Wiring run for Fridge-- experts sound-off :)

tbird911

New member
Guys,

I have a 2016 Jeep wrangler 4-door. I have recently added some power distribution to the rear of the vehicle. I come off the factory battery with 4awg marine grade wire-to a Blue Sea Systems re-settable circuit-breaker...then 4 awg cable under the side door trim and into the small space under the rear removable cover of the center console. There, I have mounted a Blue Sea Dual Bus Bar Plus. All of this , to this point is 4 awg wire, crimped, loomed and heat-shrinked with great care. Then I come off of the dual pus with a fused (15 amp) cable run that is about 11 feet long (including the power-pole connected oem power cord that is 12awg- that finally connects to the end of the fridge. From the dual bus (the "break-out point" for all of this, I also run a 4 awg negative all the way back to the battery terminal for a solid grounding-- all of this design is done to minimize voltage drop.

The issue:

I plugged the SnoMaster 82d up last night to ground power so that it could cool down while I slept...and it did. My freezer side is set to 0 degrees and the fridge to 30 degrees. This am when I left for work I drove 15 minutes to the office and parked all day-- at the end of the day, the temps were 39--(from 0) and 69 (from 30 degrees.) The unit cooled down perfectly on ac power and it has previously worked fine using the cigarette lighter adapter--although I havent used it in over a month while I was wiring all of this stuff up.

Low voltage cut-off on the SnoMaster is set to 10.5. The voltage indicator on the fridge shows (at rest) 12.1-12.5, but when the compressor comes on, the voltage goes down to 11.1 to 11.3. When I used a meter to test voltage at the battery (vehcile off) I get 12.27 volts, at the dual bus bar - 12.27 volts - on the fridge 12.3-12.5.

What say you? my theory is that the 4 awg is fine, 12 awg is fine, no voltage drop shown- no warm wires -- but I think the battery seems suspect. I will say when driving the voltage reads 13.8 - 14.2 --- Kinda at a loss....
 

dwh

Tail-End Charlie
Battery voltage 12.27v at rest?

https://duckduckgo.com/?q=battery+state+of+charge+chart&iax=1&ia=images

That can't be healthy.


A 15 minute commute isn't long enough to add any significant charge to a lead-acid battery, and that gets worse as the battery state of charge rises. If you start out with the battery at ~60-70% you'll be lucky to get a couple amp hours into the battery in 15 minutes.

Seems like you've narrowed it down just fine. It's not the wiring, that's more than adequate. The fridge apparently works on 12v since you can see the voltage dropping when the compressor comes on.


So yea, seems like the battery is dodgy. Likely as a result of long term chronic undercharging.


It might be too late to recover that battery, even with a desulfating charger such as a 'Battery MINDer'. But your next battery will likely need a couple overnight sessions a week on a shore power charger to keep it healthy.
 

snowblind

Adventurer
Low voltage cut-off on the SnoMaster is set to 10.5. The voltage indicator on the fridge shows (at rest) 12.1-12.5, but when the compressor comes on, the voltage goes down to 11.1 to 11.3. When I used a meter to test voltage at the battery (vehcile off) I get 12.27 volts, at the dual bus bar - 12.27 volts - on the fridge 12.3-12.5.

What say you? my theory is that the 4 awg is fine, 12 awg is fine, no voltage drop shown- no warm wires -- but I think the battery seems suspect. I will say when driving the voltage reads 13.8 - 14.2 --- Kinda at a loss....
Hey T-Bird

The "SnowMaster" fridges look to use the same 12v controller as my Whynter/Edgestar. From my experience that controller measures the battery voltage AFTER some sort significant internal voltage drop. IE - You're not seeing the actually battery voltage on the fridge display but (actual battery voltage - internal drop)

This internal drop is ONLY present when the fridge is cycling. Your batt voltage will jump up on the fridge display when the compressor goes off and drop back down when it kicks on. Unfortunately I have not figured out a decent way to fix this problem. For me the ideal fridge would have NO voltage cut off so I could manage that with a different device.

NOTE - A little background on how I figured this out. When using a Goal Zero Yeti 400 a forum member gets considerably more run time from his fridge using the Inverter instead of direct 12v. The only possible way for that to work is if the inverter is accessing more battery reserve than 12v. Conclusion was that the fridge was seeing ower than actual voltage when under load.


Matt
 

grogie

Like to Camp
Hey T-Bird

The "SnowMaster" fridges look to use the same 12v controller as my Whynter/Edgestar. From my experience that controller measures the battery voltage AFTER some sort significant internal voltage drop. IE - You're not seeing the actually battery voltage on the fridge display but (actual battery voltage - internal drop)

This internal drop is ONLY present when the fridge is cycling. Your batt voltage will jump up on the fridge display when the compressor goes off and drop back down when it kicks on. Unfortunately I have not figured out a decent way to fix this problem. For me the ideal fridge would have NO voltage cut off so I could manage that with a different device.

NOTE - A little background on how I figured this out. When using a Goal Zero Yeti 400 a forum member gets considerably more run time from his fridge using the Inverter instead of direct 12v. The only possible way for that to work is if the inverter is accessing more battery reserve than 12v. Conclusion was that the fridge was seeing ower than actual voltage when under load.


Matt
I have also noticed this drop with my new Snomaster 42. Yesterday, I got in my Jeep at work and it was running of an auxiliary Bluetop. The alarm was beeping as I had the cut off at 11.7v, and it said the battery had reached that. So I lowered the cut off, and the fridge came back on. When I got home, I checked the battery and at rest it was at 12.2v.

Also, that's interesting about using an inverter instead of a direct connect. My immeidate qustion about that is about the added power draw of the inverter? (If it's much at all?)

Thanks for the information.
 

tbird911

New member
This ended up being a battery on its last leg-- replaced with a NorthStar AGM34 and problem solved. Waiting to hear back from snomaster on the other issue which made this issue a challenge to troubleshoot. It seems that if I run the fridge on AC power to cool down overnight and then unplug the AC voltage--without also unplugging and replugging the DC power cord, the Fridge will show the auto-switch from AC to DC but the compressor will not come back on-- and over time the fridge will warm up inside. I thought that maybe I needed to power the fridge off then unplug the AC (allowing for a "proper shutdown", but the issue remained. Side note-- once I unplug the AC, and then re-plug the the DC the cooling doesnt start again immediately-- but it kicks in at exactly 3 minutes. This 3 minute time, seems to correspond with a "cut-out" that I've hear about which as something to do with voltage protection. So, as I said- waiting to hear back from SnoMaster. Anyone else had this problem?
 

tothetrail

New member
Any resolution to this? I have a Snomaster fridge running off two brand new batteries and the voltage reading, while the compressor is running, is usually about 1.5 volts less than what the Victron monitor is showing for the batteries. This is through an Anderson connector.

When plugged directly into the Goal Zero, along with the Goal Zero lithium regulated cable, the voltage is a pretty constant 13.5-14, even when running.
 
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