Notebook computer sized cells..... Where to buy ?

Which country? Which physical size?

In the UK you can get just about any cell from....

eg NiMH cells...

Are you trying to repair a laptop?

Yes! My own IBM Thinkpad laptops' battery pack ..... it's come to a stage where the battery can power it for only about 10 min or so after a full charge. A number of computer shops here offer this notebook "upgrading" service but the selling price of a "reconditioned" pack is about 70% to 75% of a new one. I'm wondering whether the "Sony" range of new NiMH AA cells marketed under "Stamina" and "CycleEnergy" and rated @ 2300mAh will accept sustained high current ( 1.5 - 1.8 Amp ) discharge rates? If they can, it'll mean at least one hours' usage between charges..... no?

I've got some here, 3.8AH. Any use?

Regards,

-A

I assume the existing batteries are NiMH not Lithium Ion? You must replace the cells with cells using the same technonogy or you will have problems with the charger.

What's the old pack rated at? Can you measure the old cell length and diameter?

10.8 volts 4 Ah. Each cell is 1.2 volts @ 4000 mAh / L = 2.4" / D = 0.75"

Thats close to 4/3rds AF (also called 4/3rds AU) form factor I think. eg a cell 4/3rds as long as a standard A cell.

I can't comment on the accuracy of this chart as different manufacturers have their own ideas about cell dimensions. Cells nominally from the "A" series seem to vary between 16.5 and 18mm diameter. However the standard lengths are around 42/41mm, 48.5-50mm, and

66-67mm - I think only the 66-67mm cells have capacities around 4000mAH. 66mm = 2.6" which might be too big for you..

Some manufacturers make cells with different shape +ve terminals - eg designed for welding or spring battery holders. This can effect the length by 1mm or so.

Beware: Always check the physical dimensions of any cells you are thinking of buying as many web sites are sloppy when it comes to the names they give them.

If you find cells about the right size it might help to know that you can solder most cells end-to-end without using wires if you know what you are doing and make or buy the right type of soldering iron bit....

The trick is to make sure the cells are very clean (I use sandpaper), use a flux, and a big soldering iron.

Thanks for the info Colin. I've toyed with the idea of using high capacity (2300 mAh) cells from the Sony "Stamina" and "CycleEnergy" range but am unsure if they can stand up to the sustained high current drain that a laptop requires without premature failure. Searched the web for technical data ...... so far many advertisements but no data..... As for soldering the terminals, I have always tried to avoid this and I use a Weller temp.controlled soldering iron and gold-plated strips to act as tabs...... this enables minimal heating of the cell terminal itself. On the subject of battery tags, do you know what instrument or process is used to "weld" ( rather than solder ) them to the cell terminals? Thanks ..... :-)

Are they *new* and unused? NiMH? or other chemistry? How many units? Physical dimensions? What are the markings on the cells? If you would like to sell them, whats your asking price? Where are you located? Is your e-mail valid? ... mine here is not..... :-) thnx!

Yes data does seem to be in short supply.

My hobby involves abusing NiCad and NiMH cells at currents well out of specification in electric powered model aircraft. The latest competition models (not mine!) draw 150A out of 18 cells for 2500W+. When they fail they sometimes explode :-( For years Sanyo cells were the most widely used in model aircraft at high currents and only in the last few years has Gold Peak and the ocasional Panasonic cell really started to catch up. Other makes are not so highly regarded by the Electric Flight community. (Aside: Lithium cells are now the fastest growth area).

Sanyo

Gold peak

It seems rather unsatisfactory to replace 4000mAH with 2300mAH capacity. Are you sure about those cell dimensions? I wonder who makes them?

If you can't fit bigger cells in perhaps take a look at the Sanyo HR-AU (2700mAH). They are same length as as an AA cell (about 50mm) but larger in diameter. They have been used at upto 8A continious in models.

If the charging circuit is a particularly agressive design (eg ultra fast) you might find that causes problems with smaller cells.

The Sanyo HR-4/3AU series (4000-4500mAH) might also be worth a look but they are 67.5mm long and upto 18mm diameter..

Colin

Price is a very important consideration Colin and the Sony 2300mAh AA cells can be got for just about US$ 2 or so per piece locally.... The cells in the IBM laptop battery pack have no markings either printed or stamped at all! All I know is that the cells are of NiMH chemistry, 4 AH 1v2 ... that's all ! I understand that the Sanyo HR-4/3 types are very expensive and as my laptop is becoming obsolete ( it's a 1999 model ), are not an economical solution.

9 Sonys would only cost about US$ 18 but would they work ( power the laptop for about 1 hour or so ) ? What does your gut feeling tell you ?

Yes unfortunately the Sanyo probably would be more expensive. About twice that price.

Thank you for your feedbackand links Colin .... I was surprised when you said Sanyo would cost _only_ "about twice that price" ..... the last time I checked on another website, they were much more expensive than US$4.00! I'll be taking your expert advise and fitting the Sanyo cells instead. An even cheaper battery dealer appears to be --- " amondotech.com " .... you may want to check them out? thnx! ...... :-)