2003 Tundra with tow package, not charging trailer's battery, what am I missing?

[Petrolburner]

I just picked up an Aliner pop up A frame camper and when plugged in to the truck it's not recharging the house battery. I looked in the fuse box under the hood this morning briefly and didn't notice any missing or burned out fuses. I know often times that many trucks need a fuse put in place or a jumper wire etc to make this happen. I've done some brief research without any luck. Does anyone here know the answer?

 

[ebg18t]

Which type of plug does your camper use?

Are you sure there isn't a battery switch on the camper that needs to opened?

 

[DaveNay]

I would say the first step is to get at it with a voltmeter or 12v diagnostic light.

Check voltages at the trailer plug on vehicle, ahead of fuse on trailer, after fuse on trailer, etc.

 

[toyotech]

Don't think this is possible thru the hitch trailer 4 or 7 pin plug. Those tiny gauge wires can't run enough juice to charge a battery. Maybe I'm wrong but you sure there isn't another wire from house battery to vehicle that isn't part of the trailer lights.


Sent from my iPad using Tapatalk

 

[Petrolburner]

I have the 7 pin plug and after checking the truck side it's putting out battery voltage like it should so the issue is with the trailer I guess. More investigation required.

 

[Mrknowitall]

Don't think this is possible thru the hitch trailer 4 or 7 pin plug. Those tiny gauge wires can't run enough juice to charge a battery. Maybe I'm wrong but you sure there isn't another wire from house battery to vehicle that isn't part of the trailer lights.


Sent from my iPad using Tapatalk

ON a 7-pin RV connector there is a charge circuit.
http://www.rvupgradestore.com/v/vspfiles/assets/images/z11.jpg
To charge a deep cycle battery, you don't need a ton of current- 10A is plenty. If the voltage does drop because of the wire size, it will always be above the open battery voltage, and still charge. You don't really want a dead battery sucking up all the juice it could. That'll severely tax your alternator.
I never liked that the charge circuit isn't switched, so when you stop for lunch, the trailer is still drawing from the truck. My Tundra wasn't prewired, so I threw a relay (tied to [RUN] power) in there. Also, remember that the auto-off lights don't turn off the trailer lights.

 

[cam-shaft]

For quick reference take a voltmeter to the trailer battery and make sure truck is running. Check your voltage, if it shows charge voltage then you are getting charge. The issue usually is the 7 pin plug set-up really does not provide adequate charge to a trailer house battery.
Cam-shaft.

 

[toyotech]

Wow didn't know that. Hmm. Gives me some ideas now.


Sent from my iPad using Tapatalk

 

[Petrolburner]

It must be regulated down to about 12 volts. It is working but it's not getting it the 13.8 that the truck battery is getting. I hear that guys usually run their own larger wire to charge the house battery. I might need a new deep cycle battery too. It never seems to charge up fully and it discharged this weekend after only one night of the furnace running and pumping a couple gallons of sink water. Not acceptable. It is a 2010 battery IIRC, or maybe 08. I'd like to have an AGM battery anyway.

 

[MINO]

I recall getting about 12.7v on my 2012 Tundra trailer harness. Not charging voltage, not even a trickle.
I eventually went with a battery isolator and over 20ft of 4gauge cable with a quick connect for my slide camper.

Another option is Solar. It can top off what the harness can't.

 

[Petrolburner]

For what it's worth, Saturday night when I went to go to bed the battery was too dead to run the furnace and it was cold. I was pissed. One of the biggest reasons I got a camper was so we didn't have to freeze at night in the desert. I turned the key on in the Tundra, without starting the engine, so that it could have battery voltage from the truck. I then ran the furnace until it was toasty warm in the Aliner. I shut the truck off and the furnace off and went to bed warm. Woke up the next morning and the sun was out. I was glad to have a hard sided pop up camper with good insulation. Another benefit to the good insulation is that it stays cool long enough for us to sleep in all hungover with the sun beating down on the camper.

I think the solution is to run a heavier wire from the battery/alternator to the 7 pin connector. I guess I would need a relay in there somewhere or I'd have the 2 batteries connected the whole time.

 

[jeffjeeptj]

Maybe it is the wire from the trailer connector to the camper battery. I had a Jayco (which I bought new). The dealer put an inline fuse between the 7 pin connector and the trailer battery. This seemed like a good idea, but the butt splice crimps he used did not connect well to the wire. Lots of resistance/voltage drop. Results : uncharged battery. Once repaired, charged well. BTW, the heater pulls a lot of current running the fan.

The factory trailer wiring on my Gen 1 Sequoia works pretty well, but when I put an Odyssey PC2250 in my adventure trailer, I ran a 1 gage to an Anderson 350 power pole connector via a 200 amp fuse. Never had an under-charged trailer battery after that. I did connect the ground side to the Sequoia frame. I have also NOT had any corrosion/connection issues, even after 4 years and 3 salt road winters.

 

[Petrolburner]

I measured the 12 volts at the truck side of the 7 pin outlet as well as the camper battery. I'm not real keen on running a heavy charging cable all the way back to the camper but I'm not seeing how else I can get an adequate amount of electricity back to the camper battery through the current harness setup.

 

[Mrknowitall]

I recall getting about 12.7v on my 2012 Tundra trailer harness.

If you're getting that low a voltage, there has to be some good draw on it. Open circuit should always give you full truck battery or alternator voltage. If the voltage drops to 12.7V with the trailer battery connected, then THAT is the draw, and the open voltage of that battery is LOWER than 12.8V. It all depends on your usage- if you run the battery down every night end then only drive a few hours it wont work, no matter how big the wire is. If you drive long distances and the battery stays above 50% each night, it will work.

 

[MINO]

The 2nd gen Tundra regulates voltage down to 13.2.
Which isn't great for charging.

Yes, 12.7/8 under load with the trailer harness connected to the house battery.
Now, with the a voltage booster, isolator and 4awg direct to house battery, 13.8v.