Dump load resistance

[amiklic1]

I got some 220V heaters with 70 ohms resistance. It's a wire (spiral wire) wounded in spiral onto ceramic stick (5 cm dia).

I would like to use it for dump load. How to find out how long it has to be? I'll try to take as much parts as possible to allow larger currents pass.

I got 4' 125W wind generator with 6 coils 1.4mm dia/80 turns.

[hiker]

try one of those cheap 12v-200watt. car heaters that plug into the cig. lighter..

really no heat thou......

[hiker]

[Nando]

> I got 4' 125 W wind generator with 6 coils 1.4mm dia/80 turns.

This phrase does not say anything about your voltage generated., someone may spend the time to calculate the output voltage, but even more info is needed to properly know what you have.

First: You need to inform what is the voltage of th e wind mill at the peak of the power where you need to connect the dump resistance.

Also, the current at that peak.

The resistor you have 70 ohms for 220 volts usage represents about 700 watts load.

You will not be able to take turns off, you will need to do selected short circuits to some sections to end up with the necessary resistance to protect your wind mill.

So, properly inform, in detail what you have -- accurately -- then what you need

Nando

[amiklic1]

I was pointing to this document when I said that I could shorten the wire:

http://www.oatleyelectronics.com/kits/Notes/k220.pdf

Maybe it cannot be done, but I'll try anyway. I'll measure resistance of my present dump load and try to compare.

[Opera House]

Be aware that no matter how you configure it, the wire is limited to about 3A.  You can parallel sections to achieve higher current.  If the rod is 70 ohms, limited to 3A, and load voltage is 12V you want about 4 ohms.  That means the rod could be divided into about 18 sections.  That seems a little hard to work with.  5-10 sections would be better.  Remember that high temp connections are hard to make reliably.  That is another good reason to keep the current down to about 1A.

[paulpic]

What i did for a dump load was got to the local tip and get an old 220v oven element.

Straighten it out a bit,cut off one end to expose nichrome wire with insulation powder,continually hit with a hammer removing powder,do this and at the same time pull wire the out,you will figure out how this is done.

Once wire is out cut to 1 test wire to an 18" length or so,short out to battery terminals measuring current with clamp meter or ammeter.Once done you can then cut and add wire to the desired current to suit youre application.

You may want to then wrap it around ceramic rod,i prefer to use two dump loads 1 is cooled by pc fans (18amps) and other is submerged in water (70amps.) 12volts of course

Hope this helps

[RP]

I've used old hair dryers before to make power soaks for guitar amplifiers.  The nicrome wire is good for 100-200watts witout a fan and you can easily add a small chimney to aid cooling.  There are several series runs of wire that can be reconfigured in parallel to operate at lower voltages.

[ghurd]

I have played with electric clothes dryer elements with good success. Looks like a giant hair dryer element.

G-