Trailer Battery Charging

[schultz51]

Hello everyone,
I'm new to the forum and perhaps the question has been asked and answered but here goes anyway; I just bought a 2010 Palomino Gazelle 215 to tow behind my 2000 Toyota Tundra. I bought a Prodigy 2 brake controller and the wiring installation kit from eTrailer. Install was straight forward and everything works great. My question concerns charging the trailer battery through the 12v hot lead (black wire) that comes through the 7-way plug through a 40 amp circuit breaker from the truck battery. Is the trailer wired to accept charging from the pickup through this connection while driving or do I need to connect the trailer battery in some other fashion to charge it from the pickup charging system? I disconnected the trailer battery positive wire, plugged the trailer wiring (7-way plug) into the pickup, started the pickup and while running checked to see if there was 12v coming to the disconnected positive wire. There was no voltage at the wire. This leads me to believe the battery does not get charging power through its connection to the pickup. If this is true, has anyone come up with a solution. Thank you for your help and suggestions.

[DougP47]

I think there might be another way. If you can run an extension cord from a 115vac (house circuit) plug your tt. That might charge it as well. Not sure if you have this set up or not. I think that when you took off the pos lead you opened up the circuit and it will not charge because it’s no sensing a load. Check with Herk he would be the man. Best of luck

[TURBS]

Hello and welcome to the forum !
congrats on the palomino !

your camper 7 way "should be wired to charge battery" .
What you have to understand is you bought used so someone may have not hooked it back up when and if they replaced the 7 way at one time .

Are you sure you have power coming out of the truck end ?
if so

Pull apart camper end and make sure the wire is connected there .
if it is

Follow cable back to the junction box " normally just under the hitch" and open it up to see if wire is connected to battery positive wire .

On one occasion I seen a curcuit breaker attached to the tv charge wire and it was bad so check for that as well.

TURBS

[TURBS]

Originally Posted by DougP47

I think there might be another way. If you can run an extension cord from a 115vac (house circuit) plug your tt. That might charge it as well. Not sure if you have this set up or not. I think that when you took off the pos lead you opened up the circuit and it will not charge because it’s no sensing a load. Check with Herk he would be the man. Best of luck

True the shore power cord will charge battery.

Not true that if battery cable is removed that there shouldn't be 12v their if its wired correctly through the vehicle and the tester has a good ground.

[DougP47]

By the way Congratulation on your new TT welcome to the forum .

[WolfWhistle]

Originally Posted by schultz51

Hello everyone,
I'm new to the forum and perhaps the question has been asked and answered but here goes anyway; I just bought a 2010 Palomino Gazelle 215 to tow behind my 2000 Toyota Tundra. I bought a Prodigy 2 brake controller and the wiring installation kit from eTrailer. Install was straight forward and everything works great. My question concerns charging the trailer battery through the 12v hot lead (black wire) that comes through the 7-way plug through a 40 amp circuit breaker from the truck battery. Is the trailer wired to accept charging from the pickup through this connection while driving or do I need to connect the trailer battery in some other fashion to charge it from the pickup charging system? I disconnected the trailer battery positive wire, plugged the trailer wiring (7-way plug) into the pickup, started the pickup and while running checked to see if there was 12v coming to the disconnected positive wire. There was no voltage at the wire. This leads me to believe the battery does not get charging power through its connection to the pickup. If this is true, has anyone come up with a solution. Thank you for your help and suggestions.

If the power lead, via the 40Amp fuse/breaker you mentioned, is connected properly, as in the trailer battery is wired properly... including grounded to the trailer frame, then yes the truck should charge the trailer battery. Take a look at this youtube video in case you don't know how to test the 7way connector and plug.

trailer 7 pin plug how to test - YouTube

[TeJay]

If everything is hooked correctly when you are plugged in and truck running the voltage at the camper battery (B+) should be close to the same voltage as at your truck B+. It's usually something above 13-volts. You can measure your camper B+ first unhooked from truck. It should be around 12.4 volts. Plug in, start truck and measure B+ voltage at camper. It should be around 13.6 volts. The charging voltage depends on a lot of factors but it has to be above your camper battery voltage by at least 1 volt. You will need a digital volt meter to measure voltages in the tenth's accurately.
TeJay

[38FLCamper]

Welcome to the group and congrats on your rig!

I did a quick look around on the Tundra - seems as most people indicate on the 2000/2001 the trailer plug may not have been setup with a charge line or maybe missing the relay and fuse. As suggested - I would put a meter on the truck plug to see if you even have 12 volts on the charge line.

There is a PDF file at this link that might help you:

7 pin trailer wiring

[Triguy]

I wonder if the Bargman plug is wired correctly? Its not clear to me, but both the trailer and/or the TV are used so maybe someone miswired a replacement or even disconnected the 12v battery power function. A circuit tester would be useful here.

[Herk7769]

Lots of good stuff here. I would add that the 12 volt line on your trucks' connector needs to be powered from your trucks battery fuse compartment.
You might need to make sure there is a fuse inserted in the correct socket and the wire is actually connected to the fuse block.

As shipped from the factory, GM products are "wired but not connected." You need to hook it up to make it work. Don't know about Tundras.

[schultz51]

Thank you for the great suggestions. I do have a multimeter but it is not digital so difficult to check exact voltage. I'll pick up a digital unit today and check to see how much charging is happening at the trailer battery when hooked up to the pickup. Hopefully it is in the 13+ range. If not, I'll follow the wiring back to find out where the issue is. I would have thought that I should get at least 12v on the wire going to the positive side of the trailer battery when disconnected from the battery but hooked up to a running truck. That kinda of tells me there is not a direct connection and I'll try to figure that out. Thanks again everyone and I'll let you know the results. Doing a little shake down cruise this weekend to Quartzite AZ. It's our first trailer and a new experience. We've been tenting out of our 37 Pontiac for the last 14 years and will have real walls for a change. New is good eh.....

[schultz51]

The truck came with a flat 4 connection. The kit from eTrailer uses the flat four and adds two 10g wires that run from the 7-way up to the engine compartment. The 12v hot lead runs to a 40amp circuit breaker and the positive side of the battery. The other 12g wire goes to the brake controller in the cab. The hot lead from the 40amp cb is hot at the 7-way and all the lights, turn signals and brakes function properly. I need to use the multimeter to check to see if the positive line to the trailer battery is getting 13+ volts when hooked to the running truck. I don't think it is based on what I've already checked. Everything seems to be working properly except (and I don't really know yet) the charging part.

[DougP47]

Schultz51

I just brought me tt home from dealer after warranty wirk completed. After hooking the tt up did my usual checks on light. Found i had nothing, check fuse box no blown fuses. Ehat i found was the 7 pin plug was un plugged just behind the plug. It was unplugged going to wire tie that connection. Just a thought might want to check yours and anyone else for that matter. Best of luck

[WolfWhistle]

If you have power at the power lead on the 7way, you can light a test lamp... and with them UNPLUGGED from each other, the same pin on the trailer pin you light the test lamp, you are connected and the trailer battery should charge. If you get light, you shouldn't need a digital meter. If its 12.6VDC (MOL) without the engine running, it will be higher when running. All 12VDC in the fuse box is being "charged" when the engine runs, if this makes sense. If not, even the truck battery isn't being charged. Let us know how it goes. Good coments all you other "helpers".

[BillyBass]

I do know you have to have the battery hook up for the brake to work.I have a disconnect for my battery I was told that I had to make sure I had the disconnect pull out so my brakes will work.When I had my old trailer I went to get it inspected I didn't have a battery and they wouldn't inspect it

[jeeplj8]

Originally Posted by schultz51

The truck came with a flat 4 connection. The kit from eTrailer uses the flat four and adds two 10g wires that run from the 7-way up to the engine compartment. The 12v hot lead runs to a 40amp circuit breaker and the positive side of the battery. The other 12g wire goes to the brake controller in the cab. The hot lead from the 40amp cb is hot at the 7-way and all the lights, turn signals and brakes function properly. I need to use the multimeter to check to see if the positive line to the trailer battery is getting 13+ volts when hooked to the running truck. I don't think it is based on what I've already checked. Everything seems to be working properly except (and I don't really know yet) the charging part.

This wiring concerns me. It sounds like you have a hot lead to your trailer ALL the time. Most vehicles are wired so that the 12v lead to the trailer is only powered when the vehicle is on. In your case, you will be drawing power of the tow vehicle battery whenever a trailer is hooked up. That could lead to discharge of the tow vehicle battery when parked (not running) and leave you stranded.

To your original question, your trailer is wired so that whenever there is power coming from the tow vehicle it will not only charge your trailer battery, but should work any 12v devices in the trailer.

[BillyBass]

Originally Posted by jeeplj8

This wiring concerns me. It sounds like you have a hot lead to your trailer ALL the time. Most vehicles are wired so that the 12v lead to the trailer is only powered when the vehicle is on. In your case, you will be drawing power of the tow vehicle battery whenever a trailer is hooked up. That could lead to discharge of the tow vehicle battery when parked (not running) and leave you stranded.

To your original question, your trailer is wired so that whenever there is power coming from the tow vehicle it will not only charge your trailer battery, but should work any 12v devices in the trailer.

You can go from 7 to 4 but not 4 to 7 because I have adapter for my boat and it the flat four because i don't need a electric brake for it.

[jeeplj8]

Originally Posted by bill flick

You can go from 7 to 4 but not 4 to 7 because I have adapter for my boat and it the flat four because i don't need a electric brake for it.

I think you may have missed the OP explanation of his kit. I takes the OEM Toyota 4 wires (running lights, left turn/brake, right turn/brake and ground) and adds two more circuits (12v power and electric brake) by running direct wires to the engine compartment (battery) and firewall (brake controller.) That gives him a total of 6 circuits (he is missing the yellow auxiliary circuit most often used for reverse lights.)

The problem is in how the 12v power is run, he has the correct number of circuits for his need.

[saskrick]

I have seen on gm trucks, new with factory trailer wiring with no juice for charging the trailer battery. Found out that they need to be hooked up in the fuse block under the hood, then you are good to go. My Ford was not that way though.

[NYDP77]

I found out my nissan did not have a relay needed to maintain the charge in the battery while hooked up. Found teh relay on etrailer for around $9.