# Calculating average current draw for a intermittently operating circuit

#### DieselPete

Joined Aug 20, 2023
5
I'm running a battery powered telemetry system which provides data at x (currently 15) minute intervals.
I have a level sensor powered by the telemetry system battery which is energized for 15 seconds per data period.
The sensor has a max current draw of 100 mA.
I'm trying to figure out the number to put in this box to get an accurate Battery Life Estimate.

#### Pyrex

Joined Feb 16, 2022
214
Hi,
Iavr=100mA*(15sec/15min)=100mA*(15sec/900sec)=1.67mA

#### Ian0

Joined Aug 7, 2020
8,947
What sort of battery? Some batteries might not last that long.

#### DieselPete

Joined Aug 20, 2023
5
What sort of battery? Some batteries might not last that long.
Lithium

#### Ian0

Joined Aug 7, 2020
8,947

#### schmitt trigger

Joined Jul 12, 2010
772
Even though the average current is quite low, the battery must be able to handle the peak current bursts, otherwise the battery won’t last.

Many moons ago, in another forum there was an almost identical question to which I provided an identical answer, which the TS chose to ignore and powered his project with coin batteries anyways, with predictable (poor) results.

Hope you don’t make the same mistake.

#### DieselPete

Joined Aug 20, 2023
5
Even though the average current is quite low, the battery must be able to handle the peak current bursts, otherwise the battery won’t last.

Many moons ago, in another forum there was an almost identical question to which I provided an identical answer, which the TS chose to ignore and powered his project with coin batteries anyways, with predictable (poor) results.

Hope you don’t make the same mistake.
It's running a 4 D cell lithium pack.

#### crutschow

Joined Mar 14, 2008
33,358
It's running a 4 D cell lithium pack.
Rechargeable?
Are they connected in parallel?
What is their ampere-hour (Ah) rating?

Last edited:

#### schmitt trigger

Joined Jul 12, 2010
772
Wonderful!
You are safe.
.

#### DieselPete

Joined Aug 20, 2023
5
Rechargeable?
Are they connected in parallel?
What is their ampere-hour (Ah) rating?
Non-rechargeable.
Unknown on the other questions.
This is all the info I have. Avg. Sensor Current supplied by Pyrex.

#### crutschow

Joined Mar 14, 2008
33,358
This is all the info I have. Avg. Sensor Current supplied by Pyrex.
That gives a total required battery capacity of 56.6 Ah or 14.2 Ah per cell, witch is well within the 19 Ah I have seen quoted for lithium primary D-cells.