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#16
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Stop dischargie of laptop battery by disconnecting?
mike wrote: On 11/15/2013 4:34 PM, Bill in Co wrote: mike wrote: On 11/14/2013 6:08 PM, Bill in Co wrote: Computer Nerd Kev wrote: Not all, but as far as I know, most laptop batteries have protection circuitry in the battery itself that slowly drains the charge. The effect this has depends heavily on the condition of the battery and the the individual design and specs. Reference???? What "battery protection circuitry" IN a battery? Like virtually every lithium battery made? google bq29311 for an example. Or pop the battery out of your cellphone. You're holding one in your hand. I think that bq29311 is a battery protection IC, and is not inside the battery, no? If you're talking about being inside a CELL, not usually. Although there are "CELLS" with electronics attached to the end and shrink-wrapped so that they look like a bare cell. This is one such attachment. http://dx.com/p/charge-discharge-pro...mm-1-9mm-26112 Same site has "cells" with the attachment already installed. Typically, a group of cells is called a battery. You could argue that one cell does not a battery make. If you just want to nit-pick, that's your right. The rest of us try to discuss the issue in context. No, I wasn't trying to be pedantic. If the battery packs nowadays have that built in circuitry, it's good to know. I don't think that has always been the case, however, although maybe you'd have to go back a couple of decades or so. |
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#17
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Stop dischargie of laptop battery by disconnecting?
Paul wrote:
Bill in Co wrote: mike wrote: On 11/14/2013 6:08 PM, Bill in Co wrote: Computer Nerd Kev wrote: Not all, but as far as I know, most laptop batteries have protection circuitry in the battery itself that slowly drains the charge. The effect this has depends heavily on the condition of the battery and the the individual design and specs. Reference???? What "battery protection circuitry" IN a battery? Like virtually every lithium battery made? google bq29311 for an example. Or pop the battery out of your cellphone. You're holding one in your hand. I think that bq29311 is a battery protection IC, and is not inside the battery, no? It's inside the battery pack. http://www.ti.com/product/bq29311 http://www.ti.com/lit/ds/slus487d/slus487d.pdf "...the bq29311 can activate the FET drive as a secondary protection level." "APPLICATIONS Notebook computer battery packs" The schematic on page 9, hints at what it does, but you need to look at page 6 to interpret it. The "X" connections on the left, are to the individual lithium cells. And the FETs at the top of the schematic, are series pass during charge and discharge. I'm not going to try and figure out, which features are local and purely hardware, and which ones require the laptop processor in order to work. The S-8244 is here. http://www.sii-ic.com/en/semicon/dat...ion-ic/s-8244/ http://datasheet.sii-ic.com/en/batte...on/S8244_E.pdf It looks like Q3 (2N7002) is there for series disconnection of the pack. And the S-8244 provides a second opinion on opening the circuit. Something like that. I didn't read the whole thing. But it looks like all that crap is hiding inside the battery pack. No wonder it's so big and the shape is so weird looking. HTH, Paul It was all new to me, and pretty amazing! (I guess I'm still stuck in the past with what I thought batteries were. :-) Apparently battery packs are what I'd call "smart batteries" (in a loose sense). |
#18
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Stop dischargie of laptop battery by disconnecting?
Somewhere on teh intarwebs Bill in Co wrote:
Computer Nerd Kev wrote: On 15 Nov 2013, Bill in Co wrote: Computer Nerd Kev wrote: Not all, but as far as I know, most laptop batteries have protection circuitry in the battery itself that slowly drains the charge. The effect this has depends heavily on the condition of the battery and the the individual design and specs. Reference???? What "battery protection circuitry" IN a battery? Lithium Ion batteries like to get hot and catch fire if they are charged when the voltage if too low. So there is some small circuitry to monitor this voltage and prevent charging when it is below a set threshold (and discharging below it, although the circuitry itself drains a small amount of current and thus over time self-sabotages this function (lesson of the day: keep your Li-Ion batteries charged (actually applies to a lot of batteries))). In addition, some also protect against excessive current draw or heating by disabling the voltage output when sensor readings exceed pre-set values. References? Oh all right: http://batteryuniversity.com/learn/a...y_circuits_for _modern_batteries Why I say not all laptop Li-Ion batteries have this circuitry: http://www.fonerbooks.com/laptop_3.htm http://www.thinkwiki.org/wiki/Batteries The idea of a "smart battery" was new to me. Having external circuitry to monitor it is one thing, and is something quite different. But actually having ANY circuitry built into tthe battery itself, per se, is something else, and was something I wasn't aware of. Up to this point I thought all batteries were just chemical sources of power, and that's all. 'Smart batteries' are the norm in laptops and have been for over a decade. Most of them monitor each individual cell and protect the whole pack from one bad cell going into thermal ranaway when charging. With ThinkPads (the laptops I'm most familiar with) since at least 2003 the CPU and ROM in the battery pack not only monitor the individual cells but also store information such as designed capacity, cell manufacturer, date of manufacture, date first used etc. In fact I learned when replacing cells in a battery pack that it's imperative that *some* power is maintained to the control circuitry at all times - such as hooking it up to a bench supply while you are unsoldering the old cells and replacing them. Failure to do so will result in a total shut-down from the control circuitry and a non-functioning battery pack. Removal of the control circuitry results in a laptop that won't boot from or charge that battery as there is a 'handshake' process between battery CPU and laptop when power is applied. (Most) Laptops stopped using 'dumb batteries' back when they changed from Ni-MH to Li-Ion, around the turn of the century. -- /Shaun. "Humans will have advanced a long, long, way when religious belief has a cozy little classification in the DSM." David Melville (in r.a.s.f1). [Sent from my OrbitalT ocular implant interface] |
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