Hitting some SimpBMS hurdles

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RandallATX
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Hitting some SimpBMS hurdles

Post by RandallATX »

Short and to the point:
Here's my setup: Tesla LDU with 16 Model S batteries, Simp BMS, Polykup MCU/Advantics VCU, magic smoke released from an IC.

1. I ran what I thought were economized contactors thru the HIGH control pins on J4. This led to the onboard DC/DC converter getting hot, and the teensy power LED never turning on. Negative contactor did close (no HV connected to the contactors however, so I never expected the positive or precharge to close)
2. Thinking #1 was incorrect, and discovering they were actually not economized contactors, I connected them to the LOW pins on J4 for each contactor. I connected the teensy board to USB power, and immediately the negative contactor closed. About 3-5 seconds later, I heard what I can only assume was the positive contactor closing and immediately the IC in the photo below started smoking.
Photo from the manual of IC that smoked (now has a small bump on the surface)
Photo from the manual of IC that smoked (now has a small bump on the surface)
I quickly disconnected USB first then the J4 connector. J4 had a VERY large spark with an audible pop when I separated the pins, but no obvious scorching on either connector or pins.
I've verified both contactors worked prior to ever connecting them to the BMS for exactly this reason. :( Both pulled about 1.7a at close, and went down to about 1.3a by ~10 seconds after closing while bench testing.

Unfortunately I'm now scared to plug anything else in for fear of doing more damage. Any thoughts on what I may have done wrong?
Here's a breakdown of my wiring when contactors were setup for HIGH control.
20220127_000014.jpg
And here's the damage
the_damage.jpg
Last question: I'm getting a "Series cells fault" error, even though all cells are present and reporting. Do I just have a battery setting wrong?
272982941_1360807881099332_3417064844695917854_n.jpg
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RandallATX
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Re: Hitting some SimpBMS hurdles

Post by RandallATX »

Also, if anyone can help me ID the chip that cooked, I would appreciate it. I am googling all the numbers on it, but can't find it.
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RandallATX
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Re: Hitting some SimpBMS hurdles

Post by RandallATX »

So, I appear to have detonated this controller IC. I did it accidentally shorting a contactor coil wire to ground. :?
Screenshot_55.png

I believe it is a bts5200-4eka, but hoping someone can confirm that is indeed the chip.

Also, does anyone have one they can sell to me? It's... a little hard to find right now.
tom91
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Re: Hitting some SimpBMS hurdles

Post by tom91 »

For the series cell fault check all settings on batteries tab relating to Parallel and Series cells. Then Check in the debug menu if the cells present is also set correctly.

You say 16 tesla modules so that would be : Parallel 1 Series 96 and Cells Present should also read 96.

In the manual wiring for your contactor is explained. You should measure the "coil" resistance if its a fixed lowish <100 ohm value you clearly have un economised contactors. You then wired them to the low side drive without adding a diode so huge voltage spikes thus blowing the ics.
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chris01290
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Re: Hitting some SimpBMS hurdles

Post by chris01290 »

I was getting series error on my Simp BMS and all cell where present and correct, it was basically because I was not saving the setting's. i think if I remember correctly the setting's are saved when you exit back to the root menu.
I know Tom is the designer so he knows best but this was just down to my lack of knowledge on using the simp BMS.
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