Re: Another EV bike :)
Posted: Wed Feb 19, 2014 10:07 pm
17 days later....and the four packs are complete !
Only one is fully charged and balanced, but it will be enough to start playing about for now.
I'm working out a scheme for a balancer system based on the 'flying capacitor' method, where the cell with the highest voltage charges a capacitor, which is then discharged into the cell with the lowest voltage. The problem with this method is the speed is very slow, not least of all because you don't fully discharge the capacitor, it only discharges down to the voltage of the lowest cell....
But what if the ca pacitor is replaced with a small pack of lithium ion cells ?
More specifically, two small lithium packs to provide full isolation. One can be discharging into the cell with the lowest voltage while the other is being charged by the cell with the highest voltage. There's some relay switching involved, lots of relay switching to be precise but with only a couple of dc-dc converters things could work quite well.
Or I could shell out for an isolated dc-dc supply and connect it in between the highest and lowest cells using relays.
I have plenty of ideas to play with as you can see.....
I should probably spend a bit of time sweeping the garage floor to clear it of plastic offcuts and bits of random offcuts.
Only one is fully charged and balanced, but it will be enough to start playing about for now.
I'm working out a scheme for a balancer system based on the 'flying capacitor' method, where the cell with the highest voltage charges a capacitor, which is then discharged into the cell with the lowest voltage. The problem with this method is the speed is very slow, not least of all because you don't fully discharge the capacitor, it only discharges down to the voltage of the lowest cell....
But what if the ca pacitor is replaced with a small pack of lithium ion cells ?
More specifically, two small lithium packs to provide full isolation. One can be discharging into the cell with the lowest voltage while the other is being charged by the cell with the highest voltage. There's some relay switching involved, lots of relay switching to be precise but with only a couple of dc-dc converters things could work quite well.
Or I could shell out for an isolated dc-dc supply and connect it in between the highest and lowest cells using relays.
I have plenty of ideas to play with as you can see.....
I should probably spend a bit of time sweeping the garage floor to clear it of plastic offcuts and bits of random offcuts.