Re: Battery LED flashing
On 01/02/2010 06:48 PM, Tabitha Roder wrote: resulted. We left it plugged in overnight and it appears to have charged normally and the battery now runs the laptop (when it was doing the flashing charge, the laptop would switch off immediately when you unplug the charger). http://wiki.laptop.org/go/Power_management#Battery_LED indicates flashing on charge means trickle charging. Sadly we didn't find this page when it was happening so cannot fully confirm it was flashing orange and with the 4 blinks, pause pattern. I've updated troubleshooting guide to include the flashing yellow state. The only thing that causes the charge LED to blink is trickle and error. Flashing red is error so it was trickle. 'watch-battery' from the ofw ok prompt will also tell you trickle for the status when its trickle charging. This page also doesn't give any clues as to why a battery might be trickle charging. Battery trickles when the voltage on the battery is 5.4V. This can occur if the battery is stored for a long time or if its installed in a (powered off) XO for 30-50 days. There is a small power drain even when the XO is turned off. http://wiki.laptop.org/go/Hardware_specification#Battery suggests that the battery has a Maxim DS2756 http://wiki.laptop.org/images/e/e9/DS2756.pdf chip in it, but this chip only monitors one cell, so I guess there are two such chips? No, the Cells are in series. The sensor chip measures the voltage across both of them. Overvoltage undervoltage are monitored /cell by the safety monitor but there's no communication to that chip. The /sys interface only gives information about the whole battery, it doesn't tell you about the state of each cell. The specification pdf on the Hardware_specification page describes the Embedded Controller interface to the operating system in terms of Battery, not Cell so I guess it doesn't expose each cell either? The /cell info is not exposed because there's nothing available to expose and there's not much to do if they were. There's only one path to the battery. To do anything special you would need independent charging paths. -- Richard A. Smith rich...@laptop.org One Laptop per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: [olpc-nz] Battery LED flashing
On 01/03/2010 07:20 AM, Martin Langhoff wrote: the behavious sounds exactlt like a case of trickle charge. This triggers when the batt charge is so low that we cannot charge it (or measure it). When it happens, it's ususlly because a batt has not been used for a while. The batteries are actually ok. Trickle charge is the result of the way the XO-1 power system is designed. There is no dedicated battery charger IC. The battery is connected directly to the main voltage rail. The result of this that when you turn on the charging mosfet your system rail = battery voltage. On XO-1 if you try to charge a battery that's dropped to a really low level you don't have enough headroom for the rest of the voltage regulators to work and the system dies. So we bring the voltage back up gently to a level we can deal with before opening the electron flood gates. In terms of getting more low level info, get your hands on a script called batman.fth (it's somewhere in the wiki ;-) ) http://wiki.laptop.org/go/XO_Troubleshooting_Battery#batman.fth logs of the batt levels per cell, and you can read it/change it. batman.fth does not do anything per cell. There's no user serviceable parts per cell in the OLPC battery. -- Richard A. Smith rich...@laptop.org One Laptop per Child ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: [olpc-nz] Battery LED flashing
hi Tabs, the behavious sounds exactlt like a case of trickle charge. This triggers when the batt charge is so low that we cannot charge it (or measure it). When it happens, it's ususlly because a batt has not been used for a while. It's normal that it will trckle charge for a while, and then switch to normal charge and fill it up. If a batt does not get out of trickle charge, that prob means it's broken. In terms of getting more low level info, get your hands on a script called batman.fth (it's somewhere in the wiki ;-) ) -- it collects logs of the batt levels per cell, and you can read it/change it. hth, m On Sun, Jan 3, 2010 at 12:48 AM, Tabitha Roder tabitha.ro...@gmail.com wrote: We plugged in an XO-1.0 with an unknown state LiFePO4 battery (may have been fully discharged a week before, or may have been shut down properly) and the battery LED flashed instead of coming on solid like charging normally does. The battery information in /sys indicated low battery voltage (5.something) but otherwise good health and charging state. We tried the battery in a different XO-1.0 and the same behaviour resulted. We left it plugged in overnight and it appears to have charged normally and the battery now runs the laptop (when it was doing the flashing charge, the laptop would switch off immediately when you unplug the charger). http://wiki.laptop.org/go/Power_management#Battery_LED indicates flashing on charge means trickle charging. Sadly we didn't find this page when it was happening so cannot fully confirm it was flashing orange and with the 4 blinks, pause pattern. This page also doesn't give any clues as to why a battery might be trickle charging. http://wiki.laptop.org/go/Hardware_specification#Battery suggests that the battery has a Maxim DS2756 chip in it, but this chip only monitors one cell, so I guess there are two such chips? The /sys interface only gives information about the whole battery, it doesn't tell you about the state of each cell. The specification pdf on the Hardware_specification page describes the Embedded Controller interface to the operating system in terms of Battery, not Cell so I guess it doesn't expose each cell either? Is it possible to see each cell's voltage separately from within the operating system or the open firmware? I guess if there is no other way, it wouldn't be terribly hard to program a microcontroller to talk to the cell monitors over the 1 wire bus. Kind regards Tabitha Roder ___ olpc-nz mailing list olpc...@lists.laptop.org http://lists.laptop.org/listinfo/olpc-nz -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Battery LED flashing
We plugged in an XO-1.0 with an unknown state LiFePO4 battery (may have been fully discharged a week before, or may have been shut down properly) and the battery LED flashed instead of coming on solid like charging normally does. The battery information in /sys indicated low battery voltage (5.something) but otherwise good health and charging state. We tried the battery in a different XO-1.0 and the same behaviour resulted. We left it plugged in overnight and it appears to have charged normally and the battery now runs the laptop (when it was doing the flashing charge, the laptop would switch off immediately when you unplug the charger). http://wiki.laptop.org/go/Power_management#Battery_LED indicates flashing on charge means trickle charging. Sadly we didn't find this page when it was happening so cannot fully confirm it was flashing orange and with the 4 blinks, pause pattern. This page also doesn't give any clues as to why a battery might be trickle charging. http://wiki.laptop.org/go/Hardware_specification#Battery suggests that the battery has a Maxim DS2756 http://wiki.laptop.org/images/e/e9/DS2756.pdfchip in it, but this chip only monitors one cell, so I guess there are two such chips? The /sys interface only gives information about the whole battery, it doesn't tell you about the state of each cell. The specification pdf on the Hardware_specification page describes the Embedded Controller interface to the operating system in terms of Battery, not Cell so I guess it doesn't expose each cell either? Is it possible to see each cell's voltage separately from within the operating system or the open firmware? I guess if there is no other way, it wouldn't be terribly hard to program a microcontroller to talk to the cell monitors over the 1 wire bus. Kind regards Tabitha Roder ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
