SimpBMS - contactor wiring with&w/o economizer

Basti

New member
Joined
Aug 7, 2020
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13
Hello folks.


Am working on wiring up the BMS.

I am planning on using two contactors in ESS mode.

1st for precharge (Pin5, J4),
2nd for connecting the batteries after precharge (Pin6, J4).

According to the manual (v0.22) both these connections are 12V switched (not ground switched).
On page 16 the manual mentions, that contactors without economizers need to be connected to ground switched PWM outputs. I need clarification on that.

The 2nd contractor (after precharge) is a Gigavac with economizer, so will be fine on Pin6.
The 1st contractor (precharge), should be something cheaper, without economizer, since it's only active for a few seconds.

I assume, that a "cheap" precharge contactor without economizer should be fine on Pin5, just with the limitation, that Pin5 will not provide PWM to make the contactor more efficient, which would be OK here, as there is no continuous power draw?
I wonder if I could/should use another Pin on the BMS for the "cheap" precharge contactor.
Any suggestions for a precharge contactor for SimpBMS, in a 48V setup?

Thank you.
 
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