Why aren't there any AA NiMH rechargables that are 1.5V?

[fuzzybabybunny]

Sometimes the 1.2V of my NiMH gets in the way. For example, my camera's external flash uses 4 AAs, but it charges up EXTREMELY slowly with NiMH because their voltage is so low compared to alkalines. My backpacking headlamp also isn't as bright with NiMH as with alkalines.

What is preventing NiMH from getting to 1.5V? And why aren't there any AA lithium cells? All I see are those double-AAs called CR-V3's that take up the space of two AAs but are a combined 3V.

 

[dighn]

the voltage is completely dependent on the chemistry. NiMH just gives 1.2, if not it wouldn't be NiMH.

 

[mugs]

I've experienced the opposite. Our external flashes charge up faster with a good set of NiMhs.

NiMhs actually charge up to around 1.5v, but they drop pretty quickly to 1.2v and then hold steady there until they're about dead.

Alkalines also drop pretty quickly in the beginning, but then it's a slight downward slope in the vicinity of 1.2v until they're dead.


It sounds like your batteries aren't very good. Get yourself a set of Sanyo 2700s and a good charger (like a Lacrosse BC-900)

I had a set of AA rechargeables that never worked well in our external flashes - when I got my BC-900 I found out that several of them were defective and weren't putting out any voltage at all.

Alkalines: http://www.candlepowerforums.com/vb/showthread.php?t=64660
NiMhs: http://www.candlepowerforums.com/vb/showthread.php?t=79302
BC-900: http://www.amazon.com/LaCrosse-Technolo...F8&s=home-garden&qid=1174408127&sr=8-1
Sanyos: http://www.amazon.com/SANYO-Pack-2700mA...F8&s=electronics&qid=1174408158&sr=8-1

 

[ElFenix]

Originally posted by: fuzzybabybunny
And why aren't there any AA lithium cells?

well what's that then?

 

[mugs]

Originally posted by: ElFenix

Originally posted by: fuzzybabybunnyAnd why aren't there any AA lithium cells?

well what's that then?

I think he means lithium ion rechargeables.

 

[fuzzybabybunny]

Originally posted by: mugs

Originally posted by: ElFenix

Originally posted by: fuzzybabybunnyAnd why aren't there any AA lithium cells?

well what's that then?

I think he means lithium ion rechargeables.

Yeah.

 

[fuzzybabybunny]

Originally posted by: mugs
I've experienced the opposite. Our external flashes charge up faster with a good set of NiMhs.

NiMhs actually charge up to around 1.5v, but they drop pretty quickly to 1.2v and then hold steady there until they're about dead.

Alkalines also drop pretty quickly in the beginning, but then it's a slight downward slope in the vicinity of 1.2v until they're dead.


It sounds like your batteries aren't very good. Get yourself a set of Sanyo 2700s and a good charger (like a Lacrosse BC-900)

I had a set of AA rechargeables that never worked well in our external flashes - when I got my BC-900 I found out that several of them were defective and weren't putting out any voltage at all.

Alkalines: http://www.candlepowerforums.com/vb/showthread.php?t=64660
NiMhs: http://www.candlepowerforums.com/vb/showthread.php?t=79302
BC-900: http://www.amazon.com/LaCrosse-Technolo...F8&s=home-garden&qid=1174408127&sr=8-1
Sanyos: http://www.amazon.com/SANYO-Pack-2700mA...F8&s=electronics&qid=1174408158&sr=8-1

The batteries I have are all MAHA (Powerex) 2200 mAh AAs with a MAHA charger. I tested them with a multimeter and they put out 1.3V fully charged I *think*. I think I'm going to retest them though, because I might have tested some cheaper brand and don't remember it.

BTW my flash is the Sigma 500 DG Super

 

[Rubycon]

Regulation to the rescue! NiMH will have plenty of amps so with a regulating supply the draw will be higher than alkalines but the overall performance should be better. My speedlites definitely cycle faster with NiMH vs. Alkalines. Under high loads the alkalines are going to droop below 1.2 volts/cell rather quickly too.

Li-Ion cells will give the best performance however their voltage per cell is much higher - 3.2 volts to as high as 4.2 volts (fresh off the charger). If the equipment isn't designed for this it will likely be damaged.

 

[Cerb]

Lithium Ion AAs: 14500. The problem is it's high voltage, low amp-hours.

If your NIMHs are only going up to 1.3v, they're toasted. AAs should be 1.4-1.45v just off the charger after a little rest. By the time they hit 1.2v, they should be nearly dead. It should take a week or more of self-discharge to get down to 1.3v resting.

My Sanyo (Energizer branded) 2500s come off at 1.43v, FI, which a cheapie Duracell rapid charger (cheapest 4-channel one I could find at the time).

 

[Jeff7]

Originally posted by: mugs

Originally posted by: ElFenix

Originally posted by: fuzzybabybunnyAnd why aren't there any AA lithium cells?

well what's that then?

I think he means lithium ion rechargeables.

A quick Google search turned up this page
"We believe this is because it would be too easy for users to inadvertently put them in a charger not designed for Lithium-ion batteries creating a potentially dangerous situation. (If an alkaline battery is put into the wrong charger it might leak or even burst, but a lithium-ion battery put into a NiCd or NiMH charger not designed for lithium-ion, might ignite. Also, because Li-ion batteries operate at much higher voltage (typically 3.7V per cell) than the 1.2 to 1.5V of most cell batteries, designing a 1.5V lithium-ion cell would be expensive."

So, the problems:
- Li-ion needs to be used carefully, or you get burning lithium.
- wrong voltage

Originally posted by: Cerb
Lithium Ion AAs: 14500. The problem is it's high voltage, low amp-hours.

If your NIMHs are only going up to 1.3v, they're toasted. AAs should be 1.4-1.45v just off the charger after a little rest. By the time they hit 1.2v, they should be nearly dead. It should take a week or more of self-discharge to get down to 1.3v resting.

My Sanyo (Energizer branded) 2500s come off at 1.43v, FI, which a cheapie Duracell rapid charger (cheapest 4-channel one I could find at the time).

Are you sure? I thought the point for a AA to be considered "dead" was 1.0V, with 1.2V the rated voltage, and 1.4V+ as the charging voltage.

 

[91TTZ]

Originally posted by: Cerb
Lithium Ion AAs: 14500. The problem is it's high voltage, low amp-hours.

If your NIMHs are only going up to 1.3v, they're toasted. AAs should be 1.4-1.45v just off the charger after a little rest. By the time they hit 1.2v, they should be nearly dead. It should take a week or more of self-discharge to get down to 1.3v resting.

My Sanyo (Energizer branded) 2500s come off at 1.43v, FI, which a cheapie Duracell rapid charger (cheapest 4-channel one I could find at the time).

1.2v is normal for Nicads and NiMh batteries.

http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery

 

[mugs]

Originally posted by: Jeff7

Originally posted by: Cerb
Lithium Ion AAs: 14500. The problem is it's high voltage, low amp-hours.

If your NIMHs are only going up to 1.3v, they're toasted. AAs should be 1.4-1.45v just off the charger after a little rest. By the time they hit 1.2v, they should be nearly dead. It should take a week or more of self-discharge to get down to 1.3v resting.

My Sanyo (Energizer branded) 2500s come off at 1.43v, FI, which a cheapie Duracell rapid charger (cheapest 4-channel one I could find at the time).

Are you sure? I thought the point for a AA to be considered "dead" was 1.0V, with 1.2V the rated voltage, and 1.4V+ as the charging voltage.

Look at the graphs in this thread:
http://www.candlepowerforums.com/vb/showthread.php?t=79302
For many of the batteries, at low amperage, they hover around 1.3v for most of their life before dropping like a rock at the end. So in that case, when the battery is at 1.2v it's pretty close to dead. I'm guessing that's what he's referring to. fuzzybabybunny's flash probably draws more than .5 amps though.

 

[foghorn67]

My cheap ebay wireless slaves came in today. The instructions say alkaline only due to the 1.2 volts on the NiMh. I am le sad.

 

[Cerb]

Originally posted by: 91TTZ

Originally posted by: Cerb
Lithium Ion AAs: 14500. The problem is it's high voltage, low amp-hours.

If your NIMHs are only going up to 1.3v, they're toasted. AAs should be 1.4-1.45v just off the charger after a little rest. By the time they hit 1.2v, they should be nearly dead. It should take a week or more of self-discharge to get down to 1.3v resting.

My Sanyo (Energizer branded) 2500s come off at 1.43v, FI, which a cheapie Duracell rapid charger (cheapest 4-channel one I could find at the time).

1.2v is normal for Nicads and NiMh batteries.

http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery

Normal depends on when and how you measure. They don't sit regulated at 1.2v or anything like that.

Mmmm, love those Sanyos

 

[Jawo]

Originally posted by: mugs
I've experienced the opposite. Our external flashes charge up faster with a good set of NiMhs.

NiMhs actually charge up to around 1.5v, but they drop pretty quickly to 1.2v and then hold steady there until they're about dead.

Alkalines also drop pretty quickly in the beginning, but then it's a slight downward slope in the vicinity of 1.2v until they're dead.


It sounds like your batteries aren't very good. Get yourself a set of Sanyo 2700s and a good charger (like a Lacrosse BC-900)

I had a set of AA rechargeables that never worked well in our external flashes - when I got my BC-900 I found out that several of them were defective and weren't putting out any voltage at all.

Alkalines: http://www.candlepowerforums.com/vb/showthread.php?t=64660
NiMhs: http://www.candlepowerforums.com/vb/showthread.php?t=79302
BC-900: http://www.amazon.com/LaCrosse-Technolo...F8&s=home-garden&qid=1174408127&sr=8-1
Sanyos: http://www.amazon.com/SANYO-Pack-2700mA...F8&s=electronics&qid=1174408158&sr=8-1

Thanks a bunch for the links mugs! I was wondering about battery discharge since im about to get some new ones.

 

[Cerb]

Originally posted by: Jeff7Are you sure? I thought the point for a AA to be considered "dead" was 1.0V, with 1.2V the rated voltage, and 1.4V+ as the charging voltage.

My Sanyo AAAs come off the charger at 1.392-1.398v (Harbor Freight free with X purchase and nice old Fluke, same readings ), the AAs vary more but I've always gotten 1.42+, though some other cells may only get to around 1.4, some over 1.45, etc..

I have no idea what voltage they are actually being charged with.

As for "dead," I said nearly dead, and you can see from the CPF link how they start falling after 1.2v, many even up to a 1A load. At 1.2v, you'd best be finding some fresh batteries (unless of course it's a real low drain device like my DAP, which got me starting to use NIMH batteries in the first place, where that still gives 2-3 hours on a Sanyo 900mAh).

 

[spidey07]

I'm tagging along mainly because it's cheaper for me to buy good quality alkalines and replace them (low current devices like game controls, RC transmitters/receivers, etc), plus they seem to last much longer. But you battery geeks know a lot more about it than I.

If you want battery madness check out some of the RC eletric powered stuff. They live and die by their batteries, but it's a different load.

 

[Cerb]

Rechargeable for everything could be as wasteful as alkalines or more so, depending on usage. Even when saving by it, it's got to be royal PITA. However, many portable devices, like cameras, flashlights, pocket amps , and anything else that won't last for a month or more on a pair of alkalines (or maybe even primary lithiums), will typically be cheaper after awhile with rechargeables, and may even perform better.

It's not so much a battery geek, as just being geeky in general...I, FI, don't really have to delve into things, but I can't just leave them alone and accept them as black boxes that do magic, either . If I don't have to even take it apart to use a DMM on it, what excuse do I have not to?

 

[mugs]

Originally posted by: spidey07
I'm tagging along mainly because it's cheaper for me to buy good quality alkalines and replace them (low current devices like game controls, RC transmitters/receivers, etc), plus they seem to last much longer. But you battery geeks know a lot more about it than I.

If you want battery madness check out some of the RC eletric powered stuff. They live and die by their batteries, but it's a different load.

For low drain stuff like that, I use alkalines. NiMhs will drain themselves in about a month if you're not using them, so they're not good for something like a TV remote.

 

[Joony]

Don't know about you but my Canon 580EX charges up a lot faster on some random 2500Mah NIMH AAs, as compared to Alkalines.

 

[spidey07]

Originally posted by: Cerb
Rechargeable for everything could be as wasteful as alkalines or more so, depending on usage. Even when saving by it, it's got to be royal PITA. However, many portable devices, like cameras, flashlights, pocket amps , and anything else that won't last for a month or more on a pair of alkalines (or maybe even primary lithiums), will typically be cheaper after awhile with rechargeables, and may even perform better.

It's not so much a battery geek, as just being geeky in general...I, FI, don't really have to delve into things, but I can't just leave them alone and accept them as black boxes that do magic, either . If I don't have to even take it apart to use a DMM on it, what excuse do I have not to?

LOL! I guess I just get alkalines for all my remotes, game controllers, stuff that isn't used that much. A 20 pack of AAs last me more than a year for under 10 bucks.

I always chuckle with guys getting rechargables for their game controllers - "Dude! These things last a month without a charge!"

"yeah, mine last 6 months to a year for 50 cents a piece, not to mention I don't pay the electricty to charge them"

 

[fatkorean]

For the slow draining stuff i would suggest eneloop batteries by sanyo. They are suppose to last like 2 years before being drained.

eneloops at amazon
or here at eneloop.info

-fk

 

[mugs]

Originally posted by: spidey07

Originally posted by: Cerb
Rechargeable for everything could be as wasteful as alkalines or more so, depending on usage. Even when saving by it, it's got to be royal PITA. However, many portable devices, like cameras, flashlights, pocket amps , and anything else that won't last for a month or more on a pair of alkalines (or maybe even primary lithiums), will typically be cheaper after awhile with rechargeables, and may even perform better.

It's not so much a battery geek, as just being geeky in general...I, FI, don't really have to delve into things, but I can't just leave them alone and accept them as black boxes that do magic, either . If I don't have to even take it apart to use a DMM on it, what excuse do I have not to?

LOL! I guess I just get alkalines for all my remotes, game controllers, stuff that isn't used that much. A 20 pack of AAs last me more than a year for under 10 bucks.

I always chuckle with guys getting rechargables for their game controllers - "Dude! These things last a month without a charge!"

"yeah, mine last 6 months to a year for 50 cents a piece, not to mention I don't pay the electricty to charge them"

Get Costco's Kirkland batteries. They're $10 for a 48 pack.

[Edit: I don't know about other controllers, but a Wii remote lasts 20-40 hours on a set of AAs - so that really shouldn't last you 6 months )

Originally posted by: fatkorean
For the slow draining stuff i would suggest eneloop batteries by sanyo. They are suppose to last like 2 years before being drained.

eneloops at amazon
or here at eneloop.info

-fk

Those can be charged in a regular NiMh charger, right?

 

[Jeff7]

Originally posted by: fatkorean
For the slow draining stuff i would suggest eneloop batteries by sanyo. They are suppose to last like 2 years before being drained.

eneloops at amazon
or here at eneloop.info

-fk

I'm surprised that there hasn't been more of a stir about these. Rechargeable batteries with a low self-discharge and good energy density.


As far as I know, they can be charged with regular NiMH chargers.

 

[dighn]

Originally posted by: Jeff7

Originally posted by: fatkorean
For the slow draining stuff i would suggest eneloop batteries by sanyo. They are suppose to last like 2 years before being drained.

eneloops at amazon
or here at eneloop.info

-fk

I'm surprised that there hasn't been more of a stir about these. Rechargeable batteries with a low self-discharge and good energy density.


As far as I know, they can be charged with regular NiMH chargers.

most people don't care enough to pay for the premium price (compared to cheapies anyway). eneloops are awesome though.