help, Rebuilding a better battery for no-name netbook.

Looking at the picture you took, this is one of the chips i see on it: http://www.ti.com/product/bq20z70. I briefly skimmed through its datasheet. There are two things you need to be aware of: page 21 (2.2.3 Limit based protection) and page 41 (2.5.5 shutdown mode).

Looking at page 41, it seems like when the battery is removed, the chip should gracefully shutdown. However, page 21 warns of a polling scheme to detect read write comms and data issues. If the number of faults hits a cutoff mark, it'll completely disable the smart circuit. Because you won't have access to equipment to reprogram the chip, it's a crapshoot. I would try to solder on the new cells before i remove the old ones just to be safe (since you only have 1 battery pack and can't find any replacements).

If you were to solder on the new ones before removing the old ones, I would try to match the voltage levels of the new cells withthe old ones to prevent as much tendency for the parallel cells (between old and new) to transfer change/balance. The way I would try to do this is if you can still charge your laptopbattery, drain or discharge the laptop battery to match the voltage level of the new cells you purchase. OR you can charge your new cells (but that would require you to purchase a cell charger)

Thanks howard, I Don't feel like buying a cell charger, so I guess I would use 2 3650mah batteries. Since the label said 3800, how dangerous would it be to use the 3650mah battery? thanks

can't you just get a biger battery with the same voltage and connect it with some electrical wire and then duck-tape it on the back of your netbook?? im sure it wil work, but it doesnt look very normal.

I would do that, but It will cover the air holes on the bottom. The battery is located near the front, under the arm rest area. I plan to ditch the battery housing and just stuff it in the battery compartment. the battery can't be wider than 40mm. 45mm might get in the way with the pcb.

Sorry guys been on holiday. Must say it nice to see people getting envolved. Rayjai its your project, make more air holes; or ditch the housing; or tape it up or mill a battery box, go nuts its your build mate. To avoid the triggering the cutoff, you can simply use a low current powersupply like a cellphone charger to maintain whilst you work, I've not had a chance to study the datasheet so if someone could confirm? Matching is not so much of an issue in parallel as the (cellphone?) psu will maintain the correct voltage to the smart circuit whilst you cut out the old and solder the new, but it would be advisable that they are not massively different, ~0.5 volts should be okay or ditch the psu idea and get both sets at minium capacity (like the batteries are flat) would be easier.

I know i can go nuts, but I want the laptop still be portable. The sony P (knock off) won't be portable anymore with a huge battery pack under it or on top of it. I just want to know if it's still safe to use the 3650mah batteries.

Do i solder the phone charger to the battery contacts or to the chip directly? I don't understand... I'm afraid I might desolder the battery wires as I solder in new ones. I am still a newb in soldering.

Can someone tell me if it's safe to use the 3650mah batteries, when  the battery label says 3800mah?

Here's a photo of the laptop. I have no room to fit any other larger cells and the battery is located on the front of the laptop. so if it's raised, it will be awkard for typing.

Hey guys,

So I bought 6 1700mah batteries and hooked 3 of them up in parallel. So the total mah should be 5100mah right?

But my battery life is still 1 hour. Did I do something wrong?

i know little about battery chargers.

1. chip may have shoutdown - as soon as it detects voltage out of range it will stop working for ever (do not disconnect cells before connecting new ones and use it carefully)

2. chip may have memory so it does not allow to work longer than it thinks You should - maybe there is battery test option in BIOS (enter during startup)

3. some batteries may have the possobility to be accessed through software under windows - may test capacity or replace contents of eeprom.

wanted to do similar thing as You do. finally quit.

There is also option to use external battery pack with charger and connect instead of power supply - not convinient for sure.

good luck.