[four4875]

i felt compelled to rip opem my "14 cell" battery, so i did. suprised to find 8 cells, not 14. and the small circuit with the charge lights thing, it has a temp probe on it im gonan shap a few shots with the webcam. battery is to a compaq evo N115 aka presario 700, and fits a few others.

[four4875]

heres a shot of the temp probe lifted up

im guessing its so that the laptop can monitor the temp of the battery while charging, some pretty sophistcated stuff if ya ask me. i need to figure out the wiring setup (series parallel and all) and see if i can play around with ths

[Penel]

Good sticky! For XPS owners like myself, just carry a generator with you

[eXCeSS]

Originally Posted by Penel

Good sticky! For XPS owners like myself, just carry a generator with you

LOL

Great info, thanks!

[Sjaak]

Originally Posted by Penel

Good sticky! For XPS owners like myself, just carry a generator with you

Ive seen some Yamaha generators of about 600 VA (or more?) that would fit in a large bag...only the noise

[Flamingtaco]

Originally Posted by four4875

heres a shot of the temp probe lifted up

im guessing its so that the laptop can monitor the temp of the battery while charging, some pretty sophistcated stuff if ya ask me. i need to figure out the wiring setup (series parallel and all) and see if i can play around with ths

The temp is monitored to determine the charge condition of the batteries. Batteries put out varying levels of heat, depending upon how much charge they are taking. You can also use it to determine that there are individual cells that are dying, and some mfg's use this to generate imminent failure warnings.

[TheGreySpectre]

Most laptops have an auto screen contrast/brightness drop when they shift into battery mode, leave this or even turn it down further if your on battery. On my 9300 the differcebetween max screen brightness/contrast and and min brightness/contrast is about 1hour 15 min

[Eric1285]

Great guide, I can't think of anything that wasn't mentioned in the thread already.

[Stoanhart]

How much does each of those cells produce, voltage wise? Is that standardized? If it is close to an AA battery, since that's what they look like, it would be neat to take the shell and interface of a dead battery, and make a sort of mounting system for 8 rechargable AA's.

Then buy an 8 battery charger and 16 batteries. Put 8 in while you charge the others, swap as necessary. Worth a shot... The battery is dead anyways. I guess you would have to be careful not to plug the AC in when you have the home made battery in, because I don't think the laptop's charger could properly handle the new battery.

[chrism131]

Great Thread, I really needed this information because I just bought a new battery. Thanks

[Cowboy X]

Here is some more info on the same sort of stuff :

http://www.mobilityguru.com/2005/11/...your_notebook/

or skip to the recommendations :

http://www.mobilityguru.com/2005/11/...ok/page28.html

The first article is here :

http://www.mobilityguru.com/2005/10/...your_notebook/

[chame]

I have some information about Li-Ion batt.
In Ni-Mh or Ni-Cd, the charge stops depending on the current.
There are two types of Li-Ion, the standard stops charging when the "controller" detects at 4.1 volts per cell.
The new ones are called Li-Polymer. In this case they stops charging when each cell reach 4.2v.
I did some experiment with my laptop Batt. I purchase 3 cells of Li-Polymer 3,7v 5Ah. Then I remove the old Cells and soldered the new ones. The "controller" stops charging at 4.1v (its an old laptop), so the new cells are charged only in 20%.
I calculated based on the time laptop runs.

Then I Used the same pack in the standard DC power plug in the back of the laptop. The laptop works at 19v in that plug, I used 6 cells in serial. The voltage is 4.2v x 6 = 25.2v the first 20 min(risk for the laptop, but It worked for months without problems) , then it stabilizes to 3.7v x 6 = 22.2v for about 10 hours, and finally it goes slowly down 30 min more till 17v = 2.8v per cell. The the laptop turns off.

I think that you can replace the batteries inside the laptop battery, in the case you find the proper cells, similar size, same technology.

Here you can see the discharge rate for li-polymer batteries


And the batteries I used, they are big (13cm x 4cm x 0.5cm), but you can find smaller ones.

[Flamingtaco]

I'm back...

I finally got around to purchasing 9 18650 cells to rebuild my pack. Here's the lowdown on the specs:

Original batteries = 1800mAh
Replacements = 2400mAh

Original packs:
Standard, two-stick pack = 3600mAh
Three-stick extended life pack = 5400mAh

Rebuilt pack = 7200mAh

Double capacity of the standard pack, 35% more than the extended pack.

This comes to 78Wh. If the laptop consumes at it's max of 70Wh, I get just about an hours worth of run time. That's max screen brightness, max CPU load, CPU fan on, HDD, DVD and floppy spinning, PC cards talking up a storm. Powering junk via USB. I don't think you can run a test that strenuous.

I'm going to build a carbon fiber case that will sit beneath the laptop and house at least four sticks of five 18650's. The cost to do this will be near the "big" battery packs, but instead of 110Wh, I'll get 180. That will provide 2.5 hours of max load. Probably enough power for a full day's activities. It will be a better pack, too, with an individual PCB per stick rather than one for the whole pack like the big battery makers use.

[Flamingtaco]

Found out the original batteries are not bad at all. The pack controller flaked out on me. Now I HAVE to purchase a new battery. Looks like I'll be using the nine I purchased to make a big pack soon. I think I'll do three series of 5 to start. Should be enough juice to run it all day long on battery.

[flamerail]

thanks for the tips!

[Cudor]

I picked up the Asus s96j. My dealer, who was quite knowledgeable compared to regular dealers who don't know what they're talking bout, suggested I recharge and completely drain out the battery for the first 10 charges, which will thereby elongate the battery life, and keep it at it's max charge capacity.

Any truth to this?

[K15]

Originally Posted by Sjaak

The Li-Ion batteries are newer (the used to be more expensive but that has dropped now), and they don't suffer from the 'memory effect' as bad as NiCD batteries. NiMH is somewhere in between of them.

Ni-MH batteries suffer fewer drawbacks than Li-Ion (little danger in slight overcharge, no danger in trying to charge a full-dead Ni-MH, negating the need for controllers and switches to disable the battery.)
One problem though, Ni-MH does not have the density of Li-Ion, they are much bigger for a given amount of current. In fact, the miniturization of cell phones was not so much the electronics, it was the batteries. Look how thin and tiny the Li-Ion batteries are now in cell phones, consider the idle life (my phone lasts 3 days+ idle.) and then look at the NiCad or Ni-MH phones in years past, HUGE batteries. However, Li-Ion continues to improve in life, reliability and density. Improper use and heat are the big killers of Li-Ion batteries. Using the laptop plugged in all the time with the battery at 100% is not good.
1. Li-Ion does not like being at 100% charge.
2. Laptops are hot.
Li-Ion suffer ZERO memory effect what-so-ever. The closest thing to such a thing is the "fuel gauge" on the laptop or phone, completely unrelated to the battery.
Unless i'm mistaken, the fuel gauge problem happens due to the permanent loss of capacity in the battery, through abuse or normal use.
I don't know that though, so don't quote me

Something that was difficult and is STILL difficult for me to grasp is the fact that we can (and SHOULD) recharge Li-Ions often and without fully discharging them. I grew up with NiCads and the "fully discharge, fully charge" idea was drilled into me. LiIons not only don't need to do that, they shouldn't, or should as little as is possible.

[john_hk]

No advertising.

[DayUSeX]

damn spammer

anyways my laptop battery says 44% wear, and i never do anythign like discharge it, how would I go about getting it back up. Becuase currently I have about like 1:30 left on my batter when I unplug it when I used to get something like 4-5 hours =/

[ozzlo]

I would reccomend some Full deep cycles... Start at 100% drain it to zero and do it again... It dosen't always work, kinda depends on the battery like if it's a "memory"(kinda rare nowadays) thing or an actual internal corrosion thing