Did anyone happen to notice the temperature graph of the cells? 75 deg. C is a lot! (160 deg. F) Lipos usually shouldn't go over 140 deg. F or 60 deg. C.
In case anyone didn't notice, they posted the same graphs for the regular 20C packs as the "New Formulation" 20C-50C packs. So how do we know that the cells are any different?
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Originally Posted by Nick
I love the charge rates with these packs too! Tested at 2.5c.
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While it certainly is conveniant, it also decreases the number of cycles that a pack will hold up for. Most Lipos these days are capable of 2C charges, as long as there is a balancer (the differences in the cells' internal resistances is amplified two times with a 2C charge).
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Originally Posted by BrianG
I'm all up in the air about this stuff.
One minute I want to wait for the A123Systems M1 cells from the DeWalt 36v line, but then I find they are only 2.2Ah, are kinda big (26mmD x 65mmL @ 70g), and aren't exactly like typical Li cells; they only charge to 3.6v (not 4.2v like others), which will make charging a little challenging. By the time I set up a 4s2p or 5s2p pack, I'll be at the same weight and size as equivalent NiMHs (or close to it).
Next, I think I'll try those Emoli cells from the v28 packs, but then I don't want to go with a 2p arrangement for weight and space (each cell is 26.5mmD x 70mmL @ 99g) since they don't have the burst capability.
That leaves LiMn, NiMH, or Lipos. LiMn are a bit pricey for what I need, but seem like the best choice so far despite some peoples mixed feelings. NiMH are just too heavy and bulky for what I want to use. Lipos, well, I won't go into that again.
:032: :032:
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If you are that concerned about weight, then round Lithium-based cells are not for you. They weigh more than prismatic cells mainly because of the (usually) steel casing. You just can't get much lighter weight than a plastic pouch!
If you go Emoli and use 1p, you're going to need a high voltage for the pack to hold up well.