Hi all, i hope someone can help.
i'm making a portable stereo from scratch to run from 3 lithium cells in series and i've aquired the balance charger and protection circuits but as i'm a novice i've become a little stuck.
my problem is the recycled protection circuits cut off at about 2.3v (too low) i was thinking of placing a schottky diode between the batteries and protection circuits on all 3 cells (0.4v drop) as this would fool the circuit to thinking the voltage was 0.4v lower than the actual battery voltage, therefor cutting out at a new higher cell voltage of about 2.7v.
the protection circuits interupt on the negative terminal and i want to use this "interupt" to switch 3 individual transistors which will in turn switch off a power transistor, basicaly the first to drop out will switch the whole lot off.
i've got a whole load of general purpose transistors, a couple of TIP31 power transistors (1a rated), and quite an extensive parts bin so any ideas or suggestions would be most appreciated.
another question.... can i use 2x TIP31 in parallel to provide more amps?
PS. i'm making it on the cheap from mostly recyled stuff, i know i could buy a high current 3s protection module but the cut-off is still too low on them, so decided to use a bunch of matching phone batteries (for their circuits) on some 18650 in a 3x2 arragement (3S2P) = 11.1v to run a TDL7297 audio amplifer, 50w peak 8ohm speakers.
i'm making a portable stereo from scratch to run from 3 lithium cells in series and i've aquired the balance charger and protection circuits but as i'm a novice i've become a little stuck.
my problem is the recycled protection circuits cut off at about 2.3v (too low) i was thinking of placing a schottky diode between the batteries and protection circuits on all 3 cells (0.4v drop) as this would fool the circuit to thinking the voltage was 0.4v lower than the actual battery voltage, therefor cutting out at a new higher cell voltage of about 2.7v.
the protection circuits interupt on the negative terminal and i want to use this "interupt" to switch 3 individual transistors which will in turn switch off a power transistor, basicaly the first to drop out will switch the whole lot off.
i've got a whole load of general purpose transistors, a couple of TIP31 power transistors (1a rated), and quite an extensive parts bin so any ideas or suggestions would be most appreciated.
another question.... can i use 2x TIP31 in parallel to provide more amps?
PS. i'm making it on the cheap from mostly recyled stuff, i know i could buy a high current 3s protection module but the cut-off is still too low on them, so decided to use a bunch of matching phone batteries (for their circuits) on some 18650 in a 3x2 arragement (3S2P) = 11.1v to run a TDL7297 audio amplifer, 50w peak 8ohm speakers.