Need help with battery power for LCD1602

Hi everyone. Please forgive my noobness to Arduino and electronics in general. So, I have made my wife a heartshaped box for our anniversary, and I've installed the LCD 1602 on the cover. I've managed to program it fine, and wire it all up. It works beautifully from the computer. My problem is that I need to power it on battery, so it can be portable for her to take(probably to work.) When I apply battery power to the LCD, it works fine, but the text is dark and I cannot brighten it with the potentiometer. I've tried a 9v, two AA's, and 4 AA's. Can anyone offer some suggestions to brighten up these letters?

Thanks in advance
-J

And how pray-tell, have you imagined to connect these various batteries?

Note that the LCD must have a regulated - that is, unchanging - supply of at least 4.6 V (but no more than 5.5).

Is it the characters themselves or the backlight that is dark?

Paul__B:
And how pray-tell, have you imagined to connect these various batteries?

Note that the LCD must have a regulated - that is, unchanging - supply of at least 4.6 V (but no more than 5.5).

Well, I connected the 9 volt directly to the port of the arduino, then for the AA's, I ran them in series and connected them to the 5v input of the UNO.

kamelryttarn:
Is it the characters themselves or the backlight that is dark?

It's the actual characters themselves. I can adjust the brightness with the potentiometer, but it doesn't brighten them enough, not like when it's plugged into a usb port.

6xAA
If you are hard up for space, try 2x18650.
Use a decent off-board 5v regulator and feed to the 5v pin

A regular 9V battery seems like the most commonly available option. As stated by almost everyone you will need a 5V voltage regulator and a proper resistor or constant current regulator for the backlight. Depending on your display you may need some way to generate a negative voltage for the LCD driving voltage but my experience tells me that 0V (gnd) is often enough.

You say that you have tried a 9V battery already. If you have connected 9V directly to the backlight there is a good chance you have damaged the backlight. Sometimes they have a built in resistor but not always.

kamelryttarn:
A regular 9V battery seems like the most commonly available option.

If by "regular" you mean a 9v PP3 battery, it is not an option at all. You need some power to drive an Arduino, and a PP3 has virtually no power. If you insist on using simply plugging a 9v PP3 into a Uno, you deserve all the grief you will surely get.

I submit a Uno is not really suited for battery power at all. A ProMini or the like is essentially the same but more suited to battery power and its associated dark arts. Even then, the masters of the dark arts are not too likely to use a PP3.

Well, I've taken everyone's advice. The LCD is fine, it works beautifully and so does the program when plugged in. I bought some 5v regulators and hooked up 6AA's in series...nothing. Barely any power is reaching the board. With battery power and the regulator, the lcd barely has a backlight at all. At this point, I am admitting defeat with the battery power, she will just have to plug it in. It sucks...but, it's the thought that counts I suppose.

I seem to run into this problem quite frequently. When I build robots such as otto and the likes, battery power simply does not have enough juice to run the darn thing.

Are there any suggestions on how to fix this? More batteries?!?! I dunno, its a bit disheartening.

Have you measured the voltage from each battery under load? AA-batteries should be able to power your setup for at least a couple of minutes on your workbench.

joshuajbelanger:
6AA's in series...nothing. Barely any power is reaching the board.

6xAA with a 5v regulator really should give a result. Perhaps you are using cheapo batteries, and note that I did say decent regulator - 1 amp output