mphayvanh

Originally Posted by cmdkeen

You guys sure that this is safe for the PDA? I mean, sure, the x50 charging adapter might have a protector built-in that only allows 5.4v, but as far as I know, even the unit itself has one like that built in, but at least that thing inside the PDA is not designed to last long and is just to avoid any damage to the PDA due to a higher voltage for a short time. I mean, the AC adapter converts the power down to 5.4 volt, don't u guys think it's a little dangerous to supply the PDA (or at least that one little plug) with 9volt all the time, about as twice as much as what it was designed for??

It's always good to be cautious, especially an investment like the Axim or a PSP! Those are my babies, so this is not something I do lightly. To address concerns, you might think about putting in a line-in fuse when building your own--just in case. They're less than $1 and would serve as a secondary precaution. Three 9v batteries are comparably less of a danger than the charge coming from your car, but you never know. I feel it's safe enough for me to use it now since my PSP was charging fine from the car before the modification. The Axim wouldn't fare any different.

Remember, don't try anything you're not comfortable with and if you do, please do it at your own risk!

lawman

Man, looks like you have something growing out the side of your hip... unsightly... cover it up, man!

mphayvanh

Originally Posted by lawman

Man, looks like you have something growing out the side of your hip... unsightly... cover it up, man!

LOL-- Is that Geeky or what?!

new2axim

Are you wiring these batteries in parallel or in series?

Running 27v to my Axim through a 12v car charger seems like something I wouldn't do.

YMMV.

mphayvanh

Originally Posted by new2axim

Are you wiring these batteries in parallel or in series? Running 27v to my Axim through a 12v car charger seems like something I wouldn't do. YMMV.

It's in a series with a 5.4v output charger. I wasn't comfortable with it being stacked together like that so I inserted ice cream sticks in between! Cross my fingers....

new2axim

Originally Posted by mphayvanh

It's in a series with a 5.4v output charger.

If it's in series, then you're running 27 volts into a car charger that's built to take 12v and drop it to 5.4v That doesn't sound like something I would do.

mphayvanh

Originally Posted by new2axim

If it's in series, then you're running 27 volts into a car charger that's built to take 12v and drop it to 5.4v That doesn't sound like something I would do.

I'll report back if something goes wrong. So far, 5+ hours of Spiderman 2. I'm afraid of screen burns. Is there truth to that if I let it run all night?

Update: I'm turning it off and going to bed. I'm also going to use 1 9v as a testing voltage. Don't want to tempt fate. Will revise the steps tomorrow for just 1 battery until I can find a charger that can handle inputs over 27 volts. Thanks everyone for the inputs!

Snerkel

Looking at your image you have the three batteries in parallel, so you are actually giving it 9 volt, if they are wired in series then the resulting 27 volt is definately asking for trouble.

bigbop

Originally Posted by cmdkeen

You guys sure that this is safe for the PDA? I mean, sure, the x50 charging adapter might have a protector built-in that only allows 5.4v, but as far as I know, even the unit itself has one like that built in, but at least that thing inside the PDA is not designed to last long and is just to avoid any damage to the PDA due to a higher voltage for a short time. I mean, the AC adapter converts the power down to 5.4 volt, don't u guys think it's a little dangerous to supply the PDA (or at least that one little plug) with 9volt all the time, about as twice as much as what it was designed for??

The PDA is NOT getting 9V - the 9V batteries are supplying the 12V to 5V converter and the converter is supplying the PDA with regulated 5V.

As for the 9v batteries in series for a total of 27V - don't do it. Most car adapters are designed for around 16-18 volts continuous unless you get one designed to be used in a car and an airplane, which is 12-30V. An automobile's electrical system can routinely reach 16v while charging and typically it's around 14V.
Your best bet is no more than 2 - 9V batteries in series to power the converter. Try to stay away from the real cheapo converters as they have no overvoltage protection on the output and sometimes no fuse on the input.

You really get what you pay for on these units. I've pulled apart many of these converters to modify them for varous projects. They are usually a simple switching circuit using a controller IC, small inductor (coil) a few caps and sometimes a high current switching transistor on the better units. Alot of the converters sold on Ebay only supply 600mA which is too low for the X50. Get a well made converter for the PSP that advertises it's output is protected.

Have a look at the real Sony car charger http://www.us.playstation.com/peripherals.aspx?id=psp and compare it to what you're buying for $10 - big difference. You can't pack the required protection circuitry into a small housing that plugs into the cigarette lighter socket. Is $10 a good gamble on your $300-$400 PDA?

That's for you to decide.

mphayvanh

Originally Posted by bigbop

The PDA is NOT getting 9V - the 9V batteries are supplying the 12V to 5V converter and the converter is supplying the PDA with regulated 5V. As for the 9v batteries in series for a total of 27V - don't do it. Most car adapters are designed for around 16-18 volts continuous unless you get one designed to be used in a car and an airplane, which is 12-30V. An automobile's electrical system can routinely reach 16v while charging and typically it's around 14V. Your best bet is no more than 2 - 9V batteries in series to power the converter. Try to stay away from the real cheapo converters as they have no overvoltage protection on the output and sometimes no fuse on the input. You really get what you pay for on these units. I've pulled apart many of these converters to modify them for varous projects. They are usually a simple switching circuit using a controller IC, small inductor (coil) a few caps and sometimes a high current switching transistor on the better units. Alot of the converters sold on Ebay only supply 600mA which is too low for the X50. Get a well made converter for the PSP that advertises it's output is protected. Have a look at the real Sony car charger http://www.us.playstation.com/peripherals.aspx?id=psp and compare it to what you're buying for $10 - big difference. You can't pack the required protection circuitry into a small housing that plugs into the cigarette lighter socket. Is $10 a good gamble on your $300-$400 PDA? That's for you to decide.

Thank Bighop! I'm getting a real converter designed to for a higher input voltage. In the meantime, the number of batteries use will be reduced 1 or 2.

Snerkel

Its not so much a question of how many batteries, more the way they are wired.

Code:

Definately no good ----(+) (-)----(+) (-)----(+) (-)---- Series Probably OK ----(+) (-)---- Parallel ¦ ¦ ----(+) (-)---- ¦ ¦ ----(+) (-)---- ¦ ¦ ¦ ¦

When wired in parallel more batteries will equal longer running time, when wired in series equals larger voltage (9 + 9 + 9 = 27)

mphayvanh

Originally Posted by Snerkel

Its not so much a question of how many batteries, more the way they are wired. Code: Definately no good ----(+) (-)----(+) (-)----(+) (-)---- Series Probably OK ----(+) (-)---- Parallel ¦ ¦ ----(+) (-)---- ¦ ¦ ----(+) (-)---- ¦ ¦ ¦ ¦ When wired in parallel more batteries will equal longer running time, when wired in series equals larger voltage (9 + 9 + 9 = 27)

Cool little diagram. My apologies, flunked science. The batteries are parallel. Each independent. You can use 1, 2, or 3 batteries for input. Thanks Snerkel!

bigbop

Be carefull of placing batteries in parallel. Each battery has a fixed internal resistance. By placing them in parallel, you run the risk of discharging one battery into anther with a lower internal resistance. Typically, the cheap car chargers will probably not work below about 9-10 volts so the batteries should be placed in series. Better yet, get a few Radioshack (or The Source if you're in Canad) AA battery holders Catalog #: 270-391 and place them in series. This will hold 12 AA cells. Fill it up with rechargable batteries and use this to power the converter. Then, you can recharge the stack and use it over again.

Of course, you can also get a small 12v GELCELL battery. That's what the news teams use in their batterybelts to power their Betacams.

mphayvanh

Originally Posted by bigbop

Be carefull of placing batteries in parallel. Each battery has a fixed internal resistance. By placing them in parallel, you run the risk of discharging one battery into anther with a lower internal resistance. Typically, the cheap car chargers will probably not work below about 9-10 volts so the batteries should be placed in series. Better yet, get a few Radioshack (or The Source if you're in Canad) AA battery holders Catalog #: 270-391 and place them in series. This will hold 12 AA cells. Fill it up with rechargable batteries and use this to power the converter. Then, you can recharge the stack and use it over again. Of course, you can also get a small 12v GELCELL battery. That's what the news teams use in their batterybelts to power their Betacams.

A 12v Gelcell battery...hmmm..sounds like a better solution coupled with a better converter. The only problem is that you can't just walk into any 7/11 Store and get one. Someone in another post mentioned lithium polymer batteries..cool, but very expensive and defeats the purpose. I like the 12v Gelcell as another project because I'm close to an electronic store and keep the idea of a better converter for general use.

arcticmaniac

You can always use the female end of this adaptor so that you wouldnt have to break apart the car cigarrette adaptor. And connect the batteries directly to the exposed wire on the female end.

http://www.radioshack.com/product.as...%5Fid=270-1535