Lithium batteries versus NiMH
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Russel
Enlightened
Are you trying to decide between primary and rechargeable batteries?
[edit]If you are looking for rechargeable batteries, I'll second LouRoy's recommendation: Eneloop AA cells.[end edit]
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Thank you for the quick response. I have 2900mAh Powerex that I tried in the camera but they seemed to drain pretty quickly. I bought some non-rechargable Lithiums that were 'for digital cameras' and they seem to be holding up. Pretty expensive when you have to buy them at Disneyland. I thought maybe a rechargable Lithium would be better than a NiMH.
1dash1
Enlightened
IMO...
Best all-round use: Eneloops (2000 mah)
Low self-discharge, retains 85% of rated capacity after 1 year.
Best high-capacity use: Powerex (2700 mah)
Moderately low self-discharge, retains 85% of rated capacity after 3 months.
Comments...
If you don't need the extra capacity, you can't go wrong by purchasing Eneloops. If you do need the extra capacity, I'd suggest your first option would be to carry spare batteries (again, Eneloops). Remember, it was only a few years ago when most rechargeable AA's were only 1000-1400 mah, so the 2000 mah Eneloops are no slouch!
As for the Powerex 2700's: There have been some reports of performance degradation after two years or after a large number of recharge cycles. Personally, I haven't seen any loss of power in my 3 year-old Powerex 2700's, but they've only seen a few dozen recharge cycles. I cannot attest to what happens after 100 or 200 cycles. I'm also presently experimenting with Sanyo 2700's and they seem to be performing on par with the Powerex 2700's. Unfortunately, there is no cost savings in using the Sanyo 2700's, so I'd recommend that you stick to the Powerex brand if you are looking for high capacity cells.
EDIT: I'm not familiar with the Maha 2900 cells that you referred to.
As to rechargeable lithiums, they run 3.7 volts nominal (4.2 volts hot off the charger). They would damage your camera or flashlight if you did a straight substitution for the alkaline, lithium e2, or NiMH AA cells.
Best all-round use: Eneloops (2000 mah)
Low self-discharge, retains 85% of rated capacity after 1 year.
Best high-capacity use: Powerex (2700 mah)
Moderately low self-discharge, retains 85% of rated capacity after 3 months.
Comments...
If you don't need the extra capacity, you can't go wrong by purchasing Eneloops. If you do need the extra capacity, I'd suggest your first option would be to carry spare batteries (again, Eneloops). Remember, it was only a few years ago when most rechargeable AA's were only 1000-1400 mah, so the 2000 mah Eneloops are no slouch!
As for the Powerex 2700's: There have been some reports of performance degradation after two years or after a large number of recharge cycles. Personally, I haven't seen any loss of power in my 3 year-old Powerex 2700's, but they've only seen a few dozen recharge cycles. I cannot attest to what happens after 100 or 200 cycles. I'm also presently experimenting with Sanyo 2700's and they seem to be performing on par with the Powerex 2700's. Unfortunately, there is no cost savings in using the Sanyo 2700's, so I'd recommend that you stick to the Powerex brand if you are looking for high capacity cells.
EDIT: I'm not familiar with the Maha 2900 cells that you referred to.
As to rechargeable lithiums, they run 3.7 volts nominal (4.2 volts hot off the charger). They would damage your camera or flashlight if you did a straight substitution for the alkaline, lithium e2, or NiMH AA cells.
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My take on it would be that it depends how frequently you use your camera, and how MUCH it stays on. (I think I just repeated myself)
1. If you take A LOT of pictures (with or without flash), meaning your camera would be on for a LONG period of time, during the day, then get high capacity batteries.
The Duracell 2650's are almost as good as the Sanyo 2700's, according to the NiMH shoot out charts that's posted on this forum.
Then at night, you can just charge the cells and have them ready for the morning.
I personally use Duracell 2650's from time to time for constant on items, and they last VERY long.
2. If you don't keep your camera ON for a very long time, and turn it on only to take your pictures and then you turn it off put it away, until your next need for the camera again, then I would suggest Eneloops/Duraloops.
As your camera does not stay on for a LONG time, the batteries will retain the charge longer than standard NiMH's.
So you could probably go 2 days without a charge, of course depends on how you use your camera.
I hope you get my take on it. Haha.
So to summarize:
Get high capacity if you have a constant ON device.
Get LSD (Eneloops), if you dont use your device as much, and you turn it off here and there.
As 1dash1 said, for a device that uses AA batteries, you cannot put Lithium Ion AA's in. The voltage is way too high, and you'll damage your device. Li-Ion is used only in select devices where it's designed for it, such as camera's with a proprietary battery.
You can use Energizer Lithium AA's however. Since they're primary batteries and they give out proper AA 1.5 volts.
1. If you take A LOT of pictures (with or without flash), meaning your camera would be on for a LONG period of time, during the day, then get high capacity batteries.
The Duracell 2650's are almost as good as the Sanyo 2700's, according to the NiMH shoot out charts that's posted on this forum.
Then at night, you can just charge the cells and have them ready for the morning.
I personally use Duracell 2650's from time to time for constant on items, and they last VERY long.
2. If you don't keep your camera ON for a very long time, and turn it on only to take your pictures and then you turn it off put it away, until your next need for the camera again, then I would suggest Eneloops/Duraloops.
As your camera does not stay on for a LONG time, the batteries will retain the charge longer than standard NiMH's.
So you could probably go 2 days without a charge, of course depends on how you use your camera.
I hope you get my take on it. Haha.
So to summarize:
Get high capacity if you have a constant ON device.
Get LSD (Eneloops), if you dont use your device as much, and you turn it off here and there.
As 1dash1 said, for a device that uses AA batteries, you cannot put Lithium Ion AA's in. The voltage is way too high, and you'll damage your device. Li-Ion is used only in select devices where it's designed for it, such as camera's with a proprietary battery.
You can use Energizer Lithium AA's however. Since they're primary batteries and they give out proper AA 1.5 volts.
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Sub_Umbra
Flashlight Enthusiast
FWIW NiMH cells have a longer service life -- asuming a good charger is used. Secondary lithium batteries begin to deteriorate at their time of manufacture -- whether they are in use or in a warehouse. After two years the degradation is measurable. After three years it is noticable to most. Beyond that most will have to look for replacements.
These factors are not important to many but they are absolute deal killers to many.
These factors are not important to many but they are absolute deal killers to many.
vali
Enlightened
Im not an expert in batteries but here is some considerations:
Keep in mind that there are 2 big types of lithium batteries, primaries (non rechargeable) and rechargeable (and within this type there are several types, but I will refer them as a bulk).
Primary lithiums have simmilar voltage than alkaline cells and can be used roughly as a replacement (read the manual, the voltage is similar but a bit higher and if you use it multi-cell configurations the sum can be too much and fry the electronics). The shelf life of this type is very long (more than 10 years), have larger capacity than alkalines and support higher drain applications. Remember, normal alkalines have about 2500-3000 mAh when used at about 200 mA but about half that capacity when used at 1A (It's an estimation IIRC, the gurus can give you more accurate values). This is the reason you got a bigger "runtime" in your camera. The big drawback is price, as you already noted.
The lithium rechargeable ones are a different beast. Their voltage are way higher (3.7+ volts) and will burn your camera with almost 100% probability. You need to use specific chargers to recharge them and the number of cycles is lower than Ni-MH cells. Their life is low as stated in previous post and are expensive too. The pros are the amount of energy they can store and the higher drain they can support without capacity loss (compared with Ni-NH).
With Ni-MH you can find two types of cells too.
- "Normal" chemistry: Highest capacity between NI-MH ones. If you buy rechargeable cells you probably end buying one of these. The drawback is that they lose charge very fast when not used (this is known as "self discharge) and you need to recharge them just before use. The higher capacity, the faster the self discharge (roughly). Stay away from higher than 2500 mAh unless they are proved and tested reliable.
- LSD: The "new" Ni-MH. The capacity is a bit lower than the previous group and are a bit more expensive than "normal" ones, but they can hold it very well. About 15% loss in a year and in subsequent years they are tested to lose even less than this. You can find these as advertised as "Low self discharge", "ready to use" or "precharged". Sanyo eneloops are considered the best, but you can find some tests if you use the search. They are like having alkalines that can be recharged (with even an advantage, see below).
Both Ni-MH types are interchangeable in use (but do not mix them in a device) and have a voltage of 1.2 volts. Unless stated by the manufacturer you can use them as replacement for alkalines. Even if the alkalines stated 1.5 V this value will lower as you use them, so no worries about being less than 1.5 for the Ni-MH cells. The Ni-MH can support higher drain than alkalines with no lose of capacity and their performace is almost the same until almost depleted. If you overcharge them or discharge them too much (in multi-cell devices) you will ruin the batteries and will get short runtimes.
Digital cameras are tipically high drain devices and using akalines result in lower runtimes (again, akalines subjected to high drain use will have way lower capacity than lower drain use) than Ni-MH or Lithium primaries of lower capacty (unless the you have damaged or very old ones).
To resume:
If you want a "buy and use" way, without caring too much about cost, go for primary lithium.
If you want the best cost way, use Ni-MH and a decent charger to not damage the cells. Avoid those 15 min ones and "dumb" (timed) chargers. If you use the camera/device several times a week, get the higher capacity cells. If you use you devices from time to time but want to be ready to use, go for eneloops or similar.
Keep in mind that there are 2 big types of lithium batteries, primaries (non rechargeable) and rechargeable (and within this type there are several types, but I will refer them as a bulk).
Primary lithiums have simmilar voltage than alkaline cells and can be used roughly as a replacement (read the manual, the voltage is similar but a bit higher and if you use it multi-cell configurations the sum can be too much and fry the electronics). The shelf life of this type is very long (more than 10 years), have larger capacity than alkalines and support higher drain applications. Remember, normal alkalines have about 2500-3000 mAh when used at about 200 mA but about half that capacity when used at 1A (It's an estimation IIRC, the gurus can give you more accurate values). This is the reason you got a bigger "runtime" in your camera. The big drawback is price, as you already noted.
The lithium rechargeable ones are a different beast. Their voltage are way higher (3.7+ volts) and will burn your camera with almost 100% probability. You need to use specific chargers to recharge them and the number of cycles is lower than Ni-MH cells. Their life is low as stated in previous post and are expensive too. The pros are the amount of energy they can store and the higher drain they can support without capacity loss (compared with Ni-NH).
With Ni-MH you can find two types of cells too.
- "Normal" chemistry: Highest capacity between NI-MH ones. If you buy rechargeable cells you probably end buying one of these. The drawback is that they lose charge very fast when not used (this is known as "self discharge) and you need to recharge them just before use. The higher capacity, the faster the self discharge (roughly). Stay away from higher than 2500 mAh unless they are proved and tested reliable.
- LSD: The "new" Ni-MH. The capacity is a bit lower than the previous group and are a bit more expensive than "normal" ones, but they can hold it very well. About 15% loss in a year and in subsequent years they are tested to lose even less than this. You can find these as advertised as "Low self discharge", "ready to use" or "precharged". Sanyo eneloops are considered the best, but you can find some tests if you use the search. They are like having alkalines that can be recharged (with even an advantage, see below).
Both Ni-MH types are interchangeable in use (but do not mix them in a device) and have a voltage of 1.2 volts. Unless stated by the manufacturer you can use them as replacement for alkalines. Even if the alkalines stated 1.5 V this value will lower as you use them, so no worries about being less than 1.5 for the Ni-MH cells. The Ni-MH can support higher drain than alkalines with no lose of capacity and their performace is almost the same until almost depleted. If you overcharge them or discharge them too much (in multi-cell devices) you will ruin the batteries and will get short runtimes.
Digital cameras are tipically high drain devices and using akalines result in lower runtimes (again, akalines subjected to high drain use will have way lower capacity than lower drain use) than Ni-MH or Lithium primaries of lower capacty (unless the you have damaged or very old ones).
To resume:
If you want a "buy and use" way, without caring too much about cost, go for primary lithium.
If you want the best cost way, use Ni-MH and a decent charger to not damage the cells. Avoid those 15 min ones and "dumb" (timed) chargers. If you use the camera/device several times a week, get the higher capacity cells. If you use you devices from time to time but want to be ready to use, go for eneloops or similar.
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Great stuff!! My confusion was that I have one camera with a proprietary Li cell that seems to last forever. I have another camera that uses 4 AA cells. I tried a set of my 2700mAh Powerex cells (sorry for the 2900 typo) which seemed to drain very quickly. I use the Powerex in my bike headlamp very successfully.
Recharging the day before is not an issue but if I'm in a hurry perhaps having a set of Li primaries or a set of Sanyo's Eneloops at the ready would be the way to go. If I have more time, then I can use my LaCrosse BC-900 charger to refresh as set of 2700 NiMH.
A follow-on question: to retain cell life, we elected to turn the camera on and off over leaving it on. Is one type of cell better suited for reasons other than capacity for this type of use. Or is it recommended to leave the camera on and not cycle it. It was unclear why you'd select Eneloops over high capacity cells in one case and not the other.
Recharging the day before is not an issue but if I'm in a hurry perhaps having a set of Li primaries or a set of Sanyo's Eneloops at the ready would be the way to go. If I have more time, then I can use my LaCrosse BC-900 charger to refresh as set of 2700 NiMH.
A follow-on question: to retain cell life, we elected to turn the camera on and off over leaving it on. Is one type of cell better suited for reasons other than capacity for this type of use. Or is it recommended to leave the camera on and not cycle it. It was unclear why you'd select Eneloops over high capacity cells in one case and not the other.
Turbo Guy
Enlightened
Eneloops and other LSD(low self discharge) AA NiMh have less capacity but they retain their charge extremely well during long periods of non use. Eneloops are also capable of delivering high discharge rates such as some digital cameras require.
Your Powerex 2700 cells should do well in your camera also but since you mentioned then work well in a light but not the camera I suspect they like mine have developed high IR (internal resistence). My 2700s are a few years old and their performance is rather dismal.I have cycled them several times but they will not hold their charge for more than a week. This is a somewhat common problem with very high capacity AA NiMH cells. The ones 2300 mAh and lower capacity usually have a longer service life.
Your Powerex 2700 cells should do well in your camera also but since you mentioned then work well in a light but not the camera I suspect they like mine have developed high IR (internal resistence). My 2700s are a few years old and their performance is rather dismal.I have cycled them several times but they will not hold their charge for more than a week. This is a somewhat common problem with very high capacity AA NiMH cells. The ones 2300 mAh and lower capacity usually have a longer service life.
Lithium chemistries are used due to weight. For volume, the capacities are about even between NIMH and Lithium rechargeables, but Lithiums weigh much less. In many workloads, such as cameras, neither type performs better. You can get AAs anywhere, and the user has many primary and rechargeable options; LiPo saves you an ounce or two, and lets you design a more compact camera body.
Get a set of Eneloops and try them. You may be seeing issues with the high capacity cells aging...or you may have a hungry camera. If the Lithium primaries are getting more than about 50% better life than your NIMHs, then I'd say Turbo Guy is right, and it's those cells. Older 2200mAh and so didn't have those problems, but 2500+ got them bad, fairly often.
The Eneloops can be used again and again, so economically they'd work very well. Just have a spare set ready. Also, LSD NIMHs seem to be immune to problems that crop up with high capacity cells, so are the general recommendation. I'm now using almost all LSD (Rayovac, due to retail availability when I needed them), because my other AA cells started performing like crap, eventually to the point of uselessness.
When it comes to parasitic drain, or standby drain, no kind of cell will be better than another. Or, rather, all rechargeables are bad compared to primaries. I'm guessing it's more miscommunication, because I can't find where you asked about that in the thread. However, it shouldn't be an issue, unless you're leaving it on/standby for days at a time.
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Sub_Umbra
Flashlight Enthusiast
Are you sure? That's interesting. Can you source that?
Thanks
Depends on the size. NiMH fans like to compare AA vs. 14500, which come out close to even, with Li-ion having an edge over LSD, and losing to high-capacity NiMH.
Comparing the 4/3AF to 18650, though, Li-ion wins hands-down, as 18650s are available above 2.5Ah capacity, and the highest 4/3AF I know of is 4.5Ah.
Then again, I'm not sure NiMH is as highly-developed in the 4/3AF size these days, since laptops have gone to Li-ion. Maybe the NiMH fans would point to subC or something?
csshih
Flashlight Enthusiast
according to energizer's L91 Lithium AA datasheet, the lithium cells are roughly 3Ah.
the ni-mhs the op referred to are 2.7aH? pretty close (though the high self discharge might be quite a bit...)
on the other hand, rechargeable lico2 cells ahve a very very small self discharge rate... (but they can't be used in most consumer electronic, as detailed above.)
They are pretty light. I don't have a scale on me right now.
Sub_Umbra
Flashlight Enthusiast
Thanks but that's apples and oranges. Crebie was referring to Lithium rechargeables, which have a much higher voltage than L91s, which are primary cells.
What I'd like to see are the Ah ratings for two cells of the same volume with one being a NiMH and the other being a lithium rechargable.
Sub_Umbra
Flashlight Enthusiast
Later that afternoon,
Well, this has been interesting. I've never thought of capacity in terms of volume before. I'm surprised at the results.
Common ratings for 14500 cells:
3.6v x 0.750Ah = 2.7Wh
3.6v x 0.900Ah = 3.24Wh
Common ratings for NiMH AA cells:
1.2v x 2.700Ah = 3.24Wh
1.2v x 2.900Ah = 3.48Wh
Eneloops:
1.2v x 2 Ah = 2.4Wh
Amazing.
Well, this has been interesting. I've never thought of capacity in terms of volume before. I'm surprised at the results.
Common ratings for 14500 cells:
3.6v x 0.750Ah = 2.7Wh
3.6v x 0.900Ah = 3.24Wh
Common ratings for NiMH AA cells:
1.2v x 2.700Ah = 3.24Wh
1.2v x 2.900Ah = 3.48Wh
Eneloops:
1.2v x 2 Ah = 2.4Wh
Amazing.
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Amp hour ratings would be pretty useless. 2700mah for Nimh and 750 mah for 14500's doesn't tell you much by itself.
What you would really want is Watt-hour ratings. In particular you would want WH ratings under load. But even that isn't as useful as runtime graphs of the two on the same device.
Something like this. The energy density would be represented by the area under the curve, which is pretty similar. The edge goes to the LiIon but not by the hyped amount.
The problems with these numbers is what they represent. The 2700 mAh of a Nimh is theoretically real useable capacity from the max voltage off a charger of 1.4v down to 0.9v on a low current draw. Real capacities are less.
The often quoted 750mAh of a LiIon is from 4.2v down to 0v. That would make it a one time use cell. If you stop using the LiIon at a more realistic 3.4v or so the capacity is much less. Real capacities are more like 500-600mAh for cells this size.
Not with, "Oh, here's a URL that says it," no.
Li-Ion battery shootout
NIMH battery shootout
Wikipedia list of battery sizes
I measured first by ruler/eye, so went with 14.5*50 and 17*34. Based on that, and pi as 3.14: 8252mm^3 for AA, and 7713mm^3 for CR123. Note that it's only those two. I know 18650 tends to be a good size ('naturally' good and then tons of R&D), but I couldn't find a comparison of enough cells at low current on short notice.
Note: 0.5A v. 2A is not ideal, no. But, it's more fair than 0.5A (4.1-2.5) v. 5A (1.4-0.9). Ideal, of course, would be constant wattage draw to test the batteries.
So, the CR123s I chose (good capacity, known reputable quality):
AW 750: [email protected]
Battery Station: [email protected]
Powerrizer: [email protected]
AAs (two high capacity, one I'd actually buy, if I knew when the shipments came in):
Sanyo 2700: 2.887Wh@2A
Sanyo Eneloop: 2.158Wh@2A
Accupower 2900: 2.742Wh@2A
Code:
123 Wh/mm^3 @0.5A
AW 0.000268767017
BS 0.000287566446
Pz 0.000269285622
AA Wh/mm^3 @2A
Sa 0.000349854581
Ac 0.000332283083
En 0.000261512361
Average 123 then AA:
0.000275206362
0.000314550008 (+12.5%)Now, there's lack of "perfect" data (exact diameters and lengths per cell), bias in choosing the cell (I wanted to make sure Eneloops were in the mix, FI), differences due to choice of cell because of nice measurements (AA v. CR123; no 18650), rounding error (pi and diameters, mostly), etc.. Generally, though, close enough.
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