[RESOLVED] Use Compaq A/C adapter on Pavilion?

A friend of mine recently bought an HP Pavilion DV8000 laptop that uses an A/C power brick with the following specs: 19vdc @ 4.7amps. Her previous computer is a Compaq Presario 906US, which uses an A/C power brick with similar specs: 18.5vdc @ 4.9amps. Both use barrel connectors with the center conductor being positive, and both adapters are marked 90 watt.

Does anyone know if the old power brick would work with the new computer, without risk of overheating, etc.? It would save having to buy a duplicate brick for the new computer in order to have one fulltime in the computer bag (which beats crawling under the desk to retrieve the original everytime she goes out of town).

When plugged in, the old one will either power the computer or it won't. If it doesn't power up the computer then the best thing to assume is, it won't work. I doubt you can use a Compaq AC adapter on a newer HP.

As the battery charging circuit is contained within the laptop itself, I don't see any problems at all with using that power brick, I'd be very surprised if the voltage difference is enough to affect anything. As a general rule though, you do need to be careful about using power blocks which contain the charging circuit themsleves on a different battery - Li-ion batteries are very fussy indeed and can explode if incorrectly charged :eek:

I finally got a chance to test the older A/C adapter, and it powered the laptop like a champ. While I had the battery out (no point testing it with the battery in place, right?) I saw something that confirmed SuperSparks statement about the battery charging circuitry being within the laptop -- the battery is only 14.4 volts. And if the laptop can run off of 14.4 volts, I can't see that a measly half volt drop is going to affect anything. Thanks for the input!

That's great that you got it working :)

0.5 volts is well within the sort of standard variation in voltage that you would get on a transformer block (the output is directly proportional to the mains voltage which can vary considerably). Because of that, the voltage regulator circuits require a supply that is several volts higher than their output voltage, and so you can often get away with a supply that is similar in specs but not quite identical.