np8662 8-cell battery seems like a load!

I was thinking about taking apart my spare np8662 battery to replace the cells with higher capacity cells to increase the time on battery... and I was looking up different sites on how to do that.

well looking at the specs of the battery its a 14.8V 4400mAh 8-cell battery.

Now I could be completely wrong about how this electrical math works but if you divide 8 from 4400mAh then each cell would be 550mAh

If you divide 14.8V by 8 that would be 1.85V.

Most laptop battery cells are the 18650 size type and have 3.7V Now even forgetting about the voltage, if each cell is only 550mAh sager/clevo??? how much more expensive would it be to double the cell mAh size? (as in, why didn't it already come like that = D )


-- site for batteries that you'd find in laptops --
It'd be killer to use these... but I'm sure its not that simple to just swap them out with these.
http://www.batteryjunction.com/ultrafire-brc-18650.html

 

I use Tenergy 2600mAh 18650 cells for my flashlight. They go for about $9 each the last time I checked. If you want to mod your battery, then make sure you get the cells with the pack building tabs so you can string them all together.

 

The Cells clevo uses should be each 3.7V 2200mAh.

 

Yes, you are completely wrong. There are two inline sets of 4 parallel batteries. 4400mAh / 2 = 2200mAh per cell. 14.8V / 4 = 3.7V. Sounds fine to me.

 

I see, I did notice that batteries were in parallel, but didn't understand what that to the math.

I'm guessing they are in parallel because it allows more amps to draw. Since the power supply is 20V delivering 6A I'd imagine the battery has a tough time keeping up (even in parallel). (which is why it doesn't run 100% unplugged)

 

let me know what kind of results you get. even 2200 to 3000mAh could make a significant difference

 

I will indeed keep my eyes on this thread too. It will definately help those who are looking for power with battery life in the 3-4 hour range.

 

yeah that could easily push 4hrs.

 

How much power are you usually drawing on your laptop? Those 3000mAh Ultrafires are a lot cheaper on Ebay. It would be like $54 shipped for the 8 of them that you need. You would be looking at about a 30% increase in battery life.

 

For the record, 18650 batteries are marketed with their rated capacity, not their true capacity. For example, my Tenergy 2600mAh cells have a true capacity of ~2300mAh. From what I have been hearing about the Ultrafire 3000mAh cells on CPF, they are around 2500-2600mAh tops.

 

and you don't think the batteries in the current li-ion battery pack in the m860 are rated the same way? im thinking 30% increase regardless.

 

The rating is actually based on reality. The lower current you draw, the closer to the rating you will be. The battery ratings are based on a .5 amp current draw, but may still be slightly optimistic at that level. Also those 3000mAh batteries have a high internal resistance, so they benefit more from lower currents. P=I^2*R, so the less current draw, the less percentage of energy is lost as heat.

 

So is changing the cells of batteries really easy to do? No need for special equipments?

 

http://www.candlepowerforums.com/vb/showpost.php?p=2884072&postcount=31

I'll stick to my Tenergy cells thank you very much. Ultrafire can go shove it.

 

The hardest part is opening up the battery case. I still can't do it without somewhat breaking it. The soldering is pretty easy for it.

Okay, but for light loads, the Ultrafire is the 2nd best battery you can buy after the Panasonic 2900mAh ones, which are very rare and very expensive. For my laptop which isn't for gaming, these are perfect, especially in a 3x3 configuration. I could see that if you have SLI video cards and a quad core processor you would stay away from these for something with a lot less internal resistance.

 

Hey Trottel. I purchased the Ultrafire for my new torch. So far I'm liking it. I might make the Ultrafire my primary in this light as the LED only consumes 750-800mAh on high compared to 900mAh on my older lights.

 

Cool. I actually just bought 10 of them to put in an ebay 9 cell battery pack for my laptop, which should theoretically give me 6 hours of battery time.

 

Has anyone managed to do this?

 

keep us posted

 

Guys you are missing an essential factor!

The C rating.

C is actually hom much power you can draw at once from your battery without overheating/overdischarging.

This is the reason why M860TU's with 280M shut down in gaming if they're not plugged in.

Also C-rating is in reversed proportionaly with the mAh (the higher the mAh, the lower the C), so actually a 4400mAh @ 30C will outlast a 5400mAh @ 20C if the powerdraw is 25C.
Ofcourse this depends precisely on the powerdraw(C) of the notebook wich we don't know.

So you might actually end up with a weaker battery that will not only last less, have a lower lifetime and risk random shut-downs aswell.