Battery ?? for CAP

[garman]

Hey Cap I just finished Xmas shopping and I bought my brother a new cordless phone from Uniden. I noticed inside the packaging about NiMH batteries are used and the documentation on the batteries states that the batteries have a life span of 1 year. Is this wrong or has the industry changed the technology of these batteries. Years ago I bought a cordless from the same company where it states that the battery has a potential of lasting 5 years and these batteries are NiCad and sure enough 4 years 9 months they completely failed. So what gives don't NiMh have a 1000 recharge use before it packs it in. Thanks -garman

[Capmaster]

Hey Cap I just finished Xmas shopping and I bought my brother a new cordless phone from Uniden. I noticed inside the packaging about NiMH batteries are used and the documentation on the batteries states that the batteries have a life span of 1 year. Is this wrong or has the industry changed the technology of these batteries. Years ago I bought a cordless from the same company where it states that the battery has a potential of lasting 5 years and these batteries are NiCad and sure enough 4 years 9 months they completely failed. So what gives don't NiMh have a 1000 recharge use before it packs it in. Thanks -garman

They're probably being more honest now. I doubt anyone ever got that many full charges/recharges from NiCd or NiMH batteries, since they both have memory effects. It's just marketing hype.

One year sounds realistic, if a bit conservative. Maybe they bought a marginal battery chemistry and it just doesn't last as long as the one that gave 4-3/4 years before. There are several variables .....the charging rate will affect the lifetime ...the higher, the shorter.

If they say a year, I'd believe it. But the only reason anyone would still use NiMH is because of cost. The newer LiIon and LiPolymer batteries offer plenty of capacity, discharge rate and the power density (w/cc) is higher with lithium than either nickel chemistry. They must have gotten a good deal on the NiMH batteries :P

[garman]

Now that's out in the open. Will batteries be poorly constructed this way to lighten the cost of the unit. Man I still have my NiMh it's been 3 years. They still work great. I would be reluctant to buy one that only has a life span of ONE stinkin year.
Another thing I was watching some "home shopping channel" here in Toronto, Canada and they were trying to pawn off a Mustek digital camera and sales tech mentioned that it carries a rechargable Lithium Ion battery that would last one year. Are you kidding me, spend $60-100Cnd for a battery that only last a year. Is this the direction of battery technology. I can live with 3 years but 1 to 2 years forget it! Buy hundreds of Alkalines and dump them in the land fill. Just joking, but most people will out-weigh the cost and put the money in thier pockets and forget the environment.

[Capmaster]

Now that's out in the open. Will batteries be poorly constructed this way to lighten the cost of the unit. Man I still have my NiMh it's been 3 years. They still work great. I would be reluctant to buy one that only has a life span of ONE stinkin year.
Another thing I was watching some "home shopping channel" here in Toronto, Canada and they were trying to pawn off a Mustek digital camera and sales tech mentioned that it carries a rechargable Lithium Ion battery that would last one year. Are you kidding me, spend $60-100Cnd for a battery that only last a year. Is this the direction of battery technology. I can live with 3 years but 1 to 2 years forget it! Buy hundreds of Alkalines and dump them in the land fill. Just joking, but most people will out-weigh the cost and put the money in thier pockets and forget the environment.

I'm kind of surprised that LiIon batteries are being advertised as only lasting a year. They are so much better than their nickel ancestors. Oh well, maybe they're feeling guilty for all those years they shamelessly plugged NiCd with grandiose claims of 500, 700 or even 1,000 recharges.

NAAHHHHHHH!!!

[garman]

Oh well, maybe they're feeling guilty for all those years they shamelessly plugged NiCd with grandiose claims of 500, 700 or even 1,000 recharges.
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Amen to that brother Cap!

[vitualis]

Lithium-Ion and Lithium-Polymer batteries have a much lower number of recharge rate than NiMH or NiCd batteries.

NiMH batteries if recharged properly can last a long time. Similarly so with NiCd. NiCd batteries usually fail not because of a true memory effect but rather from microcrystalisaton. If you have a high quality charger that does pulse charging, it can revitalise these old NiCd batteries (and stop the effect from happening in the first place).

Regards.

[garman]

Micheal...
If you have a high quality charger that does pulse charging, it can revitalise these old NiCd batteries (and stop the effect from happening in the first place).
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Do you know of any name brands that do a pulse charge?
Btw does the same principal apply to other types of rechargeables ie. NiMh/Li Ion. thanks -garman

[vitualis]

Don't know any brand names (there are well known brands of chargers ).

Usually, pulse chargers are MUCH more expensive and will say so on the box. Like all better chargers, they will prevent overcharging by some sensing circuitry which I can't remember how they work. They are NOT common since NiCads have long been overshadowed by NiMH batteries.

From memory, there is no benefit in using this type of charging for NiMH batteries. Li-Ion batteries need specialised charging circuits anyway... not that there are any Li-Ion AA batteries.

The worst possible type of charger are those that only do a timed charge and then trickle charge. They will either not fully charge your battery or worse, overcharge it.

Regards.

[Capmaster]

Lithium-Ion and Lithium-Polymer batteries have a much lower number of recharge rate than NiMH or NiCd batteries.

NiMH batteries if recharged properly can last a long time. Similarly so with NiCd. NiCd batteries usually fail not because of a true memory effect but rather from microcrystalisaton. If you have a high quality charger that does pulse charging, it can revitalise these old NiCd batteries (and stop the effect from happening in the first place).

Regards.

NiMH batteries have a limited number of ion exchanges depending on the chemistry. You can also "nuke" a NiCd battery by giving it a shot with a car battery charger for about 1 second (no more or it'll overheat and explode ...very dangerous). It blows off the contaminants from the cathode and restores some life to it, but there is a limited life on those, regardless of the charger

And quoting a number of recharges on any lithium battery is a meaningless number because requiring constant-voltage and not constant-current charge (like NiCd or NiMH) means float-charging is recommended for lithium, whereas nickel-based batteries recommend full discharges before charging. Full discharging of lithium batteries, like full discharging of that other constant-voltage battery we all know and love - our car battery, is not recommended.

You can use a lithium battery for 5 minutes and charge it back up without ill effects. Do that with a NiMH battery too many times and you'll see the life rapidly degrade

[zzyzzx]

I'm confused. Exactly how long are NIMH batteries supposed to last? They seem to last maybe only ~3 weeks between charges if you don't use them, but other than that I've not heard anything else.

[Capmaster]

I'm confused. Exactly how long are NIMH batteries supposed to last? They seem to last maybe only ~3 weeks between charges if you don't use them, but other than that I've not heard anything else.

That's due to its self-discharge characteristics. There are many high-impedance paths between "+" and "-". Some battery chemistries like NiMH have lower impedances there and more internal self-discharging goes on. Lithium-ion batteries are superior in this regard.

The ones that are admirable are the straight lithium batteries (non-rechargeable). When they're not used for a while, the cathode grows a film over itself that is fairly high impedance, reducing self-discharge to almost zero. Start using them again and there is a short-term voltage dip as the film is burned away, and then their voltage returns to normal.

That's why they have an insanely long shelf life,and why some have an advertised, and actual life of 5 years or more in ultra-low current applications, like watch batteries.

[vitualis]

It does depend on the individual battery.

NiMH batteries have a higher self discharge rate than NiCads. From memory, Lithium-Ion batteries are even worse but Capmaster states otherwise so I might be wrong.

There are differences between NiMH batteries as well. For example, for PDAs and Pocket PCs, people will talk of older iPAQs self discharging to the point of data loss over several weeks/month. iPAQs of course use a small current to maintain volatile memory as well. However, on one of my older Handheld PCs (same sort of idea - NiMH battery with small current required), I've turned it back on after half a year and the battery still has quite a reasonable charge so the self-discharge rate can't be that high.

Regards.

[Capmaster]

It does depend on the individual battery.

NiMH batteries have a higher self discharge rate than NiCads. From memory, Lithium-Ion batteries are even worse but Capmaster states otherwise so I might be wrong.

There are differences between NiMH batteries as well. For example, for PDAs and Pocket PCs, people will talk of older iPAQs self discharging to the point of data loss over several weeks/month. iPAQs of course use a small current to maintain volatile memory as well. However, on one of my older Handheld PCs (same sort of idea - NiMH battery with small current required), I've turned it back on after half a year and the battery still has quite a reasonable charge so the self-discharge rate can't be that high.

Regards.

The self-discharge info I posted was merely a generality ...a rule of thumb, and not intended to be applied universally to all batteries of the same type. There will be varying quality levels of any battery, or any other product for that matter. Go buy a Tadiran Lithium battery, and an Eagle Picher, and an Eveready from Walmart. Use them for 6 months. Then tell me if they perform the same. I'll bet dollars to donuts they don't

I'm sure there are plenty of anecdotal stories of batteries of this type and that type that perform miraculously. Maybe those batteries had been made on Wednesday afternoon at 1:30, with materials from an exceptionally good lot from their supplier. Whereas Monday morning or Friday afternoon batteries suck because the factory workers perform at their lowest skill level then (just getting back after a weekend ..and anticipating the coming weekend). Who knows?

I've had NiCd batteries that worked very well, and I've had many clinkers.

Your results may vary, and the author is not liable for contradictory anecdotal experience