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Same brick has both Vmin and Vmax, what is wrong?

lmore

Member
Nov 6, 2011
126
14
Trondheim, Norway
I charged a 1.5 roadster via the BMB-boards since it had a "Critical low brick voltage message" and I could not get the pin code alarm to turn off.
After charging for some days, I reconnected the correct BMB boards. The car reported that the same brick, brick #93 got both Vmin: 1.19V and Vmax: 5.00 V. See picture.
2019-03-28 18.27.10.jpg

How is it possible that the same brick has both Vmin and Vmax?
Obviously 5.00V is not correct and I believe brick #93 is the first brick in the last sheet, is there an error on the BMB-board for this sheet?
Or there a problem somewhere else?
I have a USB-device for reading Canbus-messages but have no experience.

I checked the fuses on BMB-boards for sheet 1 and sheet 11 and the fuses were all ok.
Anyone else that had this message?
 

petergrub

Member
Jul 6, 2016
184
342
Phoenix, Arizona
Can you measure the voltage for that brick with a multimeter? 5V is not likely, but 1.19V is and that would explain the low brick voltage error.

Did the BMB boards go back into the same slot they were originally removed from? The BMBs are enumerated to their position in the battery.
 
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lmore

Member
Nov 6, 2011
126
14
Trondheim, Norway
Thanks Peter, I believe the BMBs went to the same slots, but I will double-check.
I unplug and plug the service disconnect between each times I test a new BMB-position, I wish there was a better way. Not sure how many pulls the service disconnect plug can handle.

I am still puzzled by the same brick reporting Vmin and Vmax, but I had this with a Roadster 2.0 before. However this message went away, here are my 2 year old notes from this Roadster 2.0:
First brick 66 showed min. voltage of almost 0 and max. voltage 5.00, clearly wrong:
Vmin: 0.19 (#66)
Vmax: 5.00 (#66)
I thought it was strange that a brick in this sheet (not sheet 9) would show strange values and that the same brick would show both max and min, so I touched the BMB board and harness and after that, the touchscreen now showed:
Vmin: 0.08 (#81)
Vmax: 4.99 (#80)
 

petergrub

Member
Jul 6, 2016
184
342
Phoenix, Arizona
I unplug and plug the service disconnect between each times I test a new BMB-position, I wish there was a better way. Not sure how many pulls the service disconnect plug can handle.
Don't. I used to do the same, but I had no issue swapping the BMBs while the service disconnect was in. The caveat here is that I swapped in similarly enumerated BMBs, and make sure to keep the APS inhibited.

I thought it was strange that a brick in this sheet (not sheet 9) would show strange values and that the same brick would show both max and min, so I touched the BMB board and harness and after that, the touchscreen now showed:
Which BMB did you touch? 8 or 9? When you touched the BMB, did you simply push or pull the board, or unplug either of the BMBs from the harness?
 

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