Charging battery

danhave

Member
Mar 30, 2015
34
Maybe a stupid question:
I want to add a 12 v batter to my 89 Coleman Columbia. I've already ordered the harness, and know how to wire it up. I'm just trying to figure out a way to charge it while away from AC power.
I know it's possible to wire a charging circuit to the TV, but I only have a 4-pin plug, so that's probably not an option. However, my TV has a 12V outlet right inside the rear hatch. Would it be dumb to take a 12V plug and directly connect it to the Pup battery so that it charges while I drive? I would always disconnect it when the car is off, and would make sure to run the wire in such a way that it doesn't get stretched when I turn or anything.
If that's as dumb an idea as I think it might be, does anyone know of a way to charge the battery with my TV without a charge circuit?
Also, does anyone know if the Coleman converter will charge the battery when I plug the Pup into Shore Power?
 

~erik~

Active Member
Jan 19, 2015
287
North Georgia
If near AC power I'd connect a good automotive battery charger to the battery to charge it. That's probably better than the converter in the camper.

Away from AC power you could use a generator, or solar power. I guess hooking it to the cig lighter of the car would work, but it doesn't sound too efficient to rely on doing it this way while driving to a camp site when the battery could have been charged first at home with a proper battery charger.
 

danhave

Member
Mar 30, 2015
34
I would only charge it that way on multi-day trips. I would definitely use a charger while at home.
 

danhave

Member
Mar 30, 2015
34
The vehicle only has a 4 pin plug. It would be fairly easy to switch the trailer to 6 pin round, not sure about the TV.
 

Customer

Super Active Member
Jun 5, 2014
2,435
danhave said:
...I want to add a 12 v batter to my 89 Coleman Columbia....I'm just trying to figure out a way to charge it while away from AC power.

Does your converter charge the battery? What brand and model converter?

danhave said:
I know it's possible to wire a charging circuit to the TV, but I only have a 4-pin plug, so that's probably not an option....

Do it right and do it once, add a seven way connection to the trailer and TV.

http://www.etrailer.com/faq-wiring.aspx
 

teejaywhy

Super Active Member
Jul 19, 2011
1,424
danhave said:
... my TV has a 12V outlet right inside the rear hatch. Would it be dumb to take a 12V plug and directly connect it to the Pup battery so that it charges while I drive?

Those accessory 12V outlets are not typically wired to support much current. In theory, it could provide a small charge to the battery but in practicality, would not be able to flow enough current to put any significant charge back into a depleted battery.

The best solution is to rewire the TV for the 7-pin. Alternately, you could run a dedicated pair of sufficient gauge wires (10AWG min) with a dedicated connector (run through a relay to isolate the TV battery), but at that point, you might as well go for the 7-pin.
 

WingShot

Active Member
May 14, 2014
631
If this is for long-term use, I would convert everything to a 7-pin setup or some sort of solar charging system. The wiring for those 12V outlets is not sufficient for charging purposes. From what I read in the 1989 Coleman Owners manual it does not sound like your converter has battery charging capabilities.

In your case, I'd get a charger and plug it in at home. Then have someway (solar, generator, hook-ups) to keep the battery topped off while camping. I am not a fan of relying on the TV for the electrical needs of the camper.
 

lifespeed

Super Active Member
Aug 26, 2014
754
WingShot said:
In your case, I'd get a charger and plug it in at home. Then have someway (solar, generator, hook-ups) to keep the battery topped off while camping. I am not a fan of relying on the TV for the electrical needs of the camper.

The TV charge only works slowly if one has gone to the effort of wiring both the TV and trailer with adequate wire. I say even 10G is inadequate, and a wire voltage drop calculator will reflect this showing 0.5V for 20A (don't forget that 10A fridge!) at 25'. That won't really work.

It can be done, but it doesn't just magically happen with what the trailer manufacturer and U-Haul installer gave you. So yeah, 95% of the folks out there can't rely on TV charge, even though it would be convenient.
 

inthedirt

Super Active Member
Aug 28, 2012
977
SW Montana
Get a solar panel and charge controller and be done with it. You'll no longer need to worry about connecting to Shore Power or to the TV. I got my 100w panel, a controller and 40ft of cables from Amazon for $165 shipped. I will be able to charge laptops, portable dvd players, cell phones, helmet cameras, run the coffee pot, solve world peace, banish homework........
 

teejaywhy

Super Active Member
Jul 19, 2011
1,424
inthedirt said:
...I will be able to charge laptops, portable dvd players, cell phones, helmet cameras, run the coffee pot, solve world peace, banish homework........

You misspelled whirled peas.

[:D]
 

medicmike5969

Been an Apache owner since 1991 - 2nd owner
Apr 22, 2013
80
Clarkston, MI
Those "lighter" plugs that are mounted in the rear of vehicles are for VERY low current ONLY - like less then a 5 A circuit.

IF you try to use it for charging the camper battery - you will burn your plug up. Been there, done that w/ a rotating emergency light.

BEST WAY is to re-wire the TV to a 7 wire & then wire the camper to the same. That way - it's done right & correctly!
 

danhave

Member
Mar 30, 2015
34
Okay, I have an appointment with Uhaul to wire my TV for a 7-pin, and I'm going to wire the trailer for it over the weekend. Once that's done, do I connect the 12V wire from the TV directly to the battery, or do I need some kind of charger?
 

danhave

Member
Mar 30, 2015
34
And if I do use the TV wire to charge the battery, does that change how I would hook up a solar kit?
 

lifespeed

Super Active Member
Aug 26, 2014
754
danhave said:
Okay, I have an appointment with Uhaul to wire my TV for a 7-pin, and I'm going to wire the trailer for it over the weekend. Once that's done, do I connect the 12V wire from the TV directly to the battery, or do I need some kind of charger?

First of all, if you're doing a new installation for goodness sake use 8G wire at an absolute minimum! Everybody here says 10G, but a quick glance at a wire voltage drop calculator http://www.bulkwire.com/wireresistance.asp shows that 25' of wire carrying 20A (remember the fridge wants 10A) will produce a 0.5V drop with 10G. This will severely limit the speed and ability to charge to full capacity. Wire is cheap! Don't let some lazy U-Haul installer tell you otherwise. Bring them the wire if need be.

Most people don't use a DC-input charger in the trailer, but just hook the wire to the battery directly. And most just use 10G wire. And then they tell everybody that TV charging doesn't work well. You get the picture . . .

A DC-input charger like the Redarc BCDC1240 is a fantastic addition to your trailer electrical, will charge the batteries fully at a very fast rate and includes a solar MPPT controller for when you add solar. It covers a lot of functionality. And it costs money, street price is about $480.

But using 8G wire directly to the 7-pin in both the TV and the trailer is a good start even without the nice charger. You may have to adapt down to 10G for a few inches to get into the 7-pin. This is fine and will cause minimal voltage drop. They even make adapter butt splices to go from 8G to 10G. And put a circuit breaker in the car like one of these cooper-busman that causes minimal voltage drop. http://www.powerwerx.com/fuses-circuit-protection/resettable-circuit-breaker-cooper-bussmann.html Those cheaper "short-stop" type of breakers can drop a couple tenths by themselves, and are not ideal.

Good luck!
 

lifespeed

Super Active Member
Aug 26, 2014
754
danhave said:
And if I do use the TV wire to charge the battery, does that change how I would hook up a solar kit?

Most likely it won't, depending on the specifics of your solar install. If you use the Redarc charger/solar controller I mentioned TV and solar inputs will both go to it through a switch or solenoid. Regardless, having the 8G wire installed means you won't have to re-run it.

Click the camera icon to the left to see a full-featured electric install I did on my camper.
 

danhave

Member
Mar 30, 2015
34
Okay, I got a 5w solar maintainer from O'Reillys. One problem: I was reading the manual, and apparently it doesn't have any smarts, so it won't trickle charge the battery. I measured the output of the solar panel with a multimeter (and it is *sunny* today), and I got .3A at 24V. Will that amount of charge damage the battery if I just leave it plugged in while the trailer is parked?

I'm currently charging the battery with an AC charger plugged into the camper system, which is hooked up to Shore Power. But this can't be a permanent solution, as the extension cord to Shore Power goes across a small parking lot, and will get run over a lot. I got an extension cord rated for that, but I still don't want to leave it out.
 

lifespeed

Super Active Member
Aug 26, 2014
754
The current is so small from that tiny panel that it is not able to damage the battery. Of course that panel is of no value as anything but a maintainer, and I'm not even sure it can do that. If it can't keep the battery at 13.3V during the day it is not even suitable as a maintainer. Measure it. 5W is nothing.
 




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