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Topic: Coin cell (Read 5139 times) previous topic - next topic

abed443

Hi,

     I am using two PANASONIC - BR-2032/HFN - CELL, LITHIUM COIN, 3V (190mAh) to power up andruino and alpha numeric LCD.
Before connecting to the circuit, the voltage generating from the coin cell is 5.5v. The voltage generating from the coin cell and supplying to andruino and lcd  is approx 0.7V.  I am unable to understand why the voltage is going down to 0.7V.

                        Please tell me whether i have to use coin cell of 1000mAh battery capacity or any other option. I cant use AA or AAA batteries in my project.

Thanks and Regards.

abed443

Hi,

     I am using two PANASONIC - BR-2032/HFN - CELL, LITHIUM COIN, 3V (190mAh) to power up andruino and alpha numeric LCD.
Before connecting to the circuit, the voltage generating from the coin cell is 5.5v. The voltage generating from the coin cell and supplying to andruino and lcd  is approx 0.7V.  I am unable to understand why the voltage is going down to 0.7V.

                        Please tell me whether i have to use coin cell of 1000mAh battery capacity or any other option. I cant use AA or AAA batteries in my project.

Thanks and Regards.

pito

Quote
Before connecting to the circuit, the voltage generating from the coin cell is 5.5v.

That is too low for fresh batteries, you have to read 6V.

Quote
The voltage generating from the coin cell and supplying to andruino and lcd  is approx 0.7V.

Maybe your batteries are used one and empty. Moreover, those batteries are intended for currents of few mAps, so use rather the AA cells if possible.

abed443

Hi,

  Thanks for reply.

  i used new coin cell and generating power of 6V approx, but when i connect adruino and lcd, voltage is dropping to 0.7v.

  I cant use AA or AAA batteries because my project target is to make  my module very small.

Please help me.

Thanks

kf2qd

Coin cells are low current devices. They can't supply enough current to power the Arduino. Might have to use 6 or more in parallel to supply enough current. Would be better served with AA's or AAA's., but they will discharge rather quickly.

john1993

i use those same cells with arduino CHIPS and lcd no problem. i use just one though and battery life is not exceptional. either arduino BOARD or your lcd is apparently a power hog . you cannot have a bright backlight with batteries that small.

ralphd


Coin cells are low current devices. They can't supply enough current to power the Arduino. Might have to use 6 or more in parallel to supply enough current. Would be better served with AA's or AAA's., but they will discharge rather quickly.

The arduino can certainly be powered off a couple coin cells.
https://www.sparkfun.com/tutorials/309
An LCD without a backlight should be no problem either.

Paul__B


I am using two PANASONIC - BR-2032/HFN - CELL, LITHIUM COIN, 3V (190mAh) to power up Arduino and alpha numeric LCD.


And does this LCD happen to have a backlight?


Before connecting to the circuit, the voltage generating from the coin cell is 5.5v. The voltage generating from the coin cell and supplying to Arduino and lcd  is approx 0.7V.  I am unable to understand why the voltage is going down to 0.7V.


Numbers are wrong.  The resting voltage of lithium button cells is 3.3V - unless there is something very odd about the particular ones you cite - so two of them should be giving 6.6V, which is too high a voltage to supply the Arduino anyway.


Please tell me whether i have to use coin cell of 1000mAh battery capacity or any other option. I cant use AA or AAA batteries in my project.


If you are not using a backlight, then you need the version of the LCD which runs on 3.3V (it has an internal charge pump) and you run it and the Arduino on one cell.  Your working time on that cell will be about 12 hours.

If you are using a backlight, you need to use AAA or preferably, AA batteries (and a circuit to switch the backlight on only when needed).  This is not negotiable.

Coding Badly


@abed443, do not cross-post.

MarkT

Lithium coin cells (3V) are often rated at 1mA or less - totally inadequate for this purpose.
They are designed to produce microamps for years, and hold charge
in storage for 10 to 20 years  (about the only battery chemistry that can).  They are used
in calculators and watches, and RTCs.  You can power an ATmega328 from one of
these if you run it at a much lower clock frequency than the standard Arduino, but
at 16MHz it draws too much current.  You'd need a bare-bones board or Pro Mini
or some board without USB->serial chip (which itself uses as much current as the
ATmega328!)  The CR32016 is a common example.

Alkaline coin cells (1.5V) are able to generate 50mA or something like that, which is
enough, but you'll need 2 or 3 in series to get enough voltage.  They hold charge for a
few years at most.  They are found in LED torches, small toys etc.  The LR44 is a common
example.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

cld_1

You might find the following link useful for information on the various chemistrys used in coin (or more broadly 'button') cells, available sizes and typical applications:

http://en.wikipedia.org/wiki/Coin_cell

The standard numbering system used is also explained enabling different types of cells to be easily identified.



john1993


Lithium coin cells (3V) are often rated at 1mA or less - totally inadequate for this purpose.


this is not really true. you are confusing nominal discharge rating required for full capacity usage with actual maximum current capability. ie the most common cr2032 will actually supply an  amp or more as can be quickly verified with a dmm (make sure you put it on the 20a unfused range). it is fully capable of driving small motors.  as mentioned above, it will power a low current application like arduino+lcd for a long time. you wont get the full 200mah out but pretty damn close.

Excester

To get enough current from that small battery you could actually use something like Joule's Thief circuit.  :D

ralphd


To get enough current from that small battery you could actually use something like Joule's Thief circuit.  :D

Not really; the joule thief is a voltage booster.

cjdelphi

You might want to take a look at CR123 cells... (camera lithium batteries)

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