openinverter forum

newb question here so please be gentle

whilst eBaying contactors I came across this listing of a "Solenoid Relay 4 Terminal 12V Intermittent 150 Surge 800A PowerSeal DC Contactor" and similar ones claiming to be from or for forklifts (1PCS new for forklift oil pump DC contactor 684-2461-212-17 DC24V 150A), so that got me to thinkin' why can't we just use a relay like the type on the inner fender of an old Ford which runs to the starter, they sure can handle all the amps

I'm asking cause true contactors can run upwards of a $100 bucks each and these could be had for only $20, so learn me please

They are not rated for 350V+

They are not rated for the necessary voltages. This means their insulation, both internally and externally may not be safe for high voltage, and means they may not be able to prevent arcs when opening and closing, which can cause damage.

Leaving aside the ratings and so forth, the contactors in an ev conversion have 2 jobs :

1)Normal connection and disconnection of HV DC.
2)Emergency disconnection of HV DC.

Assuming you find a solenoid or forklift contactor with a continuous rating then most likely it will perform task 1 at least for a while. However, on the day that something goes wrong and you NEED them to perform task 2 RIGHT F&*KING NOW that's when your car burns down as you run around looking for a spanner or screwdriver to disconnect your battery.

There is a very good reason that I only use Kilovac / Gigavac contactors in my conversions.

Jack Bauer wrote: ↑Fri Jan 28, 2022 8:53 am There is a very good reason that I only use Kilovac / Gigavac contactors in my conversions.

Hear, hear!
Though the newer panasonic contactors use silver in contact area and a magnet under them is quite good at extinguishing the HV arc.