Wow nice to hear that!!!
I have a few dozen FlexiBMS Lite 12Ss (HW 1.0) on my shelf at the moment waiting for buyers.
Should I get my webshop back up to get them out into the world?
- Yes please, I’m interested in buying some!
- No thank you, I’m good
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Sorry for the delay in setting up the webshop.
I’m a bit busy at the moment with the TeenyBMS and FlexiPack projects, so if you want to buy units now and don’t mind paying via bank transfer, PM me and I’ll write you an invoice for the order.
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Shop is open for EU customer!
I’ll be adding international markets at the start of May.
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@SimosMCmuffin Looking for some brainstorming/insight on how to possibly calculate the total pack mAh using a FlexiBMS
To set this up, discharge the batteries all the way. Start up a Python script, set the Flexi into reporting mode, and then log the data coming back from the serial monitor. Then calculate the total mAh put into the pack from the reported current that was being inputted throughout the couple hours of charging. Probably some integral math. (Haven’t thought about that. Easier part)
Questions that arise from this would be: How accurate of a reading would we be able to get from this over like 4 hours? (Is the current sensor accurate enough? Would the exact timing of when the reports were sent have a big effect?) Maybe even implement something into the FW to do this?
My end goal would be to just monitor the pack capacity over time. Maybe just run it once a year
The preferred way to test real capacity of a pack is to do it during discharge, but it’s not too bad to measure the capacity through charging either.
There is some noise in the current readings, but it’s not unusable by any means. You can also fine tune the reported charging current with the “$23 - Gain calibration value for AD-conversion for Charge current , 0.0-2.0 [float] {1.0000}”. So if it’s reading low, increase the gain a bit, if too high, lower the gain.
If you’re making a python script, then you can get a more accurate timestamp for each of the received state messages from the PC via “import time” (or other equivalent library), you also get the current data, so you can just do integral of the current over time to see the capacity.
You could also just log the whole state printout for the whole charging period, then export it into excel and do the integral math over there. As long as you can track the overall time and how many messages in total, or just time between messages, you can just use integral math to calculate the charged capacity amount.
It’s absolutely doable with the state printout. Easiest would probably be to just log all the state printouts during charging, do a little formating to it and import it to excel or google sheet and do your maths there. Then you won’t have to write a custom python script, but with the custom script you could get a live reading of the charged capacity.
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Hi, is there a way to command open the charge mosfets to let current out of the charge port? I would love the ability of being able to power something else from the board on the go 
I just wish VESC Mobile (not full UI version) had ALL of the features/settings the desktop version has, like RT data and stuff
I know there’s the full app for Android which has the same UI as the desktop version, but it doesn’t work well on my phone apart from Samsung DeX as the GUI is too large then, but on my 55" 4K TV the text and UI gets VERY small in DeX mode lol, so since i don’t have a tablet or laptop that gets kind of annoying
see i don’t care much for “intuitive” settings, i just want em ALL and prefer the desktop VESC tool version lol
perhaps an UI scaling setting would be nice
edit: for now force DPI does the trick tho in Android dev settings
AFAIK, there’s no such command. I believe the MOSFET is open by this:
You could maybe add a custom command here:
But then I guess it would be a little involved to do this cleanly so that the BMS doesn’t get into a weird state. Opening the MOSFET would be a hack but if you power cycle the BMS afterwards (can of course be done programmatically), it will restore the correct state and all should be good.
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As @janpom said, this is correct and the charging state machine keeps calling “__DISABLE_CHG”, if the charging state is in “notCharging”, so even if you manage to enable it somewhere, the state machine will disable it very soon after. There is a hole can of worms and weird states that would need to be handled if you wanted to be able to use the charging connector in both directions, but still want it to detect when a charger is connected for example. Also the current can only be measured towards the battery, so safety wise it isn’t possible to detect if a short-circuit fault would happen, on the charging connector side.
Been busy with an aerospace gig that I got a couple of months ago and haven’t had time to develop FlexiPack (couple testers are currently hands-on field testing their prototypes) or TeenyBMS. Have been spending my free time recently on stable diffusion and testing/figuring out my travel kit for the lapland trip.
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one person working on a BMS and it isn’t the greatest thing since playdough? I’m not too shocked.
Still no shipping to uk options. Have you thought about using some one like APEX as a distributer?
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I have a FlexiBMS and an adjustabel charger. I can set voltage and amps. The problem, or maybe it is normal, when i plug in the charger amps goes up to 13A and denn back to Amps I setup e.g .6A .Voltage is set to 50.4 and battery is 12S. So I had to set $1=14000 to avoid charger_high_current fault at start of charging. Is this high Amp peak normal or is it maybe a faulty charger ? WIth the $1=14000 settings the Battery is charged normal with 6A and also balacing is fine.
Most adjustable current chargers I’ve seen have instructions to always turn the current knob down to zero before plugging the charger into the battery, so I’m inclined to believe this is just what happens when you don’t do that. I’m not certain though because I don’t have an adjustable current charger.
Thanks for your feedback . The lowest settings on my charger is 2A and also there is the peak 13Amps… Hope flexibms is ok with 13A peak.
You can use the mobile VESC Tool to send the connection to your desktop computer over wifi. Only if the phone and desktop computer are on the same wifi network, though.
1 Like