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[mickelec]

Hello, The 13.0kWh battery pack in my 2016 Zero S fell below the BMS cut off after sitting for 4-5months. Fortunately I have all cell strings back up to a safe voltage of around 110V total. They were only just below the BMS range. Problem is all attempts to reset the BMS have not worked. I've pushed both buttons according to the manual and tried every other combination I could think of. I discovered this forum from a Facebook post; Battery notes from a Farasis Engineer.
« on: December 11, 2015, 08:17:51 PM »

Any help on this issue will be greatly appreciated.

Thanks for your time.
MiC

[MVetter]

Uh. How exactly was the BMS supposed to stop the battery from going below the cutoff after 4-5 months of non-use? And why must it be reset?

[DonTom]

, The 13.0kWh battery pack in my 2016 Zero S fell below the BMS cut off after sitting for 4-5months

While I cannot offer anything helpful, I am very curious to what you left the SOC% at 4-5 months ago.


I often let several of my bikes sit for months as I have six electric bikes. But I check the SOC% every month or so and recharge when necessary to perhaps around 65% SOC on my three Zeros, ~80% on my three Energicas.


-Don-  Auburn, CA

[mickelec]

@MVetter - I don't know why, which is exactly why I put up my post, in the hope someone can help me.

[Specter]

FWIW to any who care...

I do not know exactly how this setup works, but on some BMS systems, when you hit the low cutout voltage, the BMS will essentially trip out the battery (trip it's breaker) cutting off any loads, (besides the BMS that is), and makes you do a manual / hard reset to put it back in service.

the only problem with this, and it's amazing how non intuitive this really is.. at that point the battery is one foot off the cliff and jogging that way picking up speed, there is pretty much no more usable power in it, so even tripping the main, just natural decay, and the little flea power the bms takes to monitor, will still crash it towards zxro land very fast.

A 48 volt battery system,  just as an example,  lets say its a 20 kw/hr battery pack

it might give you 10 kw hr of energy to drop from 51 to 50 volts
it might give you 3 kw of energy to drop from 50 to 49 volts
it might give you 1 kw to drop from 49 to 48 volts
it might give you 0.25 kw to drop from 48 to 47 volts
at this point it's probably / should be kicking out the bms at this point to keep you from pulling it down anymore with load.
it might give you 50 watt hours to drop from 47 to 46
it might give you 15 watt hours to drop from 46 to 45
from here it just craters.  you are severely damaging your battery at this point unless you immediately recover it and bring it back to minimum.

lets say your bms eats 2 watts / hr of power in idle / standby.  even at that tiny amount, that's still 50 watts a day it's taking.  so in 2 to 3 days can crush your battery 30 volts, or whatever until it just fails due to insufficient voltage to even run your bms. (this is why you need a soft start and manual reset, to get this system back online safely, to protect your battery)

all the above is assuming you have a better bms on your battery and it's a higher quality build.   some batteries are not this... protective of your battery, so you can do the math on that to figure out how much worse they do you.

The iron phosphate techs are a bit more forgiving on this... the chemistries normally found in vehicles.... not so much... dendrites form your battery shorts and you make the news.

Aaron

[MVetter]

@MVetter - I don't know why, which is exactly why I put up my post, in the hope someone can help me.

You fucked your battery through negligence and there's not a BMS in the world that can prevent that.

[TheRan]

He wasn't really criticising that, I'm sure he's aware that he fucked up. He's just wanting to know how to reset it. Specter seems to be the only one that has an issue with the behaviour of the BMS but he doesn't realise it's simply making the best of a bad scenario, as you say it can't magically energy out of thin air to keep the battery above a safe level so it just does what it can to prevent it being dragged down further by the user.

[Specter]

TheRan if you read what I said, you basically repeated it.  He was asking for info how the BMS works with the battery and I was giving a general scenario how it does, and basically explaining the failure mode he probably had happen to help him understand better.

Just saying you fucked it up and rubbing his nose in it is not going to help him much.  Explaining how the system works a bit to educate him so he understands how, WILL help him moving forward.  In order to do that, I had to explain the characteristics of the battery discharge a bit and what the BMS does, or can't do.  I understand how batteries and BMS work, been working with them for decades.  Take or leave what you want out of it.

@mickelec   What exactly did you to to reset the battery bms?  I used Grok and it gave me a fairly detailed spew of how to reset the BMS on the bike.  Seems there are a few methods.  You might want to do a query and get these steps and if there is something new, try it.

Remember with AI, it is NOT intelligent, garbage in garbage out, if you give it a shitty question, expect a shitty answer out.  Be specific and give details if you have them to help it narrow down specifically what you need, so it don't spew garbage and you end up walking off with a false sense of knowledge.

I used the following term to get this info you requested.

a 2016 zero electric motorcycle, battery fell below min voltage and bms cut out, how do i reset the bms once i get the battery back up to a normal operating voltage.

Basically it said to remove the covers on the battery and press the reset buttons on the board, and if that don't work, you may have blown some fuses on the bike.  It also gave some other things you can try.   Rather than cut and paste a ton of stuff you don't need, it might be easier for you to query it yourself, that way YOU can hone in on specifically what will help your scenario and ask very specific follow on questions if needed.   www.grok.com

Hope this can help you out.

Aaron

[TheRan]

He didn't ask for any info on how it works. All he asked was how to reset it. That's it. I swear some of you guys don't read what people are asking before you start posting a reply. He has tried pressing the buttons as the manual states and that's not working for him so he needs an alternative method, for example cutting all power to the BMS may work but it would be an involved process.

[Specter]

which is why i mentioned looking it up himself so it's right there in front of him to go thru step by step instead of playing he said / she said on a board full of self proclaimed experts

Aaron

[TheRan]

He's asking here in case anyone else has had to do the same thing.

[mickelec]

Hey, Firstly, thanks for the efforts in responding, regardless of the content. In response to @MVetter, perhaps you're better off putting your efforts elsewhere, unless you get a personal thrill out of trolling. If that's the case, keep it up as it makes me laugh.
To the rest... Thanks for having a genuine go at helping. I'll figure it out eventually. As I stated originally, I've managed to bring all cells back up to 80% but simply cannot reset the BMS.

p.s. @MVetter - I've decided to go to BNA (Battery Neglector's Anonymous) so thank you for gasli... sorry, highlighting my problem.