NiMH AA?

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Jazzyrigged
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NiMH AA?

Hi, It's been a little while since I have been on here, but I am investigating using a bunch of AA NiMH batteries (2500 mAH) in my 72 volt Electric motorcycle. Does anyone have experience using AA's? After much reseach I think going with AA's would be very cost effective. I tried seaching the threads, but I did not see anything on there about people using AA's for their project. My concern is generating enough amps to power the motor properly. I Have a 72 volt motor that can take 300 amps. Agin just wondering if enough energy can be created using AA's. Thanks for all the help in the past, I'm looking foreward to many more questions and answers. Thanks, Jazzyrigged. p.s. if these can work, is there anyone else in the st. louis area who would be interested in going in on a large order of AA's.

JDELUNA
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Re: NiMH AA?

Without putting the AA batteries in multiple parallels you would burn up those cells in a few seconds. The AA cells are not made for high current. At a conservative 50amps you would need to have a 60 batteries in series in a 20 parallel string or about 1200 AA batteries. Balancing the batteries would also be a big problem. Hope this helps. God Bless :)

LinkOfHyrule
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Re: NiMH AA?

I concur. AA's are made mostly for small electronics whatnot. They don't have the output capability to power more than maybe a small scooter motor.

If you really want to use commercial NiMH cells, you would have a much easier time using D cells. In fact, I could swear there's someone on here who built a chopper (bicycle) with D cells hidden in the fork.

A word of caution, though: Pay attention to the mAh rating on the cells. It's not uncommon to find D batteries that are nothing more than a AA in a bigger package. Trust me. I've seen them at Wal-Mart, Target, Fry's, and that's just within a few miles of here.

On another note: What motor are you using? PMG-132? ADC?

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antiscab
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Re: NiMH AA?

Hi Jazzyrigged,

In my experience nimh cells cant be wired in parrallel without some type of bms involved, due to the negative delta and end of charge. Basically this means the voltage across a nimh battery falls slightly at the end of its charge cycle. If wired in parallel, and both or all cells in the parallel string do not fall in voltage at exactly the same time, the weaker cell will overcharge the stronger cell. If you charge each series string separately, this is not a problem however.

hope this was hepful,
Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Brock
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Re: NiMH AA?

I would agree with pretty much everything that has been said. I did want to point out that you can get 10amps from a good NiMH AA battery; as a matter of fact I have seen some testing on some AA cells to 20 amps with the cell still above the 1 volt mark, although not for very long. I have a single AA light that pulls over three amps (in high) from the cell and will run 20 minutes easy.

Here is a link to an on going test of NiMH cells as they come out
http://www.candlepowerforums.com/vb/showthread.php?t=79302

But again that doesn't even come close to what you want to do. And series / paralleling them will cause a lot of issues unless charged individually, which would really be a pain with a couple 100 cells :)

PJD
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Re: NiMH AA?

Why are you considering AA cells? Why not D dells, or even F (long D) cells.

F cells are available with 14 AH capacity.

Deafscooter
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Re: NiMH AA?

Deafscooter Watch on you talking about AA NiMH Batteries ????
====

Here is

I use Special " Fat A Battery " are very good to handle feed PMG132 on my High speed

Check out =======>>>> http://www.austinev.org/evalbum/1263

Craig Uyeda
Deafscooter

deafscooter

Brock
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Re: NiMH AA?

Oddly enough larger D cells or even N cells with even higher capacities can't put out the higher amperage in the short term. I have a couple of 12,000 mA or 12 amp D cells and they short out at 10 amps and I have some AA cells in the 2100mA range that short out at 22 amps. I believe they could make larger capacity D or N cells with better "high output" characteristics, but the demand isn't there yet, at least not like it is in the AA size.

HCT
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Re: NiMH AA? try using Panasonic HHR650D not cheap but work ! !

Been reading about using NiMH AA? extracting real power ,two problemes I see , internal resistance and how do you connect to them , nickel strips are only good for 20 possibly 30amps .The connection has to be 10% of the cell impedance or better.
Have used NiMH "D" by Panasonic HHR650D rated at 6.5 A/H those cells have impedance of less 2 milliohms YES I DID SAY less than 2 milliohms , even build a 5000W peak power pack with 36 volts .
The cells are capable of dumbing close to 300 amps into short for almost a minute .
The biggest probleme I had whas making connection to the cells . ending up spot welding 10-32 weld stud to both end of the cells , increase the impedance by about 400 microhms each end ( 75% of it was the material 25% the weld ).
Been told that the Toyota Prius used the same cell construction but packaged into a more thermally design housing ( air cooled )

MVC-002F.jpgMVC-018F_0.jpgMVC-459S.jpg

Be glad to answer any question regarding impedance , that is the most important parametr after voltage , not capacity or whatever .
Sorry if I sound like a broken record , but after 40 years in batteries use and application . impedance dictated . loss = heat = cycle life etc......

HEAT & LOSS & INEFFICIENCY RELATED DIRECTLY to IMPEDANCE

LinkOfHyrule
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Re: NiMH AA?

Where do I go to get, like, 20 or 30 of these Panasonic cells?

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HCT
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Re: NiMH AA?

Believe that Digikey has stock on them , not cheap about $20.00 a cells .
The ones that I have are assemble in 3 cells stick end to end so do not believe that you could use them !
Regars

HEAT & LOSS & INEFFICIENCY RELATED DIRECTLY to IMPEDANCE

LinkOfHyrule
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Re: NiMH AA?

$19.05 for a tabbed cell!?!? Those better be some damn good batteries XD!

Know anything about their NiCD cells? Not quite the same capacity, but cheaper...

Oh yeah: How do NiCDs fare in parallel? If I can wire them up in parallel with one another or in parallel 36V packs I might just get the 1700mAh Sub C cells...

I hear NiMH's don't like being in parallel with other cells, but what about parallel packs? If that works I'll go with the 4/3 A NiMH cells...

EDIT: Already knew why they couldn't be charged in parallel, but what's the deal with discharging them in parallel (individual cells or packs)? Am I okay as long as I charge individual series separately? What about cell balancing within the packs? Is this not as big an issue as with SLA? HELP ME, SOMEONE!

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

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