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6v to 12 v step up power inverter to charge phone from a 6v motorcycle electrical system. advice sought. Answered

Hi, just below are two pictures and details of different mini 6v to 12v step up power inverters. I have tried to use
the smallest sized one out of the two without success. I installed the smallest one on my old 50cc moped with the
idea that it would charge my mobile phone as I rode my bike.  My bike has a 6v electrical system, hence the need for
a 6v to 12v power inverter. I also bought a 12v incar charger lead from a phone shop. Its the type of lead you plug
into your car cigerette lighter to keep your phone fully charged. It charges my phone well inside my car but not on
my bike!

On my bike. I connected the phone charger lead to the 6v to 12v step up inverter expecting it to charge my phone
just as it would do in my car. But no! It does not charge my phone correctly. It seems to send power to my phone in
short spurts and gaps. It will charge for 5 to 8 seconds. It then stops charging for 7 seconds and continues to
charge for a further 5 to 8 seconds and the cycle repeats over and over. Having it charge this way means that the
phone does not receive a good charge and eventually my phone battery goes low and then dies.

I think there could be stability issues with this 6v to 12v power inverter. I have found another type of power
inverter for sale. The seller says his inverter is quite stable. I may end up replacing the old inverter with the
one. I'm hoping it will do the job more successfully than the current inverter im trying but failing to use.

Im not technically minded. I have copied and pasted the web addresses of both inverters. On the sites you will see
the technical details of both inverters. Would someone please take a look to compare both devices for me please. I
am looking for a solution to charging my phone successfully whilst on my bike. Would the bigger inverter be better compared to the smaller one  I have allready installed?

This is the inverter I am currently using but doesn't work properly.  http://www.ebay.co.uk/itm/350436684000?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648

And this is the inverter I am thinking of getting to replace the old one.  http://www.ebay.co.uk/itm/DC-DC-Converter-Regulator-Step-up-Step-down-2-1-/150657732239?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2313e68e8f

As i said, Im not techinally minded and and looking for your advice. Would the bigger inverter be a good choice to
replace the old one to charge my phone.

Thanks for replies in advance.


What kind of phone do you have? I can't think of any phone that needs more then 5V to charge. See the car charger for your phone takes the 12V from the car and drops it to 5V for charging. You need to cut the car charger out all together, or at least cut the car plug off and use the existing wire, and create your own custom cable to connect the 6V system to your phone. You will want to solder a couple of resistors across the power leads to create a voltage divider bring the 6V down to the 5V the phone needs.

Looking at the image i've attached you will want R1 to be a 100 Ohm resistor and R2 to be a 680 Ohm resistor. This will bring the voltage down to about 5.2V, give or take, depending on the tolerance of the resistors.


Hello mpilchfamily. My phones battery is a 3.7V 1300ma. If i remove my current stepup inverter completely and use the charger lead instead to charge my phone from my bikes 6v battery I end up with the same problem. spurts a charge in spits and spats. no good. I tryed it and it didn't work!

Im wondering. should I completely take the charger lead out of the equation to try this knew idea. connect this knew fully adjustable voltage inverter that is a two in one stepup and step down output invertverter and set the output to a 3.7V to match my phones battery voltage. perhaps that will give my phone a consistent relaible charge?


What phone do you have? On your in home charger what does the brick say the output voltage is?

The battery may be a 3.7V battery but the phone may be looking for a different voltage to be fed into it for charging. Lets identify your phone and the power requirements for charging before you go buying anything else.

Hi thanks for your help so far :-) My phone is an O2 xda zest. as i said. it users a 3.7v 1300mah li-on polymer battery. that is the info printed on its battery. the 240v mains charger that plugs in to the wall says its output is 5.0v dc 1000ma. i wanted to find as much info as i could for you. I set about looking for the owners manual to find in the specifications section as much detailed info as i could but at the moment i'm at a loss to find the owners manual. Is the info given so far enough to be going on with? please let me know.


If the main charger tells you it outputs 5V @ 1A then that is what you need to provide to the phone to get it to charge. Now when the bike is running, the voltage output may be above 6V. So you will want a voltage regulator that can take 6V or more and keep it steady at 5V. But that regulator needs to offer up to 1A of current.

That inverter you linked to above looks like it may fit the bill perfectly. But what you already have may be working fine as well. You have a Windows Mobile phone so the charging cable is a mini or micro USB plug. There is a chance the phone wants to see some voltage across the data pins before it allows charging to take place.

Whatever invter and cable combo you use won't matter as long as there is only 5V going to the phone. But whichever rout you go you may have to add a couple of resistors to the setup so that you have about 2V going to each of the data lines on the USB cable to tell the phone its OK to charge. I recently completed an instructable where i added an iPod dock to a set of speakers. I had to build my own charging circuit to get my iPod Touches to charge. The image is the circuit i created for this. You don't have to worry about the Voltage regulator stuff on the left side. All you need is the resistor setup on the right to get the proper voltages to the data lines.

I found this instructable very helpful in that project.

Here is my project.

5V Charger.JPG

I cant thank you enough for your input. oh my grandfathers. im such a dummy whyen it comes to electonics lol.

Cheers mpilchfamily. Ill give it a go. hope i dont blow my fingers off while trying :-)