| |
 |
|
|
Science Forum Index » Electronics - Misc Forum » Rechargeable cells - fundamentals please
Page 1 of 1
|
| Author |
Message |
| Keiron Kinninmont |
 Posted: Fri Dec 22, 2006 8:56 am |
|
|
|
Guest
|
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 |
|
|
| Back to top |
|
| CWatters |
| Posted: Sat Dec 23, 2006 6:58 am |
|
|
|
Guest
|
"Keiron Kinninmont" <keironk@mail.com> wrote in message
news:EBQih.25737$UC.24360@newsfe5-win.ntli.net...
Quote: In brief, what does recharging do to a cell?
http://en.wikipedia.org/wiki/Rechargeable_batteries
and follow the links to each type of cell.
Quote: Does it dissapate the hydrogen
equivilent that is proeduced in lead acid cells/batteries?
The chemistry of each type is different but they all use some form of
reversible chemical reaction.
Quote: Lithium rechargeable Verses NiMH rechargeable!?
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.
Quote: 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?
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) .
Quote: Can any charger be used to recharge any cells, that is both NiMH and Cads
(i
understand the technology for Li-ion is different).
Yes it's very different.
To clarify, i have a
Quote: 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?
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"
http://www.utahflyers.org/ |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Fri Jan 09, 2009 6:27 am
|
|