Li-ion battery conservation tips?

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sb56637
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Li-ion battery conservation tips?

Hello all,

 

This is in off-topic chatter because it relates to a laptop battery.  But I imagine that you battery experts will be able to give me a good answer due to your flashlight experience.

 

I ordered a new laptop, principally because we have constant power outages here and my current laptop only lasts an hour on its old, decrepit battery.  I'd like to know for my new laptop, how can I maximize the lifespan of a Lithium Ion battery?  Does Li-Ion have a memory issue with partial charges / decharges?  Should I try to let the battery run to 0, or should I avoid it?

 

Thanks for your help!

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Don
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It might be worth your while getting a UPS - get really good life on a laptop that way - especially if you follow Dan's advice here http://www.dansdata.com/upsupgrade.htm A bunch of car batteries outside would give you heaps of reserve power. You don't need a big UPS - few laptops need as much as 85W. With some cheap car or truck batteries it'll run forever. A friend of mine used to run his whole house on a 2kVA wind turbine, a 2kVA inverter and a bank of submarine batteries (They weigh about a ton each). Basically a huge UPS.

 

As for the laptop battery pack, keep it as cool as possible. Heat and fully charged lithium ion batteries are a good way of reducing capacity. If it is possible when you don't expect the power to go out, remove the battery.

 

The cycle life in my experience is 2-300 full cycles before capacity is down to not enough to boot the box.

 

I'd not expect any laptop battery pack to live much past three years - but then a third of all laptops are dead in 3 years.

 

Most laptops charge controllers need the battery to be run flat occasionally to calibrate them.

 

If, for any reason you are storing the battery pack, discharge it to about 40% and keep it cool. There is quite a bit of useful information here

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

sb56637
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Thanks! I forgot about the batteryuniversity link, I know you mentioned it before.

They claim

Quote:

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

So when the power goes out for 20 minutes and I use only a percentage of the battery there's no need to let it discharge totally before I plug it back in?

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Don
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I always put something under my laptop so that air can get under it -- I use an old printer at home which leaves most of the base of the laptop to hang out in the open air which does make a noticeable difference to overall temperatures (Even when run full time at 100% load)

 

On my desk at work I use a couple of slide binder clips at each side of the laptop which again allows air to circulate under it.

 

In the office there's quite enough fan nose already so I don't feel like using fans to farther cool the laptop. The best way I've found of cleaning heatsinks in laptops I've found so far is to turn the laptop off. Remove the battery. (This is important). Go outside with it. Let it cool down then wedge the fans with a paper clip, toothpick or whatever. If you don't, you'll wreck the fan bearings.. Then use a can of butane as used to refill cigarette lighters and hold it upside down so it is spraying liquid butane. As it boils it shifts crap off heatsinks like nothing else.

 

Remember to let all the gas boil off and dissipate before taking it back indoors.

 

Do not do this on a humid day as ice will form inside the laptop which is invariably a bad thing.

 

Another link that might be of use.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Don
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sb56637 wrote:

Thanks! I forgot about the batteryuniversity link, I know you mentioned it before.

They claim

Quote:

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

So when the power goes out for 20 minutes and I use only a percentage of the battery there's no need to let it discharge totally before I plug it back in?

 

Laptops are harder on their batteries than most which is why I expect 2-300 full cycles.

 

On the whole, I'd not run the battery flat any more than I had to. Initially, it is a good idea to keep it running till it shuts off (At least assuming your Linux (I'm assuming it is running Linux) can support the power management circuitry) so that the controllers know what to expect. By the sound of things, with your power outages, calibrating it is not going to be an issue. Almost all batteries don't enjoy deep cycling and it is best avoided where possible.

 

Just use it and try to keep it as cool as possible.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

alfreddajero
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They also make lappy fans that you can put under your laptop.....i secured mine under the lappy itself so when i move from place to place i dont have to worry about it.  Depending on the fan you get single or dual it should do the job well.  I use a Targus Dual fan and it does the job well.  Im all about lappys and how come you just didnt get a new battery pack or take the dead pack to a pc store and have them install new batts for you, either way enjoy your new lappy.

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alfreddajero
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If your new lappy is windows based you should be able to change the power plan when its on battery power, lower the screen brightness, and also dont have or use a lot of programs if you dont have too.  Is your new lappy a single or dual core.

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sb56637
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Thanks for the tips, both of you, very helpful!  So when it arrives I will let it run to the ground once, and then I will use the battery as needed, letting it incrementally discharge and charge.

 

I'm getting an Acer Timeline 4810T.  I'm replacing my current laptop, a four year old Dell Inspiron B130 because even with a new battery it never had good battery life.  It's just not efficient.  This new Acer has a high capacity 6-cell battery and an Ultra Low Voltage (ULV) Intel processor, supposedly good for 8+ hours.  I'm curious to see how the battery life on Ubuntu Karmic will compare with the battery life of Windows Vista and XP.  It's also supposed to have some sort of patented heat sink and cool air channeling system, and the ULV processor should also reduce heat.  But its warmish and very, very damp here, so that's probably not optimal for battery longevity.

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alfreddajero
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Cool then you might be able to stretch out the 8 hours using the power management settings.  I guess its time for you to take apart that old pack and see which of the 18650's are worth keeping, then you have to get a new light to put the cells in....lol.

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sb56637
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No kidding?  They hook up 18650's in parallel inside laptop battery packs?  Precisely 3 of them in a 3-cell battery and 6 of them in a 6-cell?

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alfreddajero
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Not kidding at all Mr. Admin.....just take care in taking them apart...if you need a vid then let me know. 

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sb56637
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Huh, that's funny, the product page for this laptop had a sort of dumbed-down explanation of what is a 3-cell, 6-cell, and 9-cell battery, and they showed a graphic with 6 batteries lined up to indicate that this is a 6-cell battery.  So really that concept isn't all that far from the reality.  Thanks for the tip.  I'm probably going to sell the old laptop though, so I think I won't destroy it.  Still lasts about an hour.  According to Ubuntu, the battery has the following stats:

 

Vendor: Sanyo
Technology: Lithium Ion
Serial number: 945
Model: DELL TD6126
Charge time: 1 hour 39 minutes
Capacity: 66.1% (Poor)
Current charge: 17.1 Wh
Design charge: 29.6 Wh
Charge rate: 7.5 W
But I guess that 1 hour isn't bad for a 4 year old battery in a harsh climate...

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No not bad at all.....i see your new lappy has two cores...should make work easier and less draining on the battery.

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sb56637
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Hmmm, they call it an Intel Core 2 Solo, which is just plain deceptive marketing in my opinion.  "Core 2" is the product line name, but it doesn't actually have two cores.  The ones that have two cores are called Intel Core 2 Duo.  Pretty sneaky eh?  But at any rate it is rated as an "Ultra Low Voltage" edition made especially for high mobility laptops.  I care about battery life more than performance, so I think I'll be happy with it.

You can read about the confusing nomenclature here: http://en.wikipedia.org/wiki/Intel_Core_2#Duo.2C_Quad.2C_and_Extreme

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Darn your right......Thanks for the link, i did a bit more searching......seems to be a good efficient processor indeed.

 

Features and benefits

The Intel Core 2 Solo mobile processor has these Intel® technologies built in:

Power-saving features designed to extend the life of your battery+.

Enhanced single-core performance to handle software applications such as CAD tools, 3D and 2D modeling or number-crunching programs.

Intel® Smart Cache enables smarter, more efficient cache and bus design for enhanced performance, responsiveness and power savings.

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sb56637
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I don't know what this stands for, but the SU3500 has...

Max TDP: 5.5 W

 

...whereas the Core 2 Duo Mobile T4400 has...

Max TDP: 35 W

 

So the ULV really does seem to be a significantly more efficient, although not exactly barn-burning processor.

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alfreddajero
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You can find the information right here.....

 

http://en.wikipedia.org/wiki/Thermal_design_power

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sb56637
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So a lower TDP processor wastes less power in heat loss.

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alfreddajero
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Yes thats it.....so for you the laptop would probably stay cool.  But in the environment that your in you might want to take a look at lappy fans to keep the air circulating.....or put it on a laptop stand that keeps the grills on the bottom from being suffocated.  And it also depends what programs that your running, i deal with a lot of audio so my laptop stays warm not hot, burning cd's- movies will also work the processor as well causing more heat. 

 

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sb56637
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The program that most heats up my current laptop running Ubuntu is Adobe Flash 10, which is a real CPU hog.  The newest version soon to be released is supposed to reduce CPU usage a bit though.

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Okay....just remember that heat is killer.....dont know if you ever saw a high end gaming pc they have fans everywhere in the housing and the heatsink is something that you can stand on......and some of them are watercooled all this just to play a game, lol....might as well just get a Psp.

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sb56637
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Ha, yes I've seen those gaming machines, they sound a vacuum cleaner with those fans.

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Don
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I have an old Sun rackmount server. When it is running you wouldn't be able to tell whether a vacuum cleaner was working or not. It is a bit like sitting beside a helicopter.

 

It does run cool though.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Don
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But they need to be in parallel in order to keep the current per cell down to safe limits. A 6 cell battery pack will normally be 10.8V so three cells in series and another stick of 3 in parallel with that. Assuming 2400mAh cells that gives you 4.8Ah

 

For a laptop consuming 65W (Which is pretty high these days) at 10.8V it is pulling a hair over 6A from the battery. Each cell is seeing 3A of that which is still on the high side for 18650's though within safe limits. With a 9 cell pack, you will still have the same voltage, 10.8, but you now have 7200mAh capacity and 2A from each cell which ought to mean that each cell lives longer as they aren't being worked so hard. The maximum power draw from most laptops nowadays is only seen when charging a depleted battery. 

 

The parts cost for the cells in bulk is probably of the order of $3-4 per cell. Add a few dollars for the protection circuit and plastic casing, a 9 cell pack shouldn't cost much more than about $90 retail. But they all cost quite a bit more than that. And for older laptops they can be hard to find.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...