Quote:
Originally Posted by davlin
We are not boon-dockers, so we camp where there is electricity.... Over the next 48 hours, the voltage dropped .9 vdc while the fridge temp held (basically) rock steady at 39 degrees. The ending voltage was 12.5 vdc....
|
Nitpick: Unless the first Battery reading showed "surface charge" from a recently disconnected charge cycle, the numbers aren't quite right: Discharge from a ~95% SLA battery without "surface charge" begins at 12.8 Volts. You either burned through only .4 Volts (more likely), or your Voltmeter is really bad (less likely.)
Quote:
Originally Posted by davlin
It answered, at least for me, the question "Can I stop for a couple of hours with the TV turned off without worrying about the fridge?"
|
Definitely. But, when the weather is much hotter, the duty cycle of the Fridge might reach 80% (of wall-clock time). Since the TV batteries will take over this load when TM batteries reach about 50% ... that's our worst possible starting point. 10A per hour at 80% duty cycle is roughly the same, for the battery, as 8A continous. 2 hours would consume about 16 AH. For those of us using a pair of wally-world group 24 batteries (Capacity ~70 AH), that takes out another 11%. Not terrible for a short period, and you will be fully recharged after plugging in at camp.
But: I will SWAG that merely connecting directly between the Bargman endpoint wire nut (i.e., and the Fridge 12V input (with a breaker) improves the TV-based Voltage, available at the Fridge terminal under load, by about 0.25 Volts. In terms of SOC, that's significantly better "TM Battery Protection": When you turn off the TV, your TM batteries start downwards from about 65% SOC, rather than 50%. This is a very easy mod, and probably worth doing- if you've got a Norcold Fridge running down the road on 12V.
(Although I don't have one anymore
)