Saturday, May 10, 2014

Power your laptop from your radio Go-Box battery!

First off, I am not any kind of electrical expert.  However, that never stopped me from experimenting.
Granted fuses fear me when I come near, but if you know someone who is skilled with electrical knowledge then you have every reason to give your ideas a path to reality.

Well, Jim, K7JGM gave me a new idea for my Packet Go-Box.  He mentioned that his Go-Box contained a Powerpole outlet to power his laptop computer.  This means that it is possible to tap the 12 volt power supply for the radio to power a laptop.  You just need a way to step up the 12V to something like 18 to 19 volts.  The specific output voltage depends on which laptop you own.  In my case the Toshiba  laptop I have dedicated to my packet station needs 19 volts.  I obtained this information from the power brick included with the laptop.  The power brick tag says output is 19 volts and 3.95 amps.  Being the trusting person that I am, I measured the voltage coming out of the brick and it read 19.6 volts.  Close enough.

The voltage step up is done by using a DROK DC Converter Voltage Regulator 8-32V to 9-46V 12/24V 150W Boost Step Up Power Supply Module which is available from  The regulator can be adjusted easily to match your output needs.  However, be sure the output range of the regulator is appropriate for your particular laptop.

For your Go-Box, you simply tap the 12 volts and install a Powerpole outlet somewhere accessible for you laptop.  In my case, I already had a Go-Box built with 12 volt Powerpole outlet so, I decided to make an external 19V converter.  Below you should see the convertor installed in a plastic "case" with  Powerpole connectors on both input and output.

The case for the converter is a $1 plastic box from the stationary section at our local Fred Meyer. Several holes were cut in the case to allow the Powerpole wires to enter the box and to allow the cooling fins to be exposed.

Finally 5 small holes were drilled to allow access to the screws which secure the wires AND the voltage adjust screw.

Lastly, the scary part is cutting the wire on the power brick that goes to the laptop. This way you can install Powerpole connectors on each side of your cut, as shown here.  This allows you to connect the laptop's power connector to either its original power brick OR the new converter you just assembled.   That's it, enjoy!

UPDATE (2014-05-10) :

So, you have a Dell laptop and it has a "smart" power brick.  Well guess what!  Instead of having the typical 2 connector power port, it has a 3 connector setup.  That center pin is a way for your laptop to tell if the power brick is the correct one. Unfortunately, if it thinks the charger isn't the correct one, then it allows it to power the laptop but not charge the battery, even if it has the correct voltage.  Some folks in the various forums have suggested to just send the 19 volts down the center connector as well, but don't do it.  That connector expects no more than 4 volts so more then that may kill the "smart" chip.  See for some background.

However, all that said it is possible to use the converter with a Dell.  Since I have a great appreciation for Anderson Powerpoles that is what I used to make sure everything connects correctly.  The images show how to wire the connectors to use all three wires when the power brick is connected and how the converter connects.  Note that the Center Pin is labeled for photo reference, since the Powerpoles are used there is only one way to actually connect everything.  Red goes to the + 19 V connector which is the inner shield. One black goes to the ground outer shield and the other black (sorry I didn't have another color, which they do make) goes to the center pin.

Everything works as usual when connected to the power brick.  However, when the converter is connected the laptop whines about it being the wrong charger and it won't allow battery charging. How rude!  If you leave this situation alone then the battery slowly discharges.  You probably won't notice it because the converter is powering the laptop.  The issue occurs when you disconnect the converter and expect the battery to power the laptop.  If the battery has fully discharged, well you guessed it, the laptop goes black when converter is unplugged.

An extremely simple solution is to remove the battery after the converter is plugged in.  The only change with the battery removed is that the converter's fins warm up just a bit more than with the battery inserted.

If someone knows a way to fool the laptop into believing it has the correct power brick, please let me know.