Tuesday, October 16, 2007

Fan Power Mod

Another item off my checklist. I was annoyed that the kit wiring had the battery supporting the fans while charging, and that the fans always ran when the AC outlet was plugged in, even if the charger was not doing anything. So, I fixed it. On Zivan's website, the NG3 documentation shows what the 6 aux contacts do:

Of particular interest for this project are the AUX2 contacts, "C" and "NC" ("normally closed"). I verified with my multimeter that NC stays closed while the charger is actually charging, and then opens when complete (just like the documentation!). It supports 1A output - the fans are 0.13A each - so no fancy relays necessary. I drew up a wiring diagram (TimK was helpful with an early review):

...and then went at it with wire cutters, strippers, and crimpers. I found a small 240V AC -> 12V DC power supply at Fry's which supported 2A out at +12V (more than enough):
I mounted it next to my charger mount. I then cut the charger power cord and inserted a terminal block, where I tapped the AC lines to feed the power supply (and tie-wrapped everything to keep it neat):

Here's a view from the bottom, where you can see the labels on the power supply inputs and outputs:

The ground wire runs to the empty grounding tab on the passenger's headlight bucket:

The +12V out from the transformer runs to the AUX2 "C" connection. And then, you run another red line from the AUX2 "NC" connection...

...to the relay mount, where I previously had removed the wire from the relay to the second-from-right terminal of the fuse block (this terminal feeds the fans through a fuse):

And here is the whole project, all wrapped up, plugged in, and humming:

I verified that this powers the fans while the charger is plugged in and running, and then turns the fans off when the charger reaches 100% complete and idles itself. This means that I can leave the car plugged in pretty much all the time and it will take care of itself (other than watering the batteries :-).

Future uses of the NG3 aux outputs include two panel lights to indicate "charging" and "charge complete".

Tomorrow my controller is scheduled to arrive at Azure for servicing. Keeping my fingers crossed...

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