Need some assistance

[LeBout]

My wife and I are on the road right now and dealing with a bit of an electrical mystery. Here's the situation:

We're currently boondocking and drove about 6 hours to get to our current location. We noticed last night before bedtime that the lights inside the TT were dim, so I checked the control panel and the battery read "empty." (Again, this was after 6 hours of driving.) I have a tester to plug into my pickups RV connection and found that my 12-volt feed from the pickup IS working just fine.

It was late so we went to bed. During the night the heater came on but the fan was running in low mode, which it does if the battery is low.

This morning I began by starting my pickup and letting it run a while. (I left the pickup and TT connected overnight so we wouldn't freeze to death since I knew the TT would draw from the pickup.) Pickup started just fine but then it has a new battery.

My assumption is that the TT battery itself may be bad. (I have a single 12-volt deep-cycle battery that I bought in 2015.) I put my voltage tester on it and it registered just over 10 volts AFTER running the pickup for a bit. Not full by any means, but not down all the way.

I turned off the pickup this morning and pulled out one of my Honda generators and connected it to the TT. This is the weird part. We keep seeing the lights go from dim (about 50%) to full brightness and we hear the heater fan go from low to high all while the generator is running. Could a bad battery be the cause of all that, even when the generator is connected and running?

My plan this morning is to take the TT battery into an auto parts store and have it load tested. Anyone have any comments about our electrical weird behavior?

[librty02]

Yeah if your 12V battery is only showing 10 volts it is most likely toast. You can put it onto a charger and see if it comes back. It's a 50/50 shot that it will but being that low it will never be 100% again. Check the water level in it also it may be very low affecting the charge rate and Voltage it will keep. That battery is 4 years old now that is the avg life span for a deep cycle 12V. I've had some last a good 8 years and others that have only lasted a season. I have had the worst luck with Interstate batteries and the best with the Duracells from Sam's club over the last 22 years

[MFL]

You're welcome

[LeBout]

MFL wrote:
First of all, if your battery was low when you left, it will not charge much while driving. The small charge wire to truck plug-in is more just to maintain the battery, but will charge some. If your 12 volt battery is showing only 10 volts, it is extremely discharged. A generator alone cannot make up for a completely discharged battery, when a heavy 12 volt draw is present.

Yes, get it tested, and fully charged, if still good.

Jerry

Thank you Jerry. Very helpful.

[MFL]

If the generator has the lower draw lights on brightly, and then the high draw heater fan comes on, yes the lights may get dimmer, in a low battery situation.

Jerry

[LeBout]

Typical even when a generator is connected to have the lights go bright and then go dim?

[MFL]

First of all, if your battery was low when you left, it will not charge much while driving. The small charge wire to truck plug-in is more just to maintain the battery, but will charge some. If your 12 volt battery is showing only 10 volts, it is extremely discharged. A generator alone cannot make up for a completely discharged battery, when a heavy 12 volt draw is present.

Yes, get it tested, and fully charged, if still good.

Jerry

[Rolling_Condo]

Your symptoms are very typical of low voltage. If you do much boondocking I would suggest an upgrade in battery capacity.