18650 battery packs

[02gf74]

Im looking at higher capacity 18650 8.4v battery packs,

My understanding is in 18650 battery is li ion with 2.1 v cell voltage. To get 8.4v four are connected in series.

Now im seeing 6 cell pack, how can that work?

There has to be 2 batteries of the 4 that are in parallel, that is fine but there wlil still be 2 that are single in series so when those two run out, the extra parallel ones wilk stikk provide current but at 4.2 v so useless.

 

[integerspin]

Re:

cell voltage is around 4.2 charged. So two in series give your voltage.

 

[drystonepaul]

Re:

This is probably the least retro thread in the 'Retro MTB Chat' that I've ever seen.

Moved accordingly.

 

[02gf74]

Re:

Ok, that makes sense.

Im running two 4 led lamps. (each measured to draw1.55A) and getting about 40 mins from s4 pack,

The sellers typically claim 8800 mAh which are exagerated or i damaged the cell when applying heatshrink .

 

[mattr]

Run time will depend on how the controller is calibrated.
It'll probably switch off/derate at a set voltage rather than after an amount of use. I know my 6000mAh batteries only get about 4000mAh put back into them after i run them down as far as the controller will let them go.

 

[Matthews]

Re:

Most battery packs that come with these lights are total junk , I got one from Hunk Lee (china again but a battery supplier) that's a genuine 6000+mah from 4 genuine sanyo cells , I'd tested the X2 I've run for 2 years so knew it drew just short of 2A on full power , can now get over 3 hours on full , plenty long enough as I tend not to use full unless in the woods , battery worked out at £23 , bench tested it and it was still going strong after 3 hours on full , happy niteriding now

 

[hamster]

A lot of the suspiciously cheap Chinese ones use cells reclaimed from Laptop battery packs. The pack drops one cell and goes dead; they are dismantled, tested and repackaged. But you still end up buying a set of secondhand cells.

 

[Matthews]

Re: Re:

This is probably the least retro thread in the 'Retro MTB Chat' that I've ever seen.

Moved accordingly.

Does this mean we are not allowed to take our retrobikes out in the woods at night or that if we do we have to use eveready candle lights ?.
Sorry but I can not see how this needs moving , what's the difference between talking about putting usable lights on our retrobikes and discussing charge splashbacks, modern brake blocks, which kmc 9 speed chain to use and the list can go on and often does in the "Retro MTB Chat", it's a relevant topic to anyone that goes nightriding and is just as relevant on an 80's Overbury's as on a modern clown bike .
Not wishing to cause waves but sometimes the double standards are really silly .

 

[hamster]

The retro guys clearly go out with Davy Lamps, Ever Readys or Cateye 1W Halogens...