Keep blowing my solar panel controller

[SmellyCat]

Hi! Here is my setup. 20watt solar panel in rear window on 1980 300d diesel Mercedes. It runs through a controller that keeps the massive diesel starting battery topped off. I've blown two solar controllers and was wondering if the massive current draw from the batterywhen I start this beasty, is somehow sucking the life out of my solar controller. They work for 3 to 6 months. When I did this rig on my super Volvo, I did not have any failures. Cheers!

[SmellyCat]

I believe that is what the controller is supposed to do. Block reverse current. I ordered another one. I'm thinking of adding a switch to Cut the controller off, when I start the car. It seems dumb. Sc

[ksa8907]

What kind of controller are you using?

We use Morningstar sunsavers at work, they work great.

[Stubby79]

Specs on the controller?