7" LCD power question.

ryan brown

ryan brown

lOwEr CaSe Member
I've been contemplating which external LCD to go with for awhile now (for my SGPro), but the other day I was over at a friends house and he had one just sitting around. He said he'd give it to me for $50 if it'll work for my needs.

All other things aside (resolution, flip function, etc), I just want to power it up and give it a try.

It says on the back it takes 12V, .7amp to run, and as of now it just has a cut power line (as in it was cut with a knife, and now just has two stripped wires).

I want to hook it up to a battery(s), but don't know exactly how to go about this. I have a large 6V battery (for big flashlights) sitting here, but it doesn't say the ampage.

Could I hook up numerous double a's? how many? what about the large 6V?

I don't want to blow the thing, so I'm asking before I start randomly hooking it up to battery's ;)

-brown
 
Alright... thanks. I know nothing about this stuff.

So, the right combination in there was 10 tripple a battery's (12V up to 700mAh)

So, if I go get 10 aaa's, rubberband them together, put a metal plate on the top and bottom of the bundle, then connect my loose wires, it should power up. Correct?

If it all works well, I'll of course buy the rechargable bundle, but just to test it, this should work, right?
 
dont get confused by amps... its volts you want to match you lcd. Amps is the capacity of the battery... like your cars fuel tank its 20 gallons, 32 gallons or 40 gallons. amps=gallons. consumption is how big your engine is, and weight, speed driving conditions, etc. you need minimum 7amps to run your car or lcd, even though you have 40 gallons or amps in reserve in the tank.

in other words you get 7 miles to the gallon or 7 amps for an hour
 
Im using Tekkeon mp3300's to power my monitor.

Though, after using them in the field, I can say that it'd be nice to have smaller batteries that lasted just as long. =\

Contact BOB HILL he should be able to help you as well as these fine folks here.
 
Yeah, you need to provide it with 12v ... don't worry about giving it too many amps, just be sure to give it enough.

Given the right voltage, a device will draw as many amps as it needs from the power supply. If it's a battery, it will get enough, but smaller batteries (in terms of Amp-Hour capacity) will drain faster. If the power supply is a transformer that has a lower rated Amperage output, you can overload the transformer.

It's like plugging stuff into a regular socket at home, after enough lamps; you'll trip a breaker. But you can't fry a lamp by giving it too many amps to use.



Note that batteries connected in series (back to back (think like a maglite)) you sum up the voltage across them, but the amps available is that of the weakest battery. Like this:

[1.5v 2Ah] + [1.5v 2Ah] + [1.5v 2Ah] will give you 4.5volts, with a run time of 2Ah (2 hours at 1Amp, or 1 hours at 2Amps, etc..)


If you connect batteries in parallel, you increase their available capacity, without increasing voltage. Like this:

[1.5v 2Ah]
[1.5v 2Ah] = 1.5 volts, with a capacity of 4Ah.



And yes, you can combine them..


[1.5v 2Ah] + [1.5v 2Ah] + [1.5v 2Ah] + [1.5v 2Ah]
[1.5v 2Ah] + [1.5v 2Ah] + [1.5v 2Ah] + [1.5v 2Ah] = 6 volts at 4Ah.



So you need 12v for your monitor. And it draws (max) .7Amps, which can also be written as 700mA. If you want to run it for, lets say 2 hours per battery back, you'll need to have a "12v 1.4Ah" battery. .. which really isn't much.

So, now you can start stacking up "AA" batteries (or use "D" cells, they have a higher Ah rating), or you can go out and find a nice 12v battery. - the bigger it is, the longer it will last. You could go for a couple of days with a good car battery if you wanted to!



- Mikko ... do I sound like a nerd or watt?
 
Last edited:
rcbrown23 said:
So, if I go get 10 aaa's, rubberband them together, put a metal plate on the top and bottom of the bundle, then connect my loose wires, it should power up. Correct?
Click to expand...
I hopeing get you something more compact that ten aaa's... what a pain in the ass,
and something rechargeable too.
 
You don't mention whether the stripped wires are identified as + and -. If you hook up the battery backwards, you could damage the LC display. Hopefully one is red (+) and one is black (-).
Also, if you use alkaline batteries, you only need 8 for 12V.
And they have to be in a SERIES string, so the voltages ADD.
I'd use AA's instead of AAA's for that much current. AAA's won't last very long.
 
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