General Hello and technical electrical question

Green Machine

New member
Hello, I’ve known about this forum for a while and been reading up here from time to time.

I lived in Oregon for 15 years and had a Vw Syncro weekender for overland and 4x4 adventures for most of that time. Traveled all around the west but mostly the PNW for camping adventures.

I recently purchased a ‘75 Volvo C303 tgb11 from Europe. Having grown to love more rugged off road adventures there are simply places that Syncro‘s should not go. Looking to keep my van from being too beat up and modified it will be built more to gentle overland travel and less rock smashing. I plan to keep the Volvo mostly stock with some tasteful upgrade that don’t require major modification to its bone stock military profile.

Being a military model it’s a 24 volt vehicle. Many convert these trucks to 12 volts. I don’t want to fuss with all that work and departure from its original shape. I would like to install a 12 volt battery system to run many auxiliary components. Onboard air, outside and inside lights, 12v ports, etc. will need to be powered off a separate 12 volt system. Currently the plan is a deep cycle 12v battery charged by a victron high power 24/12v 70 amp dc-dc converter. High amp bus bar next to battery and a lower amp bus bar under the dash.

Anyway, I’m conflicted on wiring. I’ve done some background research on grounding separate voltage systems to a common chassis. I’m concerned about a non-insulated converter safety and potential grounding loops. I’ve been unable to find specific information online about this situation within a vehicle. Does anyone have guidance about grounding and dc converter selections? I’d like to run grounds back to the 12 volt battery and create a closed system, but in some places this will be pretty difficult to accomplish.
Thanks for reading and your insight.

Green Machine

New member
The Victron converters offer both "isolated" and "non-isolated" outputs.
If its non-isolated, their negative connection is common to both inputs & outputs.
On a vehicle, shared grounding of negative would be pretty much automatic when the appliance is installed.

Thanks for the quick reply...
The 24/12-70 is the non-isolated converter that I am looking at buying. The isolated versions don’t really push that many amps without pushing the price of entry through the roof. I was not aware that there was only one ground on these converters. I guess that makes separate grounding loops not possible. I guess as a fail safe measure a 70amp breaker or fuse would be in order. Thank you for the heads up.


Well-known member
Welcome to ExPo! 👋

I see you've already consulted a local electrician. For more electrical questions, you may want to post here:

There are more very knowledgeable, helpful members there, as well as some vendors that may be of some help.

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