Limit on Dell Laptop Battery Recharges?

[NW-Bound]

One more thing about Li-Ion batteries...

I only studied on how to use and charge these batteries in order to use them in circuits that I designed, but will not claim knowledge about their composition or the chemical reaction. However, I have read that Li-Ion batteries have a shelf life. Whether you use them or let them sit on a shelf, they lose their capacity in a few years. Supposedly the other batteries do not have the same problem. For what it is worth...

 

[NW-Bound]

Why didn't I think of Wikipedia?

For the inquiring mind,

Lithium-ion battery - Wikipedia, the free encyclopedia

The article contains a discussion of the relatively short life cycle of the Li-Ion battery. Makes you wonder what kind of special battery the designer of high-performance electric car Tesla Roadster plans to put in it.

 

[samclem]

Thanks for the link, NW-Bound. This part of the Wikipedia article caught my eye:

At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 °C or 77 °F will irreversibly lose approximately 20% capacity per year. However, a battery in a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures, which will significantly shorten its life. Different storage temperatures produce different loss results: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40%–60% charge level, the capacity loss is reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively

So, it sounds like if you use your laptop at home and plugged in most of the time, you could extend the service life of the battery by removing it from the laptop and storing it in a mostly discharged state inthe refrigerator (or maybe even the freezer, if the battery could handle that). If these figures are right, then it takes about 3 years for a battery to lose 50% of its capacity if kept fully charged in a laptop. If kept at 50% charge in the refrigerator, it would take about 30 years to degrade the same amount.

The cordless tools I use (Craftsman 19.2V) were originally equipped with NiCd batteries, and now Li-Ion batteries are available. I have one, and it is nice (light, good capacity, keeps its charge when on the shelf) but maybe I won't go on a tear and replace all my NiCd batteries at once. And I'll keep it partially charged and in the cool garage unless I've got a big project going.

It's too bad laptop manufacturers don't offer a low self-discharge NiMH battery as an option to replace the Li-Ion battery. They could sell it for the same price as the standard Li-ION battery,m but ti would be less expensive fir them to produce. It would be heavier and have a lower capacity than the standard Li-Ion battery, but would probably be enough for most of us and would last for the normal life of the laptop without replacement. Oh--maybe that's why they don't offer it.

 

[ERD50]

Thanks for the link, NW-Bound. This part of the Wikipedia article caught my eye:

If these figures are right, then it takes about 3 years for a battery to lose 50% of its capacity if kept fully charged in a laptop. If kept at 50% charge in the refrigerator, it would take about 30 years to degrade the same amount.
.

Or about 10 years @ 25C/77F at 50% charge. It is too bad that the laptops don't offer the option of a less than full charge, selectable at say 50,60,70,80,90% charge. Maybe it would default to 100% so people get the charge when they need it, but select less when you know you aren't going on a road trip.

This was an actual suggestion from an engineer on a product line I worked on ( @ 90% IIRC, still extended life significantly he claimed). I don't think marketing ever did anything with it though.

This is why the hybrid car batteries are lasting so much longer than many laptop batteries - they strictly limit the charge/discharge levels to extend the usable life.

-ERD50

 

[TromboneAl]

With my current battery, I started by unplugging it when using the laptop, then plugging in when it got low. I also used it with a pizza pan on my lap to keep things cool.

I leave my laptop in standby overnight. I think from now on, when I get the new battery, I'll leave it on standby and not plugged in. Plus I'll try to remove the charger whenever the charge level gets above 80%.

 

[kumquat]

I have started running mine with the battery removed.

 

[samclem]

Or about 10 years @ 25C/77F at 50% charge. It is too bad that the laptops don't offer the option of a less than full charge, selectable at say 50,60,70,80,90% charge. Maybe it would default to 100% so people get the charge when they need it, but select less when you know you aren't going on a road trip.

-ERD50

That would be a nice option. I wonder if the power management functions in laptops are strictly hardware or if there's a way to hack the software to give the user this option.
Including it as standard might even make some some money for the computer companies. I'd pay more for a larger battery if that would allow it to live 6 years and give me 4 hours of use at 50% power with an >>option<< to go to 8 hours if I really need it.