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Old Nov 27, 2005, 4:17 AM   #1
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Hello everybody!

I am about to take a trip in a month and I want to buy extra memory and an extra battery.

I have a Sony DSC-T1 5.1MP still with the original 32MB memory stick and the battery that came with it.

I am just noticing that many batteries have different Mah and I believe the bigger the number the longer the battery can hold its charge, right?

my other quesition is Can I determine the amount of hours of charge the battery can hold by looking at the Mah? Also what does 100% memory free mean?


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Old Nov 27, 2005, 10:28 AM   #2
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Hello Eljami,

The battery manufacturers rate the capacity of their batteries under more "ideal" conditions than you camera use. This means that they can end up with ratings higher than you observe in actual use.

The Amp Hour rating (or milli Amp Hour) gives you an idea of the capacity of the battery.

If you camera consumes 100 mA for every shot, a 750 mAh battery should give you about 7.5 shots. If you had a 1000 mAh battery, you could get 10 shots.

The memory free comment refers to the change in battery chemistry. Nickle based chemistry, if repeatedly charged and discharged to exactly the same state of charge, will exhibit a voltage suppression that has been termed the "memory effect."

Since both the Nickle and Cadmium chemicals exhibit this effect, the manufacturers claimed that the memory effect was no longer a problem when the introduced NiMh batteries. The fact is that it is reduced by half, however since most people do not use batteries exactly the same each time, it does not show up.

Li-Ion does not have this problem at all. This means that you can go out and take 5 shots every day and recharge every night and still have full battery capacity if you need it. As a matter of fact, you will get more life from your Li-Ion batteries if you recharge them every day, rather than running them completely down each time.

Tom
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Old Dec 1, 2005, 12:50 AM   #3
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SilverFoxCPF wrote:
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If you camera consumes 100 mA for every shot, a 750 mAh battery should give you about 7.5 shots. If you had a 1000 mAh battery, you could get 10 shots.
Tom
Not exactly, unless it takes an hour for each shot. A 750mAH battery should provide 10mA of current for 75 Hours, or 100mA for 7.5 Hours - continuously. The current used by cameras wil vary widely, depending on activity. Generally, starting up and focussing use the most. Between shots, when cam is 'idling', there is very little drain on the battery.

All other things being equal (and they never are), a 1000mAH battery will last about a third longer than one of 750mAH.

brian
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Old Dec 1, 2005, 10:43 PM   #4
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Hello Brian,

Oops... It is obvious that you shoot much faster than I do...

Yes, we must factor time into the equation.

I'll just claim a "senior" moment... Thanks for catching it and setting us down the correct path.

Tom
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Old Dec 4, 2005, 1:35 AM   #5
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dont do as i have done 200 hr later with several chargers just go buy some energizer 2500mah after 3 or 4 discharges they will do you a fine job. also there are some more good batetery out there Look at the battery shootout for info . on a charger look at the lacross bc900 also the next 50 model

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