Hi,
I have a Robot which is powered by a 3S/11.1 Lipo.
I would like the robot to dock to a charging station to charge its lipo.
Does somebody know a good solution for charging the Lipo with balancing? There are great Lipo shields. But they are for 1S/3.7V Lipos.
A solution with which the robot could stay on during charging would be perfect.
Thanks
Robert
All multi-cell LiPo chargers should be balancing chargers, LiPo's easily catch fire if charged unbalanced.
Your main problem will be docking - a balancing charger needs n+1 reliable contacts for n cells in series,
which might be mechanically tricky.
That's why I was hoping that there is something like a multi cell lipo shield. So a balancing charger I just need to supply with two contacts.
How can the charger perform balance with only 2 contacts? 'Balancing' means keeping all cells at equal voltage during charge.
With respect to preventing overcharge / overdischarge of individual cells you can implement a battery protection circuit: Tenergy Battery Pack PCB.
robvoi:
That's why I was hoping that there is something like a multi cell lipo shield. So a balancing charger I just need to supply with two contacts.
You want a LiPo battery management system on the battery, one that takes a simple 2 wire power source
as input and that can stay connected during discharge - normally this would be called a BMS.
An imbalance between cells can only be corrected if ALL cells are connected.
You want a LiPo battery management system on the battery, one that takes a simple 2 wire power source
That is the main charging current. The balancing currents travel thru smaller gauge wires.
See attached image of a 3-cell LiPo under recharge on a Turnigy charger.
Look at the earlier reference closely:
http://www.all-battery.com/protectivepcbsforli-ionandli-polymerbatterypacks.aspx
You will see the multiple connections. For example:
Charging at 2 points only cannot work because the cells cannot have exactly the same capacity. Inevitable one cell will overcharge. Overcharging not a good idea on LiPo cells. They contain finely divided Lithium metal and can burn vigourously when unhappy.
Trust me, I worked as a chemist with Lithium. You not want to see it catch fire.
Thanks for all the replies. What I then realy need is a complete Balancer and BPS - portable.
I think in this case it will be easier to build a solid five point connection for the robot and use my standard LIPO charger.
