

| Subject: | Re: Dometic Improvements Adding Fans |
| From: | David Beierl |
| Date: | Tue, 27 Apr 1999 16:06:11 -0400 |
At 10:31 4/27/99 -0700, Kevin Mikkelson wrote: > >I wanted to get the lists opinions, are there any unseen dangers (current >draw?) in my wiring the stock fan in series with a second fan? That gives you half-voltage to each fan (incidentally, "Muffin" is the brand name of the original box-shaped electronic cooling fan -- now there are probably twenty brands). At half voltage if you're lucky or if the motor is a brush-type DC motor the fans will run slower and quieter, and give less output. If you're *not* lucky and the motor is an electronic one, the fan will sit still or rotate slowly backwards. This obviously does not provide the desired effect. I'd suggest testing your fans with a varying voltage and see for yourself what voltage they need to run. If you don't have access to a variable supply, get a pack of power diodes from Radio Shack (p/n 276-1653, $2.29) and solder six or eight of them together in series with the banded ends pointing the same way. Hook the *non* banded end of the array to your +12v and then connect the +lead of the fan across one, then two, then three etc. diodes (letting it stop btw each test). When the fan quits running, go back one step and measure the voltage across the fan. Or figure that each diode is giving you a half-volt drop, that errs a little on the side of caution. Don't forget that you won't always be running with a full battery; might go down to eleven volts total, or maybe lower depending on where you get the fan power. The fans won't give you much voltage drop in the wiring, but the reefer element will. Yell if you need... david David Beierl - dbeierl@ibm.net
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