6 to 12 volt conversion

[arcturus]

Belt and braces. I'm still going down the DR road,mounting it on a heavy brass plate with thermal paste,but at the same time I have ordered a converter from Amazon.At €20 it's inexpensive insurance to have another trick up my sleeve

[142 Guy]

Brass is slightly better than steel in terms of its thermal conductivity. Make sure that it is absolutely not bronze which is decidedly worse than steel. That said, aluminum has twice the thermal conductivity of the best brass alloy which is why it is the preferred heat sink material (as long as it is not duralumin which is still better than brass; but, not as good as the more pedestrian aluminum). A copper heat sink would be the cool ticket; but, $$$$$.

[Derek UK]

Google "finned aluminium heat sink" The choice is endless. Are your resistors the big gold ones with fins on them?

[arcturus]

Originally Posted by Derek UK

Google "finned aluminium heat sink" The choice is endless. Are your resistors the big gold ones with fins on them?

The problem is mounting the DR on a finned heat sink. I have some heavy brass plate in garage (no aluminum)which I can use.

[Ron Kwas]

Arcturus;

Have you performed the tests and measured the voltage drop across various series parallel combinations to find out just how many of these 2 Ohm DRs you will need to mount to get the 6V drop, and how much heat they need to shed...by letting, for instance, the Wiper Motor run for a little while to see how hot the DRs get? (wet Windshield or lift Wipers to prevent scratching!)

It seems to me, that is what should be determined first...and knowing this, you can then make the decision if they get hotter than being able to touch, to further spread the heat out, by literally increasing separation or the number of DRs in the series/parallel array...Bill Ms solution was to simply mount the 6 DRs he needed, on an Alu plate located in the engine compartment, like so:

...of course, if you don't want them to be quite as apparent and obvious, you could locate them more discretely...like under the floor boards and the air-stream...

As far as a "finned alu heat sink" to help with shedding heat (the name of the game being high surface area and good thermal conductivity!)...I know your resources might be limited, but if you have the ability to bend sheetmetal, simply a stack of U-shaped Alu, or even a strategic stack made from Alu "L" extrusion from the local hardware chain, will do what's needed...

Good Hunting!

[arcturus]

Unable to conduct the test as my meter has gone "belly up"

[Ron Kwas]

Arcturus;

In a pinch, and before you replace your DVM, you could conceivably use a 12V lightbulb to give an rudimentary voltage indication...put 12v on it and take note the brightness and color, then put 6V on it and again take note of brightness and color (which will be notably less and more yellow) to see what you can expect at 6V, and use this indicator in parallel to your Wiper to monitor effectiveness of you DRs...

Good Hunting!