Quick question on 12v transformer

[ilovemyvan]

I'm miles away from having a strong knowledge of electricity but thanks to all of you it has improved a LOT from reading posts on this forum.

We are not intending to install a house battery for quite a while. We just finishd installing a Fan-tastic vent which needs 12v to operate. For our next outing we will have access to shore power. We intend on using a little transformer to run the fan part of the Fan-tastic vent while there. Here's the question. The transformer specs say that it is a 12v but after we hooked it up to the 120v the output was 18v (before we hook the fan to it). Should we be concern or this is the way it's suppose to be?

Thanks a bunch

-Nicole

 

[MikeRuth]

That's typical of an open voltage reading. More importantly is the Amp rating or KV rating. Is that listed on the Transformer?

Mike

 

[ccbreder]

I haven't looked at my fan, but think it only runs on 12 volt DC. Is your transformer a power supply output DC or is bit just a transformer output 12 (18) volts AC.

 

[highdesertranger]

stern needs to reply. I believe you need a 12v power supply not just a transformer. highdesertranger

 

[SoulRaven]

I would purchase an AC to DC converter with an already attached female cigarette lighter plug attached. Make sure that it has a sufficient amp rating for the fan.

 

[SternWake]

It is normal for a wall wart ac to dc transformer to read high dc output when unloaded.

Most 12 v dc devices can easily operate anywhere from 8 to 15.5 v. Many can handle much higher. But some cannot.

Dc motors will just spin faster. I have a cheap voltage booster. I can make 12v computer fans hover At 26 volts..

If the rv in question has a converter and it is plugged in. Just skip the transformer. It basically does the same thing as the converter but on a smaller scale.

Those wall wart transformers are mostly noisy inefficient junk.