PowerMax 120 VAC to 12 VDC Grounding problem

Leppad

New Member
I’ve just received a PowerMax PM3-75LK. I plugged it into a 120 VAC outlet and tested the output voltage and the device is OK, however I have serious reservations about their grounding instructions. There is a grounding lug on the back which the instructions say you have to run an 8 gauge cable from the vehicle’s chassis to the “Convert/Charger Bonding Lug”. The problem I have is that this grounding lug is only connected to the unit’s AC plug earth ground pin. That’s cool but why would I want to earth ground my vehicle chassis, given that the vehilce chassis is not supposed to be an earth ground, but merely a return path for the 12VDC appliances of the vehicle to the negative pole of the vehicle’s battery?

Isn’t using the earth ground of the PowerMax unit to ground your vehicle’s chassis dangerous? Wouldn’t that potentially fry my vehicle electronics? I would love some advice on this because right now I’m at a loss. I will be contacting PowerMax as well, and if I get a reply I will update here.
 

time2roll

Solar Addict
Every RV chassis is grounded with the utility power cord. In addition the RV chassis is the negative connection of the 12v system. The ground bond is intended for when the converter is permenently mounted and connected to the RV systems. If this PM3 is just used as a temporary portable charger I would not bother with the chassis ground while in use.
 

Leppad

New Member
Thank you for your reply time2roll. I am installing my PowerMax permanently into a Ford Transit van that I am fixing up into a camping van. I wanted this shore power option to help charge my lithium bank when I am at a campground that has shore power. I will also install a 50 amp Renogy DC to DC charger with MPPT solar. I am trying to understand the implications of grounding my Transit chassis to an actual earth ground via the ground pin on a normal 3 wire extension cord while I am at a campground.
 
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