Rechargeable cells - fundamentals please

In brief, what does recharging do to a cell? Does it dissapate the hydrogen equivilent that is proeduced in lead acid cells/batteries?

Lithium rechargeable Verses NiMH rechargeable!?

I need cells that will function better at colder temps. I was told that lithium ion was the way forward, is this so and why?

Will Li-ion cells rated at 1000mAh out perform NiMH cells at 2300mAh in any respect, including charging time, lifecycle, dissapation speed for high drain devices etc?

Can any charger be used to recharge any cells, that is both NiMH and Cads (i understand the technology for Li-ion is different). To clarify, i have a uniross charger, the universal 120 (very slow and crappy i suspect). on the back is listed certain sizes and capacities 9to fall inline with the uniross range i have no doubt). Can i charge a cell whose capacity falls between, below, above the range of and specific capacities mentioned on the back and how do work out how long for?

thanks

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and follow the links to each type of cell.

The chemistry of each type is different but they all use some form of reversible chemical reaction.

NiMH are generally earier and safer to charge. Charging Li cells can be dangerous if you don't know what you are doing. Several model flyers have managed to set fire to their cars/houses and many more have had lucky escapes.

any

What form factor do you need? You can get NiMH cell rated at 4300mA or more in a sub C size. The right cells from Sanyo of GP will produce 50Amps or more (warm) .

Yes it's very different.

To clarify, i have a

the

uniross

and

The spec for that charger appears to be...

Description : Universal 120 charger for Ni-Cd and Ni-Mh Batteries

3 functions : Tester, charger, Discharger Charging current : 120mA (AAA, AA, C, D), 14mA (9V) Safety timer : No Dimensions : 20.4 x 9.9 x 5.2 cm Weight : 430g

Which doesn't tell you a lot. Do NOT use that to charge Li cells.

Yes you can use it to recharge NiMH cells of a size _between_ those in the table. To work out roughly how long... Divide the capacity (in mAH) by 120 and multiply by about 1.2-1.4 approx.

Best not to charge cells _smaller_ than recommended as they are likely to be damaged if overcharged.

Larger cells should be ok but there is a small chance the charger maybe damaged. It depends how well it limits the current to 120mA. It will also take a long time. At 120mA a 1200mA cell takes around 12-14hours so a 4300mA cells might take 48 hours+. However it's not clear how well the current is controlled by that design. Is it really 120mA or does it increase when a flat battery is connected?

Measuring the charge current might not be easy as it might be rectified AC.

PS Best not mess with Li cells...

See the videos on the left hand side of this page marked "Lipo fires 1,2,3"

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