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Canon T70

David Lyga

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I just found out that the Canon T70 has a built in battery (like CR 1220) which is used 'to store user settings'. To replace it requires partial dismantling of the camera. It supposedly lasts five years.

My question is this: I thought that it was wholly powered by the two AA cells (in addition to the CR 1225 button cell used for the data back, if needed). Thus, am I to conclude that the T70 is powered by THREE different types of cells: the two AA, the data back cell (CR 1225), and the inner cell (CR 1220)?

If this 'save user settings' wears out, how can it be replaced AND if it wears out, can the camera still be used with the two AA cells? Thank you for any information on this. - David Lyga
 
The body memory only safes somes settings. For instance a deliberately chosen ISO setting. (With the T90 there would a few more.) But in practice the loss of such memory would not be a great loss. And in any case it could be overcome by keeping the camera loaded with main batteries, as they would save such data.

The inner cells lasts much longer than expected, as they only are drained for memory protection if the camera is without main batteries.

The basic idea behind that memory cell is to protect from data loss when changing main batteries.

Thus when storing a T70 or T90 one has to decide whether to leave the AAs inside with all risks involved but then keep the memory cell fresh for cases of main batteries change, or take them out and risk the total drain of the memory cell.
By the way, the memory cell itself might be harmful on the long run too.
 
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This is what I thought because I have never had trouble with one.

I used to despise these "T" cameras because of the auto film advance, but this particular model is better than I thought. - David Lyga
 
Why not substitute that memory cell by a super-capacitator?
 
To express my ignorance: I really don't know what 'super-capacitator' is!!!
 
It is a capacittor that yields much more capacity than otherwise for such size. On the other hand they are are only available in small sizes. They are used where only a small load is applied and in normal use a regular voltage supply is given. Thus their main application is short breakage of power supply.
(For instance a bicycle dynamo not working at stop at red light and the super-cap then driving a LED in the rear light.)
 
These capacitators are of the wet type, so longevity would be an issue. A pure foil capacitator would be better in this respect, but that lacks the capacity/volume.
 
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Several EOS cameras (along with the T70, T80 and T90) have a small long-life button cell "under the hood". This is used to maintain ISO and custom function settings in the absence of the main source of power. Though scheduled for replacement at around 5 year intervals, it is not unheard of for these batteries to last more than 20 years! My EOS 1N has one such battery and remains unserviced over 23 years. When the button cell is exhausted, settings previously mentioned will be cleared on removal/changeover of the main power source, in addition to an error message being displayed when the main power source is restored (AA or 2CR5 batteries -- variable across the range of cameras).

The battery is not user-serviceable as it is soldered integral to the flexible circuit that snakes around the underside of the top cover.
 
What I do not understand in this context is that such cell is practically buffered by the main batteries. But in case these are taken off for a long period and the cell has been drained deeply, after installing the main batteries again such cell would be in the charging mode, something which by all means should be avoided with such primary cell.
 

Wow, that seems like such a poor design. Does the Canon 1V have a soldered on battery too?
 
Cameras wear out and were intended to be a consumable, replaced when new things come along. Getting 20+ years out of a battery designed to last 5 years doesn't sound too bad. On another note, does a $30,000 car come with a battery that last 20 years? All design is compromise.
 
RattyMouse said:
Wow, that seems like such a poor design.
Click to expand...

What Darkroommike said.

Plus: Most models of disc cameras had soldered-in batteries. There is a Fuji 35mm compact that got soldered-in batteries and a Olympus flash for the AX that got such. And these all are even main-batteries, not memory buffers.

And on the other hand, the concept of the SX-70 film packs is now considered wasting, back than it was considered most user-friendly.
 
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The internal battery in my Canon T90 was said by Canon to last five years as you write David, mine has been in the camera for at least 25 years and is still going strong so don't worry about it, and a camera repairer probably wouldn't charge very much to replace it.
 
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benjiboy said:
so don't worry about it, and a camera repairer probably wouldn't charge very much to replace it.
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Oh wouldn't they!?
How does $300+ sound? This is much more than the nett worth of a good, useable T90 today.
It is not a simple open-and-shut case with any of the T-series nor EOS cameras.
 
There are also Maxxum cameras which have flat round lithium "memory" batteries. The early ones require you to remove screws from a cover plate but no soldering is needed. The lithium batteries have lasted much longer than anyone would have expected. The first of these cameras is now 32 years old.
 
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