davidcoton wrote: ↑
Thu Feb 08, 2018 9:54 am
That battery by itself will NOT work. There is no protection, no voltage regulation, and no charging circuit.
Please refer to my reply to wh7qq. USing LM39302 for regulation. Posted the battery protection circuit as well.
Please help with me with a circuit for balanced charging of two 3.7V li-ion batteries in series.
Go back to your list of parts. For each one (including the Pi), work out the peak and average current it requires, and the voltage (especially for the motors).
1. RPi 3 B : 0.5 A ideally, 0.7A avg, 1A peak
2. Wireless keyboard and mouse : 80 mA peak, 50 mA avg (may be less but not more)
3. 3.5 inch touch display : 150 mA peak, 140 mA avg
4. Atmega328p : 100 mA peak, 50 mA avg
5. Two Motor drivers : 2.5 mA peak, 2.2 mA avg
6. PiCamera & Microphone : 10-20 mA peak, 5 mA avg
7. Motors (running directly through battery voltage (7.4V)) : 150 mA each, 1 A stall
Avg adds up to 1.1 Amps and peak adds up to 2.35 Amps
The peak current will have an impact on the selection of components and wiring, so that the whole thing works safely without catching fire.
The average current allows for how much work the device does -- again, especially the motors, are they running all the time or just for a few seconds during the run.
The voltage allows us to ensure that the system can supply each part with what it needs, and also to convert the current consuption to power(W) and thus to energy(Wh), which in turn determines battery size.
Yeah I don't want anything to catch fire as I'm using chinese Li-ion batteries, can't trust them. Any suggestions on how to calculate the rest of the things you mentioned?