latching relay to add "electric start" to EV?
 

i'm converting a snowmobile from internal combustion to electric power, and one of the rules is:

Snowmobiles in this competition will be operated by judges familiar with the operation of snowmobiles. For this reason, the Zero Emissions snowmobile must be turned on and off like a conventional electric start internal combustions snowmobile.
The ZE snowmobile must have a key operation with OFF, ON, and CRANK positions. In the OFF position the snowmobile will be de-energized (contactors open) and not move when the thumb actuated throttle is moved. In the ON position, the snowmobile’s low voltage systems may be enabled, however the high voltage system must remain de-energized until the key is cranked. In the momentary CRANK position, high voltage is enabled. A green LED light labeled VEHICLE READY will be illuminated and must remain illuminated until the vehicle is shutdown or high voltage is disabled. An example of a possible state machine representation of this is shown below

http://img854.imageshack.us/img854/8...atemachine.png

any ideas as to the best way to do this?

*edit*
i think i can do it with two relays in series, where the "run" position closes the first relay. the second relay would get it's coil voltage from the momentary "start" position, but then have a Y so it can also receive power from the switched side of its own contacts. when the key is turned off it will kill the first relay, cutting the circuit, and killing the second relay.

any reasons this shouldn't work? or is there a better way?

open to suggestions :)

First here is a latching relay diagram that I think would work for you, the positive pulse from alram input would actually be your momentary start output from the key switch.
http://images.the12volt.com/12voltim...ment2const.gif

Second, as there are so many ways for you to wire this up check out Relay Diagrams - Quick Reference This is a huge resource of information that should help you figure out what you want to do :D

Impulse, that's exactly the diagram I had planned In my head! So I guess it will probably work :) now I need to find a box that holds a bunch of 12v relays good for 10 amps or so... Ev source has a nice one I will probably buy