Mike Malmberg wrote:
coil has 14 volts
The Tyco LEV200 data sheet says it has a 12vdc coil, and is rated for 9.6v minimum, 13.2v maximum. 14v is more than its rated voltage, so it would get hot.
My suggestion would be to add a series resistor, with a capacitor in parallel (called a "slugger" circuit). Choose the resistor to drop the steady-state voltage a few volts. Oddly, the data sheet doesn't give the coil resistance, so you'll have to measure it or experiment to find the right resistor value.
Then, the capacitor in parallel initially applies the full voltage, to make the contactor pull in quickly. Something like a 10,000uF electrolytic capacitor rated at 6vdc or more will do it.
I realize that the BMS should have control over that contactor, and so my charger negative should go on the other side of the contactor (controller side rather than battery side). Will that affect the contactor heating?
No. You aren't running enough current for its contact to produce any significant amount of heat.
Also, nobody responded on the bms control question, I flipped the diode the other way around and I have no throttle at all.
I can't help you there. Sounds like you had the diode the right way to begin with. Was it in fact limiting the throttle when the BMS sensed a low cell voltage?
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