Output at hot wire in trailer plug

[VicR]

Does anyone know off hand what the output of the hot wire on the trailer plug is? I can't find it in the FSM.



Thanks,



-Vic

 

[Gary - K7GLD]

WELL, it SHOULD be the same 12 volts as the rest of the truck/trailer... .



BUT, if what you REALLY mean is what PIN it is in the plug, you should probably use a test meter for 2 reasons, one, to verify it actually IS the right pin, second, to make sure power is actually there - fuse was blown on mine, so even tho it was wired correctly, there was no 12 volts present...



Meanwhile, someone who actually has quick access to the pinouts will be along with the info - I'm as lazy as you, and don't wanna do the legwork myself either...



(edit)



Well, being bored - and a generous guy, I did what many here often don't (or won't!) - used that nifty "search" feature up there in the page header - sure works neat! I simply searched under "trailer plug pinouts", and guess what...



Try this:



http://www.marksrv.com/wiring.htm



Yer welcome...

 

[VicR]

Thanks Gary - I was hoping one of the electrical Guru's would chime in. But I don't think I asked the question right. I was talking to the guy at the RV parts counter about my camper electrical and that I added a 2nd battery because I dry camp a lot, and he told me 'those darn dodges' don't have high enough voltage at the trailer connector to charge the coach batteries. So I did a little test on mine:



At the truck (and at the end of the pigtail that connects to the camper)



Off: 12. 63

Idle: 14. 1



So it seems like it is within acceptable range to charge the coach batteries.



But then I got to thinking today...



so I plugged the camper into the truck and got these readings at the camper batteries:



unplugged: 12. 8

connected/ truck off: 12. 8

connected/ truck idle: 13. 0.



Where did my extra 1. 1 volts go? If I understand it, 13. 0 is probably too low to charge the camper batteries.



-Vic

 

[Gary - K7GLD]

Either lost voltage thru the wiring run between vehicles, or thru the isolator, if there's one installed - but voltage will probably rise a bit more at down-the-road engine RPM, and will do a pretty good job of charging the RV batteries between times when shore power is available...

 

[klenger]

Here's a link to a page on my website with details on the trailer connector wiring. The battery charge wire is 14 gauge. Any missing voltage between the truck battery and trailer battery is being burned up in heat on this wire. The bottom line is that the tow vehicle charging system will never do a very good job of charging an RV battery. You could run a 6 gauge wire or bigger, and that will help, but theres's only so much you can do from the tow vehicle end. Either solar panels on the RV or a generator and good converter / charger work much better, but you have to decide how much you want to invest in an RV electrical system for how much you use it. I probably have close to $5000 invested in the electrical system in my camper, but this is more than most are willing to consider.



http://www.klenger.net/dodge/7-pin-connector-installation/index.html



Other RV electrical info here: http://www.klenger.net/arctic-fox/index.html



Good luck.

 

[Ramtough]

Voltage is not what you are looking for - to charge batteries, you need amperage. The voltage can read 14. 1 but you still can have very little amperage flowing to the trailer due to small factory wiring. Here's what I did. Run 8 guage wire from the battery through a 30 amp automatic resetting breaker, then through an isolator, back to the trailer plug. With my batteries down 50% (around 12. 1 volts) I can get an initial charge of around 15 amps which will restore most of what I lost over the past night in 6-8 hours of towing.



I do a lot of dry camping and I use 2 6 volt golf cart batteries which provide around 210 amp hours of current.



If you are using the batteries hard, you will need to charge the trailer directly from a generator hooked to your shore power. Your trailer power convertor should be capable of charging the battries at around 40 amps. I can recover 95% of a 50% - 60-% drain in around 4 hours of charging.



For charging, I use a 1800 watt Coleman Powermate generator which is excellent for battery recovery. Do not try to run an air conditioner or microwave oven on a generator this small.



If you are a serious dry camper, you need a computer in the trailer that will tell you exactly what is going on with your batteries. I use the Trimetric from Backwoods Solar. You can get information on this device at: http://www.backwoodssolar.com/Catalogpages2/meters2.htm#Meter Basics



This web site has a wealth of information on living independent of shore power. I have found their products, service and expertise to be among the best. Check them out and happy dry camping.



I charge on the road when I am travelling. When I am dry camped at a race, I can run my system fairly hard (furnace, power vent and inverter for TV/VCR) over a 24 hour period then charge for 4 hours daily with the generator.



To keep your batteries in top shape and to maximize their life, you will also need to equalize them regularly.



Good luck and happy dry camping

 

[Ramtough]

One final thought - I expected to receive more amperage to the trailer when the truck was running after my direct wiring upgrade. After all, the alternator is capable of producing 200 amps of DC power. I thought my wire size was adequate to the hitch plug - I've since found per wiring specs, it could have been 1-2 sizes larger. However, the mechanic at the RV dealer told me that larger wiring in the truck would have been a waste of money because of the size of the wiring in the trailer. Like everything else, you are always limited to the strength of the weakest link in the chain. Kind of like a big garden hose carrying high pressure connected to a small nozzle.



Fact is that neither the truck or trailer manufacturer anticipated many dry campers trying to use their trucks to charge depleted trailer batteries. Just look at the size of the wiring to your truck batteries compared to the size of the DC supply in your trailer.



With large enough wiring thoughout the system, you cold just hook the traile to the truck and allow the truck alternator to do the work while you sat back and enjoyed the sweet idle of the CTD.