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Towing Alto trailer - electric question

doghousePVD

My grandfather’s car
Dec 3, 2018
678
624
New England, USA
On maiden camping trip with 2018 100X towing a Safari Condo A2124. Had some intermittent 12 V issues earlier, which a new 12 V battery seems to have resolved.

The 7 pin plug charges/connects the trailer and car batteries. On an ICE car, it trickle charges the trailer battery - generally a good thing.

Since every mile counts when pulling a trailer, the last thing I want is discharging the car for the trailer. The trailer has PV, and we usually are in a RV park and can plug in.

Is there any downside to unplugging the fuse in the trailer so the batteries can't charge each other?

Related to this, does it make sense to keep the fridge (gas/12V/120V) turned on with 12 V? One shouldn't drive with the propane on. I know electric is terribly inefficient, but it would only be while driving, and the battery is topped off each night. At night we use the shore power to run the fridge.
 
Related to this, does it make sense to keep the fridge (gas/12V/120V) turned on with 12 V? One shouldn't drive with the propane on. I know electric is terribly inefficient, but it would only be while driving, and the battery is topped off each night. At night we use the shore power to run the fridge.
Some people, out of overabundance of caution, turn off the propane while on the road, but RV propane refrigerators are designed to safely run while moving down the road. Some tunnels and ferries require you to shut the propane off at the bottle before traveling in those areas, but otherwise, leave the refrigerator in propane or auto mode. Keeps food from spoiling, the beer cold, and the ice cream firm, too.
Refrigerator in propane mode uses much less 12v power than when in 12v mode.
 
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ShawnA

Active Member
Supporting Member
Nov 13, 2017
1,102
859
Edwardsburg, MI
Hi @doghousePVD ,

The battery charge is only supposed to go one way >>> Toward the trailer while the car is "On."
That is if you use the standard "hot" pin in the 7 pin connector.

Someone on the forum had horrible problems back-feeding the car from the trailer.
The car sees voltage coming from the trailer and goes crazy - if you back-feed from the normal circuit.
There should be a diode to prevent this back-feed.
If you want the diode you will have to install it...

Check out this thread for a reference:

Power Limited - Please Schedule Service - Potentially Trailer Mode Related?

Good luck,

Shawn
 
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ngng

Active Member
Jul 23, 2018
1,520
836
Bay Area
On maiden camping trip with 2018 100X towing a Safari Condo A2124. Had some intermittent 12 V issues earlier, which a new 12 V battery seems to have resolved.

The 7 pin plug charges/connects the trailer and car batteries. On an ICE car, it trickle charges the trailer battery - generally a good thing.

Since every mile counts when pulling a trailer, the last thing I want is discharging the car for the trailer. The trailer has PV, and we usually are in a RV park and can plug in.

Is there any downside to unplugging the fuse in the trailer so the batteries can't charge each other?

Related to this, does it make sense to keep the fridge (gas/12V/120V) turned on with 12 V? One shouldn't drive with the propane on. I know electric is terribly inefficient, but it would only be while driving, and the battery is topped off each night. At night we use the shore power to run the fridge.

if your camper has solar, disconnecting the 12v seems unnecessary. your camper battery(ies) are already going to be charged, and the 12v through the trailer connector is negligible. especially compared to all the other electronics in your x.

i would also double check and verify (if equipped) your trailer's emerg breakaway battery is still being charged as this is usually supplied through the trailer harness
 

MXWing

Well-Known Member
Supporting Member
Oct 13, 2016
7,718
23,880
USA
Notice the vehicle in the screenshot of the youtube video? :)

1620413044479.png
 

ecarfan

Well-Known Member
Moderator
Related to this, does it make sense to keep the fridge (gas/12V/120V) turned on with 12 V? One shouldn't drive with the propane on. I know electric is terribly inefficient, but it would only be while driving, and the battery is topped off each night. At night we use the shore power to run the fridge.
I always leave my Alto fridge (electric only) running while towing; in fact I leave it on all the time even when my trailer is in storage. But I have over 700W of solar panels on the trailer and 600Ah of LiFePO batteries.

Not sure I would describe an electric fridge as “terribly inefficient”.
 
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dmurphy

Active Member
Supporting Member
I always leave my Alto fridge (electric only) running while towing; in fact I leave it on all the time even when my trailer is in storage. But I have over 700W of solar panels on the trailer and 600Ah of LiFePO batteries.

Not sure I would describe an electric fridge as “terribly inefficient”.
We have a 12V Norcold compressor fridge in our Surveyor, and not only would I not say "terribly inefficient"... I'd say it's exactly the opposite -- very efficient indeed. I've got a 150Ah Ohmmu battery on the Surveyor and 80W of solar panels -- so not nearly as well equipped as you -- but we can run the fridge for 4-5 days without concern. If I fire a generator or plug into shore power, it can be almost infinite. We don't do dry camping, so it's just perfect for us.
 

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