Why is there no 12V power on my Cybertruck's 7-pin, and how do I charge my camper battery?

Answered by RV Parts Giant · Upland, CA · October 4, 2026

Short answer: Nothing is wrong with the truck. On Teslas built with the lithium low-voltage battery, from 2022 on, the owner's manual lists the 7-pin charge pin as "not supplied", so there is no output to charge from. The camper has to charge itself: solar through an MPPT controller, a lithium-capable converter on shore power, and a battery monitor.

Because Tesla does not supply it. On a gas truck the 7-pin's auxiliary pin carries a fused 12 volt feed that keeps the trailer battery topped up. On Teslas built with the lithium low-voltage battery, from 2022 onward, the owner's manual trailer-wiring table lists that pin as "not supplied". Owners on the Model Y, Model X and Cybertruck all report the same thing: lights and brakes work, the charge pin is dead.

So there is nothing to fix at the plug and no charger setting that changes it. A DC-DC charger, which is the answer on a Ford Lightning or a Rivian, has no input to work from here.

Charge the camper from itself

Solar on the roof. Panels through an MPPT controller such as the SmartSolar MPPT 100/30 or 100/50 cover a fridge and lights in most weather, and they keep working while you drive. Our MPPT sizing chart matches the controller to the panels.

Shore power at every stop. The trailer's converter does the bulk charging when you plug in. If you have upgraded to lithium, the converter needs a lithium profile; our converter upgrade guide covers which ones do.

A portable power pack at camp if the trailer has neither.

What we would not build around

Some owners run a DC-DC charger from the car's 12 volt accessory socket. Those sockets are fused low and switch off with the car, so the usable current is small and the setup is fragile.

Still worth doing at the plug

The 7-pin still runs the trailer's lights and electric brakes, so keep it healthy. A corroded or loose trailer plug causes the intermittent faults that look like a truck problem; a 7-way plug and junction box replaces it.

Know what the battery is doing

Lithium voltage barely moves until the battery is nearly empty. A SmartShunt shows real state of charge and how much the solar put back that day, so you know before a night off-grid whether the bank will make it.