I got my laptop for a bargain price, but one of the reasons for this is that the battery only lasts about 4 minutes.
I found this video: [url= http://www.videojug.com/film/how-to-replace-the-batteries-in-your-laptop ]http://www.videojug.com/film/how-to-replace-the-batteries-in-your-laptop[/url] and thought, "man, that looks like a piece of p1ss, even [i]I[/i] could do that!"
So I ordered some nice and cheap Li-ions from HK and solder them all in place (diagrams, safety goggles, etc.) I then set the laptop charging. It pained me to have to take the precaution of having it charge in the garage with my beloved bikes, but I reckon my folks would be more impressed if they were put in orbit than if they returned from holiday to find pieces of laptop welded to all the internal walls of their house and no glass in the windows.
Initially the laptop told me the battery would last for... four minutes (that was time and money well spent then). Then the battery light just flashed red and now the laptop doesn't even acknoledge the existence of a battery in it (innit).
Any experience/ideas/suggestions/accusations of being a soldering n00b?
Did you get the charger connections correct? Any left over? Sure you put the pack together the same? Technically the only othe thing you could have done wrong is damage a cell with heat, but its not likely to give you massive problems. Are you sure you got the right voltage and capacity? Did you charge the pack for a decent length of time before powering it on?
As I understand it, a 1% overcharge is enough to cause a lithium-ion cell to explode. In an unknown pack, you don't know what the protection circuitry can cope with in terms of capacity, and if you buy the cells from a 'nice & cheap' Far East source you won't know their real capacity. All in all a recipe for a melt down 🙁
Bear in mind that even big companies like [url= http://www.theregister.co.uk/2009/08/03/ipod_flames/ ]Apple[/url] etc have problems with their batteries catching fire or exploding I would leave this kind of construction to someone who knows what they're doing...
Thanks for your reply 🙂
I didn't touch the circuit board in the battery at all, just unsoldered the wires from the old cells and soldered the new cells in. I was very careful limiting the heat (even while screaming "MELT, you bastard!" at the solder I had the will power to retract the soldering gun).
I upped the amphours a bit (surely that shouldn't make too much difference, other than to extend run time, right...?), but the voltage is identical.
I set the thing charging in the laptop, then the charging light went off, so I powered up and got the four-minute-warning, tried again and got the red flashing light of doom.
Why am I such a cheapskate...?
That's, er, interesting, Simon, thanks for that.
(Shiiiiiiite! Dives behind sandbags...)
Your problems only really occur if you overcharge or over-discharge (which it seems you have here) - these points are determined by voltage on Li-ion packs I believe. If you discharge below 2.5v the supervisory circuit will take the cells out of action so they cant be charged by a normal charger without being "fixed", and anything over ~4.2ish volts per cell and they vent in a rather spectacular fashion of flame and pain (
), so they tend to have a mechanical pressure switch to cut off the charging, as well as thermal cutout etc. If you leave the circuit intact you should be safe, if left with a dead pack, unless you connected it incorrectly.
There are ways around the under-charged pack, but
a) I dont want to suggest them as it could be fairly dangerous and I'd want to be monitoring it constantly myself with PPE if I did it, and I consider myself fairly well versed in such things and...
b) It may not fix your underlying problem. Maybe it's your charger or the charge-monitoring circuit in the battery that is faulty, hence the problem with the original pack?