Battery not charging

[tony.bare]

I have a 1989 30 ft avion trailer. Looked for a long time but finally found one. I love the trailer but I have one problem with it. When plugged in to 120v AC everything works fine and the battery charges.
When I tow it, with a fully charged battery, the battery is totally dead when it is disconnected from the tow vehicle. Could anyone give me an idea of what is wrong and how to trouble shoot and fix. Thanks I am new to the forum but not to Avions. I had a 96 5th wheel for years till it started to delaminate. Avions are so nice, it makes you feel like "somebody" to camp in one.

[Rostam]

Is your fridge 3 way? (AC/DC/propane). If the fridge runs on DC when you are towing, it will discharge the battery. My understanding is that battery charging via 7 pin connector to tow vehicle is minimal and not enough to compensate for what running a fridge requires.

[KYAvion]

A few questions....

How old are your batteries?

How are you determining that the battery is fully charged or discharged?

How many hours are you towing for when you find the battery to be dead?

Are you certain the 7 way plug is wired correctly and that your battery is receiving a 12v charge?

Is your 12v kill switch in the ON position?

[KYAvion]

Rostam- you may be right, but I use to run a household fridge (i.e., compressor style) via an inverter (invertering 12v to 110v) in my prior trailer, and had no issues maintaining a charge from my 7 way plug. I had two batteries though, so that would have definitely helped with the amp draw.

[Rostam]

Good to know. Someone that ran the fridge on battery told me it drained his battery after a few hours. You brought up several good point. I guess it depends on the age and number of batteries as well.

[KYAvion]

I actually tested mine out to see how long it would run on the battery alone. I disconnected from 110v in the morning. I kept an eye on it throughout the day because I didn't want it the battery to drop below 40% (read that was hard on the battery). Anyway, later that evening I plugged it back in and was nowhere close to 40%.

Keep in mind this was a brand new compressor style fridge with a great seal. Thus, the compressor didn't have to run nonstop because the fridge seemed to maintain the temp pretty well without the compressor running. This test was done in the summer though, so it was hot.

[silverloaf]

One quick way to check the battery is to turn off the kill switch on the control panel. If it discharges, it either a bad cell, a short in the electric jack or maybe discharge at the tow vehicle.. If OK, its something downwind of the kill switch.

Systematically turning off some 12v circuit breakers might help to isolate a rogue appliance or plug. An ammeter to measure circuit flow is very helpful.

[tony.bare]

I guess my first question would be - what is the proper way to use the 12 volt kill switch? Of all the campers I have had I don't remember having a kill switch. All of my trips in the Avion have been 3 or 4 hours around Ga and Florida. I really don't remember what position the kill switch was in but with the rig hitched and 7 way plugged in the tongue jack work's but unplugged and unhitched the jack does not work. It is probably "pilot error" on my part. Could be my ignorance on kill switch. It is a good starting place. The fridge is gas and 110 ac. Battery is new. When I installed the pro pride hitch I had to lengthen the cable to the 7 way. The lights and brakes work so the only way I could screw up there would be to reverse the polarity in the 12 volt wires. Thanks for these and any future tips. I am OK with woodwork. I build mandolins and ukuleles some furniture, but even though I made my living splicing phone cables, I am an idiot when it comes to electrical systems.

[KYAvion]

The kill switch is sort of counterintuitive in my opinion. In the ON position (breaker to the right), the battery is NOT isolated. When the breaker is switched OFF (breaker to the left), the battery is isolated. I suspect that if the kill switch were off, then the battery would not receive a charge from the tow vehicle since the battery in essence would be disconnected. However, this still doesn't explain why the battery would be fully charged at departure, but depleted upon arrival. Just curious, what did you do to determine your battery was fully charged, and then later dead? Knowing this might help to figure out what's going on.

Your reply also said your fridge runs on 110v and propane. Therefore, the fridge didn't drain the battery. The battery only supplies 12v, so the only way the battery would power the fridge is if you added an inverter inline to change 12v DC to 110v AC. This is the reverse of the factory installed converter that converts 110v to 12v. Your trailer lights, furnace, range hood, water heater, etc, are all made to run off your batteries alone, which is 12v DC power. The converter allows you to run all these 12v appliances and fixtures while connected to shore power (110v AC power), and the converter keeps your batteries topped off at the same time.

[KYAvion]

BTW, the tongue jack runs off the battery, so it will operate when not plugged into anything. I've never tried operating the tongue jack with the kill switch in the off position, so unless the tongue jack is wired direct to the battery (which I suspect it might be), the tongue jack wouldn't work if the kill switch is in the OFF position. I'll have to see how my tongue jack is wired sometime.