Can I connect my laptop that runs on 18.5V directly to a 12V battery?

[axur-delmeria]

1. I'm going to assume that you're not using a Thinkpad because there aren't any Thinkpads AFAIK that use an 18.5v charger.

2. Laptops usually have a narrow range of input voltages. For Thinkpads using a 20v charger expect an input between 19.5 and 21 volts. In your case, it could be 18-19.5 volts. So directly connecting a 12v battery won't work, and 24v might kill your laptop.

3. Instead of a linear voltage regulator, you'll want a switching regulator because it's much more efficient. You'll need one that either outputs 18.5 votls, or has an adjustable output. How much current do you need? Check your laptop charger's maximum output current, then add around 50% just to be safe. For example, if your laptop's charger outputs 18.5 volts 3.5 amps, then find one that can output at least 5 amps. This one might work, but I cannot make any guarantees.

Good luck

[RealBlackStuff]

Or get a laptop car-charger such as this: https://www.amazon.com/Charger-Pavilion ... P0EZGT1YZ3

[shawross]

Feeding your laptop a lower voltage should be safer than giving it a higher voltage. This is due to Ohms law in a direct current enviroment. Laptops are designed to get a reduced voltage as batteries lose charge. If the voltage is too low the laptop should just shutdown. At lower voltages dim your display and eject DVD's etc. YMMV