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Change Batteries

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Keller

New Member
Hello All,

I have a small reed switch alarm unit which takes 3 LR44 batteries, but these batteries deplete very quickly, so I was wondering how I can find out if it will take normal batteries such as AAA or AA or PP3. I think the LR44 batteries are 1.5V each so I think 3 X AAA may work but I do not want to blow the unit and also if possible I would like to use the unit with 2 X AAA or 2 X AA or 1 X PP3 to save space.

Do I need to use a bench power supply to work this out? And if so I will need to buy one so are there any that anyone could recommend?

Thank you.
 

EN0

Member
Hello All,

I have a small reed switch alarm unit which takes 3 LR44 batteries, but these batteries deplete very quickly, so I was wondering how I can find out if it will take normal batteries such as AAA or AA or PP3. I think the LR44 batteries are 1.5V each so I think 3 X AAA may work but I do not want to blow the unit and also if possible I would like to use the unit with 2 X AAA or 2 X AA or 1 X PP3 to save space.

Do I need to use a bench power supply to work this out? And if so I will need to buy one so are there any that anyone could recommend?

Thank you.
How much current can each LR44 battery provide? A AA or a AAA might be less. You can calculate how long the battery will last using mA hours. They should have that on the batteries specs.
 

audioguru

Well-Known Member
Most Helpful Member
Three AAA alkaline cells will last 10 times or more longer than three LR44 cells.
AA cells will last more than 30 times longer.

Maybe the circuit uses the internal resistance of the tiny battery cells to limit the current. The larger cells will not limit the current which might cause the circuit to blow up.
 

Keller

New Member
Can a multimeter be used to workout if the alarm can take AAA,AA,PP3 batteries form LR44 batteries? And if so, do I use it to work this out.
 

audioguru

Well-Known Member
Most Helpful Member
If you want a battery that lasts for a long time then you need a big battery that can supply plenty of current.
Tiny LR44 cells cannot.
A little PP3 9V battery cannot.
You were showed how AA cells and AAA cells will last a lot longer.

A multimeter can measure the circuit's current which can be used in a simple calculation of how long a battery will last.
 

Keller

New Member
Because I want to workout what batteries the small reed switch alarm will take, I gather that from the answers given I will need a bench power supply.

Any tips on what type of bench power supply I should get.
 
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