So I searched and searched on here and read just about all the battery extender threads there are. I thought I had a pretty good handle of what I needed to do and what to expect. I thought I did everything right:
I bought this battery extender by Gomadic which includes the appropriate tip.
I bought 4 AA NIMH which are 1.2v, 2100mah.
Thing is, I don't get the screen flicker problem because it just plain doesn't recognize it as external power. Plugging in the extender (with the Dell battery at 100%), nothing happens. No orange power light, no change in battery status screen. Charge goes down just as normal.
With the Axim powered off, I do get the orange power light and it seems that the battery does charge, though fairly slowly. But that's not very useful, now is it?
That just doesn't make sense. If you have a multimeter I would check each rechargeable to make sure it is OK. Also (and I don't mean to be insulting) check the way you have inserted the batteries. If all is OK I would be guessing you have a dud unit.
Thanks for the reply. Yeah, it really doesn't make any sense. I suppose that based on the fact that (when active) the Axim doesn't recognize any change in power source, the only logical conclusion is that it isn't getting enough voltage to "trigger" that switch.
These are brand new NiMH rechargeables, is it possible that they need to be cycled a couple times first? I know that fresh batteries usually need a couple cycles to realize their full capacity, but the output voltage shouldn't be effected.
Man, I really hope this isn't a dud unit. I'm doing a couple cross country flights next week.
These are brand new NiMH rechargeables, is it possible that they need to be cycled a couple times first? I know that fresh batteries usually need a couple cycles to realize their full capacity, but the output voltage shouldn't be effected.
Any other ideas/suggestions?
Dude, try some fresh alkaline batteries to see if it is a battery issue. I don't recommend using the alkaline batteries to power the unit, just to test it.
Second the alkalines test. And, w3iner, wtf means "5.4V at 2450mAH?" Non-engineers, please refrain.
In my experiments, I find you can charge an X5x() series with anything from 4.9V to 5.4V. Many 2nd-party chargers use USB power to charge your Ax, or just a 5.0V regulator if they don't rely on USB. My home-made external battery uses a +5.0V regulator to deliver the power. It's my standard, at-work charger, plugged in every day.
Others have tested and shown that you can recharge Axim on, no WiFi, with a flat standard (1100) mAH battery with about 850 mA or less. Good to have the full 2 Amps capacity in your charger, however. NiMH batteries have low internal resistance, so they tend to dip less than alkalines in voltage when you load them, and their cell voltage is about 1.4V apiece unloaded, fully charged. Drops to 1.3 or so and down from there while discharging.
If you're getting no lights whatsoever and all the batteries are connected, everything is plugged in properly, you have a dud unit.
Second the alkalines test. And, w3iner, wtf means "5.4V at 2450mAH?" Non-engineers, please refrain.
In my experiments, I find you can charge an X5x() series with anything from 4.9V to 5.4V. Many 2nd-party chargers use USB power to charge your Ax, or just a 5.0V regulator if they don't rely on USB. My home-made external battery uses a +5.0V regulator to deliver the power. It's my standard, at-work charger, plugged in every day.
Others have tested and shown that you can recharge Axim on, no WiFi, with a flat standard (1100) mAH battery with about 850 mA or less. Good to have the full 2 Amps capacity in your charger, however. NiMH batteries have low internal resistance, so they tend to dip less than alkalines in voltage when you load them, and their cell voltage is about 1.4V apiece unloaded, fully charged. Drops to 1.3 or so and down from there while discharging.
If you're getting no lights whatsoever and all the batteries are connected, everything is plugged in properly, you have a dud unit.
.
I am no engineer either, but the Dell Wall Plug puts out 5.4v at 2450 mah, while there are 4 1.2v(which i guess adds up to 4.8 v or volts, not the 4.9 to 5.4 you stated.) at 2100 miliampheres(which is 8400 mah which seems enough). I am no expert but It seems to me that you have enough amps but not enough volts? Try following Pocket Brains idea of using Nickel based batteries and that might give you enough volts.
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...while there are 4 1.2v(which i guess adds up to 4.8 v or volts, not the 4.9 to 5.4 you stated.) at 2100 miliampheres(which is 8400 mah which seems enough). I am no expert but...
Batteries in series (+ to -) then you add voltage (current remains constant). If in parallel (all + tied together, all - together), voltage remains constant, and current adds together. Four 1.5V, 2000mAH batteries in series gets you 6V @ 2AH. The same batteries in parallel gets you 1.5V @ 8 AH. You can also get 3V @ 4 AH (two each in series, and that pair in parallel).
Batteries in series (+ to -) then you add voltage (current remains constant). If in parallel (all + tied together, all - together), voltage remains constant, and current adds together. Four 1.5V, 2000mAH batteries in series gets you 6V @ 2AH. The same batteries in parallel gets you 1.5V @ 8 AH. You can also get 3V @ 4 AH (two each in series, and that pair in parallel).
Thank you floor. I guess he will need his battires is series.
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I am no engineer either, but the Dell Wall Plug puts out 5.4v at 2450 mah, while there are 4 1.2v(which i guess adds up to 4.8 v or volts, not the 4.9 to 5.4 you stated.) at 2100 miliampheres(which is 8400 mah which seems enough). I am no expert but It seems to me that you have enough amps but not enough volts? Try following Pocket Brains idea of using Nickel based batteries and that might give you enough volts.
I think everyone is getting too caught up with voltage. Voltage is not important, it is current that charges the battery. Voltage is only necessary to get the current flowing.
The Axim battery is rated at 3.7 volts, therefore any voltage source above this level will cause current to flow into the battery (and thus charge it).
The big variable is the amount of current flowing in which affects how fast the battery charges. The current flowing in is a function of the voltage driving it and the ability of the source to supply it. This is why USB chargers are not very satisfactory. Their voltage level is OK but their ability to supply current is very limited.
Referring back to Ohm's Law, a higher voltage will cause more current to flow but unless the source is capable of supplying it the source voltage will drop (and the current along with it). The ideal would be a "constant current" source in a storage device (battery) but unfortunately they are not available. The nearest we can get is the NiMH so stick with them.
I lived on a yacht for 6 years so if I got my charging wrong I sat in the dark.
G'day,
The tech stuff is over my mathematically-challenged head. However I did get a battery extender for my Ipaq which worked fine in providing power when Ipaq was on. When I looked at a similar extender from the same seller for the Axim the seller specifically stated in their ad that with the X51v you could only charge whilst unit off (and if I recall correctly not a completely drained battery) given the higher power draw (in very layman speak) of the x51V.
Cheers
Bern
If you put 6 2500mah NiMH batteries in series, you get 7.2 volts with 2500mah current. Slap a +5VDC voltage regulator on there, and you get a steady 5 Volts, 2500mah (roughly 625mA, correct?). This provides more current than needed to charge the battery and use the axim at the same time (I am totally assuming that), since the axim likes around 500mA when charging.
Somebody either tell me I'm correct, or tell me how it really is
You need like 5.4v at 2450 mah if I am not mistaken. I don't think 4 1.2v double A's is enough to charge and run at the same time.
I have a battery extender that uses 4 AA NiMh batteries and it works fine, as long as I plug it in before I go below 70% or so. If above that level it both charges and operates with the extender.
I can tell you that I experimented with a USB power supply that used AA's as well, and it didn't work at all. I suspect the problem is the pin the voltage is hooked up to is wrong. Keep in mind, the Axim has 2 input pins. One is designed to be used with a USB port and doesn't operate and charge at the same time. The other input pin will. Of the 2 units I got, I suspect one is not wired properly for the Axim.
So I searched and searched on here and read just about all the battery extender threads there are. I thought I had a pretty good handle of what I needed to do and what to expect. I thought I did everything right:
I bought this battery extender by Gomadic which includes the appropriate tip.
I bought 4 AA NIMH which are 1.2v, 2100mah.
Thing is, I don't get the screen flicker problem because it just plain doesn't recognize it as external power. Plugging in the extender (with the Dell battery at 100%), nothing happens. No orange power light, no change in battery status screen. Charge goes down just as normal.
With the Axim powered off, I do get the orange power light and it seems that the battery does charge, though fairly slowly. But that's not very useful, now is it?
Any ideas?
Sounds like a dud unit. (funny me showing up in these external power threads :) )
If you have decent quality NiMh batts then you should be looking at 1.4-1.45V when fully charged (peak) and then dipping to ~ 1.2-1.3 as you use 'em.
Even cheap, crappy chemistry NiMh should cause your Axim to light up when your internal battery is full (ie: give you an indication that it's working)
If there's no change in battery status at all even with freshly charged batts then something is wrong.
Either your unit is a dud or your tip is messed up or it's the wrong tip (possible, you never know).
I've never had a problem like that before. I've got the 'el cheapo extender from pc-mobile.net and it works pretty good as long as you respect the parameters of the Axim which has higher voltage/amperage requirements than any other similar pocketpc out there.
I can charge my Ax and use it at the same time as long as the Ax internal battery is ~ 60% or more and i'm using good quality NiMh cells - which I always do because I refuse to use crap NiMh. I use MIJ Sanyo or Sony or Enegizer (Sanyo OEM last time I checked). I use a La Crosse bc-900 charger.
The other question I have is that you didn't mention if you had the regular 1100mAh battery or if you have an extended battery. If you have an extended battery like the 2200mAh or the 3300mAh then that comes into play bigtime. It's been guessed that the requirements to charge those batteries from an extender is significantly greater than the 1100mAh battery. Ballpark in the order of 1-1.5amps ... and 4x2500mAh in an extender may just get the charging going and may only last one decent half charge.
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