12vdc operating problems

[aerolitebigbird]

I have just purchased a 2006 Areolite F19 Trailer. In purchasing it we discovered that the unit was not working on 12dc battery only. Called in a tech when he advised the converter was shot as well as the battery. Put in brand new converter and new battery.
All electrical work fine on 110V with new converter, however still do not have 12DC operation at all from battery when the unit is unplugged from 120V

[swixelann]

Fuse? Thermal overload?

[persistent]

The battery may not be connected to the converter. The converter should be connected to the battery to charge it. The battery then would power the lights and other 12 volt stuff.

Maybe the battery is only used for electric brakes and is not connected to the converter.

There will be a circuit breaker or fuse near the battery. Mine has a little 3 cm metal can with "in" and "out" terminals. It is supposed to reset itself when overload stops.

There is probably a fuse in the converter/charger. Mine has two for the battery, a 30 amp and a 40 amp. The 40 amp blows when the battery is hooked up backwards. The 30 amp blows when too much power goes between battery and charger.

Get a volt meter and trace the voltage from the battery. Converter/charger should provide 13.6 volts. Battery should supply 12.7 fully charged to 11.4 volts fully discharged.

It is good practice to always test repairs before paying for the service. By test, I mean, try to use 12 volt appliances using only the battery.

Technicians are always in a hurry and often do not test. The also have a natural tendency to assume that what they did always fixes the problem. Take it back and tell them they didn't fix the problem.

Note: Always store lead acid batteries fully charged.

I wish you good luck and happy trails ahead!

[dsol]

Agree with persistent—your tech did a number on you. The only reason it likely worked after the new converter and battery was because the new battery was fully charged. Now that it is dead it will not work. I would bet that if you put a charger directly on your battery it will work again until it goes dead. For that matter your old battery might still work too but likely if it was dead for a while or run to the end a few times it probably needed replacing anyway.

But I am doubting you need the new converter and agree with the others that it is likely a fuse or some bad connection between the converter and battery.

If you told him to replace both then not as bad but if he told you they both needed replacing then I would raise some hell with him. If you find out that it was only a bad fuse or short or something after all this that will not be good.

[Snowman53]

Could there be a hidden disconnect switch? I have been surprised by no 12v operation on my 2018 Aerolite only to discover my not-hidden disconnect (it is on the inside frame rail behind the propane tanks and near the battery) was switched off. That was after it was winterized. Maybe the repair shop thought they were doing me a favor? Don't know. Otherwise the previous answers are very insightful and cover it pretty thoroughly. Good luck!

[VCToyhauler]

Check to see if you have 50A auto-reset breakers. It sounds like the one for the coach 12v power panel has failed. This has happened to me; same symptoms.

[Edbush]

VCToyhauler is correct that it may be a bad auto breaker but it also may be a manual reset breaker. Check if there is a tiny button on the breaker end and press it down to reset.

[kjlarson]

Couple of things to look at. Your unit probably has a WFCO power panel as it is the most common used. In the very bottom of the power panel is the main board assembly (MBA) which has multiple functions: in converts the 120Vac to 12Vdc when on shore power and charges the battery. Look on the back of the hinged door for the model number and get a copy of the wiring diagram for the power center, available on the internet.

Removing the front panel is easy, just don't break the two tabs on the bottom of it. If yours is like mine there will be a large red wire to a lug just above the MBA, that is the positive lead from the battery. At the top will be a black wire connected to a lug, that is the negative wire from the battery. The top lug should also have a white wire connected to it, that wire comes from the MBA for charging the battery. About an inch below that lug there is a lug labeled VCC which should have a black wire attached to it, also coming from the MBA. If either of these MBA wires are not connected the battery is not being charged. Another issue that you do not want is the MBA charge function operating when attempting to run the trailer off the batteries so you need to turn off the circuit breaker that powers the converter; you cannot charge the batteries when drawing power from them as that will damage the batteries and the converter. The 12Vdc stuff will still run as expected with the converter turned off as it is only needed when connected to shore power.

In my power panel the circuit breaker that powered the converter also provides 120Vac to the frig which I wanted to run when on the house batteries. I use a 2000 watt pass-through inverter when on the house batteries to provide the 120Vac needed to run the outlets, frig, my CPAP, etc. So, I cut the wire from the circuit breaker to the converter and extended it to the hot lead (black) of the shore power plug; now the converter only runs when connected to shore power. The inverter supplies 120Vac to the power panel whether running on shore power or the house batteries. I removed the dealer installed battery and installed three 100 amp hour RV deep cycle AGM batteries to provide the power needs of the trailer. Now all the 120Vac and 12Vdc accessories, except the A/C, operate when running off the house batteries.

Best to have a qualified "RV technician" do the electrical work because if done incorrectly sensitive equipment can be damaged or destroyed in addition the possibility of fire. I have found that the average "home" electrician does not understand the peculiarities of RV wiring. LOL and have fun out on the road and be safe.