care for lithium ion batteries?

[ShawnD1]

Lithium ion batteries are the ones used in PDAs, cell phones and laptops.

Are there any rules/tips I should know about how to care for lithium ion batteries? nickel cadmium batteries had a problem where if you discharged them half way then charged them, the battery would charge less and less and less each time. Do lithium ion batteries do that too? I have my PDA plugged into my USB a lot of the time and the battery pretty much never goes below 80%; is that bad for the battery?

I need to ask because I'm a student and I need my PDA to last me a while. I can't be going out and buying a new one because I didn't take care of the last one's battery.

[nunyadam]

http://www.nexergy.com/Reflib/Lithium_Ion_FAQ.html

[Uncle Bob]

Got to take care of those batteries. I used to do road trips to shooting matches, and had a cell phone for road emergencies. I quit the road trips,got a new car, cellphone forgotten in glove box. Battery not properly charged = expencive replacement battery.

[ShawnD1]

Great info!

Optimum charge and discharge parameters are defined during the design of the Li-Ion cell. Overcharge (voltages > 4.2V /cell) and over discharge (voltage < 2.4V / cell) will cause irreversible chemical changes to the cell. These charges will reduce the retained capacity and cycle life of the battery.

Perhaps the most dramatic increase in cycle life and retained capacity results from cycling at less than 100% depth of discharge. With a 10% reduction in discharge profile, you effectively double the cycle life of the cell. Discharge profiles of 25% have extended the cycle life of cells beyond 10,000 cycles and profiles at 12% depth of discharge have extended the cycle life of cells beyond 17,000 cycles.

Li-Ion batteries are specified to operate between –208C to +608C for discharge and 08C to +408C for charge.



Basically if I just keep the batteries charged well and not use the thing outside during the coldest day of the year, they should last a long time

Bob, you can at least change your batteries. PDAs have built in batteries so if the thing dies, I need to buy another PDA!

[Uncle Bob]

I didn't know that. No PDA for me.

[Uncle Bob]

Your post about batteries reminds me the cell phone is way past
due for a charge. I may just stop the service and throw the thing away.