Trailer Battery charge line?

[MattJ]

Please excuse my ignorance with electricity
I have read that using a 7pin trailer to charge your trailers battery wont fully charge it to 100% and will only maintain a charge and wont charge a more depleted battery back up again. The reason being they only supply 3-4amps. Will this charge the trailer battery the same way as the starter battery?

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[MattJ]

Amps aren't sent, they are drawn.
If the demand exceeds the fuse or the wire size the fuse will blow.
This system will recharge a partially depleted battery.


Not likely a problem on a low RV trailer battery without a load.
RV Batteries should not be discharged below 12.0V and are seldom discharged below 10V.
Many people charge the battery and keep a small fridge cold (for instance)

Awesome...thank you very much for your reply!!! I have a small teardrop camper and a new dometic fridge/freezer and I'm trying to get all prepared for road trips. I was considering getting a redarc 1225 to charge my battery...but not wanting to add any non Ford supported aftermarket parts and having to wire it in was kinda leery as I have a service contract and will be bringing it into dealer for services...and didn't want to have to remove anything I added before service to keep warranty good.

 

[Floyd]

Awesome...thank you very much for your reply!!! I have a small teardrop camper and a new dometic fridge/freezer and I'm trying to get all prepared for road trips. I was considering getting a redarc 1225 to charge my battery...but not wanting to add any non Ford supported aftermarket parts and having to wire it in was kinda leery as I have a service contract and will be bringing it into dealer for services...and didn't want to have to remove anything I added before service to keep warranty good.

To clarify...
The Ranger Trailer charge line charges the trailer battery... The trailer battery runs any accessories onboard the trailer.
Sort of a distinction without a difference.

 

[t4thfavor]

Do we know if there is an isolator/diode in the system? Like will it draw down the trailer battery if you say leave it plugged in, and run the truck battery flat?

 

[MattJ]

My current line of thinking is I will use the 12v power port in the truck bed to power the fridge and 7 pin to charge battery while traveling. Once to location I will run fridge off of batteries that I can help charge/maintain while parked with a solar setup I have. My trailer only needs the 4pin for its lights so i'm thinking if I wire my trailer to the 7 pin I can then run a jumper wire to my battery in rear of truck from the power slot on 7pin for charging while on the go.

 

[Floyd]

Do we know if there is an isolator/diode in the system? Like will it draw down the trailer battery if you say leave it plugged in, and run the truck battery flat?

There is no power to the trailer battery when the truck is off.

 

[Emma21]

I am a new rver and I want to know the ways to charge rv battery from vehicle? And It is a great convenience if I can recharge the RV trailer batteries while I drive. Thanks so much!

 

[RMD3819]

Not sure if this will help anyone......

I do a variation from others on this thread.

I tow my Ranger behind my RV and I use this product to keep the Ranger battery charged. I don’t see why it would not work on a trailer.

https://rvibrake.com/products/towed-battery-charger-plus?variant=13115309260823

 

[Emma21]

https://vogeltalksrving.com/how-to-charge-rv-battery-from-vehicle/
What do you think about this? I have found some information in this but I don't know if it's right or not. Who can give me some advices? Thanks

 

[Gil-galad]

Well my charge line works!
It has worked as designed since built.
It is not normal!
What is normal is that I had to figure it out for myself.

As we know, the Truck has an AGM battery and the charge system is designed for optimal care for that battery.
As it turns out, the charge line for the trailer is a part of a "TRM" Trailer Module which controls all 7 functions of the RV plug through the Module Communications Network... ostensibly via the ECM.

The truck will only recognize the trailer battery when several conditions are met, otherwise it will not submit power to the charge line.

1]The trailer battery must be low.
2] The trailer must be connected and recognized.
3] The engine must be running AND the brake engaged to initiate recognition.
4] You will not see a "normal" Voltage above 13V as in the past.
5] The TRM acts more like a smart charger than a conventional charger and shuts off when 12.7 or 12.8 is achieved.

As a result an ordinary pin test will only yield 0V.

With only one small clue as an exception, all this was determined through personal experimentation and perseverance.
I still expect that full support from local Ford techs will be forthcoming as they come up to speed on the Ranger.
Corporate is apparently no longer of any value to a Ford owner with a question or a problem.
Hopefully Ford will improve once again when they replace some of their present leadership.

The good news is that it appears now would be a good time to switch to an AGM RV battery if you primarily charge while towing.
You might still need to upgrade your onboard converter... "If equipped"... As Ford is want to say!

I can't understand why this valuable information isn't in the User's Manual. I've been gnashing my teeth all morning trying to figure out why the 12v connection on my new truck's 7-pin plug seemed to be dead when all other connections were functioning normally. I even scheduled an appointment with the local dealer's service manager to have it checked out. Now why wouldn't the service department have a canned response with the correct information available in order to avoid unnecessary service calls? This can't be the first time it's come up.

I asked the sales consultant at delivery last week if the 12v supply pin was hot or in need of a fuse. I should have known better. He was clueless.

I have a BT battery system monitor on my travel trailer but for the time being I'll be switching over to propane for in-transit refrigerator operation. I'd like to observe a history of the charging profiles before I trust it completely. I don't like showing up at a boondocking location with my house batteries at half capacity.

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