12V trouble....

[Chuck]

When I picked up my trailer the other day, the battery was stone-cold dead. (deep cycle marine/RV battery). I found that the outside light (over the door) was left on. Oh, well...things worked when connected to my truck, and I figured that it would get a charge from my alternator. So I drove it home (70 miles), parked it, and left it overnight connected to my truck. Next day, I moved it closer to the house, and plugged it into a 15 amp house circuit. Everything works when its plugged in, and I can hear the univolt humming in the back. I assume that it is "trying" to charge the battery.

24 hours later, I checked on it....univolt (or something back there) is still humming. But if I unplug the unit from shore power, I still have NO lights or anything 12volt.
what do I check first? Is it possible that the battery is gone, or possibly the univolt isn't charging?

[davidz71]

Chuck,
Is your marine/deepcycle a maintenance free or does it have water caps on top. If it has water caps, did you check the water level in the battery before charging? I would locate the univolt and check its output with a digital voltmeter to see if it is charging. Check your state of charge with no load on the battery:
12.6+ 100% charged
12.5 90
12.42 80
12.32 70
12.20 60
12.06 50
11.9 40
11.75 30
11.58 20
11.31 10
10.5 0

Make sure you let the battery sit for 2-3 hrs. before testing the voltage to give you an idea of its charge level. If this battery came with your trailer and is not new, discharging it all the way down might have killed it like it did mine. Too deep of a discharge adversely affects a deep cycle. They say that you should not discharge one below the 40 % level whenever possible.

Go to the following sites for great battery info:
http://www.progressivedyn.com/servic...ement_101.html
www.geocities.com/bjb_darden/dcfaq.htm
http://bart.ccis.com/home/mnemeth/12volt/12volt.htm
"/12volta.htm
www.e-marine-inc.com/products/conditioner.html

[davidz71]

Chuck,
I also forgot to ask the obvious question, have you checked all your 12 volt fuses closely?

[Chuck]

No, haven't checked the fuses yet. Is there one that controlls output to the battery from the charger?

I also dont' know if its "maintenance free" or not. I'll check both of those things.

If there's no/inadequate output from the univolt, then its "time for a new univolt", right?

[davidz71]

My fuse panel is in the front section of the trailer behind the entertainment center. My univolt is long gone and was replace by a Magnatek converter/charger. According to my '77 wiring diagram, the univolt positive red wire goes directly to a 50 amp. fuse and then goes to the positive of the battery. If the fuse is blown then the univolt could not do its job of charging the battery. The black univolt wire goes to a ground block. Univolt testing procedure is as follows: 1. Confirm 120 volts to univolt. 2. Remove all fuses from remote fuse panel. 3. Connect black lead of tester to terminal marked "ammeter red only". (Any one of the four terminals on the neg. side of univolt can be used. 4. Connect the red lead of tester to any fuse clip on the center aluminum bar of the fuse panel. 5. Voltage must be within 13.8 and 14.2 volts. 6. If univolt is not within these voltages, replace it.

My fuse box shows five 20 amp fuses going to + circuits to interior 12 volt lights, fans, pump, etc. There are four 50 amp fuses covering + and - circuits for the battery. There are four 15 amp fuses which cover the brake lights, turn signals, etc.

If your battery is not maintenance free, you should have individual caps for each of 6 cells or 2 plastic caps that you can pry up which cover 3 cells each.

[83Excella]

Univolt check

Do this check to see if your univolt is working;

With the Uni-volt off, measure the voltage at the battery. It should be 13.8V +/- 1V. Turn the converter on - the measured voltage should increase by about 0.5V.

John

[melprice]

Chuck,

If it is your battery that's dead then I suggest you take a look at Sears. They currently have some good bargains.

I bought a new Marine/Deep Cycle battery this weekend. I bought the medium size of the 3 they sell and it fits in the battery box of my trailer with room to spare. I probably could have gone with the largest size.

It has a capacity of 105 Amp Hours and was on sale for around $55, this was with a 12 month full replacement warranty.

Here's a link:
http://www.sears.com/sr/automotive/marine_battery.jsp

[Chuck]

Thanks for the link, Mel. I'll look into that.

I looked at the univolt last night, and it appears that all the fuses are intact. I didn't get a meter on it yet....just too darn hot. The sweat was just pouring off of me, and all I was doing was "looking" at stuff. I know, many of you guys are probably used to this heat, but here in the northeast, we're not.

[Chuck]

Ok...at least I know what's going on now. the battery is "non-maintenance free", and was very low on water. The univolt was charging it, though. Dad came over w/ his charger, we pulled out the battery, filled it with water and put in on the other charger to get some feedback. It is getting a charge...we'll see how it goes. We also noticed that the sides of the battery are a little bowed...perhaps it once froze (?). I'm thinking I should just deep-six it, and be done with it.