Electric Car Conversion's Electric Accessories

by Ron
(Bath, PA)

How do you handle the electric accessories in a conversion, like the heater, AC, cd/radio sound system and airbags? How will that draw down power? Are adjustments made in kits for such accessories?
Will crash sensors still be used with airbag systems through normal electric circuits?
Are onboard computer systems still active in the conversions?

Hi, Ron!
What you want is a DC/DC converter.

See, here's the deal on the accessories: First of all, some of those accessories (like the heater and the AC) are not electric at all - only their fan is electric. With no internal combustion engine, they will be non-functional, so you'll need to replace them with a truly electric version, or do without. The engine's computer, and all those electric sensors specifically for the internal combustion bits - I don't think you'll need them; ) As for the rest of your accessories, sure, you can run them still...but you don't want to run them directly off the main battery pack.

Why?
1) It's bad for your main battery pack. Tapping one of the batteries unbalances the pack's load, leading to unequal charging, which means ultimately you'll wear out your (expensive) batteries sooner.
2) Your wipers will be slower, and your lights will be dimmer if you're using 6v or 8v batteries and tapping one of them.
3) Your range will be affected by the accessories.
4) It's good to keep your high-voltage battery pack isolated for safety reasons.

The solution to this little dilemma is a nifty invention called the DC/DC converter (the EV's answer to the alternator), and a separate 12v auxiliary battery to run your accessories.

You could simply run your accessories off a separate 12v battery, then remember to charge it every time, but the DC/DC converter allows you to plug in your car and charge them all together.

As far as the sheer number of safety and other electric accessories on modern vehicles...it's no problem, your EV can handle them all. They just draw from the 12v auxiliary battery which gets charged back up every night when you get home. You'll want a deep-cycle auxiliary battery to handle all the extras.

Having said that...

...many EV owners cut their accessories down to the absolute minimum in order to maximize range. Everyone's got a different idea of what's essential and what's not; )

Best of luck, Ron!

Regards,
Lynne