Extending battery life

Hi there everyone!

I'm powering my project with an 11.1V battery. It includes an Arduino Mega 2560, 4 digital 7-segment display, a 12 key keypad, and a single Sparkfun Car Horn (rated at 12V, but It sounded off fine with 11.1V).

I did some 30 minute extended tests to test the battery life, and the battery only lasted about 2 tests before dropping to about 8 volts. The 7-segment display is on the entire 30 min, as well as the Arduino, but nothing else is running. The Arduino is running a timer program (which is displayed on the 7-segment) with quite a few switches and loops.

I'm wondering if there's a way to expand the battery life.


Use a bigger battery. Bigger in Amps, not voltage.
I use a 7.2 Volt 3.3 Amp RC car battery. Lasts a long time.
You can get 5 Amp batteries now.

How big is your battery in mAh or Ah?

I find it hard to belive the battery would be dead after only two thirty minute tests, with only Arduino and LED display running. The display would be about 20mA continuous and the Arduino probably about 40mA. So assuming the circuit is taking 100mA continuos (60mA plus accounting for an occaisonal horn honk (which would draw upward of 8 amps per part specs)) a 1000mAh battery would last 10 hours not only 1 hour.

So maybe the LiPo was not fully charged? Or maybe the horn is being activated a lot. But if only Arduino and display running seems odd, unless you are using a very small battery capacity.

A car horn of 8A ?

The battery is a 1650mAh battery (again, 11.1 volts). I'm recharging it right now and will run more tests to see if it runs more.


You should try putting a multimeter (in current sensing mode) between positive terminal of battery and power to Arduino to measure the total current draw.

Just be aware you may need to be in mA range to effectively see current when horn is not on, but should switch to 10A mode or higher when activating the horn as it draws 8A and you don't want to damage of blow a fuse in your multimeter.

You should take that running current and divide 1650 by that number and you will get how long it should last. So if you are drawing 1650 mA continuous it should last 1 hour.

But like I said before I would be shocked if your drawing any more than 100mA if all you are powering continuously is the Arduino and a seven segment display.


Aussie dealers are the worst on ebay lol

AU $1,121.99 for a 2000 mAh battery? What is that, solid silver?
And it's only a Ni-Mh battery. That's $1044.74 US

The worst part is it says two were sold...

The worst part is it says two were sold...


or is that $) ?