5 cu. ft. fridge too much for two 12V/390W batteries?

[Bowlegs868]

I have two 12V 390W batteries connected in series to a 24V 2000W inverter and a 60A charge controller.

If I try turning on my 5 cu. ft. fridge, my inverter will "trip" and start beeping. At least I think it's because of the inverter or maybe it's the charge controller? OR maybe I simply don't have enough batteries/power to withstand the starting draw of the fridge???

PS.... I usually have four wired in series parallel and that handles the fridge fine

The label at the back of the fridge states 115V / 1.5A

 

[timselectric]

If it worked with twice the batteries, before. Then it's more than likely that you don't currently have enough battery.

 

[jberger]

You have (2) 12V batteries wired to 24V, correct?
Please post the battery information, Inverter and fridge information.
I just don't get the 1.5a rating of the fridge or the idea of a 390W battery.

 

[Bowlegs868]

You have (2) 12V batteries wired to 24V, correct?
Please post the battery information, Inverter and fridge information.
I just don't get the 1.5a rating of the fridge or the idea of a 390W battery.

There's nothing else I can find on the fridge but I attached a spec sheet for the batteries

Additional info on the inverter is 24VDC — 110VAC, 4000W surge

 

[Browneye]

My 5 cubic foot freezer runs on 100W. My ecoflow delta mini powers it just fine.
Your batteries should last a LOT of hours - like a couple of days.

 

[Bowlegs868]

@Browneye
from the looks of it, I think you have a more capable power source than my two 390W batteries

I also think my fridge runs a bit higher than 100W

 

[Browneye]

Yeah, I overlooked 390W as 390A.

 

[WYtreasure]

Welcome to the show Bowlegs.

I have two 12V 390W batteries connected in series to a 24V 2000W inverter and a 60A charge controller.
PS.... I usually have four wired in series parallel and that handles the fridge fine

Are you certain your remaining batteries and all other connections are torqued properly. Maybe there was an oversight when removing a couple of batteries from the system.

 

[Bowlegs868]

Welcome to the show Bowlegs.


Are you certain your remaining batteries and all other connections are torqued properly. Maybe there was an oversight when removing a couple of batteries from the system.

I would like to think so
'properly torqued' would translate to 'not loose', right? or are you saying there is a specific way in doing it?

 

[Abodyofscience]

115v x 1.5A = 173w, no problem.

173w/24v = 7.2A current draw, no problem.

A touchy inverter or controller?

Bad connection? At 7A no connection should have more than 0.2 millivolts across it, clamp to post.

 

[jberger]

How old are the batteries?
They look like UPS batteries and I'm guessing that you need more of them to support the inrush current if they are a few years old.
Have you tried load testing them separately? I'll be one of them will not hold up to load.

 

[Supervstech]

A refrigerator should pose zero issues for any inverter over 1000W… likely over 500W
Either the refrigerator has lost its start relay, or the inverter has an issue.
It could also easily be a battery assembly problem somewhere.
Go over every conductor with an unforgiving eye and make sure everything is right.
I like to upgrade my refrigerators with start capacitors instead of the shunt relay most come with. Drops the inrush time needed to startup and extends the life of the compressor.

 

[Bob B]

How are you charging your batteries? Do you have a DVM to do some voltage checks? How old are the batteries?
What is the voltage at the battery terminals before and after connecting to the fridge?

Did a quick look at the specs and those are really heavy batteries for about a 30 AH 12V battery.

 

[Bowlegs868]

115v x 1.5A = 173w, no problem.

173w/24v = 7.2A current draw, no problem.

A touchy inverter or controller?

Bad connection? At 7A no connection should have more than 0.2 millivolts across it, clamp to post.

That's why I'm confused because I wasn't expecting to have an issue with two batteries but it works with four so...??‍

Guess I should just accept that and stick to four batteries

How old are the batteries?
They look like UPS batteries and I'm guessing that you need more of them to support the inrush current if they are a few years old.
Have you tried load testing them separately? I'll be one of them will not hold up to load.

They're new batteries (according to the installer that supplied them)
Haven't tried load testing them but thanks for mentioning it... I'll look into getting that done

A refrigerator should pose zero issues for any inverter over 1000W… likely over 500W
Either the refrigerator has lost its start relay, or the inverter has an issue.
It could also easily be a battery assembly problem somewhere.
Go over every conductor with an unforgiving eye and make sure everything is right.
I like to upgrade my refrigerators with start capacitors instead of the shunt relay most come with. Drops the inrush time needed to startup and extends the life of the compressor.

Interesting... I'll do some more testing after checking the conductors but that stuff about upgrading the start relay is definitely something I will be looking into right away... Thanks for mentioning!

How are you charging your batteries? Do you have a DVM to do some voltage checks? How old are the batteries?
What is the voltage at the battery terminals before and after connecting to the fridge?

Did a quick look at the specs and those are really heavy batteries for about a 30 AH 12V battery.

Currently it's two batteries in series parallel and they're new (according to the installer)

I have a DVM and I've been checking them a lot lately... they read around 12.7V at night and between 13V-14V around mid day

I haven't tried turning on the fridge since being on two batteries instead of four because I know what usually happens with two batteries but I'll give it another try

These batteries are actually 100Ah

 

[Supervstech]

That's why I'm confused because I wasn't expecting to have an issue with two batteries but it works with four so...??‍

Guess I should just accept that and stick to four batteries


They're new batteries (according to the installer that supplied them)
Haven't tried load testing them but thanks for mentioning it... I'll look into getting that done


Interesting... I'll do some more testing after checking the conductors but that stuff about upgrading the start relay is definitely something I will be looking into right away... Thanks for mentioning!


Currently it's two batteries in series parallel and they're new (according to the installer)

I have a DVM and I've been checking them a lot lately... they read around 12.7V at night and between 13V-14V around mid day

I haven't tried turning on the fridge since being on two batteries instead of four because I know what usually happens with two batteries but I'll give it another try

These batteries are actually 100Ah

Amazon.com

 

[WYtreasure]

I would like to think so
'properly torqued' would translate to 'not loose', right? or are you saying there is a specific way in doing it?

Before I got to this forum I thought "not loose" was good enough.
Here's a source where you can find excellent reading material, the link is also in my signature.

Battery Melt Down Narrowly Averted - Marine How To

Note The Melting of The Battery Case (originally published July 2012) The connections to your batteries matter. How you make them, how you torque them and how clean they are all matter. Not following best practices or marine wiring standards can impact your personal

marinehowto.com

 

[Bob B]

That's why I'm confused because I wasn't expecting to have an issue with two batteries but it works with four so...??‍

Guess I should just accept that and stick to four batteries


They're new batteries (according to the installer that supplied them)
Haven't tried load testing them but thanks for mentioning it... I'll look into getting that done


Interesting... I'll do some more testing after checking the conductors but that stuff about upgrading the start relay is definitely something I will be looking into right away... Thanks for mentioning!


Currently it's two batteries in series parallel and they're new (according to the installer)

I have a DVM and I've been checking them a lot lately... they read around 12.7V at night and between 13V-14V around mid day

I haven't tried turning on the fridge since being on two batteries instead of four because I know what usually happens with two batteries but I'll give it another try

These batteries are actually 100Ah

It would be good to get the voltage reading at the battery terminals and at the inverter terminals while under load.

 

[Abodyofscience]

Yes, not getting to the root cause of this will cause it to come back later.

Troubleshooting skills are transferable to other domains.

 

[Bowlegs868]

Amazon.com

thanks! that's a big help ?

 

[Bowlegs868]

Before I got to this forum I thought "not loose" was good enough.
Here's a source where you can find excellent reading material, the link is also in my signature.

Battery Melt Down Narrowly Averted - Marine How To

Note The Melting of The Battery Case (originally published July 2012) The connections to your batteries matter. How you make them, how you torque them and how clean they are all matter. Not following best practices or marine wiring standards can impact your personal

marinehowto.com

ohh boy! imagine you can even mess up tightening things ?? but thanks for sharing!