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Old 05-25-2018, 06:26 AM   #11
ddunaway
 
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

You can also adjust cut out voltages on this model but larger pipe as suggested is better........
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Old 06-05-2018, 12:13 AM   #12
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

Re ran the wiring to bypass the switch panel and took about 5ft of run length off as well...and it's working great! Much appreciated!
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Old 06-05-2018, 12:16 PM   #13
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

This chart might illustrate why thicker cable then one might expect is needed ...
Every time the compressor kicks in, there is an in-rush which lasts just a few seconds.
I sample the data every minute, so this momentary in-rush is not always captured (but does always happen)

Fridge Spike
by David, on Flickr
Fridge usually draws 35W when compressor on - spike increases that massively.

Not sure if US and UK standard are same (same electricity so should be, but different bodies see things differently), but a 12AWG cable is referred to as a 4mm cable in UK and has a rating of 41A in free space on minimal run.
This is the current draw on the spike above

Fridge Spike Amps
by David, on Flickr
And actually should add 16.4A (coming from Solar) onto that 47.1A draw - so that would be like 63.5A being pulled from the battery during the night - 95% of it due to the fridge.

So 10AWG would be a better cable option for anyone doing a new install unless you are nice and close to the house batteries (or even 8AWG if a distance).
(I am running an AC compressor fridge so via a 400W inverter (which does 900W peak so is ok on rush-in spike) and I am running 6AWG Cable for around 15 inches from battery posts to inverter inputs)
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Old 06-07-2018, 06:56 AM   #14
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

Wow - nearly 900 watt peak - more than I expected.
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Old 06-07-2018, 09:14 AM   #15
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

Those compressors have serious in-rush. The digital brushless compressors have a lower peak.
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Old 06-07-2018, 12:34 PM   #16
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

Most efficient DC compressor fridges burn 4A or less while cycling, and many electronics now include soft start features to reduce the startup surge.
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Old 06-07-2018, 07:56 PM   #17
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Default Re: 12v Fridge Compressor Won't Kick On Even With Full Batteries

Many (most?) DC fridges use a three phase AC compressor driven at lower voltages. The control unit is digital and slowly ramps up the input.
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compressor, electrical problem, fridge, troubleshooting

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