Surely Ernesto put this buck converter after the BMS so that it wouldn’t kill the pack, surely…
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The buck converter is on the discharge output of the bms
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So either the low voltage cut off failed or something else is draining the pack
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Is the buck converter in the Kaly always on?
The lacroix sentinel board only powers on the buck converter when it detects 5v (or 3v?) from the stormcore UART port.
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Yeah my only experience using the discharge on the LLT is with an actual physical switch.
If you leave the physical switch ON, everything stays powered and WILL drain the battery. Pretty shitty implementation there, so i guess it’s possible that it’s implemented poorly across the board
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I guess so, there is no remote/5v switch like a lot of better buck converters
I’d guess that the idle drain on Kaly boards is related to the buck being always on (and possibly stabilization servos or whatever else is connected to it).
I can only speak from my experience with 12s and 18s LLT BMSs. Mine are always findable on bluetooth, and the power draw has no noticeable impact on battery voltage if I leave my board idle for a week or a month. I like to leave my boards around 3.6 to 3.7 and I’ve never seen them dip in a way that would make me worried.
I feel so bad for the people whose houses caught fire. It’s a good reminder that an improperly built or abused board/battery system is a time bomb.
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Yeah i didn’t have the time/motivation/equipment to properly measure/test the xlr that I had here, but in my opinion it’s not the draw from the bms.
I’ve monitored the exact bms that’s in the xlr attached to a battery for nearly a year sitting idle and there was no significant drain.
The bms MAY be involved if the low voltage protection isn’t working properly, but in all honesty, I think the Spintend is to blame here.
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I guess we’re all ghost busters now….
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Or only this particular one in my experience
And there is a 16-20s version of it
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yeah somehow they get well below any bms cutoff. At least Mario Chacon’s XLR got to around 2v total.
is it a healthy ubox? might not be a great comparison if not 
ive got a factory refurbed ubox I could send you for testing if you like, supposed to be fully functional according to spintend. won’t have a use case for it for quite some time so lmk
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I agree, I currently have the 18s version of this bms hooked up to a demo unit and the idle draw is significant.
It does have a switch, (yet to hook up), so I can power the unit down completely
And to be clear, I have monitored the draw when only the bms is hooked up, as I am yet to complete this demo build.
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how much idle drain is normal?
v1 micro USB ubox
voltage as of 03/16:
voltage as of 04/19:
seems tame enough. also have lights connected
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Seems about right, I topped off my 12S4P pack with a LLT/Ubox v1 once this winter, went from 3.7v to 3.4v over ~4 months…
The bigger 12S10P on a newer LLT/Ubox v2 sees no significant change whatsoever… but at 2.5x the capacity i’m not too worried.
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Would like to see some hard data on the Spintend ESC.
I’ll add another anecdote to the mix. I’ve built about a dozen boards, none have had passive drain like the Ubox board I built. One of the boards I built last year had a first gen Ubox in it + 12s4p VTC5a. The rider who was using it reported that the board was rapidly loosing charge while sitting idle for a few days. 100% to 60% over a weekend for instance.
My initial assumption was the cells due to their age and origin (old batteryclearinghouse stock), or bms failure. Although I replaced the battery and the Ubox with a Stormcore, I haven’t seen drain on original battery after removing it/ disconnecting the Ubox. No other issues with the Ubox besides that though.
*I have two OG Uboxes and two 12s4p batteries laying around maybe I’ll do some isolated tests.
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Cough…
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Nice, so you could leave our board at only 25% charged for over a year. I would expect it would be alot worse then that so that was nice to know. The drain people have got on XLR was not related to the esc. If you believe it could drain a 20s8p that has not even been out in 1 year yet I don’t know what to say. The drain on XLR was the external buck converter. This you tagged me in does not change anything I stated before, it did actually prove what I said.