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Things You Should Know About Lithium Ion Battery

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By Xenova, Senior Member on 14th July 2011, 02:48 AM
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4th October 2011, 11:32 PM |#221  
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Originally Posted by scyld

I'm working on my PhD in materials science... but not in any sub-field related to batteries

Thanks for the info! I thought that my Li+ battery practices were "bad" (keeping my battery in my notebook when on AC power, recharging my phone even when the battery is not near completely used up, etc.), but apparently they aren't!

So, here's my question: with regards to preventing the battery from becoming overly depleted, what % is too low? I have used my battery on my phone until it hits 8%. Is that too low? It has a capacity of 1750 mAh, which is pretty much standard for phones these days, well at least for smartphones.

If it's possible to give a rough estimate of what charge levels could be damaging to a battery, I'd appreciate it.

Thanks!

It's gauged by cell voltage rather than remaining capacity.
Your phone will turn off above the safe minimum cell voltage.
If you then leave it off the cell will slowly discharge and eventually will drop below the safe voltage.
This is why it is suggested that if you're not using a battery for a few months you should leave it with 40% charge, and also why if you find an old phone that you've not charged for a year or so, the battery may never charge properly (just had to replace the battery in an old ipod due to it being packed away for the past 2 years).
When you charge the battery you're forcing current through it which produces heat and particulate buildup inside which reduces the life of the battery, which is why top up charges are better for lithium batteries rather than running the phone down to 0% and doing a long charge.
5th October 2011, 12:08 AM |#222  
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Originally Posted by xaccers

It's gauged by cell voltage rather than remaining capacity.
Your phone will turn off above the safe minimum cell voltage.

I realize this... there's no way for the circuit to detect "charge." But voltage is an easily measured quantity.

Likewise, your "charge" indicator determines % of capacity left via voltage, so when you talk about "40% charge," based off the phone's reading, this too is determined by voltage.

But what I was asking was: is there a % capacity that we should not go under when using the battery? I.e., is there any charge % below which lifetime decreases more dramatically? I'm talking here about a battery that is being charged and discharged, not one in storage.


I guess the answer to my question is: there isn't any % of capacity used under which battery degradation gets worse during recharging, and if there is, it's lower than the phone's switch-off circuit allows.
5th October 2011, 12:24 AM |#223  
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Quote:
Originally Posted by scyld

I realize this... there's no way for the circuit to detect "charge." But voltage is an easily measured quantity.

Likewise, your "charge" indicator determines % of capacity left via voltage, so when you talk about "40% charge," based off the phone's reading, this too is determined by voltage.

But what I was asking was: is there a % capacity that we should not go under when using the battery? I.e., is there any charge % below which lifetime decreases more dramatically? I'm talking here about a battery that is being charged and discharged, not one in storage.

Sort of, in that the lower you run the battery the longer you have to charge it for back to 100% which will shorten it's life compared with say always only letting it run down to 60% and then charge it.
I've not seen any research that covers exactly what I think you're asking though. Something like battery life run at 0-20%, 20-40%, 40-60% etc
Would be interesting to look into.

Talking of checking capacity, I have known someone who misunderstood and used an ammeter on a 9.6V NiMH battery, resulting in them coming to me saying "I connected it up and there were lots of sparks and now my battery isn't working, did I do something wrong?"
5th October 2011, 01:19 AM |#224  
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Originally Posted by xaccers

Talking of checking capacity, I have known someone who misunderstood and used an ammeter on a 9.6V NiMH battery, resulting in them coming to me saying "I connected it up and there were lots of sparks and now my battery isn't working, did I do something wrong?"

HAHA... whoooops!

Incidentally, someone on like the 2nd or 3rd page recommended keeping a Li ion battery's charge in the 20 to 80% range, though he didn't really cite a source for the info.
5th October 2011, 03:12 AM |#225  
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thanks ..really good post
19th October 2011, 01:13 PM |#226  
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so u mean even though my LG O1's battery fully charges in about 3-4hrs, if i leave my phone on charging the entire night that wont reduce my battery life..??
19th October 2011, 01:55 PM |#227  
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Originally Posted by vj_dustin

so u mean even though my LG O1's battery fully charges in about 3-4hrs, if i leave my phone on charging the entire night that wont reduce my battery life..??

Yup. Mostly of the people I know and myself doing this way.

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19th October 2011, 07:39 PM |#228  
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I always put my batteries in the fridge....whether they are lithium or not and no matter what kind it is they go in the fridge if they are not used for a long period of time. Also I would prefer more than a 40 percent charge on the battery if you want it to remain in a healthy state. As for the temperature, that is up to user how hot or cold they keep their phone as many people put their devices and the heat generated from their body does in fact have an effect on the battery to a small degree. The higher the temp, the more likely you will lose charge at a higher rate than you're used to.
28th October 2011, 06:10 PM |#229  
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Cool
Was really helpfull and neat
30th October 2011, 04:33 PM |#230  
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was very helpfull indead...thx alot man...u own man...haha
1st November 2011, 03:42 AM |#231  
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I love hear it
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