EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Boscoe on June 08, 2020, 08:57:00 am
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Hi all,
I wonder if someone could help me.
I'm looking for a simple, low cost BMS solution for two series li ion cells. All I want is over voltage, over current and under voltage protection. When there's a fault, the MOSFETs get switched off. TI don't seem to do over current and if they do the IC is horrendously complex for what I need. I've looked through Digikey and the usual suspects but nothing. I'm currently looking at designing something discrete which I really don't want to do for something safety critical.
Thanks
Boscoe
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Will this be installed mass-produced equipment? Or just personal? If it's mass produced, I'd highly recommend using an industry trusted lithium-ion protection IC. At least here in the US, people are getting sued left and right for improper lithium-ion deployment...regardless of which party is actually at fault. Voltage sensing I feel is easy to do correctly with discretes, but over-current (over-discharge), maybe a little more challenging to prove you have a robust solution. Typically those use a timers and delays to check for recovery conditions, etc.
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Hi all,
I wonder if someone could help me.
I'm looking for a simple, low cost BMS solution for two series li ion cells. All I want is over voltage, over current and under voltage protection. When there's a fault, the MOSFETs get switched off. TI don't seem to do over current and if they do the IC is horrendously complex for what I need. I've looked through Digikey and the usual suspects but nothing. I'm currently looking at designing something discrete which I really don't want to do for something safety critical.
How about using a readily made Li-ion battery pack? That is a much better solution; but make sure it has the right certifications.
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Thank you for the replies and yes it's going to be implemented in a mass produced product. My other problem is that I can't use a dual MOSFET switch was the body diode drop is far too high at the currents it will be used at (~15A), I see drops of up to 1V in typical devices whereas I need something like 10mV!
We have been looking into custom packs but our manufacturer does not provide BMS solutions.
Currently I'm using a voltage monitor and a current trip sensor (INA300) to form HW interlocks with the rest of the circuitry. It seems solid to me but I've got a nagging feeling I'm doing something stupid. The interlocks will cut the charging source and any loads reducing the consumption on the battery to uAs from the MCU and glue.
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It is best to provide detailed electrical parameters, such as the most important operating current.
Generally, small current (such as 1A、2A) can use S-8232 of SII.
https://www.ablic.com/cn/doc/datasheet/battery_protection/S8252_C.pdf (https://www.ablic.com/cn/doc/datasheet/battery_protection/S8252_C.pdf)
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Maybe you've already looked, but for something like this I would turn to Linear Technology's datasheet search (https://www.analog.com/en/parametricsearch/11145#/p5380=Li-Ion&p5555=15|max&qsfv=chem|Li-Ion_vmax|_icharge|15). You don't specify the capacity of your cells, or the desired input voltage, but I'm pretty sure you'll find a suitable chip in the LTC space. Perhaps something like the LTC4020 (https://www.analog.com/en/products/ltc4020.html) is a good fit?