How big are alkalines?
- Thread starter zmoz
- Start date
Posted this in another thread:
from http://www.buchmann.ca/Chap17-page2.asp
Capacity (alkaline)
AAA Cell AA Cell C Cell D Cell 9 Volt
1100mAh 2500mAh 7100mAh 14,300mAh 600mAh
from http://www.buchmann.ca/Chap17-page2.asp
Capacity (alkaline)
AAA Cell AA Cell C Cell D Cell 9 Volt
1100mAh 2500mAh 7100mAh 14,300mAh 600mAh
JSWrightOC
Enlightened
I have not heard anything about Alkaline capacity other than this forum, but I seem to be a bit skeptical of these numbers.
Keep in mind, though, that a NiCd or a NiMH will have a fairly flat discharge curve, whereas Alkaline cells have a bit more of a slope to them. That's why they start out bright, and then drop off and slowly diminish. This is also the reason why you can measure an Alkaline cell's voltage and get a good estimate of its remaining life.
If you really wanted to know, you could do a modified version of the good ol' "which battery lasts the longest?" high-school science fair project, only use an LM317 for the purpose of constant-current sink. Time the discharge to 1.2V/cell and multiply by the discharge rate. Tada!
Keep in mind, though, that a NiCd or a NiMH will have a fairly flat discharge curve, whereas Alkaline cells have a bit more of a slope to them. That's why they start out bright, and then drop off and slowly diminish. This is also the reason why you can measure an Alkaline cell's voltage and get a good estimate of its remaining life.
If you really wanted to know, you could do a modified version of the good ol' "which battery lasts the longest?" high-school science fair project, only use an LM317 for the purpose of constant-current sink. Time the discharge to 1.2V/cell and multiply by the discharge rate. Tada!
Brock
Flashaholic
Check out
http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM
down at the bottom the same test that is run on NiMH's is run on alkaline, they don't fare very well.
Basically alkaline batteries don't take well to high discharge rates, and 1/3 of their mA is below 1 volt, unless your using regulation, pretty useless at that point.
http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM
down at the bottom the same test that is run on NiMH's is run on alkaline, they don't fare very well.
Basically alkaline batteries don't take well to high discharge rates, and 1/3 of their mA is below 1 volt, unless your using regulation, pretty useless at that point.
JSWrightOC
Enlightened
[ QUOTE ]
Brock said:
Basically alkaline batteries don't take well to high discharge rates, and 1/3 of their mA is below 1 volt, unless your using regulation, pretty useless at that point.
[/ QUOTE ]
I can attest to that. I have an HPI Micro RS4 (1/18th scale electric R/C car) that has a 4AA/AAA holder, as well as a 5 cell NiCd race pack (they look like half-length A size or something like that). Even though the NiCd pack is rated at only 600mAh, it has a LOT more "punch" than even good quality alkaline AA cells. An R/C car's "punchiness" depends a LOT on the motor, speed controller, and the battery...if the batts can't source enough current, the whole system bogs down and is sluggish to start out off the line. Alkaline cells are not much my friend...
Brock said:
Basically alkaline batteries don't take well to high discharge rates, and 1/3 of their mA is below 1 volt, unless your using regulation, pretty useless at that point.
[/ QUOTE ]
I can attest to that. I have an HPI Micro RS4 (1/18th scale electric R/C car) that has a 4AA/AAA holder, as well as a 5 cell NiCd race pack (they look like half-length A size or something like that). Even though the NiCd pack is rated at only 600mAh, it has a LOT more "punch" than even good quality alkaline AA cells. An R/C car's "punchiness" depends a LOT on the motor, speed controller, and the battery...if the batts can't source enough current, the whole system bogs down and is sluggish to start out off the line. Alkaline cells are not much my friend...
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Alkalines seem much more suited to long-term low-current applications. Not only does the voltage sag under load, but it sags as the battery discharges.
Those numbers from Buchmann don't have matching voltages. The manufacturer datasheets are much more specific. For example the Duracell MN1500 AA (non-ultra):
http://www.duracell.com/oem/Primary/Alkaline/mn1500.asp
The datasheet says it can sustain a 0.25 A load for 8 hours, equalling a 2 Ah capacity. But pull 1.0 A, and it lasts barely an hour, for 1 Ah.
Those numbers from Buchmann don't have matching voltages. The manufacturer datasheets are much more specific. For example the Duracell MN1500 AA (non-ultra):
http://www.duracell.com/oem/Primary/Alkaline/mn1500.asp
The datasheet says it can sustain a 0.25 A load for 8 hours, equalling a 2 Ah capacity. But pull 1.0 A, and it lasts barely an hour, for 1 Ah.
JSWrightOC
Enlightened
That sounds like an internal high cell resistance. Not good for Modders. /ubbthreads/images/graemlins/smile.gif
Alkalines do have their virtues...like you said, low current applications are one of them. Their relatively long shelf life makes them doubly suited to slow discharge. Obviously, putting a NiCd or NiMH cell/battery on something that draws 2mA isn't going to last nearly as long as an Alkaline; the self discharge becomes a huge factor in considering battery life. So, put alkalines in your low-powered LED mods, and NiMH/NiCd's in your mini-suns. /ubbthreads/images/graemlins/grin.gif
Alkalines do have their virtues...like you said, low current applications are one of them. Their relatively long shelf life makes them doubly suited to slow discharge. Obviously, putting a NiCd or NiMH cell/battery on something that draws 2mA isn't going to last nearly as long as an Alkaline; the self discharge becomes a huge factor in considering battery life. So, put alkalines in your low-powered LED mods, and NiMH/NiCd's in your mini-suns. /ubbthreads/images/graemlins/grin.gif
I put NiMH's in almost everything because I regularly swap out the cells. That way I have a like-new charge whenever I want without the guilt of trashing half-dead alkalines.
I've got a nice box of them now for my pocket LED lights. Those darn alkalines just won't die-- I've never bought new batteries for my CMG's or my Opalecs.
I've got a nice box of them now for my pocket LED lights. Those darn alkalines just won't die-- I've never bought new batteries for my CMG's or my Opalecs.
jimbob
Newly Enlightened
In short:
NiMH: High-drain use but short charge retention.
Alkalines: Lower-drain use but long shelf life.
NiMH: High-drain use but short charge retention.
Alkalines: Lower-drain use but long shelf life.
JSWrightOC
Enlightened
[ QUOTE ]
Blikbok said:
I put NiMH's in almost everything because I regularly swap out the cells. That way I have a like-new charge whenever I want without the guilt of trashing half-dead alkalines.
I've got a nice box of them now for my pocket LED lights. Those darn alkalines just won't die-- I've never bought new batteries for my CMG's or my Opalecs.
[/ QUOTE ]
Ha ha! I like the way you do your work. I just put a BB400 mod in a minimag (works GREAT!!!) and I keep a spare set of AA's with me because there is little warning of dying power. I might just swap them out every other day or so, to guarantee that I have plenty of juice.
I know what you mean about those darn Alkaline cells, I still have some 16 (some partially discharged) left over. I don't think I would even use an Alkaline in an incandescent flashlight, I would rather put up with the slightly dimmer (but more consistent) glow from the NiMH. Oh well, that issue is far behind me anyway. /ubbthreads/images/graemlins/grin.gif
Blikbok said:
I put NiMH's in almost everything because I regularly swap out the cells. That way I have a like-new charge whenever I want without the guilt of trashing half-dead alkalines.
I've got a nice box of them now for my pocket LED lights. Those darn alkalines just won't die-- I've never bought new batteries for my CMG's or my Opalecs.
[/ QUOTE ]
Ha ha! I like the way you do your work. I just put a BB400 mod in a minimag (works GREAT!!!) and I keep a spare set of AA's with me because there is little warning of dying power. I might just swap them out every other day or so, to guarantee that I have plenty of juice.
I know what you mean about those darn Alkaline cells, I still have some 16 (some partially discharged) left over. I don't think I would even use an Alkaline in an incandescent flashlight, I would rather put up with the slightly dimmer (but more consistent) glow from the NiMH. Oh well, that issue is far behind me anyway. /ubbthreads/images/graemlins/grin.gif
JSWrightOC
Enlightened
[ QUOTE ]
zmoz said:
So alkalines are good for remote controls. That's it. /ubbthreads/images/graemlins/grin.gif
[/ QUOTE ]
No, actually Lithiums would probably be better /ubbthreads/images/graemlins/yellowlaugh.gif /ubbthreads/images/graemlins/grin.gif
Although....it has been YEARS since I last replaced AA's and AAA's in remote controls, I think the only battery swap I ever did in most of mine was to take out the !@*$$& carbon zinc cells from the mfgr.
zmoz said:
So alkalines are good for remote controls. That's it. /ubbthreads/images/graemlins/grin.gif
[/ QUOTE ]
No, actually Lithiums would probably be better /ubbthreads/images/graemlins/yellowlaugh.gif /ubbthreads/images/graemlins/grin.gif
Although....it has been YEARS since I last replaced AA's and AAA's in remote controls, I think the only battery swap I ever did in most of mine was to take out the !@*$$& carbon zinc cells from the mfgr.
