I am in need of a electronics circuit that converts the D.C output of batteries(12v 28W) to charge a laptop of power rating 18.5v 65 Watts or other similar device.
The output power of any device will be less than the input power, so if you need 65 W output, you will need more than that as the input.
The you can use a small inverter to produce 120 V AC from the 12 V, and then the laptop's normal mains power adaptor. Or you can get adaptors that convert directly, such as this:- **broken link removed**
I do suggest buying a device from www.igo.com. The "tips" determine the voltage and current limits and for the most part when you upgrade, the supply will still work for the price of a "tip".
Thank you all for your response.
What i need basically is voltage convertion. 12v to 18.5/19v
I was actually looking at designing a big battery pack for laptop power supply while avoiding the the power loss due to voltage invertion.
The car computer psu cannot power the laptop while it is in use, it can only charge the laptop.Is there any solution even it means using a bigger battery or combining more smaller batteries together to achieve this feat.
Thank you in anticipation of your responses.
I'm confused. I use the iGo adapter in my car to charge and use my laptop, but the CIG lighter DC plug is at least rated for 10-15A which is >100W and the laptop supply is also about 19V, so it works.
Power in has to be > Power out because of inefficiencies.
Batteries are typically rated in AMP-Hours and their spec sheets will show what you can draw from them. If you want to say charge a laptop with two 9V rectangular batteries it isn't going to happen.
What's this "car computer PSU" that your talking about?
A typical car has a huge amount of battery capacity.