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JJH3rd · 04-17-2019, 11:37 PM

Our 05 Dolphin 5342 has a Xantrex Fredom 458 inverter/charger and two new 12v 800 amp/hr deep cycle batteries in parallel (~ 1600AH).

Would operating the Norcold 1200 (3.5 A/Hr) on 120V generated by the inverter for about 8 hours a day (drive time) kill the batteries?
Inquiring minds want to know (befoer I ruin the new batteries)

Skip426 · 04-17-2019, 11:58 PM

The fridge won't be running, ( drawing power ) continually when it's down to temp , and the engine alternator should stay ahead of the draw while driving .

Stopping for lunch , start the gen set or switch to propane .

twinboat · 04-18-2019, 12:15 AM

First off, a 12 volt 800 AH battery would be huge, or about the equivalent of about 8, standard 12 volt batteries.

I'd guess that you have 2, 800 CCA, 4D or 8D, batteries, maybe 225 AH each.

Beyond that, the fridge will draw about 40 amps @12 volts, while running thru the inverter. Not bad as long as the engine is running and they should last 4 to 6 hours, while the engine is shut down.

As far as the fridge cycling on and off, absorbsion fridges tend to run almost constantly in hot weather.

Its A lot of energy trading, for a small amount of propane.

vsheetz · 04-18-2019, 12:20 AM

The norcold 1200 is very power hungry on 120vac. For this reason, the unit is usually not on a inverted circuit. Much better to operate it on propane, where it's very efficient.

Rick 2005 Dolphin 5376 · 04-18-2019, 06:14 AM

I do it all the time. I've gone as long as 14 hours and still had battery life left over

JJH3rd · 04-18-2019, 10:51 PM

We have been letting the Norcold run on propane while moving but it doesn't seem to stay cold (lots of defrosting & water dripping). We don't see that when on 120v so that is why the question about using the inverter & 120v while in motion.

BTW from the Xantrex users guide:
"Deep cycle batteries are usually rated in amp hours. The amp hour rating is based on a 20-hour discharge rate; ... a 100 amp-hour battery can deliver 5 amps for 20 hours."

Norcold tech specs claim 3.5amp-hour, & the Xantrex 485 claims .12a. So if JUST the refrigerator is running from the inverter, it "should" draw less that 4ah (average)

The tech specs on the batteries claim 80AH (not 800) each X 2 in parallel = 160AH

So 160AH/4A = 40 hours to 100% depletion, so < 10 hours use should be about 25% or less depletion

Is this logic / math sound?

Mr_D · 04-18-2019, 10:56 PM

120 volt draw through your inverter from your batteries is approx 10 times the amps so 3.5 amps is actually 35 amps from your batteries.
Batteries should never go below 50% so you have 80 amp hours to use or a little more than 2 hours of run time to needing to recharge.

twinboat · 04-18-2019, 11:11 PM

Quote:

Originally Posted by JJH3rd

We have been letting the Norcold run on propane while moving but it doesn't seem to stay cold (lots of defrosting & water dripping). We don't see that when on 120v so that is why the question about using the inverter & 120v while in motion.

BTW from the Xantrex users guide:
"Deep cycle batteries are usually rated in amp hours. The amp hour rating is based on a 20-hour discharge rate; ... a 100 amp-hour battery can deliver 5 amps for 20 hours."

Norcold tech specs claim 3.5amp-hour, & the Xantrex 485 claims .12a. So if JUST the refrigerator is running from the inverter, it "should" draw less that 4ah (average)

The tech specs on the batteries claim 80AH (not 800) each X 2 in parallel = 160AH

So 160AH/4A = 40 hours to 100% depletion, so < 10 hours use should be about 25% or less depletion

Is this logic / math sound?

4 amps at 120 volts = 40 amps at 12 volts.

With that figure, the math changes significantly.

With a healthy charging system and constant traveling, it can be done. Just don't take long breaks without switching to gas.

gpounder · 04-18-2019, 11:23 PM

I get why the inverter does not run the Norcold but I would like to run the Icemaker. I am doing a 12 volt compressor upgrade and while the box is out I will run 110 VAC inverter line to the icemaker.

vsheetz · 04-18-2019, 11:46 PM

I initially missed you want to power from the inverter while traveling. So updating my responce. If charging is occuring while traveling it should be ok. I used to do this. But dont leave it parked without charging for long.

RandyKoth · 05-02-2019, 07:16 PM

Have you checked your 1200 to see if the Recall/service bulletin has been performed??

If not stop using it!
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That being said, I am curious why you would want to run it off the inverter and not propane. It doesn't consume very much. As compared to the propane heaters. I did read that it doesn't cool as well. Not sure why that it happening but there could be something in the flue keeping the heat from the flame from rising.

One last suggestion I know that works is to pull the fridge and turn it upside down for a week. And while you have it out if there are a couple of fans attached to the fins it's a good time to inspect them. After a week turn it right side up and reinstall it and allow it sit overnight. It should cool fine after that.