The Canon T90 has a small, internal 3V lithium "standby" or "backup" battery (designated B-2, type BR1225 or CR-1220, Canon part number WK1-9022-000) recommended for replacement at approximately five-year intervals. The battery lives on the third printed circuit layer, to the user's right of the prism. It powers memory for the LCDs and retains stored data when the primary (AA) batteries are removed. I understand a weakness in the battery is indicated if "ISO 100" flashes in half-second intervals on the main LCD panel.

Are there any mechanical/functional symptoms of failure of this battery? I have my hunches but I'd rather have them confirmed by someone else out there. Thanks.

-- Robert Segal (robertsegal@juno.com), November 05, 2001

Answers

Robert,As I understand it, the internal battery only provides power for the camera's memory - iso setting, frame counter, etc. The camera will still work it its bad. I ended up going to Comet Camera in Philadelphia. They gave me outstanding service. Check out their website: http://www.cometcamera.com/ They will give you a free quote. My charge, including cleaning, lube, etc. was $169.95 with 5% discount for Internet users. My problem actually was worse than you describe, ie, a totally dead camera. Good luck. Tony

-- Tony Cerbino (cerbino@HOME.COM), November 06, 2001.

Tony is right. However, you can test the battery right away. Just make sure you have film in the camera and check the ISO to see if it is correct, then remove the AA batteries for a few minutes and put them back in. Re-check the ISO, if it has changed, your internal battery is dead (same goes for the frame counter).

Also, from the Manual:

================================================================ The T90 has a built-in back-up battery which memorizes the display panel data, such as the frame counter number and the ISO film speed, when the AA-size batteries are being changed. Battery life is about 5 years. When voltage becomes insufficient, "lSO 100" will blink (at 2 Hz) on the display panel after loading batteries for normal camera operations. If the back-up battery is removed, the memory will be erased. In this case, reset the film speed. ================================================================

So the display should blink ISO 100 if the internal battery is low.

Roger

-- Roger B. Clark (rclark@dbt.net), November 06, 2001.