Designing a Lithium Ion (Li-Ion) battery discharger with current and voltage sense.
Hi, I'm trying to design a discharger for a two cell Li-ion battery. The purpose of the discharger is to measure the capacity of the battery, so in addition to the discharger I'll need a current sense and voltage sense circuit.
I have already found a circuit from Sparkfun that does pretty much what I want (see the attachment - contains a saved webpage that doesn't seem to be up any more), but it uses a lot of active components (op-amps). I am trying to make this circuit as cheap as possible while also maintaining accuracy when calculating capacity, so I am looking for ideas/suggestions on achieving this, mainly using discrete components (basically alternative designs). For example using a current mirror to sense the current ect. If you also have suggestions about improving the accuracy and filtering the ADC values so that they are clean that would be good too.
I am going to be using this discharger with a Beaglebone Black (BBB), so I am aware that I am going to need to change the voltage dividers for a start (BBB has 1.8 V tolerant ADCs and has 3.3 V IO pins).
Hi, I'm trying to design a discharger for a two cell Li-ion battery. The purpose of the discharger is to measure the capacity of the battery, so in addition to the discharger I'll need a current sense and voltage sense circuit.
I have already found a circuit from Sparkfun that does pretty much what I want (see the attachment - contains a saved webpage that doesn't seem to be up any more), but it uses a lot of active components (op-amps). I am trying to make this circuit as cheap as possible while also maintaining accuracy when calculating capacity, so I am looking for ideas/suggestions on achieving this, mainly using discrete components (basically alternative designs). For example using a current mirror to sense the current ect. If you also have suggestions about improving the accuracy and filtering the ADC values so that they are clean that would be good too.
I am going to be using this discharger with a Beaglebone Black (BBB), so I am aware that I am going to need to change the voltage dividers for a start (BBB has 1.8 V tolerant ADCs and has 3.3 V IO pins).
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