Safety Last?

When it comes to EVs, some back-yarders may well be up there with the Harold Lloyd types, dangling on a high voltage precipice. What am I on about? You’ll recall my expensive BMS master controller I griped on about some time ago – it handles the high current charging brought into the car via a relay in the box which also houses the comms relay for battery management. The 12v line was built into the same box on a board my mother could have etched (actually, she’s pretty cool at offering board, so sorry Mom) and there were some safety/durability issues we were concerned with. Nakey’s actually got me a separate box for the 12v line, plus a separate relay box for the DC-DC converter for which I cut a hole out the other day in the opposite pillar from the charger. Keeping primary and secondary lines separate, and ensuring absolute safety against grounding the high voltage to the car is paramount.

Charge port relay and BMS housing.

Time To Get The Accessories Sorted and Install Safety Breaker

For accessories, a DC to DC converter (such as the Curtis 1410) is used to buck down the 144v (actually higher on peak charge) from the Thunderskys to an isolated 12-14 volt source for accessories such as lights, radios, airhoon, ahem I mean horn etc (which an alternator would otherwise handle in a gas car).

DC-DC converters can also be set up to charge an accessories battery and I’ll probably use a smaller gel-cell (had originally put aside an Optima D36 but weight and space were an issue -and the Optima weighs 25kg!). Although you can get away using the traction pack instead, I prefer a separate accessories battery.