Ground question connecting Renogy dc-dc charger to starter battery

[Roger58]

Hey,
Friend has a 300w solar mounted in transit van. Solar array does not appear to be grounded to chassis etc. Definite difference in potential between house and starter battery. Meter does not read any voltage between the 2 grounds nor does ohmmeter show continuity. However did get a rather large spark when touching ground from the dc charger and starter battery. Do not want to proceed without asking for advice. Is this normal or does solar setup need to be chassis grounded?

 

[S Davis]

I think it depends on if the D/C to D/C charger model is isolated or not, if not both systems share negative and would be bonded to the chassis already.

 

[Reed Cole]

Are you talking about a ground wire going from the panel frames to the body of the van? They are likely already able to pass current to the chassis unless they are mounted on plastic or rubber mounts or something.

 

[mikefitz]

Engine starter battery will be connected to van metal. The Renogy unit may be a DC to DC charger alone, or a combined unit with MPPT.
Which do you have?
Is the solar connected to a seperate controller?
Panel details?
Assuming it's a Renogy DCC 50 or 30 amp unit with MPPT, it connects up as shown, note, the starter battery negative, house battery battery negative and solar panel negative, all connect to the DCC negative and to the van metal.

If you get a serious spark connecting the house battery negative to vehicle metal there may be faults, not yet found, with the house battery circuits. The house battery positive feeds should all be fused, so check none of the fuses have failed.
House battery negative needs connection to van metal for safety.