
How to prolong lithium-based batteries - paulgerhardt
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
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Gonsalu
\- Charge frequently and don't allow full discharges (Li-ion batteries don't
have memory);

\- Keep batteries at temperatures lower than 30ºC;

\- Charge with voltages lower than 4.1V/cell.

~~~
hammock
I would just add to this, don't keep battery at 100% (unplug it when it's done
charging)

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coin
> I would just add to this, don't keep battery at 100% (unplug it when it's
> done charging)

Absolutely incorrect. What makes you think that keeping a 100% charged battery
plugged in bad? The device has its own charging circuitry that stops charging
when full.

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sireat
Anedoctal evidence, my SOs Dell's battery is basically dead(about 2-3minutes
of charge) even though it has spent 95% of time plugged in fully charged.

Laptop forums are full of stories like this.

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coryrc
Thinkpads offer a way to limit the percent State of Charge (SoC) while
charging. AFAIK this is the only laptop which does so.

I do this manually by removing the battery from my laptop once it reaches
70-90% SoC (and I'm plugged in, obviously). This is superior for battery
protection because the temperature is limited to room temperature, but
inferior because the laptop shuts off on power loss.

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teaspoon
Are the battery life savings really worth the hassle and potential for lost
work?

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icegreentea
Since I've picked up my Thinkpad, I really wonder why Lenovo doesn't stick in
a small internal battery ontop of the removable (say good for like 10 minutes
or something...) so that: a) On power loss (battery removed), it can still
dump into hibernate (the real one) b) So you can hotswap the external
batteries. I have two batteries, and when I'm out for long periods, it annoys
me that I have to dump it into hibernate so I can swap batteries. It's just an
extra few minutes that really annoy me.

~~~
snes
Some laptops have room for two batteries. My old FSC Celsius H did.

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nitrogen
Wouldn't total mAh delivered be a better metric than charge cycles, since less
power is delivered per cycle with shallower discharges? Some quick
calculations, assuming a linear loss of capacity over time:

Assume an example rated battery capacity of 1700mAh

The average capacity over the life of the battery (i.e. reaching 70% capacity)
is 80% (assuming batteries start at 90% and drop linearly to 70%).

At 100% DoD, 500 cycles * 80% * 1700mAh = 680Ah

At 50% DoD, 1500 cycles * 80% * 50% * 1700mAh = 1020Ah

At 25% DoD, 2500 cycles * 80% * 25% * 1700mAh = 850Ah

At 10% DoD, 4700 cycles * 80% * 10% * 1700mAh = 639Ah

So clearly a 50% DoD is better than 25% or 10%, but where does the optimum
lie?

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jessriedel

       Depth of discharge |    Discharge cycles
    
        100% DoD          |         500
    
         50% DoD          |        1500
    
         25% DoD          |        2500
    
         10% DoD          |        4700
    

So....4700 discharges with 10% DoD. Isn't that just like 470 full (100% DoD)
discharges in terms of total energy supplied? In other words, the battery
lifetime can be described by a single amount of energy (e.g. 1000 kWh). It
doesn't matter if you use that much energy interspersed with frequent
recharges, or with full discharges each use.

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kragen
The products are 500 discharges, 750 discharges, 625 discharges, and 470
discharges, so it turns out that it does matter a bit; you can store 50% more
total energy in the battery over its lifetime if you discharge it 50% each
time than if you discharge it either 100% or 10% each time.

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dedward
Hmm. I have 15 minute interval logs of battery stats for my mbp since the day
I have it logged (with gaps when it was asleep/off) .... about 20,000 entries.

I could extrapolate the data based on my usage patterns (the
charging/discharge/etc are all in there)

Anyone know offhand how to tell the charing circuits in the mac to stop
charging at 50% capacity? I'm thinking I could easily automate that for a few
weeks or months and check out the log data...

