Weidenhoff Model 818 Magnet Charger

David Cave creates his own documentation through this internal and external examination of his Weidenhoff model 818 magnet charger.

| August/September 2020


I have long had an interest in old equipment used around our gas engines. In pursuit of that interest, nearly 20 years ago, I found and bought — sight unseen — a Weidenhoff Model 818 magnet charger. Sitting on a bluff overlooking the Mississippi River, even unrestored, it was a beautiful sight to see. But why the fork lift? The advertisement made no mention of its weight. Back to Arizona we headed with the rear of our 4-wheel-drive SUV sitting low. Loading it with a forklift was easy, unloading it with a cherry picker was another story. Getting the cherry picker boom in under the SUV roof line and above the Weidenhoff and chains to the corners of the pallet was a challenge. Once it was unloaded, I estimated its weight to be between 500 and 600 pounds by measuring how many pounds it took to pull the picker pump handle and multiplying that by piston diameters, arm lengths, etc.

Since then, it has sat in my shop on a Harbor Freight dolly regularly recharging magnets. There have been a few cases where I have tested a low-tension magneto whose magnet had just been recharged on a home brew charger and one case after being recharged on a super charged John Rex style running on 24-volt. After a second recharge on the Weidenhoff the magneto output current of those magnets improved as much as 30 percent which translates to a 69 percent hotter spark.

Shown from the top, the Weidenhoff 818 features a John Deere magneto with pole piece storage area to left.

More recently, after I had originally written this article, I received a very weak welded John Deere magnet from Mitch Malcolm of Lightning Magneto. Knowing the condition of the magnet, Mitch felt I would be unable to revive it, and if I did it wouldn’t last more than a few days laying around without a keeper. The Weidenhoff brought it back to a very good level, not the best but never the less very good.

I pulled the magnet off the magneto base and test stand and laid it on my wood workbench. The following week it was put back on the set up and tested again. Indeed, it lost 12 percent of its output but that still left it in the range of pretty good magnets I have tested. Five Mondays in a row I have put it back on the test stand, it has lost no strength since the first week.


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