Can I replace a laptop battery with one of a different voltage?

Can you use it? Yes.

Safe to use it? NO!

Will the computer fail if you use it? Yes.

Will the battery fail if you use it? Probably, and it certainly won't charge properly.

In short, there were a bunch of errors committed here. Trying to cheaply fix up a laptop that was worth nothing anyway, getting cheap and buying off eBay from China, accepting whatever junk they sent.

Get the correct battery, or junk the notebook (best move) and have a beer. Forget the Chinese seller, and eBay the battery they sold you and maybe you will recover *some* of the money you wasted.

Thanks for the advice. Unfortunately my friend is chronically ill, and is on an extremely tight budget. So while you or I might have junked the old machine and forked out £400 for a much superior model, she is not able to. She also felt that spending over £100 on a new battery was just not possible at present.

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Hungerdunger
To reply by email, remove the MARX from my address

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I've never heard of an 11.1 V battery - something is wrong here.

HR Bob raises a good point. Maybe it's 11.1 volts *because* it is dead.

Or maybe you are measuring in British volts. Volts sterling, I think they are called.

If you are inclined to email me for some reason, remove NOPSAM :-)

I've never heard of an 11.1 V battery - something is wrong here.

No it isn't - I've got the battery sitting here in front of me.

You can also go here for a picture of it:

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Hungerdunger
To reply by email, remove the MARX from my address

Maybe it's just me, but the quote from that ebay site says:

THIS IS A BRAND NEW GENUINE 11.1V, 4000MAH, PACKARD BELL EASYNOTE F5 SERIES BP-8X99 BATTERY. (THIS BATTERY CAN'T REPLACE 14.8V BATTERY)

Please tell us your laptop model and the voltage of your original battery(11.1V or 14.8V), because we are NOT responsible for this mistake.

Sounds pretty clear to me.

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Return address is VALID!

14.8V and 11.1V batteries are different batteries and not interchangeable. the higher voltage battery actually puts out 1/3 more voltage (3.7V / 11.1V = 0.33) than the proper one, and this would likely stress or fry the voltage regulators in the computer. I say likely because many voltage regulators have a wide range of input voltages they can handle. Having the voltage regulator drop an extra 3.7V will generate more heat, and heat is the killer of all electronic components. Laptops are the most susceptible to heat because of the limited air circulation in the small case. Depending on what the ad said, you should have some recourse through eBay. If you paid through paypal, you might have some recourse there. In my experience, however, both these organizations' claims of "buyer protection" are a load of s**te, they will not lift a finger to help you. If you used a credit card to pay, even if you paid through paypal, your VISA/MC institute very often has the ability to refund your purchase price.

If you're handy with electronics, you could calculate or measure the laptop's current draw, and add in a power dropper resistor to the battery's output based on ohm's law... if the unit draws say 500mA, then 3.7V / 0.5A =

7.4ohms. This resistor would dissipate 3.7V x 0.5A = 1.85W of power, so by putting a 7.4 ohm, 2W resistor in series with the 14.8V battery you'd get your 11.1V. You'd need to likely do some wiring/soldering, perhaps make an exterior enclosure for the battery, and it might look ugly but it's simple, cheap, and 100% functional.

Dave

You'll ruin it and may cause a fire.

I don't think you'll find a definitive answer, but I would try it and see what happens, the computer is not really worth anything and you already have the battery.

I question the voltage of the original, 11.1 is not a multiple of 1.2V. Also the voltage from the charger is irrelevant, it will be higher than the voltage of the battery, it has to be, it is internally regulated in the laptop.

No, that's not true. It would be if the laptop used a linear regulator, but it does not, it has a switching regulator. The heat output of these is not proportional to the difference between the input and output voltage.

Don't switching regulators as a rule allow a fairly wide range of input voltages? Given that the duty-cycle can be adjusted for a wide range of outputs, one might assume that said duty cycle could accomodate at least a moderate range of input voltages... or not.

Many laptops have batteries available that are at different voltages. My Toshiba has available 3 cell 11 volts, 4 cell 14 volts, 6 cell

11 volts and an 8 cell 14 volt batteries. There is a switching power supply (several actually) inside which works over a reasonable range of battery voltages. Do not put a resistor in series, it will just waste power and generate more heat.

Lithium cells have about 3.7 volts per cell. 3 cells is 11.1 volts.

4 cells is 14.8 volts.

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Well, the range of the mobo switching supplies could be wide enough that you could use either battery, and there could be ID pins (or I2C bus) to tell the charge switcher what voltage to output, and there are numerous battery suppliers who specify a 14.8V (8 cells @ 1.85V per) pack for this model, but Packard Bell lists the battery as 11.1V (6 cells @ 1.85V per), and a few battery sites indicate that the two batteries are not interchangeable. Perhaps there was a switchover from 6-cell to 8-cell during the production run (or they reused the model number).

OP: Have you asked Packard Bell about this?

(US readers - PB appears to still exist in the UK)

And are you sure the original battery is dead? This model reportedly had a charging problem that was fixed with a BIOS update:

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• Make that 2 parallel strings of 3 cells: 3 * 3.7V =3D 11.1V

• Make that 2 parallel strings of 4 cells: 4 * 3.7V =3D 14.8V

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Or he could just remove two cells from the battery pack (making sure that it's one from each series string.

TM

What's that got to do with it?

Try collecting donations at local markets, charity, or other avenues.

And if she is so short of money, why did she gambol on a Chinese battery from eBay? She has now lost more than she would have had she just bought the proper battery from a reputable seller.

It's from China...

The easy answer is that you did not pay attention to the eBay listing. At this point, if you ordered it on your own initiative, the right thing to do is consider it a bitter lesson learned. My opinion is you should buy the right battery and try to sell the wrong one on eBbay and eat what it costs you. It is definitely the wrong battery.

Charlie (both a buyer and seller on eBay)