Originally Posted by
Gemini Rides
Hello
Following you will find the info I managed to get from the data sheets I have in my hands using my limited electrical engineering knowledge. We also received your e-mail at
info@gemini-lights.com. I am going to mail you the data sheets both for the battery cell and the battery pack.
Brand: BAK (NASDAQ Listed: CBAK), cells used in DELL and HP products.
Cell Model:C18650CC (UL registration no. 09CA63004)
Capacity:2250 mAh
Battery Pack Nominal Capacity 5200 mAh
Care to reconcile those two numbers? When cells are wired in series the mA-hr numbers don't change (but the voltages would add), whereas when wired in parallel the mA-hrs would add (and the voltage would be unchanged). I presume your battery pack wires pairs of cells in parallel and then takes two of those pairs and wires them in series to get the voltage up to the nominal 7.4V (Li cells are nominally 3.7V each). But if each cell is 2250 mA-hr, then wiring a pair in parallel would get you 4500 mA-hr for the pack, not 5200 mA-hr. Conversely, if the pack had a total of 6 cells (groups of 3 in parallel with the 2 groups in series) then you'd get a total of 6750 mA-hr for the pack. I can't see any way in which you start with individual cells at 2250 mA-hr and end up combining them in a battery pack that has 5200 mA-hr.
High Mode: 900 Lm Drive:2.4A
Low Mode: 300 Lm Drive: 0.6A[
This also raises questions. Drawing 2.4 A from a battery pack that has 5200 mA-hr (= 5.2 A-hr) would yield a run time of 5.2 A-hr/2.4A = 2.2 hr
(and if the pack capacity is really only 4.5 A-hr, then this would drop to under 2 hours).