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Nucleophobe

Thu Jun 07 2007, 10:19PM

Registered Member #108 Joined: Thu Feb 09 2006, 11:44PM
Location: Billings, MT
Posts: 61

My laptop has been shutting itself down after only 5-6 minutes of use lately even after a full charge. I was afraid that the battery was shot, but it's only a year old so I didn't give up right away. Instead, I turned off the auto-shutdown feature to try to totally drain the battery (and then recharge it). The battery in now showing 7% battery life and has been for about 10 minutes.

Is there some kind of calibration for the battery monitor that could cause windows to be miss judging the amount of power left in the battery? This has not been a problem until just a few days ago...

Thanks

Adrian

Fri Jun 08 2007, 02:17AM

Registered Member #697 Joined: Thu May 10 2007, 12:28PM
Location: Australia
Posts: 22

The voltage monitoring(?) part of the battery might be damaged/dying. On most of the laptops I've had, the remaining % of battery life windows displays was always very inaccurate especially when the battery was nearly exhausted.

Carbon_Rod

Fri Jun 08 2007, 07:35PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

There are battery "Profile" routines some laptops perform (some are even run from CMOS setup.) Check your battery properties in the OS for such a routine too.

Let the OS handle your APM, check CMOS setup for conflicting system overrides.

Some batteries have a thermal fuse that sometimes only partially fails. You may want to get a new battery as the $100 will cost you less in the long run.

Conundrum

Fri Jun 08 2007, 08:17PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Actually most "dead" laptop batteries are nothing of the sort. The clever chip (normally a bQ2060) which stores the battery parameters such as remaining charge, number of cycles etc sometimes miscalculates remaining charge, eventually this manifests itself as a loss of perceived capacity.

There are ways to reset them using the I2C bus on the battery, but you need to know what you are doing.

I've revived my Toshiba with the same fault by a little-known procedure called "juicing". You drain the battery until the laptop shuts down, then put a small 12V fan in parallel with a voltmeter across the + and - terminals. When the voltage drops to a level around 3.6V/cell then you immediately stop the discharge and put the pack back on charge.

As long as the cells are correctly balanced, this should trick the pack into accepting a full charge.

*BEWARE*. DO NOT allow the voltage to drop below this limit or you could permanently damage the cells. If the pack's open circuit voltage on shutdown is below an average of 3.2V/cell then the cells are badly out of balance and the repair illustrated here should not be attempted.

In this case, I would recommend buying a new pack for safety reasons.

-A

Carbon_Rod

Fri Jun 08 2007, 11:06PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Conundrum,
You can also download tools from HP/Acer/Toshiba to reset the internal counter via a wizard. (btw: re-profiling should automatically do this.)

However, the 93LCxx or 24LCxx eeprom saves the battery ID serial number so each battery profile will function correctly with the APM system (that is how the pop-up tells you a battery change occurred when you boot-up.)

Steve Conner

Sat Jun 09 2007, 09:55AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

First of all, it is quite possible to ruin your battery within 1 year if you run your laptop all day off the AC adaptor. Li-Ion batteries hate being hot and fully charged.

Next off, I have tried what conundrum calls "juicing" using a 12v halogen lamp, and got some improvement from old tired batteries, but not much. I think I got one from 5 minutes up to about 1/2 hour after half a dozen rounds of charging and discharging.

All Li-Ion batteries (that I know of) have an electronic protection board built in that will interrupt the power after a certain amount of juicing, when it judges the voltage has got dangerously low.

Like carbon_rod said, I gave up trying to revive them, they don't live for ever and need replaced every couple of years.

Dr. Shark

Sat Jun 09 2007, 02:40PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

I agree with Steve in all respects: You cannot kill a battery by what you call juicing since the protection circuit is in the battery pack, not in the laptop. BTW 3V is still an acceptable minium cell voltage, cutting off at 3.6 is way too early. As said above, the battery takes care of balancing itself.

I also had batterys die after only one year of use, upon dissection it turned out though that only a single cell from the pack failed. On eBay you can get individual 18650V cells for as little as 2.50, so you may want to repair the pack yourself rather than plunging down $100 for a new pack.

Nucleophobe

Mon Jun 11 2007, 02:36AM

Registered Member #108 Joined: Thu Feb 09 2006, 11:44PM
Location: Billings, MT
Posts: 61

Well It still needs some work but now I'm getting about 40 minutes of charge out of it. I do leave my laptop plugged in a lot, I guess I'll start removing the battery when I do that.

Thanks for the advice, I saw a video on replacing the individual cells. If the problem persists I guess I'll try that.

...

Mon Jun 11 2007, 04:58AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

As to leaving it plugged in/unplugged, \I have found the contrary to be true. The primary battery (which gets charged/discharged on a regular basis) was down to about 20 minutes of run time (from 3+hrs) after 2 years of use, while the backup battery (which just sits there) has been going for 2.3 years now and it is still lasts a solid 2.5hrs..

I think it has to do with how full the charger tries to run the batteries, since manufactures want to get the max run time when you pull it out of the box (so reviewers give them the 4+hr battery life) and want you to replace the battery on a regular basis then set the charges to overcharge the cells a little--greatly reducing their life over what it could be if they charged them to a more reasonable value...

Conundrum

Tue Jun 12 2007, 10:14PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Actually I found that 3.2V is the "shut down now" point, at least on the Sony pack I took apart. Draining the cells individually to rebalance them might help, though this would require opening the pack (Bad Idea!)

-A

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