Monthly Archives: April 2010

So, the cunning plan.


I bought a similar voltage/power battery off Ebay, cheap.
Dismantled it.
Used the cells in the original laptop battery.

Job done!

Or not.
Unfortunately these cells refuse to hold a charge longer than 5 minutes either.

Plan D is to somehow try to fabricate a power pack which can hold ordinary rechargeable AA batteries. I’ll post an update after I’ve blown myself up.


I should have known.

The Li-ion batteries I pulled from the old battery pack turned out to be past their sell-by date. Well past their sell-by date.

Although they were showing 3.7V, they had insufficient oomph to even turn the laptop on despite charging for an hour.

Back to the drawing board!

I do, however, have a CUNNING PLAN.

More details later.

Today I have mainly been…..


Now I should explain; I bought an old Sharp laptop off Ebay for next-to-nothing. Very good condition and the build quality is excellent; the only problems were that it did not have a hard disk (I have an old one), the keyboard doesn’t work (I’m working on that) and the battery doesn’t hold a charge.

So today I tackled the battery. 

In accordance with article 27 subsection (c) Paragraph ii, as described here, I dismantled the Sharp laptop battery.
9 NiMH cells. Size 4/3A. 4500mAh, 1.2V.

So I searched. And searched. And finally found a site in the States that sells these cells by the sea shore. But at just over £7 per cell, you’ve got to be ‘avin’ a larf. Innit?

Eureka! I then had another idea.

I’ve still got a long-life battery from a long-deceased Sony Vaio which has been up for sale for about 2 years on Ebid, and on Ebay whenever there’s a free listing day. Nada. So, out with the hacksaw.

Screwdriver? Check.
Blunt chisel? Check.
Hammer? Check.
Spanners? Che… what?

So some hammering and drilling later, the Vaio battery lay exposed before me. Rolling up my trousers, I examined the cells. Ah-ha! Lithium-ion! Excellent – these don’t have a memory effect. And they’re the same physical size as the old batteries too! (Well, 1mm shorter but that’s dandy).




Hang on a minute.

9 cells times 1.2V = 10.8 V. Correct, that’s what it says on the bottom of the Sharp battery.


3 cells times 3.7V = 11.1V. Ah-ha! That’s within range! But each cell is….. 3 down carry 1, add 27, take away the number you first thought of…. 1800mAh. And I can fit 9 of ’em in there. That means 3 x 1800 = 5400mAh! This laptop battery should last for days between charges! Muwahahahaha.

So it’s out with the soldering iron.

The battery is now back together (held together with sticky tape for the time being) and back in the laptop (which has been placed carefully in the middle of a large sheet of cardboard just in case it blows up).
Plug in adaptor. Check.
Plug adaptor into laptop. Check.


Eeeh by gum! A charge light! So far so good; now we’ll see how long a charge lasts. I’ll do a full charge/discharge cycle a few times first.