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Author Topic:   NiCd vs NiMH Rechargeable Batteries?

Newtauk1 posted 07-06-2008 09:46 AM ET (US)
What is the difference between NiCd and NiMH rechargeable bateries ? I have 6 SAFT NiCd rechargeable AA batteries in my Icom IC-M3A VHF Marine Transceiver(Radio). These batteries came with the radio to my surprise. Is NiCd SAFT company trademark? Can I use NiMH batteries to replace. I know I can use alkaline.
Chuck Tribolet posted 07-06-2008 10:55 AM ET (US)
Icom gets points for using standard cells and not making
you buy a $100 battery pack.
NiCD = Nickel Cadmium
NiHM = Nickel Metal Hydride.
NiCD is obsolete technology. I think the best AAs were
around 1500 mAH, if that. NiMH AAs come in up to 2700mAH.
Now, can you replace NiCD with NiMH. They are roughly the
same voltage, and the hight mAH just means the device will
run twice as long. The question is the charger. There are
some NiCD chargers that won't charge some NiMH batteries.
NiCDs. As you charge an NiCD, the voltage goes up, and then
just before full charge, it comes down a little. Some NiCD
chargers detected this (it's called negative delta V), and
used it to shut off charging. Early NiMH batteries didn't
do this, the voltage stopped going up, but never came down
(zero delta V) and the chargers that looked for negative
delta V just kept ramming electrons through. More recent
NiMH batteries seem to have a negative delta V again.
I've personally not run into this problem.
Both NiCD and normal NiMH batteries will self-discharge by
10-25% per month. There's some new low-discharge NiMH
technology that doesn't do that, but it's lower mAN (2100
typ. for AAs).
http://www.thomas-distributing.com/rechargeable-batteries.php
is a good source. I personally like the Maha batteries and
Maha and Ansmann chargers. I have a six foot power strip
full of various battery chargers:
two for my underwater strobes
12 AAs worth for Linda's UW strobes
16 C cells worth for the UW flashlights.
My Nikon D70
Her Nikon D40
My handheld VHF.
Two FRS radios.
And a few more I can't think of off hand.

Chuck
Newtauk1 posted 07-06-2008 08:57 PM ET (US)
As always...thanks Chuck. The charger that came with the radio plugs into the radio. I do not have to remove the batteries from the case. The charger is described as an AC adapter (BC-131A)
Jerry Townsend posted 07-06-2008 11:39 PM ET (US)
Newtauk - one BIG difference is that the NiCd cells have a memory - they work just like our kids - if you don't make them work, they won't. That is, if a NiCd is used for a couple of hours and then charged - that is about all the "work" that you can ever get from the battery - unless it is totally discharged and then start over. But, like Chuck mentions - the NiCd cells are about "history".
As far as I know - the NiCd chargers cannot be used for the NiMH cells - as they have different charge/discharge characteristics. But it has been long time since I have bought NiMH cells or chargers.
The bulk of the NiMH batteries and chargers I have came from Radio Shack - and I have been really impressed by their performance. ----- Jerry/Idaho
davej14 posted 07-07-2008 10:11 AM ET (US)
Unless your iCom radio states it is ok to charge NiCads or NiMH cells then I would recommend that you either stick with NiCads or get an external charger for the NiMH cells. Using the NiMH cells in the radio should not be a problem but the charging control within the radio may not be compatible. With a proper external charger you could also consider LiIon cells for even more life.
Chuck Tribolet posted 07-07-2008 12:01 PM ET (US)
I haven't seen any LiIon AAs. And LiIon cells are about 3V.
The M3A manual says it takes 15 hours to charge the NiCDs, so
it's a simple C/10 trickle charger and should be fine with
NiMHs, though it will probably take more like 30 hours. You
can tell it's done when the battery pack gets a just a little
warm. I'd put NiMH batteries in it, and keep a close eye
on it while charging the first couple of times.
NiCD "memory" is a very overrated problem. I used NiCDs for
years in my strobes, and never had a memory problem. What
did kill a bunch of them was leaving them on a trickle
charger for weeks on end. They grow little whisker crystals
called dendrites that short them out internally. The other
thing that kills them is running the device until the
weakest cell is completely dead. It then gets reverse
polarized (ruined) by the others.

Chuck
fishgutz posted 07-07-2008 09:19 PM ET (US)
Chuck's right. I've had very similar experiences. I have used Duracell batteries (AA and AAA)and a Duracell quick charger for years now. I'll bet I have 24 AA maybe more and at least 12 AAA. I made a trickle charger for my batteries too. Marine handheld, 2 GPS units, RC Sailboat, Xbox and Wii remotes, all use them.
Chuck did the math correct, too. I'll bet with the right information he could tell you EXACTLY when your batteries are fully charged. I could too but not now. My brain is fried.
I'm impressed.
My West Marine radio came with a NiMH battery pack with a typical trickle charger and a battery "tray" that can use any AA batteries. I carry the loaded tray fully charged in a plastic bag in my ditch box.

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Author	Topic: NiCd vs NiMH Rechargeable Batteries?
Newtauk1	posted 07-06-2008 09:46 AM ET (US) What is the difference between NiCd and NiMH rechargeable bateries ? I have 6 SAFT NiCd rechargeable AA batteries in my Icom IC-M3A VHF Marine Transceiver(Radio). These batteries came with the radio to my surprise. Is NiCd SAFT company trademark? Can I use NiMH batteries to replace. I know I can use alkaline.
Chuck Tribolet	posted 07-06-2008 10:55 AM ET (US) Icom gets points for using standard cells and not making you buy a $100 battery pack. NiCD = Nickel Cadmium NiHM = Nickel Metal Hydride. NiCD is obsolete technology. I think the best AAs were around 1500 mAH, if that. NiMH AAs come in up to 2700mAH. Now, can you replace NiCD with NiMH. They are roughly the same voltage, and the hight mAH just means the device will run twice as long. The question is the charger. There are some NiCD chargers that won't charge some NiMH batteries. NiCDs. As you charge an NiCD, the voltage goes up, and then just before full charge, it comes down a little. Some NiCD chargers detected this (it's called negative delta V), and used it to shut off charging. Early NiMH batteries didn't do this, the voltage stopped going up, but never came down (zero delta V) and the chargers that looked for negative delta V just kept ramming electrons through. More recent NiMH batteries seem to have a negative delta V again. I've personally not run into this problem. Both NiCD and normal NiMH batteries will self-discharge by 10-25% per month. There's some new low-discharge NiMH technology that doesn't do that, but it's lower mAN (2100 typ. for AAs). http://www.thomas-distributing.com/rechargeable-batteries.php is a good source. I personally like the Maha batteries and Maha and Ansmann chargers. I have a six foot power strip full of various battery chargers: two for my underwater strobes 12 AAs worth for Linda's UW strobes 16 C cells worth for the UW flashlights. My Nikon D70 Her Nikon D40 My handheld VHF. Two FRS radios. And a few more I can't think of off hand. Chuck
Newtauk1	posted 07-06-2008 08:57 PM ET (US) As always...thanks Chuck. The charger that came with the radio plugs into the radio. I do not have to remove the batteries from the case. The charger is described as an AC adapter (BC-131A)
Jerry Townsend	posted 07-06-2008 11:39 PM ET (US) Newtauk - one BIG difference is that the NiCd cells have a memory - they work just like our kids - if you don't make them work, they won't. That is, if a NiCd is used for a couple of hours and then charged - that is about all the "work" that you can ever get from the battery - unless it is totally discharged and then start over. But, like Chuck mentions - the NiCd cells are about "history". As far as I know - the NiCd chargers cannot be used for the NiMH cells - as they have different charge/discharge characteristics. But it has been long time since I have bought NiMH cells or chargers. The bulk of the NiMH batteries and chargers I have came from Radio Shack - and I have been really impressed by their performance. ----- Jerry/Idaho
davej14	posted 07-07-2008 10:11 AM ET (US) Unless your iCom radio states it is ok to charge NiCads or NiMH cells then I would recommend that you either stick with NiCads or get an external charger for the NiMH cells. Using the NiMH cells in the radio should not be a problem but the charging control within the radio may not be compatible. With a proper external charger you could also consider LiIon cells for even more life.
Chuck Tribolet	posted 07-07-2008 12:01 PM ET (US) I haven't seen any LiIon AAs. And LiIon cells are about 3V. The M3A manual says it takes 15 hours to charge the NiCDs, so it's a simple C/10 trickle charger and should be fine with NiMHs, though it will probably take more like 30 hours. You can tell it's done when the battery pack gets a just a little warm. I'd put NiMH batteries in it, and keep a close eye on it while charging the first couple of times. NiCD "memory" is a very overrated problem. I used NiCDs for years in my strobes, and never had a memory problem. What did kill a bunch of them was leaving them on a trickle charger for weeks on end. They grow little whisker crystals called dendrites that short them out internally. The other thing that kills them is running the device until the weakest cell is completely dead. It then gets reverse polarized (ruined) by the others. Chuck
fishgutz	posted 07-07-2008 09:19 PM ET (US) Chuck's right. I've had very similar experiences. I have used Duracell batteries (AA and AAA)and a Duracell quick charger for years now. I'll bet I have 24 AA maybe more and at least 12 AAA. I made a trickle charger for my batteries too. Marine handheld, 2 GPS units, RC Sailboat, Xbox and Wii remotes, all use them. Chuck did the math correct, too. I'll bet with the right information he could tell you EXACTLY when your batteries are fully charged. I could too but not now. My brain is fried. I'm impressed. My West Marine radio came with a NiMH battery pack with a typical trickle charger and a battery "tray" that can use any AA batteries. I carry the loaded tray fully charged in a plastic bag in my ditch box.