Question : Problem: car charger on laptop

I have a IBM Thinkpad T30 laptop and I am not sure on its power consumption but I have a old ibm car adapter its says on the car adapter "For portable computers using 15 to 17 VDC at less then 3.5 amps"  
on the normal power cord for my laptop it says that is uses 16 volts and 4.5amps output
will it damage my laptop if I use this car adapter?

I tried it for a sec or two and it seemed to work

Answer : Problem: car charger on laptop

That sounds resonable but you would have to know if the battery recharging draw is actually less than 3.5 amps. Remember its going to try and charge the battery as fast as it can and use all the available power to do this. Check the batteries Voltage and amperage ratings. It may fall within the adapters capabilities, but I still cannot recommend this as a solution as electrical properties are measured and built accordingly by the laptop manufacturer for good reason.