Re: [MV] Electrical Problem/Trailer Hookups

From: David Cole (DavidCole@tk7.net)
Date: Sun Apr 27 2003 - 22:00:44 PDT


They make wire wound resistors with a slide center tap on it that could
easily be used to make the electric brakes work properly. They aren't too
expensive especially if you have access to a good surplus electronics
store. I'd guess that you'd need a resistance range of about .5 to 2
ohms. Probably something that could handle 50 watts or so would work.

As for the lights. All you really need to do is to drop enough voltage so
that when the lights are on they do not draw excess current. If you have a
meter that reads 0-10 amps dc (very common). Put the meter in series with
your light circuits when being powered by a twelve volt source and
determine the current draw for the brake lights, the right and left turn
signal, and the running lights. If the car is supplying normal voltage,
12.5-13.5 volts, then take that voltage and divide the current by it. Ex:
13 volts/1.5 amps = 8.6 ohms. Buy some ceramic power resistors that add up
to something close, I'd go with 10 ohms and see how bright the lights are.
10 ohms is a standard size. This resistor will need to be able to handle
the heat, and the wattage require is the amps x volts at the device. So 13
x 1.5 = 19.5 watts. I'd go with two 20 ohm, 10 watt resistors in parallel
for this. I've had good luck using terminal strips to mount these
resistors. These devices get hot, so you have to mount them away from
plastic or electrical wires or else they might melt whatever they touch or
get near. If you shop around and perhaps find a surplus store, you can
probably buy all of the parts for $20 or less. My M51 has a 12 volt fuel
pump that runs off the 24 battery pack via a couple of voltage dropping
resistors I got from radio shack. Some test leads with alligator clips can
make this entire exercise short work. I think I would mount all of this
stuff in a metal box attached to the trailer. That way you could wire the
trailer with two cords, one for a 12 volt hook up and one for a 24 volt
hook up.

Dave

On Fri, 25 Apr 2003 18:30:59 -0700 (PDT), Joe Foley <redmenaced@yahoo.com>
wrote:

>
> --- bobbyjoe@chartertn.net wrote:
>> could you add resistors to the brakes? any
>> electrical geniuses out there
>> have any ideas?
> +++++++
> I used to have a truck with a resistor bank under the
> hood to be used to "fine-tune" the trailer brakes
> depending on load.
>
> Ask U-haul or some other trailer hitch dealer who
> knows their stuff, this has to be a common problem for
> them.
>
> The problem with light bulbs is that they're fragile,
> resistors will have to be able to handle the current
> required which will cause heating of the resistor.
>
> Do the math,
>
> Joe
>
>
>
>
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-- 
Dave


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