Originally Posted by
HarryC
It's possible that you are not charging them correctly. Despite being lithium ions you do not use the Li-ion setting on your charger. The Li-ion peak voltage used by a charger is less than the peak voltage of Jeti Power Ions, so they will be under-charged and therefore give less than the claimed capacity. The peak voltage of Power Ions is 4.2V per cell and you should charge them using the Lipo setting on your charger.
HarryC,
Thanks for the great suggestion. I did not realize that they should not be charged as LiIon. Given how cautious we all are with any Li-based battery I found it interesting that the pack had a label that said "Nominal Voltage: 7.2V max". That led me to treat them as LiIon. Oh, and they are labelled "Power Ion" :-)
So I was _very_ careful about where I put them when I tried to charge them as LiPos to 8.4V in case of any safety issue. But of course they were fine (btw I was using the AstroFlight charger in both cases .. to charge as LiIon with the A123/LiIon charger and as LiPo with their Lithium charger).
The discharge curves for the two packs, charged as LiIon then as LiPo, are posted below. I discharged with a West Mountain Radio CBA II set for a 1A discharge current.
Just as you suspect, I was not fully charging them when treating them as LiIon. I only took them down to 6V in the test below but the capacity looks plausibly close to the spec when charged properly.
Interesting too see how different the discharge curve is than an A123 which is much flatter...
Dave
Jeti Power Ion pack, charged as LiIon and LiPo.