zim2dive

Originally Posted by lwalker

I have been making these for awhile starting with an iPaq 3600 in 2001 You can use regular batteries AA, AAA, C or D or a 6v lantern battery. (40000 Mah.) You need to use a cheap diode inline to reduce voltage to 4.8v.

More importantly, an inline diode may prevent reverse charging... ie the big danger with these devices is that if you are using rechargeable batts, and if the batts end up being more drained than your Axim, the Axim battery will end up being drained instead.

Mike

wkriesel

For extending the X50's run time I use a $16 adjustable voltage regulator:

http://www.dimensionengineering.com/DE-SWADJ.htm

Power source is 12v from a 8 cell, AA pack from RS. Either alkaline or NIMH cells will work. It is 90% efficient and I get 12 hours of movie watching from $6 of alkaline batteries purchased at an airport.

Wiring and connections are from my used (i.e. crashed) model airplanes.

darkdestroyer

Ic. I just fixed mine up with a new incarnation. Zim2dive is right, inline diode will probably prevent reverse charging. I havn't had any issues with that yet, we'll have to see when I go on my business trip on sunday. Im probably not even going to bring the cradle, just my battery pack and some spare batterys.

Here's an attached picture of my second battery pack, this time using better looking parts.

Henros

Darkdestroyer, 2 comments:
1. Ditch those puny black and red wires that came with the battery holders and solder in some thicker wires instead. The original wiring is not designed to pass 1A+ current comfortably and will probably cause the screen to flicker when the axim's battery is a little low.
2. While a diode will protect against reverse charging, it will drop too much voltage and not allow the full capacity of the external batteries to be used. This is because you are only using 4 cells which will have a loaded (ie axim connected) output of around 5.2-5.6 V (1.3-1.4V per cell, NiMH and alkaline alike). Subtract approximately 0.7V due to the diode, you don't have much voltage left to begin with. If you have to use one, use a Schottky diode (eg 1N5822), as they have a lower forward voltage.

darkdestroyer

Thx for the comments. I dont use this charger to power my axim, only to charge it while off. The wiring works fine for that, although i will consider changing them when i have the time.

hellas

what happened to your ax??? is that vinyl tape on it?, holding it together????

darkdestroyer

LoL!! It's a layer of Electric tape to prevent the silver lining from being scratched when i slide it into my Rhinoskin case. Works well and the color complements everything else that I have.

Don_S

The AC-to-DC power adapter supplied with the x50v ouputs 5.4v at 2.4A. I have a PSP car charger from Pelican that outputs 5v at 2A. The 2A should be plenty to charge the Ax when it is running with WiFi or Bluetooth on without the screen flickering. Also, the power tip of the pelican car charger fits perfectly with the Ax connector/Adapter. My question is this: are there any long-term ill effects (on the Ax) of operating it or charging it on 5v when the specs state 5.4v?

darkdestroyer

I dont believe so. My X50v has been working perfectly, despite me charging it via my AA battery solution. I've even resorted to charging it with 4 AA disposable 1.5 V batterys when my NiMh one's ran out of juice in the car. (forgot to charge them), apparently it works fine for chargin the X50v.

Don_S

But have you used these voltages over extended periods of time? the Ax may function OK over a voltage range of 4.8 - 6.0 V in the short term, but I would be worried about running it at non-standard voltages continuously (like on long car trips). Does anybody know the specs on the Dell-branded car charger?

Henros

There will be absolutely NO long-term ill effects. It's well within the tolerance of modern portable electronic devices such as the Axim.

Rainh2o

Originally Posted by Snerkel

If only it were that simple... the 78m05 is only good for 500mA no where near enough for the ax

not really...

If good heatsinking is provided you can pull a bit over 1 amp with a LM7805. I use one to charge my axim in the car. I dont think its heat sinked very well either. I have it enclosed in a small plastic black box. The regulator is mounted to a small metal plate inside and I can feel the heat through the box. It was something I put together quickly and in a bind but it has lasted for over a year with constant use. The LM7805 is practically indestuctible since it has internal thermal protection. My axim only pulls about 650 ma when dead but that goes down quickly. I think it pulls close to 1 amp if the battery is dead and I turn it on when its on charge. The LM7805 will handle the load.

Rainh2o

Originally Posted by darkdestroyer

Will not work with regular batterys. Those batterys have a charge of 1.5, while the NIMH batterys have a voltage of 1.2. Therefore 4 series 1.2 = 4.8, the necessary charge needed to maintain and charge a Dell PDA. Does anyone know the exact specifications of the Dell PDA Power requitements? Because the 9600mAh Li-Ion pack only supplys 3.6 V of power, not nearly enough for the Axim. I believe its ~5 v?

My wall adapter has 5.4 volts steady out of it. I charge my axim at the office on my power supply unit in the lab on 5.5 votls. I would venture up to 5.6-5.7 but I am not brave enough to go past this. I charge it in the car at 5 volts.

Tim L

Originally Posted by darkdestroyer

I've even resorted to charging it with 4 AA disposable 1.5 V batterys when my NiMh one's ran out of juice in the car. (forgot to charge them), apparently it works fine for chargin the X50v.

Would standard AA cells be up to running an X50v? I was thinking that with a zener diode in line the voltage would be dropped to about 5.3V for new ones.

When I finally have some more spare time I'll have to crack the books open and educate myself on this subject.

privard

Regulated power supplies, soldering in diodes and capacitors? That's the beauty of 4 NiMH AA's in series--they're simple and safe for those of us who aren't electronics engineers. Fresh off the charger they'll give you just over 5 V (not enough over to do damage), then almost immediately settle down to 4.8 V of steady output for a long time. Anything that'll take a charge off the constant 5 V provided by USB won't fry (unless you hook up the wires backwards). Here's a simple way to do it without getting the wires backwards: get one (or two) 4-AA battery holders from Radio Shack or equiv., the ones that have tabs to fit a 9 V battery clip. Buy one (or 2) 9 V battery clips, too, and then get a USB extension cable. Cut the cable, strip the wires on the female end, and connect the black or brown wire on the female end of the USB cable to the black wire(s) on the 9 V battery clip(s), then the red to the red. Solder the connections if you like, use twist connectors, or just twist them tight; then tape or epoxy the connections and the ends of the two unused USB wires, just so they don't make electrical contact with anything else. Put the clips on the battery pack(s), put your charged NiMH batteries in the pack(s), and you're ready to charge anything that has a USB sync/charger cable--it'll work with ANY PDA as long as you have a cable for it--and there's no risk of hooking up the wrong wires and reversing the polarity, or of overloading and frying your equipment. 15 minutes of effort, tops, even for the novice.