Will a laptop battery continue to "drain" even when the computer is off?
 

I have an HP dv9000 and I haven't used it for several weeks. I just went to turn it on and the battery was nearly drained of any power.... is this normal for a laptop turned off for lengthy periods of time to have the battery drain out?

In a word - no.
 

Not a well-designed computer like an HP or Compaq, anyway. With computers designed to market and not serve the customer - maybe.

When the CPU and display aren't drawing current, the drain on the battery is minimal (there's a little tiny digital clock in the CMOS chip that keeps time, but it wouldn't drain the main battery in a hundred years).

So you either have a defective circuit that's pulling down the battery, or the battery has reached the end of its service life. How old is it? How long will run the machine when freshly charged?

Yes - some worse than others.

If left sitting, my Sony VAIO SZ battery will be about 1/2 drained within two weeks. My IBM Thinkpad T61 loses the same half-charge over a several month or so period.

Since Sony makes batteries for so many laptop companies, I always wondered if this draining problem was due to some defective technology on their part as, for example, my Nikon DSLR lithium ion batteries will hold a charge seemingly forever.

Self-discharge on the battery will drain it within a few weeks.

The computer and battery are new.... (less than year)This is my first HP. My previous laptop was a Dell and I do not remember this "problem" with the Dell.

Was the computer shut down, put in standby, or in hibernation. Standby does use power, shutdown or hibernate normally don't.

Any battery of this technology will self-discharge within a few weeks. There may be variation between batteries, but they will all suffer from the effect.

It's also possible that the PC may have an effect, but the self-discharge current is the ultimate limitation. You should not be surprised that after "several weeks" the battery is low. It is perfectly normal.

Self-discharge isn't the problem.
 

If you have ever bought a battery, you know this isn't true. They are charged when they are manufactured. Then they are in transit for weeks or months before reaching the consumer. If the internal resistance of the battery were sufficient to discharge it, batteries would never reach a store in a charged state.

Required reading: http://www.buchmann.ca

a google search for 'laptop self-discharge' seems to indicate that the phenomenon is designed into this type of battery.

Laptop batteries are very different from the pack of AA's we buy to get our TV remote control working again.

@ the OP:
Yes. This is very normal.

Every battery has internal resistance. In some batteries (and chemistries) it is very high - meaning that the discharge takes a long time. In others, it can be shorter.

Evidently, the reported behavior is a function of the design. Some laptops discharge themselves. Some don't. Some catch fire. My HP and Compaq laptops worked right out of the box (one of which was drop-shipped directly from the factory in China). My anecdotal evidence is as irrelevant as anyone else's.

Panasonic, Sony
 

My Panasonic R4, which I like very much, loses battery power within a day if the battery is attached and the computer is off, even though the charged battery lasts for 5 - 7 hours. For traveling, I disconnect the battery and it holds its charge quite a while.

My prior Sony Vaio (FX series?) battery didn't lose the charge in a noticeable way when connected to a turned off computer. The off-label extra batteries I bought held the charge less well than the ones from Sony.

Sylvia

Quite normal.

Charge it fully, leave it out of the machine for a few weeks, it won't be fully charged anymore.

Something I tend to forget when I pack the extra battery pack for a trip that was fully charged :mad:

I certainly does seem to vary. I have an extra battery for my laptop, sitting on the shelf, the battery does lose charge over time, but still has well over half a charge after sitting for several months.

For the OP, I would try testing with the battery both in and out of the laptop and see if it differs, that will tell you if it's just the battery, or something in the computer discharging it.

Is this something I can do "at home" with out any special equipment?