Quote:
Originally Posted by Sammus
linc: why dont you like internally paralleled cells? I always imagined them to be better...
|
Actually I have really thought about this, and can find no benefit at all with internally paralleled cells. Unless they are matched perfectly at the factory, you always end up with one strong cell attached to a slightly weaker cell. When you approach the pack limits the weak cell can't keep up, and often the weak cells puffs, or the strong cell handles the load, but it will decrease that cells life cycle. Plus the strong cells will hold voltage better, and packs with internally paralleled cells will require some cool down time to eqaulize voltage between the pairs.
Now if you have a pair of packs you can run them in parallel and then charge them in series. That way you can balalnce all of the cells during the charge, and not pairs of them... You will need a charger/balancer combo that can handle that many cells in series, which does get expensive. But you can charge the packs seperately, and as long as they take a full charge they will be quite close in balance.
You will also notice that most of the "better" lipo producers do not make packs that have internally paralleled cells. Flightpower will make paralleled packs, and their cell matching is 2nd to none... Maxamps have a few internally paralleled packs (8000, 6000, etc) and I have seen many of those fail, mainly due to poor QC and matching...