Charging while towing

[terrymorse]

In case the wiring of a DC-DC converter/charger is unclear to anyone, Renogy has a simple diagram to use with their converter:



Renogy's unit can be configured to only charge when the engine is running, but it does require running a separate wire from the ignition to the unit.

Here's where I found that diagram: Renogy 12V 20A DC to DC On-Board Battery Charger

[angelagbra]

I note that these posts are from 2009....but....For some reason, our battery in our TTT does not charge. We have a 2017 Ram truck and a 7 prong plug. Are you supposed to unplug it at night? Could that be the problem? Is there anyone still on this post? Thanks.

[Tom&Shelly]

I note that these posts are from 2009....but....For some reason, our battery in our TTT does not charge. We have a 2017 Ram truck and a 7 prong plug. Are you supposed to unplug it at night? Could that be the problem? Is there anyone still on this post? Thanks.

A lot of us check out the newest posts on the folder, so we're here. How long have you had your TTT? How old is the battery? Has it charged before while you were towing it?

Unlikely it is simply a problem of leaving the plug in overnight. Some vehicles shut off when the auxiliary power when the vehicle's engine is off, others leave it connected to the vehicle battery. I'm not sure about the 2017 RAM truck. The potential issue is really discharging the vehicle's battery.

You may have some bad wiring, or an old battery, or something else. We need a few details to help diagnose it.

Tom

[Pugwinkle]

A lot of us check out the newest posts on the folder, so we're here. How long have you had your TTT? How old is the battery? Has it charged before while you were towing it?


Tom

I'm glad someone is still here!
I have a 7 prong on my TV and a 4 prong on my TD. Do I simply have to change my 4 pin to a 7 pin so that I can charge my battery while I'm driving? If so, can you give me a link to what I need to purchase. I'm in Canada so if you can find something on Amazon.ca or Canadiantire.ca that would be appreciated.

[troubleScottie]

Generally speaking the 7pin does not have the power or wire gauge to allow charging ie 20-40A. It is designed to run small items -- emergency break battery charger for instance

Think like you are attaching a big subwoofer or amplifier for you car. Large gauge eg 4awg. You would do well to run a separate line (well 2) from the battery to the TD with fuse, isolation switch, anderson connectors, glands, etc. Good example on page 15 or 16 with pictures.

The gauge is dependent on distance and power draw. There are charts.

[Tom&Shelly]

A lot of us check out the newest posts on the folder, so we're here. How long have you had your TTT? How old is the battery? Has it charged before while you were towing it?


Tom

I'm glad someone is still here!
I have a 7 prong on my TV and a 4 prong on my TD. Do I simply have to change my 4 pin to a 7 pin so that I can charge my battery while I'm driving? If so, can you give me a link to what I need to purchase. I'm in Canada so if you can find something on Amazon.ca or Canadiantire.ca that would be appreciated.

Ok, so you can't charge the battery with a 4 pin connector, so the question is: Can you change that for a 7 pin connector and then take the aux power out to your battery to charge? Short answer is yes.

We used a 10 gauge wire from the trailer connector to our battery. That and the stock wire from the Tacoma (also 10 gauge, IIRC) and we were able to charge our battery from a night or two's use in about a 5 hour drive.

If you want to improve performance, you might try a DC/DC converter that will step up the voltage a little to what the trailer battery wants to see. I can't recommend a specific device because I haven't tried this. (I am an electrical engineer, and that makes sense.)

Tom

[featherliteCT1]

What would happen if you connected a Lifepo4 battery to the tow vehicle’s starter battery without utilizing a DC to DC charger like the Renogy model shown in the first post of this thread?

[Tom&Shelly]

What would happen if you connected a Lifepo4 battery to the tow vehicle’s starter battery without utilizing a DC to DC charger like the Renogy model shown in the first post of this thread?

It would be bad

https://www.youtube.com/watch?v=wyKQe_i9yyo

Unless the battery has built in current limiting electronics. You need something to limit the current into those kind of batteries. I forgot to mention, in my comments above, I assumed a lead-acid battery. Good safety tip.

Tom