LPF Site Supporter
- Jul 10, 2015
The NCR18650GA at 3450mAh (probably highest mah you can get right now) do extremely well,
internal resistance is on par with VTC6 30Amp 18650's and doesnt seem to drop too fast driving at 4.5A.
44/47A's that drive 5A+ for 8W and higher will need the 26650's definitely.
Looking at the Panasonic 18650GA cells they say 10a discharge and don't say anything about being IMR/INR formulated, actually they are ( LI-ion ) the EFest 18650 IMR are rated at 20a for the 3500 mAh 18650 size cells that are IMR and for the 3000mAh 18650 IMR formulated cells are rated at 35a discharge, they are ( LiMN ) which will be slightly less capacity but have a higher discharge rate with less voltage sag.
Typically the higher capacity ( mAh ) will not give as much current without voltage sag, however the IMR/INR formulated cells can give a higher discharge current without as much voltage sag, but they have to give up some capacity for the higher discharge capable IMR/INR formulation. The trade off is well worth it in cases where minimum needed voltage is near normal charged voltage.
If you get good results with the Panasonics then great, if not you may want to try a higher discharge rated cell, but don't go by the mAh rating, that's just the battery capacity, go by the formulation when your normal charged voltage and your driver minimum Vin is close, that being typically 2 x 3.7 ( 7.4v ) and driver cutoff ( 6.8v ) Granted your cells will float at 4.2 fully charged, but you may need to recharge before they expend anywhere near 3450 mAh because of the driver cutoff.
This is not a critique but an effort to share useful information for all readers to consider, I personally have gone with 3 cell builds for 4.5a LD demands, but if you don't have a long duty cycle or lase a lot then you may be happy with just 2 cells, you can also go with a higher discharge rated 18650.