Question about Lithium-lon battery

[chr00t]

I want to know where can i find highest mAh of AA Lithium-lon and my friend wanted build a emergency backup battery for his HP IPAQ H6315 pda. The backup battery look like this url: http://www.boxwave.com/products/batteryadapter/index.htm


Which do you recommend the AA battery Lithium-lon or NiHM to gives longer runtime on PDA?

 

[cypher2001]

Do you have any circuits in mind to do the transfer/protection for the battery?

This item looks interesting. I'm not interested in spending 20.00, but if I could build the same thing for my IPAQ , I would be interested.

(STANDARD DISCLAIMER, I know less than nothing about this, but below is my guess..)
It looks like its a 6 V battery pack that has a buck converter to step it down to about 5V, <= 500ma. This emulates the USB connection for the IPAQ. IPAQs (Mine included) can charge over a USB power cord (as mine is now).


It looks like they just give you a USB power supply and a USB sync cable.

To do the same with Lithium-Ion... I think would be complicated.. but fun..

 

[chr00t]

I will use the adapter usb to direct plug on the IPAQ. Here the url: http://www.boxwave.com/products/directsync/index.htm

I was plan buy 20 dollars and put highest mAh NiHM or Lithium-Ion using my rayovac charger for NiHM. I do not know lot about Lithium-Ion. I am not expert, that's why i asked this post to see if I can use the battery rechargerable then put on emergency battery backup (4 of AA batteries).

The IPAQ H6315 uses Lithium-Ion 1800mAh and i found extend battery 3600mAh but if i could find highest mAh than 3600mAh? Will it work with iPAQ pda?

 

[cypher2001]

I understand now.

I am by no means an expert on the IPAQ system. BUT.. I would recommend the following:

Buy some good NiMH batteries and put them in this unit. If you buy (4) 2300mah NiMH, you should be find.

I would not recommend the following:

Finding a 3rd party lithium ion battery and placing it in the ipaq (IE: one not designed for the ipaq)

Replacing the NiMH batteries with Lithium Ion will require changing circuity and chargers. You would NOT be able to use your Rayovac charger for the lithium-ion. They will explode.

Just my .02

 

[chr00t]

Ok thanks! Last question, I wonder if we could use D battery with 11,000mah at 1.2volt. Will it damage to the IPAQ pda?

I mean NiMH AA battery 2300mah at 1.2 voltage vs D battery 11,000mah at 1.2 voltage. It should gives us longest runtime on ipaq pda by battery pack with D battery 11,000mah 1.2voltage? Do i need a regulation on the volt/amp flow or what is your recommend?

 

[Steelwolf]

I have something similar to that and mine does not appear to have any sort of circuitry inside. I'm guessing it relies on the pda itself to have a circuit to stop the charge. In itself, it appears to be nothing more than a battery box with the correct connecter and a switch. But I could be wrong.

chr00t: Do not substitute NiMH with Li-ions unless you have some plan to limit the voltage. Li-ion delivers between 3.6V to 4V. So maybe you might only require 2 Li-ion cells instead of 4 NiMH, but I wonder how safe it might be since at full charge there would be a 3V difference between what you have and what you need.

If you're planning to build a battery pack using 4 D cells instead of 4 AA cells, I don't see much wrong with it. Except, of course, it will be big, bulky and heavy. And I've found that with big, bulky, heavy things, you tend to leave them at home just when you need it most.

Personally, I've found that AA cells will recharge my pda (Toshiba e310) just fine. And there always seems to be extra charge left over, so I'm guessing my pda cell's capacity isn't close to the 2100mAh of the AA cells I'm using.