if possible: Bulk > Absorption > Float.