Towing Alto trailer - electric question

[doghousePVD]

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.

 

[glide]

I thought Tesla disabled the 12V connection on the Model X for towing?

 

[sdmack]

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.

 

[ShawnA]

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

 

[doghousePVD]

I pulled the fuse in the trailer to disconnect the 12 volt connection. I never want the car to supply power to the trailer and viceversa.

I have PV on the trailer so it gets charged, and I never want the car to waste range to the trailer.

 

[ngng]

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]

Notice the vehicle in the screenshot of the youtube video?

 

[ngng]

Notice the vehicle in the screenshot of the youtube video?

View attachment 660308

"most efficient trailer to tow" i was getting better efficiency towing an open trailer that weighed 1000lb more

 

[Len_X_from VA]

"most efficient trailer to tow" i was getting better efficiency towing an open trailer that weighed 1000lb more

Hi, how did the trailer affect mileage for you? I have been planning to buy this trailer.

 

[ngng]

Hi, how did the trailer affect mileage for you? I have been planning to buy this trailer.

I don't own the Alto

 

[ecarfan]

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”.

 

[dmurphy]

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.

 

[doghousePVD]

A gas/electric fridge is very inefficient when using electricity.

A DC compressor electric fridge is often very efficient.

My fridge is gas/electric. Electric only was not available on my model.