# AA batteries



## arklan (Dec 10, 2012)

iv been trying to find on here any threads related to using AA batteries
the search function searches for just batteries when i type in aa batteries and going through the list of threads about batteries doesnt help either
does anyone have a list of threads about AA batteries?
if not lets make this thread the list.

i remember someone saying that AA batteries are the most used/sold in the world so they would have the most technology in them and energy density.
at around a dollar a cell the battery pack would be reasonably priced
2.9ah per cell (according to google)
1.25v per cell
using 3000 cells would give 90ah at 120v with a 31p 96s

just to add, having so many cells id have them in little blocks of 31 so theyd all balance off each other, this would make sure theyr always balanced. if theres a dead cell it would bring the whole block down which would be pretty easy to diagnose with a multimeter.


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## crackerjackz (Jun 26, 2009)

I was used these aa lithium cells for a kids 4 wheeler ... Worked great lol plus i had uped the voltage to 18 volts instead of 12 . Made a very fast machine for a 4 year old . You can even get them with weldable tabs ...


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## Hollie Maea (Dec 9, 2009)

arklan said:


> iv been trying to find on here any threads related to using AA batteries
> the search function searches for just batteries when i type in aa batteries and going through the list of threads about batteries doesnt help either
> does anyone have a list of threads about AA batteries?
> if not lets make this thread the list.
> ...


The technology you are describing (AA format, rechargeable, 1.2V) is NiMH. Not the most modern of technologies, and certainly not advantageous enough to make it worth the hassle of using a small form factor. Also by definition, a rechargeable AA battery needs to be close enough to replace an alkaline battery (1.5V) so there aren't any lithium ion versions. It sounds like you are kind of confusing this with using lithium 18650 cells. Now that is something that some do (Tesla is the main example) and has some of the advantages you listed. But it is a MUCH more difficult task to make a functional traction pack from 18650s, so most DIYers stick with large format cells, which are easier to deal with, that use LiFePO4 chemistry which is more forgiving than the chemistries used in 18650s.


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## Karter2 (Nov 17, 2011)

> 2.9ah per cell (according to google)


 dont believe everything you see on the web !
Any idea what "C" rate (discharge rating) those cells might be ?
..and you might want to look up the issues around using/charging NimH in parallel sticks !


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## arklan (Dec 10, 2012)

http://www.ebay.com.au/itm/ENERGIZE...ronics_Batteries_Chargers&hash=item486142be01

i was referring to something like this
theyr 1.5v not 1.25v but i was trying to give myself some margin

http://www.powerstream.com/AA-tests.htm
according to these tests the AAs cant handle much individually

http://en.wikipedia.org/wiki/AA_battery
according to these tables, a AA battery will have the 2.9ah under a load of 50ma
so when i try to suck 500amps out of them they might cry for mama
back to the drawing board i guess


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## Hollie Maea (Dec 9, 2009)

Those eBay batteries are primary lithium cells, not lithium ion. They are NOT rechargeable!


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## arklan (Dec 10, 2012)

u can get rechargeable ones

anyway further research shows they only handle about 2 amps continuously

anyone else thinking of using AAs can learn from this :'(


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## Hollie Maea (Dec 9, 2009)

arklan said:


> u can get rechargeable ones
> 
> anyway further research shows they only handle about 2 amps continuously
> 
> anyone else thinking of using AAs can learn from this :'(


Not lithium based ones. For a battery to be classified as a AA battery, it has to have a voltage close enough to that of alkaline batteries (1.5v) to be used as a replacement. There is NO rechargeable lithium ion chemistry that achieves this voltage--they are all around 3v or higher. There ARE lithium chemistries that can be used, but they are not rechargeable. Therefore, rechargeable AA batteries are limited to Nickel based chemistries, which with a voltage of 1.2V, are close enough to be used.

Now, there are rechargeable lithium ion cells with a similar form factor to AA cells, but they are NOT actually AA cells. They are a slightly different size, and they generally are 3.6V. And they aren't called AA cells, so if you are searching for AAs, you won't find them.

I'm trying to explain it the best I can.


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## EcoReality (Mar 10, 2014)

Think about economy of scale -- or lack thereof.

Each cell needs a connector and a steel jacket, whereas if you make them bigger the power density goes up as the cube and jacket material only goes up square.

So in my humble opinion, an EV pack made up of AA cells would be heavier and end up costing more than a pack of equivalent energy storage made up of bigger cells.


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## rwaudio (May 22, 2008)

18650's would be the cell to use if you are going for a small AA style cell (18650's are larger than AA).
There are power tool variants with high current output and with enough of them would drive an EV nicely. Consider the amount of work required to wire up 3000+ cells though, sure Tesla does it (6000+ cells) but can you do it?


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## Newbiee (Feb 16, 2011)

is there a specific 18650 battery that handles high EV amperage? or would any 18650 battery be up to the task when put into series parallel combinations. Lets say a random 3.7v 6000mah battery from ebay?


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## sergiu tofanel (Jan 13, 2014)

I've looked into Nimh batteries a while back and decided that even lead acids are better in the long run. AA batteries have too much internal resistance. For high current applications you need to look into C or sub-C batteries.


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## major (Apr 4, 2008)

Newbiee said:


> is there a specific 18650 battery that handles high EV amperage? or would any 18650 battery be up to the task when put into series parallel combinations. Lets say a random 3.7v 6000mah battery from ebay?


Sure, there are 18650 Lithium Ion cells which are EV capable, in series parallel configurations. Not from eBay with 6Ah claims  There's a lot of wimpy cells around and plenty of sellers with big claims. Don't waste your money. Study up on the subject and look at C-rates and real test data. The members over on Endless-Sphere have tested about everyone worthwhile and posted results. You can also find threads on how to package, charge and balance them.


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## Hollie Maea (Dec 9, 2009)

Sony VTC4 is a pretty good one for smaller packs. 2.1ah, but rated at 30A (about 14C). So you don't need a massive pack for good power. But they are kinda pricy. If you have a bigger pack, you don't need as powerful cells.

As far as the practicality, you either have a high quality tab welder, or you don't. If you do, it's more work than prismatics, but doable. If you don't, it's only feasible if you are crazy. But you can achieve energy densities hard to achieve otherwise. I am leaning towards using 18650s on my conversion.


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## arklan (Dec 10, 2012)

say for example it was 30p
id get a block of 6x5 batteries with a piece of aluminium top and bottom so they would form 1 battery thus they would keep each other balanced
then they would just sit in there nice and tight with no welding required
some dimples can be punched in to the aluminium if necessary


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## Karter2 (Nov 17, 2011)

Have a look at these guys building large 18650 packs..
http://www.diyelectriccar.com/forums/showthread.php/tesla-style-cell-level-fuses-94331.html

..and the Tesla pack..
http://www.teslamotorsclub.com/showthread.php/21850-NHTSA-Opened-Up-the-Model-S-Battery-Pack-Pics


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## dougingraham (Jul 26, 2011)

arklan said:


> say for example it was 30p
> id get a block of 6x5 batteries with a piece of aluminium top and bottom so they would form 1 battery thus they would keep each other balanced
> then they would just sit in there nice and tight with no welding required
> some dimples can be punched in to the aluminium if necessary


The approach Jehu is using is only viable because he is paying 25 cents per cell. It looks like he is paying about the same amount for the plastic clips. The 2 ah cells are capable of doing 2C. The current levels of the available controllers would require this many cells in parallel and a cell of some enormous capacity results.

Zilla 2k 2000 amps 500P 1000AH
Netgain 1400 amps 350P 700AH
Soliton 1000 amps 250P 500AH
Curtis 1238 650 amps 162P 325AH
Curtis 1239 500 amps 125P 250AH
Alltrax 400 amps 100P 200AH 
OEM stuff 360 amps 90P 180AH

If you think about it a little you realize that an arrangement like this is not appropriate for high current DC systems. There are just too many cells needed to reach the power levels. I've got 163 volt pack now and if I wanted to use these cells at 1000 amps I would need a 45S 250P arrangement (11250 cells). This would be a pack that has 81kwh but my little car has no place to carry that many cells and it would weigh too much as well. It would be a $5625 pack for cost of cells and clips. It would weigh over 495kg for just the cells.

I can see this as a possibility for larger vehicles that are not performance oriented. Pickup trucks or E-Samba vans for example.


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## Karter2 (Nov 17, 2011)

18650 cells are certainly not the "holy grail" of EV battery's , but they do have several attractions.
* They have some the best energy density of any rechargeable cell @ 260W/kg
* they are available with integrated safety features to protect against over charging, over discharging, thermal overload, reverse polarity, etc.
* they are readily available in quantity.

however, as with most things in life you have to make choices/compromises to suit you own circumstances...
Cost..Weight,...Performance.
Pick any two,!..... you will not find all three combined in any one cell.

Tesla have managed to make them work successfully at reasonably high performance levels, but at a high price !


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## Tomdb (Jan 28, 2013)

Price is not a problem.
If you buy in bulk, lets say 10,000 cells at once the price is very reasonable.

We have shopped around a little genuine Panasonic or lg cells for about 350 euro/KwH

Cells with a burst (10sec) rating of 5c. 

Pack specs for the price request:
Cells serie: 120 (bms reasons)
Cells parallel: 70 (current requirement)
Total energy: 90 KwH conservatively
Total weight: 350kg of cells

Cell specs
Energy: minimal of 3.0 Ah

Biggest problem for diy'ing is the cell connection. We had speced an semi automated battery assembly plant along with the purchase of these cells. The cost for these cells and assembly was lower then cell modules for EIG or Enerdel.


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## Karter2 (Nov 17, 2011)

> ....Price is not a problem.


 ??
Maybe not to you, but i find even those prices (genuine quotes , im sure !) you have been quoted, surprising.... especially for the large quantities .
I have seen other quotes for "similar" quality 18650 cells from Panasonic, Samsung, LG, Sony etc at around $3-$4 (UD$ per cell) for 2.5Ahr and 2.9 Ahr cells in much lower quantities ( <1000). 
..and from reliable retail sellers that any member of the public can access.
If you go via "Ali baba", etc,and ask for volume quotes you get even better pricing.
Industry trade insiders have reported that wholesale costs of "Quality cells" ( name brand genuine non reject) is around $1 per cell ( us$100/kWhr) and not likely to increase in the future due to the surplus of 18650 production capacity as laptop sales ( the main user) are falling fast.

There is much "financial adjustment" between the manufactures cost and the selling price !


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