Installation Instructions

EE-213R Rev 0
9
6 Electrical Specifications
6.1 Electrical Characteristics
Conditions: Operating voltage 3.0V unless otherwise specified
The ESL is in sleep mode almost the entire time. It only wakes up at regular intervals (called the
poll time) and then it transmits a poll, which is essentially a request for data, to the base station.
When the base station has no data to send it will acknowledge 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 interval will decrease the power consumption but will increase the
response time.
Even though the minimum poll rate is configurable, the actual poll rate is dynamically increased
if necessary. A base station can handle the polls from 25 ESL’s per second, so if you have e.g.
1000 ESL’s, the minimum poll rate will be increased to 40 seconds.
6.2 Battery
The power is supplied to the ESL by 2 CR2450 batteries:
• Nominal capacity: 1200 mAh
• Nominal voltage: 3.0 V.
• Maximum self-discharge rate: <1% per year
• Battery life: 7 years minimum (Update frequency: 4 times per day, poll time 20 seconds). A
more detailed set of conditions is listed in the table below.
The battery life is made up of several factors. During transmission e.g., the current consumption
is much higher than when the ESL is sleeping. The table below shows the various factors that
make up the entire current consumption, plus the conditions under which the lifetime calculation
was done.
Factor Conditions Correlation * Influence **
Data communication
Poll 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
Yes
20%
No connection with base station
(Out of range or 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 under ‘Conditions’ increases (Yes)
or decreases (No) the battery life of the ESL.
** The influence shows the percentage of the specified factor on the entire current consumption.
Parameter Unit Remarks
Operating voltage 1.9~3.3 V Two CR2540 Lithium primary batteries
Sleep current <1 µA When the transmitter and receiver are idle
Minimum poll interval >= 20 seconds See below