Shelf Life of NiMH Batteries

Hey All! I never knew there were people like me! I just love batteries and flashlights!

Recently a local Home Hardware had some NiMH AAA and AA's on sale. They were 1600mah and made by Leap. The prices were 4xAAA = $2.99cad and 4xAA = $3.99cad

The prices were amazing so I purchased about 6 of each packs. That gives me new 48 batteries to play with. I was just wondering if Leaps are Repackaged Maha's. Someone told me that but I can't find anything to back that up. Also what is the shelf life of NiMH? They have probably been sitting on the shelf for 3-4 years already and I just wanted to know how long I had before they go bad. I don't intend on using them all at once. I plan on using a bunch until they die and then opening up the new batch...

Thanks a lot!

Sorry to disappoint you buy if I were you, I wouldn't have bought so many in one go even though they were on sale. I would have bought just enough cells for current use. They keep making cells with larger capacity, 2200mAh. So I can replace broken/used cells with larger capacity.

On the other hand you are right too, I don't know how much these cells are worth in Canada or the US I am sure the 2200mAh cells are much more expensive than yours. So you can keep them in the shelf and keep them cool. Unlike Lithium Ion rechargables, NiMh can last for quite sometime, up to 5 years in cool environment. NiMh has high self discharge rate, top it off before use.

Vince.

Vince,

Are you saying that Lithium Ion rechargables cannot last for quite sometime, up to 5 years in a cool environment?

Paul

I had been told several years ago by a Motorola tech that the L-Ions basically had a life of 1 - 2 years, regardless of the use. In reality, I haven't found that to be completely true. I guess it refers more to getting the full capacity out of a battery. I have a high capacity battery on a phone now that hasn't been used in over 3 years and the battery hasn't been charged for 1 or 2 years and I bet I can turn it on and use the phone directory.

PaulW,
I am just stating what I've learn over the net of what I read. Feel free to correct me anyone. I know the chemical in Li-Ion start to degrade slowly once it comes out of the factory. Personally, I have 4 year old 17670s Li-Ion with 80% capacity when full charged. So the capacity reduces as the life gets shorter.

I don't mean 5 years of life time and they go dead, I mean 5 years of good shelflife and start to degrade. True?

Vince.

Once a Li-Ion cell is manufactured, it has a finite amount of time before it reaches the magical time when it's considered to be "expired". As koala said, they slowly degrade, there's no sudden failure (unless abused, of course) of the cell. So, you have to decide at what point the cell no longer provides useful runtime for your application.

Factors that can accelerate or otherwise change this expiration are elevated temperatures, charge/discharge cycles, stress (such as high currents), and of course the quality of the cell. Cheap knockoffs may not last as long as a quality Panasonic or Sony unit.

Vince (and others),

It wasn't my intent to contradict you. I'm just surprised by what you said. I seem to remember reading somewhere that Li-Ions have a long life--almost as long as Lithium primaries. It appears now that I must have misread that.

I'm learning about this stuff, just like everyone else. /ubbthreads/images/graemlins/grin.gif

Paul

PaulW no worries man /ubbthreads/images/graemlins/grin.gif. Personally, I don't feel that you are contradicting me at all, you actually made me re-read what I've wrote.

cheers
Vince.

The 1-2 year lifespan of Li-Ion cells as specified by the manufacturers is relatively conservative. I had a cell phone that lasted me three years and the Li-Ion battery was still going relatively strong. I could get a full days' runtime out of it, with a good deal of talk time. I left the phone on 24/7 and put it on the charger at night.

I had a Dell Li-Ion laptop battery last me about 3 years before it started going funky, and this was with moderate to deep discharge/recharge cycles on a daily basis. Strangely, I didn't lose a whole heck of a lot of capacity, it would just poop out under load at lower temperatures. If I warmed the battery pack to 85-90 degrees Farenheit or so it would work fine. One time I needed the computer with my mapping software and GPS to get home, and my battery "died" on me...so I parked at a gas station with the battery in the sunlight on the dash for 15-20 minutes and it worked well enough to get me home.

That's helpful info. I can apply it to my situation. Thanks Jeff.

Paul

Glad I could help! BTW, which are you talking about...the 3-year tested lifespan or the battery-warming? /ubbthreads/images/graemlins/grin.gif

He he. The battery-warming idea is a nifty thing to know in a pinch, and I won't forget it. But I was referring to your experiences with Li-Ion battery life. Knowing that it's on the order of a single handful of years, rather than two handfuls of years, means that batteries on sale that are a couple of years old aren't the bargain they seem. So, I won't buy any of those now on eBay that are marked March 2001.

Paul