FlexiBMS Lite - Flexible Configuration BMS w/ CAN-bus

Best integration in the world😍

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I had a bad P-group on the battery pack that I only recently replaced. I yet have to charge it individually to make it match the other groups.

In fact, it’s pretty good for demo purposes so I think I’ll leave it lower for now. :slight_smile:

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Yeah it would be interesting to see if the BMS could balance this pack back to level.

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I have already experimented with that a little bit. Getting a single low cell balanced is a lot trickier than balancing a single high cell since it requires leeching all other cells and that emits a lot of heat.

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This will help a noob like me attempting my first battery build soon.

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Yes I’m in the same boat

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No reason why it couldn’t. It would just take a long time to bleed the other cells down to the low one.

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Maybe a good test case for that always on balancing :wink:

Any idea on when you will be selling them? Would love to use it to monitor my battery :slight_smile: @SimosMCmuffin

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So I went ahead and tested it. It can surely do it. It just takes a lot of time. This was on a 15 Ah battery. Obviously, the higher the battery capacity, the longer it takes to bleed the parallel groups.

Yellow bars indicate which parallel groups are being discharged. Current setting is that at most 5 bleeding resistors can be used at the same time so that the BMS doesn’t overheat. The temperature was below 60 Celsius all the time. No heatsink or any kind of active cooling was used (except for me putting my finger on the BMS MCU a few times to cool it down so that I can sanity check the temperature readings :smile:).

This was my starting point:

After 3 hours:

After 5 hours:

After 7 hours:

After 14 hours:

Note that I had the DAVEGA and Unity powered from the battery pack all the time for monitoring, which is the reason that all the cells were loosing charge. This wouldn’t happen otherwise (or at least not to this extent).

I’ve been experimenting with the FlexiBMS extensively in the last couple of days and I’m gaining a lot of trust in it. I found a few minor problems in the firmware that were easy to fix. Hardware wise, it seems rock solid though. So far it handled anything I have thrown at it like a champ.

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@janpom, so flexibms has the canbus protocol identical to diebiems?

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Yes, I implemented it that way. Well, not in full. I implemented the 3 main commands that both DAVEGA and Metr use to get data readings. More can be added later as needed.

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How is the cabling done?

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Awesome! great little test @janpom cant wait to use the bmw with the DavegaX aswell in the future :slight_smile:

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See here:

I’m using a nrf dongle and Davega X and Metr Pro and two trampa vescs with canbus. Holy Moly. :woozy_face:

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Adding the FlexiBMS to the system won’t be a problem since you can have (almost) any number of devices on the canbus.

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Yea, but the realizesation how many extras I have on my board, is blewing me away. :joy:

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But what about your socks?

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