EE-290
V-0.4
7 Electrical Specifications
7.1 Electrical Characteristics
Conditions: Operating voltage 3.0V unless otherwise specified
The ESL is in sleep mode almost the entire time. The device wakes up at regular intervals
(called the poll time) and it then transmits a poll request to the base station. When the base
station has no data to send, it acknowledges the poll after which the ESL immediately goes
back to sleep. The minimum poll rate is configurable and is set to 20 seconds by default. A
higher poll rate will decrease the power consumption but will increase the response time.
7.2 Battery
The power is supplied to the ESL by 2 CR2450 batteries:
• Nominal capacity: 1200 mAh (two times 600mAh)
• Nominal voltage: 3.0 V.
• Maximum self-discharge rate: <1% per year
• Usable time: 7 years minimum (Update frequency: 4 times per day, poll time 20 seconds)
The operating time of the batteries is based on any of the following factors that influence the
battery life:
Factor
Default values and
estimated averages
Correlation *
(Higher is better)
Influence
Polling for data &
reporting settings
Interval: 20 seconds
Retransmissions: 10%
Report ratio: 1 to 39
Yes
No
Yes
61%
Display updates
4 updates per day
Temperature: 15-25° C
No
No
20%
Out of range /
base station OFF %
Not connected: 2%
Number of channels: 5
No
No
4%
Sleep time
99,9%
Yes
9%
Battery self-discharge
1 % / year
No
6%
* The correlation shows whether increasing the listed value increases or decreases the power
consumption of the ESLs.
For example:
• Increasing the poll interval lowers the power consumption
• Turning off the base stations increases the power consumption
• A lower operating temperature increases the power consumption
• More display updates per day increase the power consumption
Parameter
Typ
Unit
Remarks
Operating voltage
2.3-3.3
V
Lithium primary battery
Sleep current
2-5
µA
When the transmitter and receiver are idle
Poll time
>= 20
seconds
See below
9
