I have a Canon powershot A1100is dig camera. When I try to turn it on, it reads need new batteries. even if I change the batteries. Sometimes it wont even turn on. Help

This kind of problem happen because not all of AAA batteries in market are match with canon standards. so changed his mind about using disposable batteries on new models. your camera need new DC/DC board which is expensive(between 50 to 90 dollars). there is video in you tube to how replacing the board. But better suggestion is getting a new camera with chargeable battery.

Kurt- I have successfully completed a d-i-y battery door replacement on my Canon A1100IS, and I make no claims about being an "expert." My training was watching u-tube videos of guys disassembling digital cameras (other models). Here's how to open the case on the A1100is, which is not really much different than opening the case on most any compact digital camera.
Using a size #0000 phillips screwdriver (Sears sells a set of 6 minis--slotted and phillips--for $10), I removed the nine screws from the side and bottom of the case plus one inside the mini-usb cover and the one inside the battery compartment.
Then, I gently worked the front and rear of the case apart (the top of the case halves have two snap clips that hold them together. Unlike some cameras, the A1100IS does not have any flexible cable straps between its front and rear covers.
With the case halves removed, I then used a tweezers to move the straight end of the hinge spring out of its original place next to the tripod socket. That released spring pressure on the hinge and I could then easily remove the hinge pin with the tweezers.
Then, it's simply a matter of placing the replacement door's hinge/spring combo in the proper location and inserting the hinge pin to hold it there. I purchased a new door from Canon for $8.42 plus shipping). Then, I used the tweezers to position the straight hinge spring end in the slot next to the tripod socket.
The only thing left was to wipe my fingerprints off of the LCD screen and then gently replace the front and rear case halves--snapping the case's top together and then replacing the nine screws.

Hello

If the batteries are indeed new batteries and you are continuing to get this low battery warning, there is a defect within the camera. However, it may or may not be critical.

Test out a new set of batteries, if they last you a typical amount of time, the error is a false reading and can be ignored. However, if the batteries drain at an advanced rate, there is a short in the camera and it will need to be sent in to Canon for service.

Try this.

1. turn it off
2. remove the batteries and memory card
3. reinstall new batteries and the memory card
4. turn it on.

If this doesnt work it will need servecing/repair.

According to Canon, your camera needs servicing.

Make sure you are using Lithium batteries. Alkaline batteries will go dead immediately in this camera. I've tried it.

Try lithium batteries. Sometimes regular batteries even when new cannot run a digital camera.

Check the batteries, and if they are bad, replace them. If it has rechargable batteries, just get rid of them and try regular alkaline batteries. That should be the fix.

Digital cameras really are battery hogs (especially cameras that use only 2 AA's). Some brands of batteries will have problems just starting up the camera. This may be true even if they're alkaline, brand new, and just out of the package.

Recommend rechargeable NiMH batteries only for your camera. Believe Canon even states this in their user manual. Walmart sells these for around $7 for a package of four (about $15-19 for the batteries with charger). Keep in mind they'll save you big bucks in the long run over alkalines, AND they'll last for at least 100 pictures per charge (and probably many many more). You'll be very pleased with their performance, and may slap yourself for not buying them sooner. When at the store, look on the package for a power rating of at least 2500 mah.

If the above doesn't work, here's some other things to try:

http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html

Here are some simple things to try first for a camera that won't power on:
http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html