Well, I ended up ordering one from china (ugh) ... probably need to pay tariff on them, but oh well... or really?
Since it will take a month before I get it, I decided to draw up a circuit using easily available parts to build one that assumedly has the same structure as the made in china ones:
- 4S
- Protection from overdischarge
- Protection from overcharge
- Balancing function
The design I came up with is pretty horrible, uses about 5 or so mA which will consume and then proceed to kill a 2Ah pack in 2 weeks with no load. Alas this is about as good as it gets, using generic ICs - used generic LM324 and LM358 op amps, and all through hole components.
Then I decided to see what would happen if I tried to layout the design so I could possibly fabricate it with a bit of ferric oxide and a blank. YOW, too many parts and wires to draw, too lazy. I ended up shelving this for now *sigh* ... BOM is like:
- 2 LM324
- 1 LM358
- 5 2n7000
- 2 IRF630
- ~25 resistors
- ~10 signal diodes
- ~5 zener diodes
and though it's still not perfectly accurate, it should be able to both protect charge and discharge, as well as rudimentary balancing. There's no microcontroller so there's no fuel gauge, but the protection should work I hope.
I probably could omit the balancing and charge protection for my purposes but they would be very helpful to have since I don't have a charger and needless to say no balancing charger...
So anyone come across a simpler 4S design that uses off the shelf parts?
Since it will take a month before I get it, I decided to draw up a circuit using easily available parts to build one that assumedly has the same structure as the made in china ones:
- 4S
- Protection from overdischarge
- Protection from overcharge
- Balancing function
The design I came up with is pretty horrible, uses about 5 or so mA which will consume and then proceed to kill a 2Ah pack in 2 weeks with no load. Alas this is about as good as it gets, using generic ICs - used generic LM324 and LM358 op amps, and all through hole components.
Then I decided to see what would happen if I tried to layout the design so I could possibly fabricate it with a bit of ferric oxide and a blank. YOW, too many parts and wires to draw, too lazy. I ended up shelving this for now *sigh* ... BOM is like:
- 2 LM324
- 1 LM358
- 5 2n7000
- 2 IRF630
- ~25 resistors
- ~10 signal diodes
- ~5 zener diodes
and though it's still not perfectly accurate, it should be able to both protect charge and discharge, as well as rudimentary balancing. There's no microcontroller so there's no fuel gauge, but the protection should work I hope.
I probably could omit the balancing and charge protection for my purposes but they would be very helpful to have since I don't have a charger and needless to say no balancing charger...
So anyone come across a simpler 4S design that uses off the shelf parts?
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