Originally Posted by E350
So, assuming that I am not using a Surepower or other separator and have completely separate house and starting battery/charging systems, should I:
1. Connect the house battery negative post to the starting battery negative post?
2. Or should I not connect the house and starting negative posts together?
3. Ground my house battery and my house 12v components to the chassis/frame/body?
4. Or run all my house battery 12v negatives back to the house battery?
5. Ground my house battery to the van chassis/frame/body?
6. Or not ground the house battery to the van chassis/frame/body?
Alot of these shunt type battery monitoring devices like Victron Energy's BMV600S are installed on the negative post on the battery. Are their readings messed up when the negative posts on the house and starting batteries are connected?
Is a PWM or MPPT solar charge controller confused when the positive lead is going to the house battery and the house battery is not connected to the starting battery, but the negative battery posts on the house batteries and the starting batteries are connected?
Do any of the above answers change if the 12vdc house battery system is grounded to or not grounded at all to the van's chassis/frame/body?
I guess in summary what is the best way to wire a completely separated house and starting battery system?
E350 (formerly aka "Learning slowly..." currently aka "Confusion abounds...")
The short answer is 1-6 will all work fine.
Longer answers are:
1. On a schemtic, it may be shown this way but in reality they are both typically tied to the chassis somewhere......the chassis is a ground buss.....think of it as a giant fat wire.
2. See the answer to 1. above.
3. Sure, no problem, then both systems share a common ground (the chassis)
4. You will have to do this if you do not tie the house batteries to the chassis/body. If you ground the house -ve post to the chassis, you can either run individual negative conductors back to the house battery or just connect negatives to the chassis. Not grounding the battery -ve technically requires twice the wires compared to grounding it, manufacturers like to save pennies, so they use the chassis as a ground; this also makes for simpler wiring.
In designing audio stuff, this mix of grounds can create ground loops which make hum, but will probably not matter in your van....
5. See the answer to 4. above.
6. Same as 5 above.