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Battery Voltage Drop Off

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roadkillbunny

New Member
Hi,

I heard that the voltage drop-off point is when the battery stops suppliying battery. But when I did my experiment (9V battery connected to a resistor) and got under 4V what is the drop-off for enengizer the LED still lit. I also tried it when I was at around 1V.

One more question. When I disconnected the battery overnight, I found that the voltage increased. Can you point me please to a site that explains why this happens?

Cheers,
Karol Krizka
 

Nigel Goodwin

Super Moderator
Most Helpful Member
roadkillbunny said:
Hi,

I heard that the voltage drop-off point is when the battery stops suppliying battery. But when I did my experiment (9V battery connected to a resistor) and got under 4V what is the drop-off for enengizer the LED still lit. I also tried it when I was at around 1V.
The point where you decide the battery is flat varies on your application, alkaline and NICAD's drop off very suddenly at the end of their life.

I would probably consider a 9V battery flat at 7-8V, if it's feeding a 7805 regulator, 8V is probably where the 5V rail will start to drop.

You can view some discharge tests I did years ago at http://www.lpilsley.co.uk/viewbatt.htm.

One more question. When I disconnected the battery overnight, I found that the voltage increased. Can you point me please to a site that explains why this happens?
I couldn't tell you the chemical reason why it happens, but if you leave a battery it will recover very slighty - for a remote control it may allow you to get one extra button press. But it is more a question of it's voltage recovering, rather than it's current providing capacity.[/url]
 
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