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Where does the charge go in rechargable batteries

Community Veteran
Posts: 7,149
Thanks: 51
Fixes: 2
Registered: 30-08-2007

Where does the charge go in rechargable batteries

Got a heavy photo weekend coming up, so I thought I'd recharge a couple of dozen rechargeable AA's of various powers. I finished this morning, as I use a fairly slow re-charger that takes 8 - 10 hours a set of 4, its taken a while.
Each set of 4 has been placed in a proper battery holder where there is no chance of them shorting out on each other. Out of curiosity I just popped the first set charged back into the charger, and they've been there for 4 hours now charging up!! Now I wonder why batteries that were fully charged 48 hours ago, not used, now apparently need charging again...
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
7 REPLIES
Community Veteran
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Registered: 16-02-2009

Re: Where does the charge go in rechargable batteries

Depends on your changer, the age of the batteries etc.
A smart charger will discharge before re-charging. a dumb one is just a constant current source.
Old batteries tend to loose their charge more quickly (Although 48 hrs is a bit quick!), and dependent on the charger they may not have been "fully" charged when they left the charger, even though they had been on charge for 8 hrs.
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Where does the charge go in rechargable batteries

and it depends on what type they are  NiCd  (nickel-cadmium) has a shortish shelf charge state, supeceded by NiMH (nickel-metal hydride ) which is better, but the newer ones are lithium
try reading this http://electronics.howstuffworks.com/battery4.htm  and this for Lithiums http://www.greenbatteries.com/libafa.html
Community Veteran
Posts: 38,251
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Registered: 15-06-2007

Re: Where does the charge go in rechargable batteries

I use the Eneloop batteries which hold 75% of the charge almost indefinitely http://www.amazon.co.uk/s/ref=nb_sb_ss_i_0_3?url=search-alias%3Daps&field-keywords=eneloop&sprefix=e...
Community Veteran
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Registered: 06-04-2007

Re: Where does the charge go in rechargable batteries

Quote from: Petlew
... I use a fairly slow re-charger that takes 8 - 10 hours a set of 4, its taken a while.

Such slow charging is not efficient, anything longer than a 2 hour charge time is likely to result in a battery not being fully charged, maybe +90% at best. But as others mention, the self discharge of NiCd/NiMH is pretty high, maybe losing 50% of charge in 14days is not untypical.
Also if some batteries have been left unused for sometime, it can take a few full charge and discharge cycles before they will hold close to full capacity again. This is likely to be what you have experienced.
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Community Veteran
Posts: 7,149
Thanks: 51
Fixes: 2
Registered: 30-08-2007

Re: Where does the charge go in rechargable batteries

Thanks guy's, I've ordered a new charger, as it seems that is as much the problem.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
Community Veteran
Posts: 16,836
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: Where does the charge go in rechargable batteries

Just found this......
http://www.amazon.co.uk/Duracell-Supreme-2450mAh-Rechargeable-Batteries/dp/B0031OE6LG/ref=sr_1_2/276...
which is a pretty good price for Duracell Re-chargables...(set of 4 = £4.09 )
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Where does the charge go in rechargable batteries

you have to watch the postage on that sort of sale, its not Amazon, but 7dayshop
not Duracell, but got them even cheaper from Lidl £2.50 for four 2500 mah AA NiMH  local to me so no postage either