On 4/28/13, Riccardo Mottola <riccardo.mott...@libero.it> wrote: > Hi Alan, > Although the document contains interesting "internal details" about the > hardware, I don't think these are very useful when dealing with broken > batteries. Most of the communication is shielded by the APM/ACPI/other > power manager. Being the author of BatMon for gnustep and owner of > several laptops with different operating systems, I have some empirical > experience. > You may try to use http://gap.nongnu.org/batmon/ and depending on the > OS/BIOS/Battery you might get a little interesting information
sysctl | grep bat shows me hw.sensors.acpibat1.volt0=11.10 VDC (voltage) hw.sensors.acpibat1.volt1=9.30 VDC (current voltage) hw.sensors.acpibat1.current0=0.00 A (rate) hw.sensors.acpibat1.amphour0=3.04 Ah (last full capacity) hw.sensors.acpibat1.amphour1=0.43 Ah (warning capacity) hw.sensors.acpibat1.amphour2=0.13 Ah (low capacity) hw.sensors.acpibat1.amphour3=0.00 Ah (remaining capacity), CRITICAL hw.sensors.acpibat1.raw0=2 (battery charging), OK by reading from the acpi. the hw.sensors.acpibat1.volt1 was at 10.97 2 days ago. That's the only change I've seen. This is on a CD/DVD bay battery, the other one is not recognized at all since the Windows crash, so I took it back out. What the be2works setup uses is an adapter designed by Philips to connect from a USB or parallel port to a battery pack after you take the battery pack out. It talks to the gas gauge chip directly, without acpi getting in the way. smbus is just 2 wires (plus ground), and you don't hurt anything if you get the clock and data backwards, it just doesn't work. The adapter is mostly a 74LS05 set of inverters, but you could use a few transistors to do the same job if you don't have a 74LS05. Just level translation mostly. The be2works download includes a schematic of what to build, but it's a copy of what Philips designed. I've seen that 80% figure before, it's what lithium ion batteries go to after about 400 charge/discharge cycles. NiMH would be about useless by then. This is my 4th Dell laptop. I've also got a C610 that takes the same battery as the CPIa before it, and I haven't bought a new battery for that in several years. It's down to the 80% point but still working. I don't think that's a smart battery, and this one did come from eBay. But why would Windows crashing because of a wrong driver for a WiFi card kill a battery? Neither Windows or Openbsd recognizes it, they both say the battery is absent. I think the internal fuse blew. The CD/DVD bay battery is recognized, supposedly it's charging, but it never gets anywhere. After 2 days charging it still won't boot the laptop. And both of these batteries are less than 1 month old. Or at least I bought them that recently on eBay. I don't know what's in them exactly. Could be old cells or cheap cells. I don't believe in trying to rejuvenate a battery pack any more than a CRT. There's some good information (and a lot of batteries) at http://www.batteryspace.com/ If you look at what the be2works program does and what's in the TI PDFs I think it's possible to write something that talks directly to a gas gauge chip in (an unplugged) battery with an adapter. Alan > > I think that when a battery goes bad, everything which is problematic is > inside the battery. > I also do think that the powermanagment more than often does a bad job, > but there isn't much you can do. I have batteries which sometimes do run > for 1 hour or more, but the power manager reports them as dead (= little > internal capacity). > > The chip inside tries to know: 1) the design capacity 2) the maximum > capacity reached after the last charge 3) current capacity. Furthermore > usually it tries to count the cycles > > 1) is always correct for original equipment batteries. I have seen > "cheap oem" batteries with wrong values and it might be wrong if you > susbstitute the elements inside with wrong > > 2) and 3) are what go wrong. Usually, you should see 2) slowly > decreasing with each cycle. A "sane" but "old" battery drops about a > small percent each time, so that perhaps after 400 cycles you are to 80% > capacity. Nothing you can do about it! > > Sometimes the battery "thinks" it has a too low capacity. In this case, > weird things happen. THee best case is that you will get like "5 minutes > left" but actually your computer continues to operate. Most often you > will get an abrupt drop and you rcomptuer goes off before giving a > meaningful warning... or whatever else. > > Sometimes this might happen if just one of the elements goes bad. Laptop > batteries do not have a balancing method, as far as I know. > > Anyway, the battery should recalibrate itself after a full discharge > cycle (Li-Ion don't have memory, but their chip drifts). But I have > noticed that more recent and smarter batteries essentially fail to do that. > > But essentially, other than trying to reset and force a recalibration > with a tool from the host, I don't know what you else could do. Most > tools are more like "smart dischargers" that end up trying to make the > battery pack recalibrate itself. > > I have found a lot of "voo-doo" on the web.. and found many bad batteries > :) > > One last thing. If one or more elements of a LiIon cell drop below a > certain value, a circuit breaker opens the battery. No voltage out, but > apparently in my experience, no way to recharge such a battery pack > either! A LiIon cell should never discharge below a certain level, thus > it is better to store batteries half-charged, not discharged. This is > also the reason why LiOn batteries come pre-charged. Not for courtesy, > but because they need to! > > Riccardo > -- Credit is the root of all evil. - AB1JX
