For a solar power installation in a van/RV, should the negative terminal of the house battery —the battery that is charged by the solar panel and used to power devices and appliances whether or not the vehicle engine is running— be grounded to the vehicle chassis? If there are multiple batteries (connected in parallel for a 12V system), should each battery be grounded to the vehicle chassis, or should only one (or none) of the batteries be grounded to the vehicle chassis? System capacity is fairly high, with inverters capable of putting out up to 300A @12VDC. There will be a connection to the house batteries from the vehicle alternator/batteries to allow them to be charged from that power source.

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    \$\begingroup\$ Usually the installation manual for the inverter will cover this. You mean 400, not 4000A, right? Typically, alternators rely on the vehicle chassis as the negative conductor. So if you want to charge from the alternator, you will absolutely have to connect to the chassis. Basically, if the starting battery and house batteries are not 100% completely separated at all times, then you have to connect the house battery negative to chassis somehow. I would recommend you use a short fat cable close to the battery bank. But check the inverter manual. \$\endgroup\$
    – user57037
    Commented Aug 1, 2018 at 4:34
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    \$\begingroup\$ possibly 4000VA \$\endgroup\$ Commented Aug 1, 2018 at 5:08
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    \$\begingroup\$ Here's a nice crescent wrench used as a 5000 Amp fuse youtu.be/DJOX0c60wQE?t=525 \$\endgroup\$ Commented Aug 1, 2018 at 5:13
  • \$\begingroup\$ Whoops, yes, I was thinking 3-4000W. Question corrected. \$\endgroup\$
    – intuited
    Commented Aug 1, 2018 at 6:16

1 Answer 1


possibly something like this.


simulate this circuit – Schematic created using CircuitLab

the battery interconnection forms a diamond shape so that each battery sees the same load and charge voltage, the system is grounded so that the alternator can charge the batteries and so that low power 12V loads can use the chassis as return. a switch is fitted so that discharging of the engine battery can be prevented.

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    \$\begingroup\$ That switch you mention could be a split-charge relay which will connect / disconnect automatically. \$\endgroup\$
    – Solar Mike
    Commented Aug 1, 2018 at 5:34

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