Battery charging

[Dr Dan]

I have been working on a 1965 Tradewind for at least a year. It is wonderful to have found this website, it has been sorely needed.

I still have the Univolt system and it appears to be functioning. I just purchased a new battery, Turned every light on in the trailer and ran the battery down and then charged it back up by plugging into house current.

When I first changed out the 7way plug in the trailer the lights came on in the trailer. That no longer works and I am going to look at the connections in the trailer side of the plug as well as the truck side. Once I get that up and running again can I assume that the trailer battery is charging? Or do I need to do my run the battery down test again?

What all this is leading up to is a fishing trip on Wolf creek where I have no electrical hookup. How long can I expect the battery to last if I am conservative with electrical use and how long should it take to re-charge with a vehicle alternator? I know the vehicle battery is recharged in 20 minutes or so, is a deep cycle the same?

[raebaker06]

No The Vehicle battery is not fully charged in 20 minutes. That is only a partial charge. You need a slow charge to fully charge the battery.
The length of battery time is dependant on the capacity of the battery and by how much current draw you use. Depends on your conserve meaning. a Deep cycle battery will give you a longer discharge cycle but it can only hold so much. You need to do some math to determine that.
A 100 amp battery will only deliver about 10 hrs at a 10 amp draw.

[easyride]

Don`t know what your tow vehicle is,on my Chevy fuse is under hood for aux. 12 volt to trailer.that 12v wire on your t.v.should be between 10o`clock and 11 o`clock on yor plug.Dave

[68 Overlander]

I'm not sure why you ran the battery down, just to charge it back up. You don't need to do that.
Measure the output voltage of the Univolt (at the Univolt) and you will know if it charges. 13.8 and you are in business. Why it is not a good charger is a whole different story but lets get you to Wolf Creek this time.
You didn't say how many days you will be camping but did ask how long the battery (one) will last if you are conservative. About one day if you run the furnace. Maybe two if you keep the lights off most of the time and run the furnace only in the morning to get warm.
You really would benefit from a generator if you plan to do these sort of boon docking trips often. That way you can replace at least some of the amp hours consumed by running the univolt to charge. Don't expect very much but you will see some.

[Mexray]

1. take a look at all the fuses inside the trailer to check if the one from the tow vehicle charge wire in the 7-way plug is good.

2. if all fuses are good, use a voltmeter on the charge wire fuse in the trailer to see if you are receiving voltage from your TV...make sure you're not plugged into AC power. if you don't have 12 volts coming from the RV, check the 7-way plugs for good contact, and then find the fuse in the TV for this charge wire to make sure it's also good - when checking voltage, make sure the TV ignition is 'ON', as there's usually a relay to make that circuit complete only when the TV's engine is running.

3. just an additional note...lead-acid type batteries don't like to be completely discharged...it will shorten their life if you do this all the time...most battery guys will tell you only discharge about 50% to get the maximum battery life in years of service.

4. the older univolt converter/chargers tend to overcharge the batteries if you leave the AS plugged into to shore power all the time, while not using the trailer's 12 volt systems...it will run the voltage up so that the battery fluid will begin to evaporate, and if you don't catch it in time, will ruin the battery.

[Dr Dan]

Attached (I hope) are some photos of the system I have in the trailer. All original I think. There is an amp meter mounted on top of the univolt, an add on I suspect, which dosen't tell me much. I started out with 12 amps from the univolt plugged into shore as I read it, and 12 volts on the disconnected battery, with nothing happening, that I could tell, on the amp meter, then I ran the lights for 3 hours, disconnected the battery and it read 11.5 amps. I did notice that as I reconnected the battery, before I plugged back into the shoreline, the amp meter was reading a negative 30 amps? Then I plugged into the shore line went to bed and the battery was back to 12 volts, disconnected in the morning.
I wasn't sure that half a volt wasn't a screw up in my ability to see for starters (over 50) or just poor technique, so I turned the lights on and went to work. After a longer day than expected the battery was reading ZERO, but it charged back up so I KNOW the univolt charges it. And looking at the amp meter closely it may have been a hair to the positive side while charging. I got to thinking that 2 amps on a 0 to 60 amp meter wouldn't necessarily show much. You folks talking about only using down to 80% and the like, are you guessing or do you have a way of knowing?
It is so great to have somebody to bounce this off of. I've been working in a vaccume up until now. Thanks

[Dr Dan]

Thought of something else as to charging from the truck. I found a panel where the electrical hookup from the vehicle attaches to the wiring of the trailer, what a blessing. A continuity tester across the relay showed that it was working plus I temporarily by-passed it with no luck. I finally got mad and turned the truck around and wired it straight from the battery and everything powered up in the trailer. Yea! I have power in the female part of the coupling in the truck, and have continuity from the male(trailer) side to the trailer wiring but darned if I can get it to connect at the coupling. And the male side of the plug is only 6 months old. Is their some type of electrical connector dope to slather on to the connections I cant exactly get in there with sandpaper?