I have a Dell laptop that I've been troubleshooting. The second battery the user had installed never held a charge longer than 30 minutes or less. I purchased a new replacement battery for them as well, and this new battery only lasts about 1.5 hrs after giving a thorough first charge. I think this is a little low. The user/owner had lost the power supply/AC adapter and got a replacement from RadioShack. Targus type ac90u. Specs are 15-24V and 90W Max output. The original power supply for this laptop was rated at 19V and 3.16A. That's requiring 60.04A for the laptop. I'm getting 14.4V from the replacment adapter. My question is obviously the adapter is running a little on the low side, but can provide much more power than is necessary. Could this adapter be over powering the batteries by offering up to 90W or does the laptop regulate this to prevent any damage to the batteries? Is the 4.6V deficit enough to limit the batteries run time?(4400mAh). Original battery spec. is 29WH and I'm not sure how to convert that. I'm also not sure what the rated draw is for the laptop.