[ltp] Battery issue with R31 (any battery experts out there)

[Dmitry E. Mikhailov]

On Wednesday 11 June 2008 10:43:57 pm michf@post.tau.ac.il wrote:
> Hello, it's a bit off topic for this list but maybe someone
> knowledgeable enough is lurking here.
>
> The battery on my r31 died completely (I mean, I don't get even 1
> second of life from it). That led me to suspect that due to the fact
> that the machine has been lying around unconnected it may have dropped
> bellow the minimum value and the protection circuit is preventing it
> from charging.
>
> Does anyone know if this is probably, if so, if it is possible to
> check if that is the issue and if it is, is it possible to forcibly
> reset the protection circuit (will bypassing it to charge the battery
> once work?)
>
> I have access tomorrow at work to proper equipment to do this if this
> is necessary (controlled power supply, oscilloscope, proper soldering
> iron and most importantly, people who know how to use them ...). Since
> I fly on Sunday evening and I haven't managed to put my hand on a
> replacement battery, this is the last chance to get the machine
> working for the trip, it is thus a little urgent.
>
> Thanks for any suggestions.

WARNING WARNING WARNING: the battery can EXPLODE resulting in INJURY OR DEATH 
if mishandled. You do everything at your own risk. YOU ARE WARNED.

I've done it to my extra old Roberbook laptop once and several times to my 
friends PPC batteries. You need a voltmeter, ammeter, and a controlled power 
supply. DO NOT DISCONNECT battery control circuit from battery because it's 
settings may be volatile. First, connect two wires to the raw battery (before 
the controller). Connect it to voltmeter. 

Look at your battery casing: the rated voltage should be printed there. If 
there's something about 14...16 volt, it's a 4- or 8-cell battery. If it's 
10...12 volt, it's a 3- or 6-cell battery. The minimal voltage per cell is 
2.4v to 3.0v (according to wikipedia). So if you got 4- or 8-cell battery, 
you should charge it to at least 4x3.0V=12V. If you got 3- or 6-cell battery, 
you should charge it to 3x3.0V=9V. Monitor the battery's voltage with 
voltmeter.

On the controlled power supply initially set the same voltage, as on battery. 
Connect in serial an ammeter and controlled power supply to the same wires 
you connected to raw cells, a '+' of the power supply to the '+' of the 
battery, '-' of the power supply to the '-' of the battery. 

WARNING WARNING WARNING: If you manage to reverse the polarity, the battery 
would likely VIOLENTLY EXPLODE and the power supply could be fried by 
overcurrent. 

You should also know the rated battery capacity in A*h or mA*h. If the battery 
is 10 000 milliAmperes*hour it means you can draw the current of 10 000 
milliamperes (10Amps) for 1 hour or draw a current of 1Amp for 10 hours.

You should charge your battery with current of NO MORE than 1/10th of it's 
design capacity. Yes, that means full charge would take 10 hours but it 
decreases the chance that metallic lithium inside undercharged battery would 
blow the whole thing away. So if you got a 4400mA*h battery, you should 
charge it with current of less than 440 mA. Let's say it's 300mA.

After you connected the controlled power supply to the battery, start slowly 
increasing the voltage on the power supply while looking at the ammeter. The 
charging current would rise with the voltage. You should stop increasing the 
voltage when current is at it's 1/10th capacity limit.

Every ten minutes disconnect the regulated power supply (but don't reset it's 
voltage) and check the battery voltage with voltmeter. When you get above 
3.1Volt per cell (that's 12V for 4-cell and 9V for 3-cell battery), you're 
finished.

If you're lucky, when you stick the battery to the laptop it would start the 
charge. But the battery controller may be permanently shut down and stop 
monitoring the battery. In this case you should reprogram the battery 
controller, but I can't help you with that.

	Good luck,
		Dmitry