Battery negative return

SpinnerUp · Jun 7, 2019

I'm about to start the wiring on my cargo van conversion. I've got 220ah of deep cycle batts, 320 watts of solar going on with a Victron SmartSolar MTTP 100|30 charge controller. At this time, no attachment to or use of the vans electricals in any way. No DC circuits will have the negative to van body or chassis, they will all go to a negative bus bar and then to battery. Is there any reason at all that I would need to install a chassis/body ground to the negative side of this system? In the future I will go to DC-DC charging via alternator, but I'm only concerned about the present requirements. Thoughts?

Also, I want to that I have no 120v circuits/converters/inverters/chargers either..

Trebor English · Jun 7, 2019

It will work totally isolated. Golf carts have a big motor, forward/reverse switch, and 6 batteries with nothing connected to the chassis. If one wire, any wire but just one, chafes against a sharp edge and makes contact there will be no current flow, no problem. When the second wire makes contact a problem could happen. Golf carts typically have no fuses in the high current motor circuits. Sometimes people add radios or lights using fuses but they are not necessary as long as all wires remain isolated.

Once the alternator is involved it changes. The alternator minus side, the case, is tied to chassis.

highdesertranger · Jun 7, 2019

I had a old truck and a tractor that both had positive grounds. many of your cheap solar controllers are positive ground. highdesertranger

Ticklebellly · Jun 7, 2019

SpinnerUp said:
Is there any reason at all that I would need to install a chassis/body ground to the negative side of this system?

No. For the system as described. No.

wayne49 · Jun 7, 2019

gsfish said:
Even a system that is isolated should have equipment fused. It is to protect the wire. A good example would be a boat that has no chassis but still has all equipment fused.

Odd fact... my first car had a positive ground system.

Guy

Something British? With three phase Lucas electrics, Off, On, Flicker.

bullfrog · Jun 7, 2019

One of the main reasons the British drink warm beer is Lucas makes refrigerators also!!! LOL! I always consider a circuit to be a closed loop connected by wire. Most well built vehicles run both a power and ground wire to a load.

SpinnerUp · Jun 9, 2019

I couldn't think of a reason that a chassis ground would be needed here either, but this is my first. Thanks for the various confirms.

Doubleone · Jun 9, 2019

It should work just fine as an independent 12v system. Only reasons I can think for bonding the ground would be if an AC power inverter, on-board generator, or jump start system is used, or if you get RF interference/static on radio gear. My batteries are bonded to the chassis, plus I have a redundant ground wire. Main reason mine is bonded is because I have a generator. In addition I use a switched solenoid on the positive side so I can combine the start/house batteries to jump start or charge either way. I can charge the house from the alternator while driving, or charge the start battery while on short/generator.