When assessing if the Hawk is fit for purpose for a particular application - a battery life estimate is invaluable.
However it can be hard to make accurate predictions given the vast array of configurations and sensors which can be fitted to the Hawk. Different sensors will have different power draws, warm up times and sampling times which make estimations difficult.
However we can make some rough estimates:
- The Hawk uses a 3500mAh LiPo rechargeable battery.
- LiPo batteries have a 1-5% self discharge rate per month - given this, the battery will self discharge (even when the Hawk is not in use) - over 20 months in the worst case (5% self discharge rate). This puts an upper limit on battery life
Approximate Upload Energy Usage
| Cost per upload connection | 4.86E-05 | Ah |
| Cost per record upload | 4.40E-06 | Ah |
The above shows the approximate energy per successful upload in good signal (i.e. no connection retries/timeouts etc)
Example
- Device with 1 x I²C sensor, which draws 30mA for 2 seconds when taking a reading
- Sampling sensor every 10 min, upload hourly
30mA for 2 sec = 1.66E-05 Ah
Monthly Sensor Draw (Ah)
30 days * 24hrs * 6 readings per hr * 1.66E-05
= 0.072 Ah
Monthly Upload Cost
30 days * 24hrs * (4.85 * 10E-05 + 6 * 4.40E-06)
= 0.0539 Ah
Self Discharge 2.5% per mth
= 0.0875 Ah/month
Months life = 3.5 / (0.0875+0.0539+0.072) = ~16 months