Minimum Voltage to Start Engine

[elliott9]

My JL has the 2.0L w/ eTorque.

Going to connect a SmittyBilt Arctic Fridge which has a physical toggle switch that enables low voltage detection so it cuts itself off prior to the battery getting so low the engine cannot turn over.

Switch options
LOW 10.2V
MED 10.7V
High 11.7V

Anybody know the minimum voltage needed to start the engine? I could play it safe and use High, but I'd like to elongate how much time it can cool without having to start the engine for the alternator charge the battery.

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[entropy]

My JL has the 2.0L w/ eTorque.

Going to connect a SmittyBilt Arctic Fridge which has a physical toggle switch that enables low voltage detection so it cuts itself off prior to the battery getting so low the engine cannot turn over.

Switch options
LOW 10.2V
MED 10.7V
High 11.7V

Anybody know the minimum voltage needed to start the engine? I could play it safe and use High, but I'd like to elongate how much time it can cool without having to start the engine for the alternator charge the battery.

You should never drop the battery below 50% I would never go below 11.7V. thats already low for a 12V AGM battery. But I dont know what kind of battery your Jeep has.

 

[Some Random Guy]

Voltage alone is not the full picture. As a battery ages the internal resistance rises. So at any given voltage it can’t produce enough amps to satisfy the starter because the internal resistance is eating more and more volts.
So, I’d run what you want and once the starting struggles move to a more conservative value.

 

[Russ Chung]

Be sure to run heavy gauge wiring (10 ga or better) between your battery and the fridge. If you use the cig lighter it’s only 18 ga, and the voltage drop due to resistance will trigger the low voltage cutoff at the fridge even though the battery voltage is good.

 

[Reinen]

It will do for now, but an AGM battery is not the best power source for a fridge. For an AGM battery that's also your starter you want the 11.7v cutoff. Especially on a JL with the linked Aux battery.

In the long run you'd be much better off powering the fridge with a separate lithium battery charged with a DC-DC charger switched to ignition so it only charges when the engine is running (or if you connect a solar panel). Then you can use those lower voltage shutoffs. Lithium batteries don't mind being run low and there is no risk of being unable to start the engine.

 

[elliott9]

Thanks for the tips. I'll stick with 11.7v for now.

 

[Craigzjeep]

Hey Elliott9,
I couldn't help but notice, it appears you have the wrong end of a blue Ethernet cable in your mouth,
I work with those cables everyday, but not that way.

 

[elliott9]

My throat can form a perfect RJ45 connection point for the cable. ?

 

[Retrograde]

My throat can form a perfect RJ45 connection point for the cable. ?

Uhh... that's what she said.

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