It takes around four hours for a freshly charged main battery to charge the internal backup battery. It you do that and it still doesn't charge it, you need a new internal battery. The fully charged internal battery in most of them will hold the charge for up to 3 weeks with the main battery out of the camera.
Camera either has a bad date and time battery (requires opening up the camera to replace) or it may have a short or possibly corrosion in the camera. Best bet is to just have it serviced. This is the best place for the Canons: www.CamerasAndParts.com It's all they work on and they are not expensive at all. It's who we recommend for help with these cameras.
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It takes around four hours for a freshly charged main battery to charge the internal backup battery. It you do that and it still doesn't charge it, you need a new internal battery. The fully charged internal battery in most of them will hold the charge for up to 3 weeks with the main battery out of the camera.
Camera either has a bad date and time battery (requires opening up the camera to replace) or it may have a short or possibly corrosion in the camera. Best bet is to just have it serviced. This is the best place for the Canons: www.CamerasAndParts.com It's all they work on and they are not expensive at all. It's who we recommend for help with these cameras.
You need to put a new internal battery in as the old one is not keeping the internal clock running
With most cameras, after entering the date and time, you need to press the ok/set button twice.