Which is the most efficient battery for Arduino Uno?

Well there is no shield pin named Vcc so you either mean the 5V pin or the Vin pin?

As everything seems to be being powered by the 9vdc battery, then the best measurement would be to break the positive wire from the battery and place your series current meter on that wire, that would give you the total current draw for the complete project, arduino board + your breadboard mounted stuff.

Yup I meant the Vin pin.

hmmm my 9V battery is connected to the arduino via a jack barrel adapter..So I have to remove the wire from the jack barrel adapter? That would be quite tedious to remove and put it back..

Or is there a way to measure the current drawn by the components only? I have only have a LCD display and 2 pushbuttons connected to the arduino..

kurtselva:

Well there is no shield pin named Vcc so you either mean the 5V pin or the Vin pin?

As everything seems to be being powered by the 9vdc battery, then the best measurement would be to break the positive wire from the battery and place your series current meter on that wire, that would give you the total current draw for the complete project, arduino board + your breadboard mounted stuff.

Yup I meant the Vin pin.

hmmm my 9V battery is connected to the arduino via a jack barrel adapter..So I have to remove the wire from the jack barrel adapter? That would be quite tedious to remove and put it back..

Or is there a way to measure the current drawn by the components only? I have only have a LCD display and 2 pushbuttons connected to the arduino..

Can't you just unsnap the positive button from the battery, rotate it 180 degrees with the negative post still attached and wire your current meter leads in series from the battery positive to the battery connector positive?

One needs to think outside the box once in awhile. :smiley:

Lefty

dc42:
To measure the current, connect your multimeter in series with the 9V battery. To get 10 days battery life, you'll need a battery capacity of at least 10Ah or so even if you are not powering anything else. A 6V SLA battery is probably the best option.

If you're serious about getting long battery life, you should move to a standalone atmega328p design (to avoid the current consumption of the USB-to-serial converter), consider using a clock frequency lower than 16MHz, and put the processor in sleep mode when nothing much is gong on. Then you will be able to use a smaller battery.

The arduino will be connected to a LCD display and two pushbuttons. And the a servo is also connected but it has its own external 6V battery supply. So basically, the arduino only powers the LCD display..So if this is the case, would a 2500mAh battery capacity be sufficient?

Can't you just unsnap the positive button from the battery, rotate it 180 degrees with the negative post still attached and wire your current meter leads in series from the battery positive to the battery connector positive?

Wow ok. Why didn't I think of that :blush:

Haha

kurtselva:

Can't you just unsnap the positive button from the battery, rotate it 180 degrees with the negative post still attached and wire your current meter leads in series from the battery positive to the battery connector positive?

Wow ok. Why didn't I think of that :blush:

Haha

Because you were stuck inside that box I mentioned. :smiley:

Lefty

kurtselva:
The arduino will be connected to a LCD display and two pushbuttons. And the a servo is also connected but it has its own external 6V battery supply. So basically, the arduino only powers the LCD display..So if this is the case, would a 2500mAh battery capacity be sufficient?

No. The Arduino Uno draws about 42mA, the LCD draws about 5mA plus whatever current you run through the backlight. So that's 47mA even with the backlight turned off. Your 2500mAh battery will last (2500/42) = 53 hours, so just over 2 days - and that's without the backlight illuminated.

On the other hand, a standalone atmega328p running at 8MHz draws about 5mA, giving 10mA in total, so just over 10 days from a 2500mAh battery (without backlight). For longer battery life, you can use a lower clock frequency, or put the microcontroller in sleep mode and turn off the power to the LCD when it is not in use.

No. The Arduino Uno draws about 42mA, the LCD draws about 5mA plus whatever current you run through the backlight. So that's 47mA even with the backlight turned off. Your 2500mAh battery will last (2500/42) = 53 hours, so just over 2 days - and that's without the backlight illuminated.

On the other hand, a standalone atmega328p running at 8MHz draws about 5mA, giving 10mA in total, so just over 10 days from a 2500mAh battery (without backlight). For longer battery life, you can use a lower clock frequency, or put the microcontroller in sleep mode and turn off the power to the LCD when it is not in use.

Oh no.. What my program does is it rotates a servo motor at MOST 4 times a day at 6 hourly interval and the user uses the LCD to input some information such as the number of times to rotate per day, number of days, etc. So if I put the arduino to sleep mode after the program is made to run, the program will stop am I right?

You can use sleep mode, and have the mcu wake up at regular intervals (so you can turn the servo) and also whenever the user presses a button (so that you can turn on the lcd and respond to user commands). However, if you use your Arduino Uno, then although you can put the atmega328p to sleep, the USB-to-serial converter will still be drawing power. That's why I said you need a standalone system.

You'll either need to power your mcu directly from a 3V to 5V battery (e.g. 3 x AA cells, if 4.5V signal is enough for your servos), or you'll need to use 6V or more battery and a micropower 5V regulator such as the MCP1702.

dc42:
You can use sleep mode, and have the mcu wake up at regular intervals (so you can turn the servo) and also whenever the user presses a button (so that you can turn on the lcd and respond to user commands). However, if you use your Arduino Uno, then although you can put the atmega328p to sleep, the USB-to-serial converter will still be drawing power. That's why I said you need a standalone system.

You'll either need to power your mcu directly from a 3V to 5V battery (e.g. 3 x AA cells, if 4.5V signal is enough for your servos), or you'll need to use 6V or more battery and a micropower 5V regulator such as the MCP1702.

But won't the servo require continuous power and control pulses to hold any load they might it be trying to maintain? If so I don't think any 'sleep' mode would work well?

Lefty

dc42:
You can use sleep mode, and have the mcu wake up at regular intervals (so you can turn the servo) and also whenever the user presses a button (so that you can turn on the lcd and respond to user commands). However, if you use your Arduino Uno, then although you can put the atmega328p to sleep, the USB-to-serial converter will still be drawing power. That's why I said you need a standalone system.

You'll either need to power your mcu directly from a 3V to 5V battery (e.g. 3 x AA cells, if 4.5V signal is enough for your servos), or you'll need to use 6V or more battery and a micropower 5V regulator such as the MCP1702.

Hmmm.. I guess I'll just have to live with the 9V battery for now. Cos I need to present my project in school soon and I wont have time to come up with the standalone system so soon..

So comes another qn: is a 9V battery better or a 3 AA battery connected directly to the 5V pin of arduino better?

retrolefty:
But won't the servo require continuous power and control pulses to hold any load they might it be trying to maintain? If so I don't think any 'sleep' mode would work well?

I thought servos only move when you send them pulses?

kurtselva:
So comes another qn: is a 9V battery better or a 3 AA battery connected directly to the 5V pin of arduino better?

3 x AA will last a lot longer. But check that your LCD works OK on 4.5V.

dc42:

retrolefty:
But won't the servo require continuous power and control pulses to hold any load they might it be trying to maintain? If so I don't think any 'sleep' mode would work well?

I thought servos only move when you send them pulses?

Lack of servo pulses but with power still applied to a servo is simply a undefined state for any servo, they just are not designed to perform any specific action in that state, it may move un-commanded or not move. They are designed under the assumption that if they are powered up there will be continuous position pulses being sent, even if to just maintain the present position.

Also without servo power all 'holding torque' is lost and depending on external load on the servo and the friction value of the servo's gear train the servo can lose position as the external load forces movement.

Lefty

dc42:

kurtselva:
So comes another qn: is a 9V battery better or a 3 AA battery connected directly to the 5V pin of arduino better?

3 x AA will last a lot longer. But check that your LCD works OK on 4.5V.

Sounds good. So for a current drawing abt 50mah from the arduino and the LCD, how long more would the 3 x AA battery power last as compared to the 9V battery?

How much mAh rating does 1 AA alkaline battery usually have? Tried searching online but the values are ranging from abt 700mAh to as much as 2000mAh..

And would it be better to use rechargeable batteries or normal ones?

http://data.energizer.com/ will give you typical capacities for alkaline batteries and the lithium versions of standard batteries. If you use rechargables, bear in mind that NiMH cells are about 1.2V not 1.5V, so you probably want to use 4 of them instead of 3.

dc42:
http://data.energizer.com/ will give you typical capacities for alkaline batteries and the lithium versions of standard batteries. If you use rechargables, bear in mind that NiMH cells are about 1.2V not 1.5V, so you probably want to use 4 of them instead of 3.

So am I right to say this:

Say I am using 4 x 1.2 V AA NiMH battery (2000mAh each). So total is 8000mAh and hence the battery would last for 8000/50 = 160 hrs which is slightly more than 6 days?

No, the batteries are in series, so the capacity will be 2000mAh.

dc42:
No, the batteries are in series, so the capacity will be 2000mAh.

Oh darn. But normal alkaline AA batteries has abt 2500mah, compared to 9V batteries that has only abt 600mah..

So I'll just go with 3 AA alkaline batteries, as it would at least be able to work for 2 days..

Just another doubt to clarify: the 4.5V supply wire has to go to the 5V pin or the Vin Pin of the arduino?

Oh no! Just checked the datasheet for my LCD display and it needs 5V supply.

So can I use 4 AA battery and connect it to the power socket in the arduino? WIll it loss too much power due to the 5V regulator heat dissipated?