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Originally Posted by aureusy
Good day,
I have my iPAQ cradle installed in my car. To power up the iPAQ, I use a car power adaptor (that plug into the cigarrete "lighter"). It works well initialy for the first few days. Now, it still charges well but only when the iPAQ is OFF (standby), when I turn it ON, the power LED behaves strangely. It blinks repetitively at a somewhat rapid rate. The iPAQ does not seems to be charged at all. I'm using a 5V output adaptor, althought the ampere is lower than the original charger adaptor. USB charging (with USB car adaptor) works well but only manage to "maintain" the battery level, that's why I prefer to use the car power adaptor.
By the way, no charging at all if I use a lower output voltage. What is going to happen if I use a higher voltage to charge the PDA (>5V)? Dare not to try yet..
Thanks..
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This question is a very complicated one.
1. most (cheap) car chargers only deliver 1 Amper (or even less), which isn't enough for charging a PDA if its battery is (deeply) depleted and particularly if it's switched on. Then, typically, the needed current is well over 1 Amper - around 1.5-1.7 Ampers with most current PDA's (no wonder the official HP/ Fujitsu-Siemens chargers are all 5V/2A, while the Dell Axim x50(v)/Asus 730(w) chargers are even 2.4A!).
For example,
here is a real-world example of the Fujitsu-Siemens PL720's amperage requirements during (re)charging – pretty instructive if you want to know why for example USB/cheapo char chargers don't work with (deeply) discharged PDA's.
2. the more the power consumption, the less the voltage with all voltage converters/regulators, including car chargers. I really recommend
this thread for some examples of this effect in practice.
That is, if the charger is forced to produce, say, 1A, its voltage may decrease to, say, 4.6-4.8 (or even less) Volts. Under a certain voltage threshold (about 4.8V for a 5V device like iPAQ's - unlike Dell Axims, which require 5.4V unless they're in the USB charge mode where they're charged with 5V only - see
this blog entry), they will simply not charge.
3. the symptom you've described may be caused by two things:
a, something in the charger is dead/doesn't work as good as it used to.
This is highly probable, especially with cheaper ones – after all, during regulating (converting 12V DC to 5V DC) a LOT of heat is made and wear/tear done, which really pushes the regulator chip to its capabilities' end. No wonder some of them just burns out (one of them has also burned on me.)
b, the charge level of your iPAQ battery is considerably lower than in the first few days and this is why it's not more charged, unlike earlier.
If this is the case, you're lucky. Then, all you need to do is charging the PDA up in a wall charger or switch it off while it's on the char charger, it will top up and then, you won't have problems any more.
The most generic solution: get a car charger that has higher amperage output. (See the above-linked Dell blog entry for some Dell-specific examples.)
(Please note that the same stands for USB-based charging as well. The (same) problems with USB charging are even more known because USB hosts are only meant for providing 0.5 Ampers at 5V, which is barely enough for a PDA that is switched on and/or more than slightly depleted.)
(Also posted this post, slightly generalized, to my blog at
http://www.pocketpcmag.com/blogs/ind...my_car_usb_cha )