Battery not charging.

[linux3]

I THOUGHT I had a dead battery on the trailer. I couldn't run the power jack on battery power. I had to be plugged into 120 V or connected to the truck.

I bought a new battery and the TT has been sitting plugged into shore power for the last week.

I unplugged from the wall and tested the jack. Nothing but a little hum.
Shore power, truck plug and the jack works.

I checked all the fusses and they appear to be OK. Nothing is labeled as the battery charging circuit.

Thoughts, suggestions?

[flybouy]

Is there a battery disconnect switch? Sounds like you could have a battery ground issue. The truck and the converter would have a ground if the battery is not grounded. Check the negative cable from the battery to the frame for corrosion or broken terminal. Do you have a multimeter and know how to use it? Check battery voltage between the battery terminals then check from battery positive post to a good ground on the trailer. If the voltage is low or zero then it's your ground that's an issue.

[MarkEHansen]

Also, be careful about using any heavy load (like slide motors, tongue jack, etc.) without a good, fully-charged battery in place. The converter may not be able to handle the load on it's own, and could get damaged.

When plugged into shore power, what voltage do you read (using a multimeter) at the battery cables? It should read 13.4 (or so) volts DC. If not, then you're not getting any charge current from the converter.

Keep in mind that fully-discharging a battery (whether intentional or not) is not good for the battery. It will reduce it's life greatly depending on the specific type of battery. If it turns out that your new battery is in fact fully discharged, it may be ruined - or at least have a much shorter life.

[linux3]

Voltage across the battery is 12.87 VDC.
Battery to ground is 12.87 VDC
I took the cover off the control panel, disconnected the cables to the battery and plugged in shore power. 13.7 VDC at the converter. Reconnected the cables at the control center. Disconnected the battery and measured at the cable. 13.7 VDC.

Humm, put everything back. With just the battery I put the meter across the battery and tried to run the jack. It wouldn't run but more importantly trying to run the jack didn't pull down the battery voltage and it should.

Took a 5th look at the inline fuse and checked resistance.
A black tie wrap was holding the jack 12 VDC wire to the body of the jack and it broke.
Now the jack works on battery power......... Sigh

All I can come up with is a poor connection in the inline fuse holder.
But, but why then would it work with shore of vehicle power.
Anyway, I replaced the inline fuse and fuse holder.

Thanks for the suggestions as it led me down some interesting paths.
I now know way more about my TT's electrical system.

[MarkEHansen]

These motors draw a lot of amps and that can do funny things when the connections are not perfect. Just pulling the cables off of the battery and putting them back on may have cleaned the connection enough to improve things a bit. I don't know what year your trailer is (please add this to your signature) but if it's more than a year old, you may want to go through all the outside connections and make sure they are clean, tight and corrosion free.

[linux3]

I don't know what year your trailer is (please add this to your signature) but if it's more than a year old, you may want to go through all the outside connections and make sure they are clean, tight and corrosion free.

It is and I did.