The car is supposed to work with 6 AA-cells in series. Only rechargeable cells are an option here.
- Putting six of them in series, also adds all their source resistances in series. When high current is drawn, the current will sink a lot, leading to power loss
- The Goldpeak cells I use suffer from high self-discharge. Panasonic Eneloop should be better in this respect.
- Using a LiitoKala NCR18650B
- Charger : TP4056
- Protector : the single 8205A doesn't allow enough current. So the over-current protection had to be bypassed. This also disables under-voltage protection. When someone forgets to turn off the car, the battery will be drained to death (as has happened already)
- Boost circuit to boot the Li-ION cell voltage to 9V using XT1208 (advertised differently). This seems to work well.
- Using 1 or 2 18650 cells.
- Charger functionality removed
- Li-Ion protection : see Power Management.
The charger has an XT60 connector, so charging is easy. There's no longer a risk of incorrectly plugging in the battery after charging.