trevorz
Senior Heliman
Location: Calgary, Alberta Canada
| Charging LithiumI think one of the reasons you do not see big amp chargers for lithium cells is 'most' lithium cells do not allow it.
We are currently building a windows CE device at work, which is using a lithium battery, and the battery is limited in it's maximum charge rate, specified by the manufacturer. So I believe that is why you do not see it yet.
I also investigated using a 3S4P pack in our device, and the battery manufacturer recommended against this. They said a 3P system will be ok, but a 4P system will reduce the life of the batery (number of cycles), because your different series chains will cause the battery to become unmatched, i.e. one of the parallel sets will be weak, and be abused, while the other stronger legs will be underused.
I know there is a conditioning cycle that can be performed on Lithium batteries to bring them back from the dead, I do not know the details of it though, but this may be necessary to bring your 4S4P cells back after many cycles. (i.e. split the pack, re-condition the cells, and reassemble) to gain maximum life.
From what I have seen of the lithiums we use, the failure mode is the inability to either charge the battery, or hold the charge for very long. We have seen batteries that just will not reach full charge, or discharge very quickly. The inability to charge should be caught by the charger (duh!).
These have been my current experiences with using these batteries. I do believe though that these batteries are the future, and will re-define how electric heli's are viewed in the eyes of all heli pilots. |
