Electrical help

Long story short I installed a fridge over the weekend. I am seeing some pretty bad voltage drops and I think I have too much going on. When the truck is off and just sitting there I am reading anywhere from 12.7 v at the battery to 13.5( this is right after a drive).

I have a blue sea fuse panel (the 6 slot one) tied to the battery with a 4 gauge wire to 100amp breaker then 4g to the blue sea.

I used a 30 amp fuse and ran 10g all the way back to the bed of the truck and into a bed cubby. From there I have another blue sea fuse panel inside the cubby with a 15a fuse running to a 12v plug that my fridge is plugged into. The issue is the fridge keeps seeing a voltage drop and shutting down.

Do I have too much happening here and should I remove second blue sea all together run the 10g straight to the 12v plug then replace the 30 amp fuse with a 15a fuse?

 

You should start by checking the voltage at the fridge with your meter. When everything is off, it should essentially be the same as the battery (12.7v). But when the fridge turns on, then you can measure and see how much voltage drop is happening along that 10ga wire to the back. Keep in mind worst case should be when the truck is off.

Check out this article, specifically the wire sizing chart
https://www.bluesea.com/resources/1437

Edit: We also need to know what the max amperage draw of your fridge is. Values for both start-up current and normal operating current would be nice.
Personally I would run a single fused circuit back to the fridge. If you want a 2nd fuse box in the rear, run a new cable dedicated for that, sized and fused appropriately of course

 

Where did you ground the fridge?

 

would be helpful if you knew the amp draw

 

What fridge/size do you have? It's normal to have a lower voltage at the battery when the truck is off, vs when it's on and the alternator is going. I have a 10 gauge run going straight from battery back to an outlet and don't have issues with the fridge. Depending on the fridge, you can set the threshold for when it shuts itself off. I have my dometic on "medium" sensitivity.

 

Is 10 gauge wire enough? Seems too small for the distance and assuming the fridge would draw more than just a few amps.

 

So I just checked the voltage at the 12v socket. 12.4v which is weird because while I was in there I checked the blue sea 12.2. But the first blue sea I am only seeing 11.0v

 

10 awg is good for 30 amps

 

The fridge is a stakol. I didn’t want to invest into a dometic in the event we didn’t use it as much as we planned

 

Most fridges only draw a couple amps. They're wildly efficient. That's how you can run it for multiple days without starting the truck, usually.

 

The fridge is set to eco medium which according the owners manual means it will shut off at 11.9 v. The voltage meter on the fridge however displays only 9.9-10.2 volts.

the overall plan is to install a second battery ran off solar that would control the fridge. Since my truck is outside 99.9% of the time I assumed the solar would always keep that second agm battery topped off

 

^
This. Your fuses shouldn’t be a problem if the current draw of your fridge is less than ~75% of 15A = 11.25A with your fridge running. Like the man said check voltage at the fridge and the current draw specs (or measure current) of the fridge then look at the table he linked to and see if your 10awg wire is adequate.

 

What fridge do you have? What are the power requirements in the specs?

 

Check all your connections. A bad connection will drive up your total resistance of the system and cause your voltage to go down. Make sure they are clean, everything is tight

 

9.9-10.2 v tells me there are bad connection(s) somewhere. But again, you'll want to confirm that with a known good multi-meter and the fridge under load. Wouldn't be impossible for the fridges voltmeter to be defective (with that being said its still far more likely theres just a bad connection somewhere)

 

From the owners manual of the fridge

rated current for DC: 3.75/1.875a
Power 45w

 

like the man said you have to check all points for voltage under the same conditions. like the example the OP gave above you can not get higher voltage downstream in a circuit. You ether did not have good contact with the meter at one of the two points or the frig was not one when you measured one point and it was on on the second measurement....

 

45 Watt is 3.75 amps at 12 VDC. does it have a switch to tell it if you are using 12 0r 24 volt? live a toggle switch

 

I personally wouldn't run a fuse panel off of another fuse panel, I would use a 50amp breaker and place it next to the battery to run your rear fuse box.

Its also impossible to have voltage increase down stream, there's no way for voltage to just magically increase.

 

I am going with the assumption that you have a very large Stakol fridge. The one I found on Walmart says it has a rated power of 45W, which turns out to only be 3.75A at 12V. All things considered, you shouldn't have any issues. EDIT: Yes it is...

Let's assume you have 110Ah in your battery, so with this fridge you will have about 29.333 hours before the battery is fully drained, which we do not want to see. Depending on how long you leave the car off with the fridge on, I would not be surprised to see a huge voltage drop.

Worst case scenario, your battery might be old and not holding charge as well as it used to.