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HP Forum Archive 19

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current draw from CR2032 coin cells
Message #1 Posted by Eric Smith on 2 Nov 2010, 11:22 a.m.

TI's applications engineers for Bluetooth low energy products studied capacity of CR2032 coin cells in pulsed operation at 15mA peak and 30 mA peak. CR2032 coin cells are usually rated for 15mA peak current. The best coin cells showed very little capacity degradation compared to constant current. This is reported on their blog and they've written a white paper.

Their measurements also showed how much variation in capacity there is between vendors, with Sony, Panasonic, and Maxell being the highest they measured, and GP and two no-name brands having only about 50% of the capacity of the better brands.

      
funny sidenote (history repeating)
Message #2 Posted by Frank Boehm (Germany) on 2 Nov 2010, 12:22 p.m.,
in response to message #1 by Eric Smith

I think Mr. Sinclair was first to use this pulsed power to save button cell battery life - sporting a TI Chipset - within the Sinclair Executive. TI said, it couldn't be done. Back then :)

      
Re: current draw from CR2032 coin cells
Message #3 Posted by Egan Ford on 2 Nov 2010, 12:30 p.m.,
in response to message #1 by Eric Smith

I hope this means that you or someone else will create an RPN calculator with BT. I was actually looking for one yesterday. I would really like a 30b with a BT send function so that I can quickly send the results to my current open application on my desktop.

BT calcs exist and they double as numeric keypads, but none sport RPN.

            
Re: current draw from CR2032 coin cells
Message #4 Posted by Eric Smith on 2 Nov 2010, 6:04 p.m.,
in response to message #3 by Egan Ford

I really only brought this up because it had useful information about coin cell capacity, and not for anything about Bluetooth.

If you had an RPN calculator with Bluetooth support, what uses would you expect the Bluetooth to support?

                  
Re: current draw from CR2032 coin cells
Message #5 Posted by Egan Ford on 2 Nov 2010, 6:47 p.m.,
in response to message #4 by Eric Smith

Quote:
If you had an RPN calculator with Bluetooth support, what uses would you expect the Bluetooth to support?
Two functions. One, act as a BT keypad for my Mac. Two, have a send button to send the results as keypad input to my Mac. They exist today, but without RPN.

Now, if a programmable RPN had BT, then it would be a crime to not allow backup and restore via BT.

The above would require two BT profiles. If a serial profile was added then programmable I/O becomes a possibility.

            
Re: current draw from CR2032 coin cells
Message #6 Posted by hpnut on 4 Nov 2010, 12:32 a.m.,
in response to message #3 by Egan Ford

Quote:

BT calcs exist and they double as numeric keypads, but none sport RPN.


I would be the first to buy an RPN USB numeric keypad :-)


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