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My thoughts on Over-charging Batteries

For those that don’t know me personally, I work for the government on special projects, and we’ll just leave it at that. However, in the course of normal work, we talked in depth to a National Lab in regards to batteries. One of the discussions was charging. I can’t post the actual info I got from them, however, here is a good stand in:

This is an except from here:
No trickle charge is applied because lithium-ion is unable to absorb overcharge. A continuous trickle charge above 4.05V/cell would causes plating of metallic lithium that could lead to instabilities and compromise safety. Instead, a brief topping charge is provided to compensate for the small self-discharge the battery and its protective circuit consume. … Typically, the charge kicks in when the open terminal voltage drops to 4.05V/cell and turns off at a high 4.20V/cell.

There is a whole lot more info on that site, but I’ll sum up the excerpt, if you continually charge a Lithium Ion battery, it will degrade, and worst case explode, but hey, at least it looks cool when it does.

Just don’t end up like others have, for example, a Chinese man who took his phone off the charger, put it in his pocket, and then it exploded.  To read a little more about that, check out EnGadget, if you want to see the phone, Tech-Ex.  Here’s another one, no one was killed, but it burst into flames, over on PCWorld.

I’m not sure if those were good factory batteries or the cheap Chinese knock offs, but either way, if you decide to assume the risk, that’s your decision.  However, my decision is NOT to hack the battery code.

I hope this explains why I have not or WILL NOT modify the battery code.

Z

January 2, 2011 @ 23:23
Android Development

23 Comments

  1. Ping from dkz:
    Sunday, January 2nd 2011 at 23:45 | 

    great article mann..

  2. Ping from wtf911:
    Sunday, January 2nd 2011 at 23:47 | 

    Intriguing. You do indeed have a point. I’m sure you can see where I’m coming from, always wanting a full battery when i take my phone off the charger…but I can definitely understand what you’ve said being an important factor in the decision to implement SBC…Hmm…fair enough Mr. Ziggy. 🙂

    …Thank you for your continued contribution to the community.

  3. Ping from apfrost:
    Sunday, January 2nd 2011 at 23:58 | 

    I use a Lithium-Polymer battery, would the same still occur?

  4. Ping from Tweets that mention My thoughts on Over-charging Batteries -- Topsy.com:
    Monday, January 3rd 2011 at 00:05 | 

    […] This post was mentioned on Twitter by Brice Exley. Brice Exley said: RT @Ziggy471: Why I will NEVER 'hack' the battery code – http://tinyurl.com/29f966x […]

  5. Ping from Trident:
    Monday, January 3rd 2011 at 01:19 | 

    Note from the referenced article:
    The charge process of a lithium-ion-polymer is similar to lithium-ion. These batteries use a gelled electrolyte to improve conductivity. In most cases, lithium-ion and lithium-ion-polymer share the same charger.

    While I certainly respect your plan- and still plan to use your kernels- it should be noted that the examples given are by no means proof that over-charging or trickle-charging are at fault. Each of the damaged batteries/phones had various contributing factors that could have caused the damage.
    The article does make some excellent points and I think that extra care is in order when doing any modification to the kernel that involves battery charging.

  6. Ping from MIC:
    Monday, January 3rd 2011 at 06:45 | 

    GITHub your code so we can implement the battery charging code into it ourselves 😉

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  8. Ping from PhilE:
    Monday, January 3rd 2011 at 11:05 | 

    I appreciate that you don’t mess with the battery code. I agree with you why. The phones do charge up to 100% fine, but if you leave it plugged in, it will drain a bit, which is fine, given the alternative.

    And your kernel charges very fast, which is more important to me, that I’m getting great battery life overall.

    Just an FYI, I took my phone off the charger when it hit green, let it sit overnight, and sent maybe 3-4 texts (very minimal use) I got 10hours of unplugged time and it was 92%. This was with your 12/19 kernel. Normal use still nets me good times above 90%

  9. Ping from Schnello:
    Monday, January 3rd 2011 at 14:31 | 

    With the latest original HTC Kernel (incl in 2.29.405.5) the charging was changed (allways on 100%). Is this fix implemented into your kernel?

    Kind Regards, Christian

  10. Ping from wtf911:
    Monday, January 3rd 2011 at 18:28 | 

    …Ziggy I understand it’s your kernel and you can do with it as you please but I would appreciate the option of having SBC

  11. Ping from Mr. X:
    Tuesday, January 4th 2011 at 09:23 | 

    The option of SBC will be in the source only so if you wish to have a health and fire hazard as a cellular device then you can do so on your own merit.

  12. Ping from Mr. X:
    Tuesday, January 4th 2011 at 09:24 | 

    Or i should say option for you to add it to the source he wont include it. to clarify.

  13. Ping from wtf911:
    Tuesday, January 4th 2011 at 18:06 | 

    Health hazard lol…if you look into the incidents Ziggy pointed out they were caused my faulty batteries…it had nothing to do with how they were charged.

    • Ping from Mr. X:
      Saturday, January 8th 2011 at 10:47 | 

      You’re an idiot if you don’t think this is a health hazard. Ignorance is not always bliss.

      Go do a simple google search on overcharging lithium ion batteries and then come back and have your “lols”

    • Ping from Mr. X:
      Saturday, January 8th 2011 at 10:58 | 

      PS: “if you look into the incidents Ziggy pointed out they were caused my faulty batteries…it had nothing to do with how they were charged.”

      Even if this were true (which its not, you’re still an idiot because lithium ion batteries cannot absorb over charge hence why HTC has it charging the way it does) How can you tell if you battery does not have a faulty cell and wont catch fire or explode on your night stand while you and your family sleep? Not

      You cant. So you continue telling your self that its a safe practice, but its not.

  14. Ping from glockliberty:
    Thursday, January 6th 2011 at 23:14 | 

    thanks ziggy.

    don’t know why anyone would take the risk on this. I tried an SBC kernel for a few days and ziggy’s kernels still give me better battery life.

  15. Ping from conflikt:
    Friday, January 7th 2011 at 21:50 | 

    http://forum.xda-developers.com/showthread.php?t=904577
    Battery on fire, 2 threads where battery discharged fully and were rendered useless.

    • Ping from Mr. X:
      Saturday, January 8th 2011 at 10:51 | 

      Ziggy is a smart guy, You can always trust his better judgment on what we need in the kernel.

      Not only that he isn’t aiming to have your battery explode and injure you, your phone or even cause a fire.

  16. Ping from PrfectOne:
    Sunday, January 9th 2011 at 09:27 | 

    Netarchy took it out too because a significant number of people were having failing batteries. They don’t need to go supernova to know it is an unwise decision. Cheers for taking a stance Ziggy.

  17. Ping from t.bo:
    Sunday, January 9th 2011 at 22:24 | 

    I have a general question about the charging that confuses me…

    On a Sense ROM, it charges to 100% and quickly falls off to 93% (usually, though sometimes I get it to “stick” higher). I loaded CM6.1 this weekend, and I noticed the LED turns green at 91%. You can leave it plugged in until the meter says 100%, but it quickly drops off to 91%.

    However, if I turn the phone off and charge, it will get to 100% and drop normally. There is no quick drop off.

    Now… I am not asking for kernel battery hacks. Rather, just trying to understand the difference. Why when the phone is off is it fine to charge it higher, but not when the phone is running?

  18. Ping from PrfectOne:
    Monday, January 10th 2011 at 00:59 | 

    xda explains it better but generally once the charge hits 90-91% it switches gears and charges less aggressively. Then at 96% or so it shifts even less aggressive. Once it reaches near 98-100% it is barely pushing in voltage. It reads 100% but isn’t really empirically what the battery can hold at 100%. The quick drop off occurs when you remove the ac source because the system then calibrates the actual charge to total charge to get a more “accurate” percentage.

    I can’t speak for why cm changes its notification led at that point but it may have something to do with that kernel’s charging routine. As for turning it off, remember you aren’t needing charge to the hardware so everything goes straight to the battery and charges quicker. I also assume, fully knowing the risk of doing such, that since the hardware is off, the kernel has no role obviously so there must be a hardware default charging routine. Please correct me if I am wrong about that.

  19. Ping from Biker Dude:
    Tuesday, January 11th 2011 at 23:41 | 

    when i heard about ziggy i tried one month ago and it failed to boot past white screen so i thought ‘this guy might not be as good as some of the others’ and didnt really care for kernels in general aside from the decent kingxbfs 11.

    When i read the whole trickle charge kernel release thing, i was tempted but knew it would have faults and fortunately stayed away.

    Then i read your recent post on this topic, and i was sold! Ziggy knows exactly wats up, and he does things properly it seems, stability before risk. so i took another shot at your newest beta

    the reason the first ziggy kernel i tried did not work is this: EACH EVO IS DIFFERENT, KERNEL WORKS JUST NOT WITH EVERY EVO OUT THERE!

    i read a comment posted here recently where ziggy said he preferred the bfs kernel, and yet the cfs works best for my phone. again not kernels fault, phone just responds better to cfs kernel.

    finally, my thoughts on this kernel are that it seems stable so far, gets better benchmark score then previous built-in kinghavs bfs11 and netarchy 4 that i briefly tested as well. the ziggy bfs works better then cfs but i get a weird tearing issue with ziggy and kingx bfs kernels. the fact that ziggy knew the negative sides about the trickle charging well before damage reports like this is a great demonstration of ziggy’s knowledge. based on my somewhat limited experience with the Jan. 2nd kernel i encourage everyone to try ziggy471 kernels, both cfs and bfs. its definitely top-notch stuff!

    now i have one good question for ziggy or anyone else who knows: i have recently been setting scaling to performance, oc’d to 1152, and having the clock only drop to 422 when screen is off. battery life seems to be better and overall as good as ive ever had it.

    im thinking the cause of this is something ive suspected from the first time the evo got clocked up! and that is the kernel scaling feature uses CPU resources (as little as it may be) to scale up and down. if you watch the clock speeds, they jump around quite a lot.

    by disabling scaling (except for when screen is off), you essentially prevent any resource being used up correct? ive also noticed better battery having it scale up and down in bigger frequency steps which i figured is due to less scaling occuring as a result.

    this cpu scaling concept came from pc’s but it seems to be a software implemenation here on the evo whereas pc’s get it builtin at the hardware level. any thoughts on this would be appreciated!

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