NiMH volume effeciency

[evan9162]

My fascination with odd-sized batteries got the better of me. I made this table showing different sized NiMH batteries and their relative energy density. The last column is the kicker - you can see where the R&D effort is being put.

</font><blockquote><font size="1" face="Verdana, Arial">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> dia height cap vol
(mm) (mm) (mAh) (mm^3) mAh/mm^3
1/3AAA 10 14 150 1100 0.136
1/2AAA 10 20.5 210 1610 0.130
2/3AAA 10 28 300 2199 0.136
AAA 10 44.5 700 3495 0.200

1/3AA 13.9 16 300 2428 0.124
2/3AA 13.9 28 650 4249 0.153
AA 13.9 48.5 1800 7360 0.245

SC 22.5 42.5 3000 16898 0.178
C 25.5 49.5 4000 25280 0.158

1/2D 32.5 36.5 3500 30280 0.116
D 32.5 60.5 9000 50189 0.179
</pre><hr /></blockquote><font size="2" face="Verdana, Arial">I wish the smaller sizes were up there with the storage density of AA's

-Darin

 

[Doug S]

You will find that the best 4/3A cells do well also. These are commonly used in laptop battery packs.

 

[evan9162]

I grabbed data from just one manufacturer's page (to keep some consitency). I might look up more of the larger sizes (A and C based) from other mfgrs to get a better picture of things.

-Darin

 

[bmsmith]

A D cell with 9000 mAh of capacity? drool....

Just curious, which manufacturer did you get these specs from?

- Brian

 

[lemlux]

Evan:

2100 mAh AA cells are being sold in Hong Kong.
4500 mAh C NiMHs are available (I have 6)
3300 mAh Sanyo sub-C's are now being released.
3800 mAh 1/2 D's are advertised by Powerstream.
2450 min 2700 typical mAh A's are offered by Sanyo.(I have a bunch from laptop packs)

Silviron reports that the 4/3 A cells are 3800 mAh.

It's very hard to keep up. Someone will probably show that I'm understating one or more sizes.

 

[dark star]

CCrane sells D cells with supposed 9000mAh- $9.95 with free shipping
http://ccrane.com/nickel_metal_batts.asp

 

[evan9162]

Originally posted by bmsmith:
A D cell with 9000 mAh of capacity? drool....

Just curious, which manufacturer did you get these specs from?

- Brian

<font size="2" face="Verdana, Arial">http://www.batterieswholesale.com/nimh.htm

Though you can't really get them (they say something about not being able to process orders until November). I just used their spec table since it was right there, and had all the information in one glance.
-Darin

 

[evan9162]

lemlux-
Thanks for the info - here's your data compared to the table above:

</font><blockquote><font size="1" face="Verdana, Arial">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> dia height cap vol mAh/mm^3
(mm) (mm) (mAh) (mm^3)
AA 13.9 48.5 2100 7360 0.285
C 25.5 49.5 4500 25280 0.178
SC 22.5 42.5 3300 16898 0.195
1/2D 32.5 36.5 3800 30280 0.125
A 17 50 2700 11349 0.238
4/3A 17 67 3800 15208 0.250
</pre><hr /></blockquote><font size="2" face="Verdana, Arial">The A and 4/3A sizes are right up there with the super-high capacity AAs.

-Darin

 

[lemlux]

Evan:

I forgot to thank you for your table. I'd tried to use mental Kentucky windage to consider relative volumetric efficiency, so your table is very appreciated.

It's interesting how relatively inefficient the 1/2 D's are. I guess that's because they are made in the exceptionally low volumes.

Gee - I just noted that I thanked you on post # 1,000!

 

[evan9162]

No problem - I do this kind of thing all the time (making excel spreadsheets comparing things in all sorts of ways).

I got to thinking about how much cell volume is required for the simple basics of the battery (casing, anode, cathode, etc). I was wondering why certian sizes had SOO much more capacity relative to their volume compared to others - guess the best ones are where it's most profitable to invest the time and energy

-Darin

 

[PsycoBob[Q2]]

Well the most common rechargeable battery size is AA... or perhaps 12v Lead-acid car batteries.