question: hardware for laptops

[umit]

But, onkko is right, that a battery cell has a fixed amount of voltage, as a matter of the known physics of batteries.

Now, batteries eventually do wear out, so their individual cell voltages drop to zero, but that's not a *new* battery.

Well, it seems both of you were either missing or sleeping when your physics teacher was talking about ampere and parallel circuits

Now, as a matter of known physics, if you connect two batteries (which have a fixed amount of voltage, let's say 1,2 V) on a series circuit you get 2 x 1,2 = 2,4 V. However, if you connect the very same batteries on a parallel circuit, you get the same amount of the voltage of the each battery, which is 1,2 V, but you get double ampere (if the batteries have 1900 mAh each, 2 x 1900 = 3800 mAh). Ampere (actually, mili ampere hour - mAh) is something to do with the capacity of the battery. The higher the ampere, the longer the battery lasts...

That's why 12 cell laptop batteries are expected to last longer than 6 cell ones...

This physics lesson was free, a thanks is enough...

[Upphew]

Now, as a matter of known physics, if you connect two batteries (which have a fixed amount of voltage, let's say 1,2 V) on a series circuit you get 2 x 1,2 = 2,4 V. However, if you connect the very same batteries on a parallel circuit, you get the same amount of the voltage of the each battery, which is 1,2 V, but you get double ampere (if the batteries have 1900 mAh each, 2 x 1900 = 3800 mAh). Ampere (actually, mili ampere hour - mAh) is something to do with the capacity of the battery. The higher the ampere, the longer the battery lasts...

That's why 12 cell laptop batteries are expected to last longer than 6 cell ones...

This physics lesson was free, a thanks is enough...

Enlighten the ignorant (me): how it is beneficial to have double the number of cells vs. having twice as big cells? Wouldn't more cells need more wiring and thus more losses/resistance/whatever?

[umit]

Enlighten the ignorant (me): how it is beneficial to have double the number of cells vs. having twice as big cells? Wouldn't more cells need more wiring and thus more losses/resistance/whatever?

Ummm... Well you shouldn't mix physics with marketing. Producing two different types of cells would increase the cost, as it will require two different production lines and more research... That's why sometimes 1,6 engine cars have speedometers with 260 km/h maximum speed, while they can only make 190 km/h. However, if you think rationally, they would save some plastic and paint by making a 200 km/h speedometer. It would make a few milligrams of difference to the weight of the car, thus less fuel consumption and CO2 emission...

[joanmanuel]

well I have just remember my high school lectures, well anybody knows where I can find that stuff?

[maxxfi]

I understand that nobody pays for the free lessons,
but the final conclusion could have been written better:
There are two mistakes in this sentence:

The higher the ampere, the longer the battery lasts...

1) When you talk about concepts, you use the measure (current), not the unit (ampere).
2) After all, here it's about battery capacity (the one you measure in ampere-hour) , not current

So: the higher is the capacity, the longer the battery lasts (for a given voltage and current in the circuit, i.e. for a given laptop).

[maxxfi]

Enlighten the ignorant (me): how it is beneficial to have double the number of cells vs. having twice as big cells? Wouldn't more cells need more wiring and thus more losses/resistance/whatever?

The production economy reason explained by umit is already a good one alone to go for a double amount of cells.
Another one could be (although I haven't been able to find supportive documents on google for this hypothesis)
is that a bigger cell implies electrodes farther away and so a higher internal resistance.
In the end, more energy is wasted in heat, and batteries are already dangerously hot nowadays...

[umit]

I understand that nobody pays for the free lessons,
but the final conclusion could have been written better:
There are two mistakes in this sentence:

The higher the ampere, the longer the battery lasts...

1) When you talk about concepts, you use the measure (current), not the unit (ampere).
2) After all, here it's about battery capacity (the one you measure in ampere-hour) , not current

So: the higher is the capacity, the longer the battery lasts (for a given voltage and current in the circuit, i.e. for a given laptop).

Right... I just wanted to keep the lecture simple for the beginners. But, already mentioned your last statement:

Ampere (actually, mili ampere hour - mAh) is something to do with the capacity of the battery.

@joanmanuel: Having given lots of free lessons to others, just realized that I ignored the main point. I think you also need a free lesson about "how to use a laptop efficiently" if you think it is a pain in the butt to recharge the thing every three hours. It's not bad if a laptop works 3 hour with battery... Where do you use your laptop, at the park??? Then a buying a solar power supply would be better option. But, hey we are in Finland, forget it! Whenever there is a power supply around just use your laptop plugged (I guess you don't use it while roaming inside the apartment all the time). Don't worry about the over heating charger. If it causes a fire, you can sue the HP and get good amount of money or a new one at least

[raamv]

Well..
Since others have only pointed you to known stores..
There is an HP retailer..But parts are double than the hp part surfer site ( navigate from HP site)..
My guess is that your battery quest will set you back around 90-120 Euros here.
I got 2 HP batteries( original) + Canon battery all for 80€ including shipping from ebay from China...and no customs..
One of them went dead and I sent it back to ( UK : Surprise ..these people had a UK re-cycle address) and got a new one again!!
Dunno of the top of my head who it is( Since have not been to ebay or this forum for a while )..but can post it later..