# NiMH batteries confusion



## pesco (Aug 25, 2011)

I've been reading few topics regarding batteries and something got my attention.
All price lists for spent rechargeable batteries listed price of Li-ion batteries higher than the price for NiMH.
This is the thing I don't understand. Ages ago, for the chemistry course I have done presentation on NiMH batteries so I know they do contain on average :
- 60-70% Ni 
- 3% mixture of La, Ce, Pr, Nd
This ingredients have some value.

On the other hand, when I looked at Li-ion information I couldn't find anything what would justify their higher price. Small to tiny percentage of Co, Ni, Ti and Ge that is all I could find. Could it be Li itself? As far as I am aware there is no market for it unless you have few metric tonnes of Li2CO3

Am I missing something ?


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## NoIdea (Aug 25, 2011)

pesco said:


> This is the thing I don't understand. Ages ago, for the chemistry course I have done presentation on NiMH batteries so I know they do contain on average :
> - 60-70% Ni
> - 3% mixture of La, Ce, Pr, Nd
> This ingredients have some value.
> ...




Hi Pesco - I have been looking into this as a form recycling and obtaing the for mentioned elements.

Check out this link, interestion, might be a good place to start for a looksy.

http://www.ysxbcn.com/upfile/soft/2009331/35-p0468.pdf

Thanks for the info

Cheers

Deano


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## escrap (Aug 26, 2011)

Pesco,

It all has to to with the reuse factor in many cases. Li-ion batteries have a market as a marketable product and with reuse comes the higher prices. Hope this helped. 

Zack


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## pesco (Aug 26, 2011)

Noldea:
Thx for cool pdf. I have some materials regarding recycling NiMH, but it will take a bit of time as I would have to translate it from Polish :mrgreen: 


escrap:
I was thinking of that possible reason, but to be honest I can't see a man going through few metric tonnes of batteries and picking by hand the ones which are not cracked and he thinks might still work. After he selects "good batteries" he has to use some magical process to revitalize them :mrgreen: 
I'm 99.9999% certain it is not the case, however I left 0.0001% as my safety line as there is a extinguishable slim chance he employs R2D2 to do the picking and Marlin to do revitalization :mrgreen:


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## escrap (Aug 26, 2011)

Pesco,

R2D2 is a good robot. But I can tell you from experience, that when we sell them by the gaylord, they go to a location to be reused. It is like memory, when we get in big amounts we go through them to look for those units that may be worth 5.00/stick compared to .75/stick. It is a long process but it is worth it. Same with these batteries, they might find one worth 10.00 instead of 1.00.


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## pesco (Aug 26, 2011)

OK,
I take your word for it, however there are two problems:
1) Li-ion cell life is not great, they are loosing around 20% capacity per year, is there a method to "revitalize" them ?
2) if somebody reuses Li-ion then why NiMH are not reused the same way ?


On the other hand I found that recently there supply of Ni exceeds demand while it is the opposite for Li.
Maybe that's the reason for difference in price ?


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## dtectr (Aug 26, 2011)

NiMH batteries are VERY unstable - prone to explosion/overheating at the most inopportune times. Ever wonder why rechargeable power tools went back to Ni-Cad? For example, many mines refuse to have Ni-MH underground, though they perform better than Ni-Cads.

Li-Ons have about the same life, with more power, with 20% less weight, than previous forms.
Every rechargeable battery, with the exception of Lead Acid, are good for about 1000 charge cycles, with, after the first few initial charges, a fairly stable, exponential reduction of life/power.

It isn't the TIME, its the CHARGE CYCLES, that determine the life of any rechargeable battery, again, with the exception of lead acid (which is STILL the only rechargeable battery which will automatically dissipate an overcharge, that is, one effected by leaving the battery on the charger too long). So, that is why recharging your cell/cordless phone, power tool, or laptop, before the charge has run out, shortens the battery's life. Ever wonder why Grandma's 20 year old cell phone still has the same battery & you (or I) have replaced ours 2 or 3 times?

Li-ON batteries do not have a memory effect _as bad_ the previous forms do/did, but it still has one. If your Li-ON battery is 66% discharged, you usually can recharge without sacrificing life.

Remember (if you're over 40  ) the battery rejuvenation process you could get for early rechargeables at places like RadioShack or your cell phone retail store? It was merely a forced, rapid, 100% discharge/charge cycle, performed 2 or more times, which usually dissipated most of the memory effect created by too frequent recharging. The 1000 charge/discharge rule still applied, but you were given a reprieve, only temporary unless you learned to follow proper recahrge protocols.

BTW - according to USPS regulations, it is _officially_ illegal to _intentionally_ ship rechargeable batteries, via normal (non-HAZMAT) USPS services. Look at the poster next time you're at the post office.

Just my dos centavos, probably unrelated to your current query, but garnered from 2 decades in the trenches, metaphorically speaking.


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## macfixer01 (Aug 27, 2011)

dtectr said:


> NiMH batteries are VERY unstable - prone to explosion/overheating at the most inopportune times. Ever wonder why rechargeable power tools went back to Ni-Cad? For example, many mines refuse to have Ni-MH underground, though they perform better than Ni-Cads.
> 
> Li-Ons have about the same life, with more power, with 20% less weight, than previous forms.
> Every rechargeable battery, with the exception of Lead Acid, are good for about 1000 charge cycles, with, after the first few initial charges, a fairly stable, exponential reduction of life/power.
> ...





Back in the late 80's through the early 90's I used to do computer work for a doctor in my spare time. He was quite an interesting guy, he went back to school for a legal degree and had interests in a lot of different subjects really. I also ended up getting involved in assembling some of his other projects like an early cloning method for his Motorola phone, and a radio receiver which allowed him to receive some pay stock quote service on his computer for free. Anyway one device he picked up and I assembled for him was this kit that was supposed to refurbish NiCad batteries that had developed a memory and wouldn't take a full charge anymore. The theory behind it was that they claimed thin whiskers of metal grew inside NiCad cells over time that acted as partial shorts. This capacitive discharge device was basically like a photoflash unit with the battery attached in place of the flash tube. Zapping the battery with it was supposed to burn away those internal metal whiskers and restore charge capacity. I don't recall if he ever said it worked or not though?

macfixer01


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## escrap (Aug 28, 2011)

Pesco,

Yes there are ways to revitalize these batteries. Here is an example of a company that offers these types of service, I personally have never used these people as we have other vendors, but just as an example. 

http://www.gogreenbattery.com/


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## pesco (Sep 2, 2011)

OK guys, maybe this is the bit I was missing in the first place,

Its easy to imagine this scenario with common AA, AAA, C, D and PP9batteries, 
Its more difficult to imagine this scenario applied to laptop/cell phone batteries as there is so many types. Maybe the price compensates time spent for fiddling around with them ?

Thanks for input


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