Battery Issues

We have about 18,000 miles on our TrailManor 3023. We very quickly replaced the single 12 volt battery delivered with the unit with two deep cycle 6 volt batteries. These have worked very well for many thousands of miles.

However, the trailer batteries never receive a full charge while being towed. I can think of only one explanation for this which comes from my boating days - battery isolators. On boats when there are several battery banks (house batteries & engine starting battery), to avoid one system discharging the other, diode isolators are installed. This works fine providing that there are diodes on both battery banks and the alternator is adjusted properly. If there is a diode on only one battery bank, the other battery will never get a full charge because there is a one volt plus voltage drop across the diode. I suspect that this is what is happening in our trailer.

Has anyone else had this problem? And if so, what have you done about it? Does anyone know where the isolation diode is located?

Thanks

Originally Posted by mehitabel

However, the trailer batteries never receive a full charge while being towed. I can think of only one explanation for this which comes from my boating days - battery isolators.

You will probably get several fine replies on this issue from this astute user group . Here are my thoughts: I am not aware of any isolation diodes in the Trailmanor to cause a voltage drop. However, if while driving, you are running the refrigerator on 12VDC, the voltage drop in the wiring of the tow vehicle and the Trailmanor will prevent the battery from ever fully charging. In fact, several users have discovered their TM battery discharged upon arrival because of this voltage drop.

[Bill]

Hingarfi is exactly right. The TM does not (and could not) contain a battery isolator. This function must be located in the tow vehicle.

There are two types of isolators. One is the diode isolator, and it suffers from exactly the problem you describe - the voltage drop across the diode. You mention adjusting the alternator to make up for this voltage drop, and it would be the right thing to do, if you could do it. Boats may be different, but I am not aware that any modern car/truck has an adjustable alternator. Last time I saw one was in the 60's, in a car with a separate (and mechanical) voltage regulator.

The other type is a relay isolator - the power to the trailer is switched on (by the relay) when the engine is running, and is cut off when the ignition switch is turned off. My Explorer runs this way, for example, and if you need to buy an aftermarket isolator, this is the kind to go for.

Some vehicles have no isolator at all, so if you stop for lunch (for example), the trailer will drain the tow vehicle battery. In this case, it is important to unplug the trailer connector when you stop. Even more important to remember to re-plug it when you start out again, of course!

There are a number of threads referring to the refrig problem that Hingarfi describes. An Advanced Search will turn up a lot.

Bill

Originally Posted by mehitabel

... the trailer batteries never receive a full charge while being towed.

As previously stated, the TM doesn't have an isolator between the vehicle and the "house batteries." There are some basics you should check.
1. Do you have the TM plugged into 120 VAC at least 24 hours before you leave? The house batteries will be charging during this time off the TM's internal converter. Check the battery water level frequently. Your TM batteries should fully charge within 2-3 hours of driving if there is no other load on them.
2. Is your tow vehicle equipped with some sort of isolation? If not, install an after-market isolator. I prefer the diode style, but either will do the job. This prevents the batteries on the TM and the battery on the vehicle from "feedback" and possibly discharging while the vehicle is parked for a period of time (at a restaurant, or shopping).
3. If you have the refrigerator in the 12VDC mode, it draws approx. 10 amps. As other's have suggested, if the gauge of the wire supplying 12VDC to the trailer is too light, it isn't carrying the current (amps) needed to supply the refer and the batteries. You should use at least 10 gauge (stranded wire) from the new isolator you're going to install back to the 7-pin plug. If your tow vehicle was equipped with the 7-pin plug at the time you bought it, this wire may need to be upgraded.

I don't want to start a controversial subject, but if you pre-cool your fridge at least 24 hours before you leave, it should stay cool for at least 8 hours after you close down, giving you time to reach your destination and either plug in to 120VAC or switch to propane. The other option is to run it on propane while you travel, but then there are those who are opposed to this solution.

Find what works best for you.