Powering 12 volt freezer from trailer connection

[bclinton]

Looking for some suggestions on powering my 12 volt fridge/freezer while it rides in the back of my Prius riding on my tow dolly. Right now I use a 7 pin to 4 pin connector to the dolly for lights. There appears to be a 12 volt power lead on the 7 pin that is not used now. Would like to be able to keep the fridge going without using the prius power (don't want to chance draining the battery). The fridge needs about 40 watts. What would be the easiest/safest way to use that lead to get power to the rear of my prius while it is on the dolly?

[DES-1]

You want to use the power line on the 7-pin from the Prius, yet you don't want to use the power from the Prius for fear of running down battery?.


You've just ruled out the simplest way to power the fridge.



You could add another battery to run the fridge and connect it up to the Prius battery/alternator with a battery isolator, essentially a relay that disconnects the 2nd battery when the car isnt running. That way, fridge can only run down the 2nd battery.


If this is an occasional ad hoc use, your better off just remembering to unplug the fridge when you stop the car.

[bclinton]

Originally Posted by DES-1

You want to use the power line on the 7-pin from the Prius, yet you don't want to use the power from the Prius for fear of running down battery?.


You've just ruled out the simplest way to power the fridge.



You could add another battery to run the fridge and connect it up to the Prius battery/alternator with a battery isolator, essentially a relay that disconnects the 2nd battery when the car isnt running. That way, fridge can only run down the 2nd battery.


If this is an occasional ad hoc use, your better off just remembering to unplug the fridge when you stop the car.

Right now I am only using a 4 wire adapter to the tow dolly. Nothing is currently connected to the Prius. The 7 pin from the MH is converted to a 4 pin for the dolly lights. I'm thinking about running a 10 amp wire from the power pin on the MH to the battery terminal of the prius along with a circuit breaker. That should be able to maintain the prius battery while the fridge draws from it.

[wrapperman]

I use a 7 pin connector to a 6 pin trailer plug so then, you could cut off the 4 pin connector on your trailer and attach a 6 pin receptacle. Then use the 12 volts at that 6 pin receptacle to power your fridge. Does this make sense?
I do it this way so I can keep my Honda CRV's battery charged while towing it.

[rsdata]

quick and easy

a LI-ion portable jump starter with a 12V adapter plug should supply 40 watts for hours if not a full day... plug into 120 VAC to recharge at the end of the day.

Other brands models do about the same... from Walmart and others

$60 on sale or with 20%off coupon

https://www.harborfreight.com/lithiu...ack-62749.html

[bclinton]

Originally Posted by rsdata

quick and easy

a LI-ion portable jump starter with a 12V adapter plug should supply 40 watts for hours if not a full day... plug into 120 VAC to recharge at the end of the day.

Other brands models do about the same... from Walmart and others

$60 on sale or with 20%off coupon

https://www.harborfreight.com/lithiu...ack-62749.html

I looked at these but they look like they would only power it for an hour or 2 unless I am reading the specs wrong. The Jackery type battery packs are rated in watt hours and would probably work but for a 300 WH pack,which would keep it up for a 8 hours but they run upwards of $300. Just tryong to come up with a cheaper solution

[bclinton]

Originally Posted by wrapperman

I use a 7 pin connector to a 6 pin trailer plug so then, you could cut off the 4 pin connector on your trailer and attach a 6 pin receptacle. Then use the 12 volts at that 6 pin receptacle to power your fridge. Does this make sense?
I do it this way so I can keep my Honda CRV's battery charged while towing it.

Yes, that makes sense. I think I will go that route

Thanks!

[TitanMike]

Why not just add a 7-wire cord to your tow dolly. Attach lights to the appropriate wires. Extend a separate negative and positive wire from the 7-wire cord to a stand alone 12 volt power receptacle that can be run in through a window of the Prius and then power the freezer.

This would give you a direct connection from freezer to tow vehicle 12 volt system. This 12 volt supply line could have an SAE 2-pin connector near the 7-wire from the tow vehicle so the excess wire and receptacle could be stored when not needed and not left to possibly drag on the highway.

Just a thought and if I had a similar setup this is what I'd "build".

[rsdata]

quick and easy

MY BAD...

misplaced a decimal point... yup maybe 3 hours of run time using the 12,000 mAh they publish...

sorry I mislead you

[bclinton]

Found this on Amazon. Looks like the way to go.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Thanks!

[bubbles]

Not 100% sure about your GT3 but the GT 378 has a trailer charge line to the 7 pin toad connector. Look at the upper right corner of this view and you will see a trailer charge line powered via the MH chassis battery. Not sure which pin at the 7 pin connector it is connected to.

[TitanMike]

Originally Posted by bclinton

Found this on Amazon. Looks like the way to go.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Thanks!

That could work. Just plug dolly into 4-pin and get Plug that matches receptacle to run the + and - leads back to your freezer.

Not what I had in mind when posting but it too could work.

[DouglasReid]

Ya know, I just finished installing a Marine 12V outlet in the bed of my pickup for precisely the same reason.

I ran a separate power wire from the under hood fuse box (using an "Add A Fuse"). I used a fuse that is not powered up when the key is off so as not to drain the truck battery if we have any extended stops.

Going to test it out on our next trip the first weekend in March when we are going to Pensacola.

[bclinton]

Originally Posted by bubbles

Not 100% sure about your GT3 but the GT 378 has a trailer charge line to the 7 pin toad connector. Look at the upper right corner of this view and you will see a trailer charge line powered via the MH chassis battery. Not sure which pin at the 7 pin connector it is connected to.

Yup. Same setup.

[5picker]

I agree with TitanMike... just convert your tow dolly to a 7 pin and use the extra wires to charge the toad battery or just the fridge whatever you choose. I'd sooner have the toad battery in the mix as charging ballast.

You can use adapters but every connection causes resistance and voltage loss. Eliminate them all and wire up the proper umbilical cord to your tow dolly and be done with it.

[Doug Eichel]

RVi has a product called a toad charger for just this purpose. I use one to keep the battery in my toad charged while towing behind the MH. It gets its power from the 7 pin connector and work’s great.

[bclinton]

So....my plan is to use this to keep the fridge going while in the tow car......my normal max driving day is about 6 hours so this should just about cover that. If it doesn't I will install a charge line from the RV to this battery to keep it charged. This battery looks like it could be useful for many things.....

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Iggy]

If its just a 12 volt freezer why not just add a 12 volt plug in the motorhome from the house batteries and you can keep the portable inside the motorhome while driving.

Just a thought

[bclinton]

Originally Posted by Iggy

If its just a 12 volt freezer why not just add a 12 volt plug in the motorhome from the house batteries and you can keep the portable inside the motorhome while driving.

Just a thought

You make a good point....my initial reason was for space but I have more room now that I removed my jackknife sofa. I may give that a shot. I'm probably over thinking this my number one flaw!