here's one for you tech experts. and i 'm sure there are some of you here.

we have a debate at work about which we should do and whether one would keep our mem card lasting longer or cutting its lifespan.
same with battery recharge. so 2 questions really:

1) do you delete as you shoot, or do you wait till you're finish and upload to your computer then reformat ?
2) do you recharge each time you're going out for a shoot. even if the battery is not almost empty? or do you wait till you get the low charge warning?

do either method for each one affect the lifespan of the mem card, or battery.

I delete images with every next session, even if card is not near half full. Oposite for battery, I wait for it to drain completely, and my cammera tels me "Replace battery" (I have 2 batteries so one is always ready).

Yes , you will improve the lifetime of your batteries if you use them until there is no electricity anymore before recharging them. For cards I dont think that matter very much...
jean

cool, thx everyone .
from what you say, i think i need to get a new Compact Flash card.
i used to have no problem when i was travelling shooting HQ.

 but 2 weeks ago, i did some test shoot for trying out a new aspiring model ...
and right in the middle of shooting i ran out of mem.  Horrors!

reason: i started shooting only in RAW since i started shooting for stock. and it was quite frustrating having to edit on the spot. i am sure i lost quite a lot of good shots, rushing to edit to make space for more shots.
it was a sunday and the camera stores were closed.

on another thread here, someone mentioned SANDISK compact flash card 8 gig at walmart for 35 dollars.(canadian ? US?)  that sounds like a good deal
considering i paid 200 bucks in 2005 for 2 gig. time to get that 8 gig .
no more worries of running out of memory. i have 2 batteries.

keep them coming, it 's nice hearing your comments. very helpful for a non-tech minded artsy-fartsy like myself ! 

wow, AA non rechargeable batteries.
must be expensive not having a rechargeable!

I have more CF cards and I use them in rotated order. Reason: I don't like to delete a card before I make the backup from my computer. The images on the card are a kind of backup, so during the post processing I'm 100% sure if I delete something accidentally I have a back-up copy.

A memory card's life depends on number of write/erase cycles (number over 10.000) but usually the card becomes obsolete in terms of capacity and speed before it broke.

For the Li-ion batteries it doesn't matter when you recharge. For Ni-MH batteries it does matter when you recharge them, as follows: wait until they are completely discharged, the best thing is to use a discharger (my old Fuji Finepix S7000 had a discharge function), after this charge them fully. If you charge a Ni-MH battery that is not empty, you will shorten it's life.
http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery
http://en.wikipedia.org/wiki/Li-ion

I format and charge everything as soon as possible.  LOL, some weeks I'll have 20 team shoots.  All the outlets in my house are filled with some kind of charging device during busy season.  I haven't had any trouble with cards or batteries yet.  (But I don't want bad karma, so you didn't hear me say that.)  I even washed and dried a sandisk CF once and it works fine, didn't even lose any of the shots on the card.

I have more CF cards and I use them in rotated order. Reason: I don't like to delete a card before I make the backup from my computer. The images on the card are a kind of backup, so during the post processing I'm 100% sure if I delete something accidentally I have a back-up copy.

A memory card's life depends on number of write/erase cycles (number over 10.000) but usually the card becomes obsolete in terms of capacity and speed before it broke.

In  other words, someone could format their memory cards every day for about 27 years before they would be expected to fail.  Lets say they were really faulty and only good for 1000 formats, that would be three years, in which case, you are correct. By then most of us will spend $15 for some card that is 4 times larger.

What I'm getting at is that I don't think anyone needs to worry about how many times they format their cards. They will be obsolete before they reach their expected life cycles.

Li-ion cells must never be discharged below a certain voltage to avoid the possibility of irreversible damage. Mixing fully charged and partial charged batteries can reverse a cell and ruin it. Using mixed capacity batteries can do the same thing. I run mine in sets of four, but that doesn't guarantee that one won't go weak before the rest and then go completely off and become useless.

Because of the drain that cameras, especially with flashes, put on batteries, a non-rechargable will have a higher initial capacity but will go dead faster because of the current draw surge from a camera. Rechargables with less mAh last longer.

Neither battery type has a memory like the old NiCads, but if you always short charge, you will get shorter cycles from NiMH until you draw them down all the way and recharge them. So it's not going to harm the battery to cycle them and re-charge or just charge after you shoot. Li-ion it doesn't seem to make a difference.

The bit about mixing batteries just means that if you have 1300 mAh batteries mixed with 2300 mAh batteries, when the smaller capacity ones get low, they draw current through them from the higher capacity batteries and this could reverse the cell and destroy it. Real easy, don't mix different types, capacity and avoid running one old battery and three new ones. (for example)

Heat is the enemy. Fast charging shortens the battery life. I have one of those 15 minutes chargers, for emergencies. I use the slow chargers the night before I'm going out. Might as well toss in that NiCad chargers are not suitable for the new batteries. They work, but may overheat them and cause shorter life.

In the end, they are just reusable batteries, they get weak and I use them in radios or flashlights, better yet, in TV remotes, or throw them out and get new ones. They aren't that expensive in the long run. If it's a battery pack for a camera, that isn't good for anything else, you can carry it as an emergency pack, which will get a few photos, and that's better than nothing?

Last of all. We need to dispose of batteries and get them into the recycling containers so they don't end up in landfills.