Laptop battery: is voltage really important to respect?

Solution 1:

OK. After some digging, a typical mobile PC (from 2006) can handle 18V to 7.5V at the input either from an AC Adapter or a Battery. Also, the typical voltage for a battery is 11.1V or 14.8V depending upon the numbers of cells. The risk that 14.8V won't work on your laptop is extremely small.

Your laptop supports:

• 71 Wh, 4800 mAh (8-cell) Li-ion battery pack
• 44.4 Wh, 4000 mAh (6-cell) Li-ion battery
• 29.6 Wh, 2000 mAH (4-cell) Li-ion battery

Typically, laptops can work over a pretty wide range of input voltages. 14.8V doesn't sound too high to me. I can't find any specs from their website to confirm that 14.8V is OK, though.

Going from 6 to 8 cells will increase the voltage proportionally. Think of going from 6 to 8 AA batteries.

Here is an article on Notebook Battery Cells that presents an 8-cell battery being 14.4V as pretty common.

Solution 2:

Based on my electrical engineering knowledge, I believe most of the electronic circuitry work on pretty lower voltage than 11.1 V or 14.8 V both. The first stage is adapter which is nearly 5 V higher than the battery rating voltage to charge it faster to the full. Now the second stage is the motherboard or processor which typically runs at 5 V and for that you have voltage regulator inside.

The question is why can not we install a battery of voltage rating of 5 V and why we need a regulator at all? Answer is, unlike power adapter, the battery output voltage constantly decreases as it loses its charge since V = Q/C, Q is charge and C is a constant capacitance. Hence, A fully charged battery can power the laptop for few hours until its voltage drops down to the minimum acceptable level.

Therefore it really does not matter much if you use 11.1 V or 14.8 V. To me, 4400 mAH with 14.8 V would be almost same as 5200 mAH with 11.1 V in terms of time of powering your laptop as what finally matters is WH (watt-hour).