why do companys that re-cell batterys quote such high values

[big-all]

if you fit new cells into an old battery the maximum you can charge is governed by the charger
if the origional batteries where say 2amp hours [2 ah] then perhaps you could maybe achevie 2.2ah if the electronics are over engineered but you are so so unlikly to get more than as few percent extra perhaps 10%
so why do re-cell companys put in much larger cells than the charger can handle and quote the larger capacity say 3ah or 4ah when its never acheivable!!

http://cgi.ebay.co.uk/Bosch-24v-4-0...Home_Garden_PowerTools_SM&hash=item2a07d46171
bosh dont do greater than 2.6 ah in this design

 

[plugwash]

Surely that depends on how the charger is designed. If it's a simple timed charger then it won't put much more in than the original battery expected but if it uses one of the better charge termination methods (or doesn't have a charge termination system at all) then I don't see any reason it wouldn't charge a larger battery to full capacity.

 

[wreckedit]

I think that the amount of charge(current input) is based on the voltage the cell obtains so when its at max i.e. 18v or a bit more it will switch off. The charger is voltage sensitive and will keep charging until it reaches the set voltage. A smaller charger with low amps output will take longer to attain the voltage or if larger battries are used then its the same thing. With controlled chargers(tools) the amps ouput is controlled as well so that they don't get charged quicker than specified.
I would say that if a pack has larger batteries in it then its still ok to use your charger pack but it will take longer to charge.

 

[Nige F]

It`s the Re sell Price Index in the Post Thatcherite Free Market Economy

 

[big-all]

surely as the battery charges and the resistance builds the amps will rise to a point where the charger decides its at or just above its maximum to a point where it
[A] stops charging
blows a fuse
[C] catches fire

do they really build up to 100% redundancy into chargers!!
or am i completly misunderstanding how they work

 

[JohnD]

no, higher voltage means it takes less amps. If the battery reaches the same voltage as the charger, no current will flow.

Higher resistance also means it takes less amps.

 

[big-all]

i understand less flow but you need greater pressure/load to overcome the resistance hence higher amps!!
or have i got that wrong as well lol

 

[wreckedit]

With the correct battery charger voltage for the when the battery voltage is low it will push in many amps but this amount is governed by the resistance of the battery and charger. As the charge continues the voltage rises in the battery to that of the charger and the amps drop accordingly because of the reduced voltage difference. As said previusly.
For a really comprehensive answer then google, battery charging

 

[big-all]

cheers chaps i think i must be confusing my self with back emf on a traction motor