Battery not keeping up with fridge - while running.

[Blue Bear]

On a recent trip from Seattle to Moab, I had my Dometic 35 plugged into the rear cargo 12v port. Along the way, I noticed that the fridge had shut itself off since the voltage was below the threshold I had set (medium). I thought that since the Jeep was running, it would keep up with the fridge. What's the deal? Do I need to do anything different, or would a dedicated larger wire to the main battery be a better idea? Does the 12v plug run off the main battery or the aux battery?

Thanks!

Matthew

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[Vanburi]

What voltage does 'medium' refer to regarding the fridge setting?

 

[C.Sco]

Can you change the voltage threshhold on the fridge, to be less sensitive to voltage drop? Try "Low", I guess?

The 12v outlet runs off the main battery when the engine is on, and the aux battery when the car engine is stopped (automatically e.g. at a stop light).

I'd say there's a good chance that the problem is that the fridge is drawing too much juice from the aux battery when the engine is stopped. Solution: get rid of your auto stop/start function. There are a few ways to do that.

 

[Fudster]

Can you change the voltage threshhold on the fridge, to be less sensitive to voltage drop? Try "Low", I guess?

The 12v outlet runs off the main battery when the engine is on, and the aux battery when the car engine is stopped (automatically e.g. at a stop light).

I'd say there's a good chance that the problem is that the fridge is drawing too much juice from the aux battery when the engine is stopped. Solution: get rid of your auto stop/start function. There are a few ways to do that.

I'm sorry. I don't mean to disrespect but that 12v outlet runs off of both batteries from the factory, regardless of whether the vehicle is on or off, except during ESS events when it runs only of the ESS battery.

By factory default that cargo area plug is always energized, but this can be changed by moving its fuse to its alternate location. Either way it carries up to 20 amps.

https://www.jlwranglerforums.com/JL-Wiring-Diagrams/POWER-OUTLETS.pdf

Add to that the alternator when the vehicle is cranked.

If during an ESS event the appliance were to draw too much current from the ESS battery the voltage of the battery would drop, which would trigger a premature end to the ESS event before the operator takes their foot of the brake, where after all batteries and the alternator would supply the needed power.

More information as to the power draw of the appliance when set to medium, and the state of your batteries and perhaps alternator needs to be known for us to continue.

 

[Blue Bear]

What voltage does 'medium' refer to regarding the fridge setting?

It was showing 12.2v, which is right at what the manual says it should. I was just surprised it was not working since the drive was so long.

 

[Blue Bear]

I'm sorry. I don't mean to disrespect but that 12v outlet runs off of both batteries from the factory, regardless of whether the vehicle is on or off, except during ESS events when it runs only of the ESS battery.

By factory default that cargo area plug is always energized, but this can be changed by moving its fuse to its alternate location. Either way it carries up to 20 amps.

https://www.jlwranglerforums.com/JL-Wiring-Diagrams/POWER-OUTLETS.pdf

Add to that the alternator when the vehicle is cranked.

If during an ESS event the appliance were to draw too much current from the ESS battery the voltage of the battery would drop, which would trigger a premature end to the ESS event before the operator takes their foot of the brake, where after all batteries and the alternator would supply the needed power.

More information as to the power draw of the appliance when set to medium, and the state of your batteries and perhaps alternator needs to be known for us to continue.

No problem. You didn't come across as short. I wondered if it had something to do with the aux battery since it's tied to the main battery. I think what I might do is simply run it from a powerpack like an Ecoflow or a Jackery. That eliminates the whole worry about draining the Jeep's batteries.

 

[Fudster]

On a recent trip from Seattle to Moab, I had my Dometic 35 plugged into the rear cargo 12v port. Along the way, I noticed that the fridge had shut itself off since the voltage was below the threshold I had set (medium). I thought that since the Jeep was running, it would keep up with the fridge. What's the deal? Do I need to do anything different, or would a dedicated larger wire to the main battery be a better idea? Does the 12v plug run off the main battery or the aux battery?

Thanks!

Matthew

Matthew:

Are you familiar with how to display the battery voltage while cranked on the EVIC (i.e, dash)?

I'd be curious to see what voltage the vehicle thinks that your batteries are at versus the refrigerator in the rear.

You could have battery issues, voltage sensor issues with the appliance, both, or yet something else.

What amperage does the refrigerator pull? Hopefully not more than the 20 amp limit I discussed above.

 

[jaymz]

You probably have a charging system issue. 12.2 volts isn’t even a fully charged battery at rest, let alone with the engine running.

 

[Fudster]

No problem. You didn't come across as short. I wondered if it had something to do with the aux battery since it's tied to the main battery. I think what I might do is simply run it from a powerpack like an Ecoflow or a Jackery. That eliminates the whole worry about draining the Jeep's batteries.

Matthew: it was @C.Sco's guidance to you on which batteries are used that I sought to remedy.

We're good.

 

[Fudster]

You probably have a charging system issue. 12.2 volts isn’t even a fully charged battery at rest, let alone with the engine running.

Jay, I'm guessing the 12.2 volts may have been the refrigerator's reading, not the EVIC's.

Thoughts Matthew?

 

[Fudster]

Matthew: it was @C.Sco's guidance to you on which batteries are used that I sought to remedy.

We're good.

You can change the cargo plug to only be energized, as mentioned, when the vehicle is cranked.

I find it hard to believe that a jLs working batteries and an alternator can't energized your refrigerator and that a dedicated external battery should be necessary while your cruising.

 

[Blue Bear]

Matthew:

Are you familiar with how to display the battery voltage while cranked on the EVIC (i.e, dash)?

I'd be curious to see what voltage the vehicle thinks that your batteries are at versus the refrigerator in the rear.

You could have battery issues, voltage sensor issues with the appliance, both, or yet something else.

What amperage does the refrigerator pull? Hopefully not more than the 20 amp limit I discussed above.

No, sir. I'm new to Jeeps, so everything is different to me! I think I check it from the EVIC while in ACC mode, yes?
Not sure about the amp draw. I've seen conflicting reports from 3.5 an hour to 1.5 depending on ambient outside temps.

 

[Blue Bear]

Jay, I'm guessing the 12.2 volts may have been the refrigerator's reading, not the EVIC's.

Thoughts Matthew?

That reminds me - what IS a fully charged main battery? From my volt meter, I get a reading in the 12.8 range just sitting there, but the EVIC says 13.6 and above depending on when I take a reading.

 

[jaymz]

That reminds me - what IS a fully charged main battery? From my volt meter, I get a reading in the 12.8 range just sitting there, but the EVIC says 13.6 and above depending on when I take a reading.

12.6v is the minimum I’d expect to see. 13.6v is just above the 13.2v that you’d get by multiplying cells X volts (6 X 2.2).

 

[Fudster]

That reminds me - what IS a fully charged main battery? From my volt meter, I get a reading in the 12.8 range just sitting there, but the EVIC says 13.6 and above depending on when I take a reading.

The EVIC is far more a representation of that the (smart) alternator is pushing than what is in the battery or how healthy that battery is. In fact consistently high, like 13.6V readings suggest that the alternator is trying to push current into a set of batteries that may not be able to accept charge well due to age or malfunction.

I refer to the alternator as smart because it varies the current it pushes based on battery need and draw to save gasoline when it can.

Given the newness of your vehicle I'd be inclined to have the dealer load test each battery separately, to see if your ESS battery is defective and cannibalizing the main battery.

Issue could lie at the appliance but my first place to look would be the ESS battery.

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