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Old 10-21-2014, 05:26 PM   #122 (permalink)
e*clipse
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First qualification: I haven't read the whole thread.

Issues that bother me:
1) Isolation. What is the rated voltage? Yes, there is one. Remember, we're talking about 650V here. Many isolators, etc have voltage limitations far below that.
2) GND is local - the cell's local ground, I assume. This is ok, BUT data must be completely isolated from GND. (see below)
3) Dout is near the cell's voltage. That is fine when we're talking about cell 1. how about cell XXX - the one near 650V??
4) Any safety for the balance resistor's control? If it locks on, any sensor or override? Lee Hart has some excellent suggestions about this.

In one of my basic "how to convert an EV" books, it makes the very wise suggestion that the ENTIRE drive train's HV system is completely isolated from the frame. This book was written for relatively simple 144V DC conversions. Any detection of a frame to battery/drivetrain connection shuts down the main contactor. This is kind of like ground fault detection, but helps prevent a "hot" chassis. It's imperative that the BMS doesn't form this connection.

I'll pass. I've gone through that learning curve.

I'm sorry I don't have any better suggestions or alternatives. I do like that it prevents the spaghetti wiring, which (believe it or not) is all over my Leaf battery pack.

- E*clipse
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