Having initially intended building Zero's PWM but I was offered locally a Maxx Tronic MX067.

I have now wired this up but is not making much sense to me. I have discovered that it will not work if the cell is grounded to the chassis which creates a big problem in mounting it.

For information the cell is -5N+5N- configuration with an internal 130mm square effective area. Without the PWM it runs at 21 amps or 14 at tickover, does not heat nor does the amperage increase. With the PWM installed and the cell not grounded it will not run over 14 amps. Grounding it will then take it up to 21 again. I am using a 25% solution by weight though using a weaker solution does not make much difference.

Maybe the cheap Chinese meter is lying but it is protected by 20 amp fuse.

I am a bit puzzled over this. I am tempted to ditch the PWM.

Would welcome any comments.