BMS Component ID Help
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Hey Y'all,
I've been going crazy trying to figure out what component I punted off my BMS while violently unplugging an XT60.
I tried following the great troubleshooting steps in the SMD Reference thread but I just got stuck in a loop of step 3 & 8 over and over again.
It is one of 15 duplicated components to the right side of the output XT60 and directly above the 6-pin connector.
(Not my actual BMS, just a reference image, don't panic)The PCB silkscreen reads C11 and with the component missing and the connection open the 11th cell in any pack connected to the BMS reads as overcharged.
Based on the visual appearance and silkscreen code I'm assuming a capacitor, but that's not much to go off of. I can't find text on any sides of component and it measures 2mm x 1.5mm.
Any help would be greatly appreciated.
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@ando Hiya :)
C11 is definitely a capacitor. I’m measuring 2x1.2mm meaning it’ll be a 2012 (metric) / 0805 (imperial) sized component.
Without desoldering one I’m measuring 0.95 uf across all of mine.
That leaves the voltage. These all are for the balance lines so I don’t imagine they will see voltages above 4.2v so anything 5v and above is probably fine. I see these usually in 16,25 and 50v versions so should be more than enough headroom.
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Thanks Lia!
You're likely right on the 1.2mm width, I didn't remove the conformal coating to measure.
I'm a bit hesitant to toss a 1uf capacitor on the board and call it good. From my limited research it's difficult to measure capacitance on soldered components.
I plan to enlist my EE friend who's much better as surface mount soldering than I am. Hopefully he can lift a capacitor or two to get an isolated reading.
Or we can just send it and see if OWIE reports cell 11 in line with the rest of the pack. ¯\__(ツ)_/¯
Anything else I should be planning for before I hand the BMS over? Thanks for getting me most of the way to the solution.
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@ando Welcome :)
I've tried to de-solder mine with my reflow station but I can't seem to get enough heat there before the ground plane saps it all away so I can't measure one of mine for you sadly.
Your EE friend will probably have the gear to remove one to test it isolated or know enough to ballpark a replacement. Thn it's just a case of ordering one o of somewhere like Mouser.
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@lia said in BMS Component ID Help:
I've tried to de-solder mine with my reflow station but I can't seem to get enough heat there before the ground plane saps it all away so I can't measure one of mine for you sadly.
Ah bummer. That makes me a bit less optimistic that this will be an easy fix for him, but hey, it's not like he could break it much more.
It's crazy generous of you to try on my behalf though. Do you have some spares or did you tear into your board on a whim? (Or more logically, some experience from a past attempt.)
Feels like I should start searching for a spare myself, just in case. Maybe a dead board to keep costs down. =P
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@ando I pulled a few off a dead bms, I couldn't get a accurate capacitance reading. They can be sodered on with a 35 watt soldering pencil.
Where are you located?
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@lemur : I'm in MN, USA.
Would you be willing to toss a couple in the post? I would be more than happy to cover costs and buy you a long distance pint. -
@ando oo someone else from MN??? Hi friend!!!
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*waves excitedly *
Where are you located? Always looking to expand the local riding group (or alternatively, build a list of cool places to ride for weekend trips).
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@ando I will dm yo u
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@ando Hi there! I had to replace that same capacitor. it is a 1uF 2012 package and I used a 10V rating. You can buy them in Newark
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Thanks so much for adding a confirmed ID for these.!
Surely I'm not the only joker that will damage one of those caps with that big ol' XT60 connector. Whoever does it next can enjoy some immediate gratification.
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Just wanted to close the loop. I got my CBXR up and running! I also [unnecessarily] changed the bearings while I had it apart and it's like a whole new board. Between the CBXR and the ReWheeled Quart I've been too busy having fun to report back.
Many thanks to @Lia and @vulkito for offering their knowledge and an extra special thank you to @Lemur for going above and beyond and mailing me some spare capacitors.
Photo Tax, because it will never look that clean ever again.
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@ando Love to see a board back out there. Well done with the repair and slick looking makeover!
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@ando please advice - Where could I buy BMS XR?
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Witz Wheel in the US, eBay internationally, or get connected with local riders and figure out who has the largest stash of spare parts.
Best of luck!
