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Minimum starting voltage?

Posted: Sun Mar 17, 2013 3:40 pm
by leadpig
Anyone know how low you can go? Reason I ask is because I have an ARB 12v fridge freezer. I can set it's battery monitoring feature at several levels, but on all but the most relaxed it cuts out because battery voltage is lower than threshold. Start the vehicle and everything is fine, of course. The low setting, however, would allow the batt to drop to 11.1v...I'm testing it overnight tonight, but anyone care to guess if I'll be reaching for the jump leads in the morning? Right now I have the engine off, freezer holding at -6C and get 12 v across terminals while it's running, 12.2 when not (it was only 12.25 before I started).

As an extension to that, to have a resting battery at about 12.25 v seems a tad low to me, even my wife's Versa shows 12.5. Is this just a function of the crappy oem battery or am I wrong about what I should see across the terminals with everything off? She starts vigorously every time (except maybe tomorrow...).

Posted: Sun Mar 17, 2013 5:18 pm
by leadpig
Update -I realized after I posted the question that the interior lights were on, hence the lower voltage. Doh! :oops:

Right now after a couple more hours I have 12.38 resting, it drops by about 0.2 when the fridge cycles on.

Posted: Mon Mar 18, 2013 7:12 am
by leadpig
No jump leads required - 12.1v across the terminals this morning with the freezer not running, fired right up. Might be a different story if it was colder, I don't suppose the garage went below 60 last night.

Posted: Mon Mar 18, 2013 9:03 am
by CPLTECH
Just a comment,
Batteries for cars are designed to give lots of cranking amps for a short period whereas RV/marine/solar backup/EV batteries are designed/rated to give “X” amount of continuous amps per hr over a 20 hr period where it then reaches a max discharge of 80%. If not discharged to that extent, the longer the overall batt life.
---Lessons learned from an EV conversion