Sorry about the lengthy post, but I want to describe this situation completely…
I have a 2014 Tacoma 2-wheel drive with the factory tow package. I tow a 2014 16 ft Casita travel trailer equipped with a Dometic brand small fridge, which can run on Alternating Current (AC), DC, or propane. I recently (for the first time) ran the refrigerator on DC while traveling for a couple of hours. So far, I have always hooked up to electricity when camping, and had never run the fridge on DC. I have a battery minder in the trailer to monitor the trailer battery. According to Dometic, the fridge uses 9.58 amps per hour running on DC.
Here is the sequence of events which seems to indicate either a bad battery, something wrong with the DC operation of the fridge, or something else:
1. Leaving the campsite, I unhooked the AC power (battery showed fully charged – 13.79 volts before AC disconnected), switched the operation of the fridge from AC to DC, hitched up the trailer and plugged the trailer electric into the truck.
2. I drove for about an hour, then stopped for a break, and battery showed around 10 volts (too low!)
3. I unhooked the trailer electric connection to the truck, turned off the fridge completely, and went for lunch.
4. I returned about 90 minutes later, and trailer battery showed 9.79 volts (yikes)
5. I reconnected truck to trailer, turned on fridge (DC), and the battery immediately went to 12.07 volts.
6. Reached destination a couple of hours later, unhitched/unplugged trailer from truck, hooked up trailer to AC and switched the fridge to AC operation. Battery immediately went to 13.79 volts (typical when using AC for everything).
7. Some time later, to experiment, I disconnected the AC, and I watched the battery condition without anything turned on (no lights, no fridge, just the propane detector). Within one hour, the battery went from 12.97 to 12.64. Talking to another trailer owner, this appears to be an excessively fast decline in voltage with no load, perhaps indicating a bad battery.
8. I kept the trailer on AC, and did not have anything running in the trailer overnight.
9. The next day, I disconnected the AC, and with nothing turned on in the trailer, I hooked up the trailer to the truck. I started the truck and the trailer battery stayed above 13 volts
10. With the truck running, I turned the fridge on to DC, and the trailer voltage immediately dropped to 12.61, and within one or two minutes, it had dropped to 12.39
11. Wanting to compare using my truck with using a friend’s truck (2012 Tacoma), I hooked the trailer to the 2012 Taco. With nothing turned on in the trailer, the trailer battery voltage went from 12.67 volts before starting the truck, to 13.16 volts immediately after starting the truck. Within one or two minutes, the trailer battery voltage had risen to 13.42 volts.
12. With the friend’s truck running, I turned the fridge on to DC, and immediately the trailer voltage dropped to 12.7, and continued to drop to about 12.5 volts, with the truck running. I turned off this truck, disconnected trailer, and turned the fridge off.
Observations: The behavior of the trailer battery seems to be the same with both trucks when nothing is turned on in the trailer (trailer voltage holds above 13 volts), and also when the fridge is turned on to DC (trailer voltage drops below 12.5 volts very quickly)
I took the trailer battery in (it was under warranty, only 6 months old). They gave me a new battery, but did not say what was wrong with it, just that it was bad. I asked if it had a bad cell, and they said “no, it’s just bad”. They did not seem interested in discussing whether the problem came from my use of the battery or a defect in the battery.
Now that I have a new battery, I want to make sure that I am not doing anything wrong. On a Casita forum, a similar situation is described, and one contributor says that the truck wiring may be too small a gage. If that is the case, it seems that both trucks might have the same problem.
I would like to check with other Tacoma owners (especially 2014 with the factory towing package) to see if this seems to be a likely problem.
Would the tow package wiring requirements be different for a truck towing a small travel trailer like mine, equipped with things like this little refrigerator, trailer brakes and a 120 volt trailer battery, compared to a truck towing a work trailer with just trailer brakes and brake/signal lights? In my situation, I am towing a fairly light load, but have devices requiring power. This seems different from a heavily loaded work trailer that has the trailer brakes and lights, but no other electric devices.
Thanks for any input.