The easiest thing to do is to replace the battery... and you can buy a couple of them together...

Most of the power panels have a glow plug output, and you need a glow plug clip.

Direct 12V over the glow plug burns it in no time.

There are still possibilities...

Use a series resistor....
Use some electronics to reduce the voltage... or to generate a PWM with an average voltage around 1.2V...


I would look first for a battery...then a cheap glow starter.... (I bought one for 7EU)...and then for a power panel....and so on..