Well, i have been sick as hell lately.. 50-60deg weather here in Colorado and i'm in home thinking about how cool it would be to ride.. -_-
But... the first round of 15C zippy packs just arrived
As promised, the Zippy 15C 6S packs are actually... get this... the same size overall as the Turnigy 20C 5S, plus or minus a MM here and there.
I do not have a scale, but just going off hobbyking specs..
Turnigy 5S 5AH 20C : 666g
Turnigy 6S 5AH 20C: 793g
Zippy 6S 5AH 15C: 681g
Zippy 6S 5AH 20C: 754g
Zippy 6S 5AH 40C: 834g
( wow, the higher the discharge, the bigger and heavier these get, by a notable amount. )
According to the 'pick it up' test, i cannot feel any difference in weight between the turnigy 20C 5S and the Zippy 15C 6S. For now, i will believe the specs
Let's talk about performance..
When i got my Zippy 20C, average internal resistance was 9 mOhm. 1.5 years later, it's avg. 11mOhm.
When i got my Turnigy 20C, average internal resistance was 2 mOhm. 1 year later, it's avg. 3mOhm.
These Zippy 15C test out at an average of 12 mOhm internal resistance. That's actually not so bad. Not as overrated as the 20C Zippy was.
That's a big difference. The heavier turnigy 20C thus has 1/4th of the discharge rate.
My rule for good RC Lipo performance ( low sag, virtually no heat ) is to run 1/3rd-1/4 the maximum C rate / amps of the battery. This applies to other lithium chemistries such as lifepo4.
So, 5AH X 15C = 75A would be the maximum output for this pack.
1/4th C rate discharge:
5AH = 18.75A
10AH = 37.5A
15AH = 56.25A
20AH = 75A
So anyway.. 100W halogen discharger, at an average of ~4.25A: ( almost 1C )
The watt meter is saying i'm getting 5.5AH out of these during a 100W halogen discharge test.
I know this is wrong.
The iCharger is saying that i'm putting back 4.84 AH back in.
I trust the iCharger more, but i do wonder!
What i'm getting out of this is that i need more expensive measurement equipment
... maybe a CBA-II is really in order..
But thus far, these cells are the real deal. They'll work great in a 30AH configuration with a peak 56 amp draw ( may tune it down to 50A ).