Battery

cyclenut1952

Pedelecer
Nov 6, 2019
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Leeds
as a complete novice could i ask? why do they use lots of single cells as opposed to 1 large cell?
when battery charger shows green light as it then balanced all the cells.
i know they seem pathetic but i dont have a clue.
thanks to anyone not too embarased to reply
 

vfr400

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Jun 12, 2011
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Basildon
Lithium batteries only go as high as 3.6v, so you need at least 10 for a 36v battery. They're also used in laptops, powertools and things like that, where small cells would be more convenient. You can get big 3.6v lithium cells, so you'd only need 10, but I guess the smaller ones are cheaper because they make more of them.

The green light means charged, not balanced. You never really know if they're balanced unless you measure the voltage. The closer the battery's voltage is to the charger's voltage after you take it off charge, the more balanced it is. The balancing system works on the basis of a little and often, which is why it's important to charge to 100% as often as is practical.
 
Last edited:

soundwave

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May 23, 2015
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each cell is 4.2v charged so you would have 1 giant cell with a lot of capacity but limited voltage.

each cell you add in series doubles the voltage 4.2-8.4 ect to make a packs voltage and the cells in Parallel doubles the capacity.

33230
 

Nealh

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Aug 7, 2014
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Smaller single cell use makes it more viable to use in multiple items/enclosures. radio's, torch's and fans etc etc. They can fit in to any designed small space so the market is huge. You only have to look as SLA batteries to see the issue.
A single smaller cell is less dangerous then a massive larger single unit.
Cost would likely be prohibitive as well as design.
As it is only so much capacity and working current can be used in cells.
18650 has reached it's limit at 3500mah for a cell and 20 - 30a.
Even newer 21700 can only just about match the current ampage , though capacity has increased a bit more.
 
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RossG

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Feb 12, 2019
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I believe one of the highest rated cells currently available is the Molicel INR 21700 P42A 4200 .


There's some good reading on that site incidentally.
 

Nealh

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I believe one of the highest rated cells currently available is the Molicel INR 21700 P42A 4200 .


There's some good reading on that site incidentally.
The format is getting better but price wise they tend to work out more expensive unless you have deep pockets, a few have started to filter down in to ebike batteries.
 

vfr400

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Jun 12, 2011
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I believe one of the highest rated cells currently available is the Molicel INR 21700 P42A 4200 .


There's some good reading on that site incidentally.
One cell - 1,000Ah 10,000 amps.
 
Last edited:

RossG

Esteemed Pedelecer
Feb 12, 2019
302
201
That's Woosh's neck of the woods, he could report back on the effects of the Super-Vape mushroom cloud fallout as it drifts over Shoeburyness.
 

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