When i try to charge my battery the red light keeps flashing

If it is a Makita battery charger it means the battery has died or has an internal fault, or is too hot.
Take it out of the charger, let the battery cool down if required and try again.
If both red and green lights are flashing, try a different battery.
It might be time for a replacement battery.

A red light indicates the charger is charging the battery, an amber light means it has switched from fast rate charging to trickle to keep the battery topped off, and green would mean the battery is completely charged. But don't be fooled waiting for green, many times the charger will only be on green for a moment before changing to amber and keeping the battery topped off.

Flashing can be a sign of a problem on some chargers.

A rapid flashing red can on some chargers indicate a bad or shorted battery, or a bad battery contact in the charger itself. If in question, try a different battery on the charger or compare with another charger to determine if the blinking is normal.

Best regards.

I had the same issue -- charged it for days and still red light flashing. I was ready to break it open and see if I could replace battery. Then I looked on the opposite end of the charger and seen a little round hole thingy. I put the end of a pen in there and pushed it twice and -- the red light went away . Plugged the charge in and steady red then purple and now blue. Looks like that is a reset ..Try it -- it worked for mine.

new battery flashing red light means bad battery

Dust getting in the charger is a problem, Try blowing it out with a moisture-free dust remover, found at most any store. Green flashing means improper power, due to dust or power from the outlet, try a differant wall outlet. Red flashing means the charger or battery is to hot and must cool down before it will charge. The charger will not charge a battery if the lights are flashing. Solid Red light means it is charging and solid green light means it is charged. Plug the charger in first before putting the battery on the charger. If the charger has been droped or hit the floor the coil inside could have broke loose and dammaged the charger requiring it to be replaced.

How old is the battery? Keep in mind they aren't meant to last for more than a year or two, regardless of how often they're used. Generic replacements are actually inexpensive these days. Here's some from Amazon:

http://www.amazon.com/s/ref=nb_ss_e?url=search-alias%3Delectronics&field-keywords=s880+np-20+battery&x=12&y=22

It's a known Fault with the NP-20 battery don't order one and pay for it, ring or e-mail casio customer service they should send you one out for free!! When you receive the new one don't let it die, make sure and keep it partially charged at all time or the charger won't recognize it. Really casio should recall this battery but for some reason they insist on replacing faulty batteries with more faulty batteries!??!

I've had this happen to me in the past.  It generally means that your charger has died, or your battery's connections need to be cleaned.
Try using a Q-tip and some Windex to clean the contacts on the battery.  Let it charge overnight. 
If that doesn't work, and you're still under warranty, contact Casio. They replaced a charger I had a few years back, no hassle.  They know it's an issue, and are pretty quick about replacing the defective one.
If you're not under warranty, a Casio battery charger can be found on eBay for a few dollars.

i have same camera.. but i dont think this is a problem.. while charging light keep flash.. when it completes charging it shows u solid red light..

Casio says:

Red blinking light = defective battery

No flashing light = possible defective charger.

What you can do is send all your stuff into casio and they will test everything for you and see what they could replace for you.