Refrigerator question

[Lollygag1]

I have noticed that after a few hours of running my refrigerator the battery voltage indicator drops to 11.2 v. shut the fridge off and it pops back to just over 12. Worried that this is somehow draining the batteries. Thoughts/ remedies/ am I paranoid?

 

[Comodave]

Are the batteries being charged during the refer usage?

 

[Lollygag1]

I typically leave it on when I charge. This is a relatively new development it usually stays on and the indicator stays at 12v. I recharge every 12hrs

 

[SteveK]

12v is a 50% discharged battery.

 

[Comodave]

If it is getting low voltage after just charging then maybe the batteries are getting old and don’t have as much in them. Do you have a battery tester? If not get one and test the batteries. They are relatively cheap, I got one on Amazon for under $30. That would be my first step.

 

[Lollygag1]

I guess my question is why when I turn the fridge off the the meter go back to reading normal?

 

[Comodave]

It isn’t under load. Batteries can show good voltage and then when you put a load on them they drop. Usually an indicator of a dying battery.

 

[Lollygag1]

Thanks

 

[Comodave]

This is the one I got from Amazon. It was $28 and some change. Worked ok for me.

TOPDON AB101 Car Battery Tester 12V Car Battery Load Tester on Cranking Charging Systems, 100-2000 CCA

 

[C lectric]

Batteries have internal resistance themselves. When a current is flowing that causes a battery voltage drop. Even a brand new battery will exhibit this. The question is how much voltage drop over how much time.
Any load will drain a battery but depending upon the battery capacity , load draw, battery age and charging regimen it may draw down quickly or not quickly.

How old are the batteries used for the fridge? What is the battery size? Maybe they are just getting to old which means capacity has been lost so the voltage will drop faster than when the batts. were new.

What current does the fridge draw, name and specification plate, when the batteries are fully charged?

There have been lots of threads here about how to help minimize fridge draw, power useage, by ensuring adequate exhausting of the heated air the fridge compressor pump removes from the fridge inside and the food. If the fridge cannot eliminate heat easily it will run and run and run pulling battery power.

 

[Lollygag1]

4 golf cart size batteries (crown) purchased in 2019. Everything is wired in series so none are dedicated specifically for the fridge.

 

[Comodave]

4 6volt in series would give you 24 volts, is your boat 24 or 12? They may be in series parallel which would give 12 volts.

I always add ventilation and a fan to the refer compartment, vent low to let cool air in and a vent high to let hot air out. I use 50mAmp fans so they draw almost nothing as far as current. This is the fan I use. Got them on Amazon.

Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown), compatible with Desktop

 

[Darlin]

You cannot test a battery by checking voltage alone. You have to add a load.One bad cell could cause your problem. Disconnect all the batteries from citcuits and each other. Then test with a load tester.

 

[Don L]

I have noticed that after a few hours of running my refrigerator the battery voltage indicator drops to 11.2 v. shut the fridge off and it pops back to just over 12. Worried that this is somehow draining the batteries. Thoughts/ remedies/ am I paranoid?

Not uncommon But resting at only 12v indicates batteries that either not getting fully charged or are going bad.You don't give the amp load, battery capacity, or how long this takes so who knows. Bit I bet it is both undercharged and drying batteries.

 

[Portage_Bay]

Agree with Don L's assessment. Your refer's voltage cut out is telling you your battery bank has issues. Undercharging, dying batteries or both. Pay attention to it. I'm going though the same learning curve. It can get expensive in a hurry.

Here's a good read to get started understanding using voltage to assess state of charge.

Under-Load Battery Voltage vs. SoC

If your golf car batts are FLA consider getting a quality hydrometer and having a look. By quality I mean the kind with a glass barrel and float along with a thermometer for temperature correction. The cheap tilting needle kind won't give you the details you're looking for.

I have noticed that after a few hours of running my refrigerator the battery voltage indicator drops to 11.2 v. shut the fridge off and it pops back to just over 12. Worried that this is somehow draining the batteries. Thoughts/ remedies/ am I paranoid?

Not uncommon But resting at only 12v indicates batteries that either not getting fully charged or are going bad.You don't give the amp load, battery capacity, or how long this takes so who knows. Bit I bet it is both undercharged and drying batteries.

 

[ronobrien]

If it is getting low voltage after just charging then maybe the batteries are getting old and don’t have as much in them. Do you have a battery tester? If not get one and test the batteries. They are relatively cheap, I got one on Amazon for under $30. That would be my first step.

This was my first thought also.