Glossary

Standby current

Unit mA

What is Standby current?

The current a system draws even though everything seems to be switched off: monitors on standby, alarm systems, gas detectors, radios on receive, chargers without load.

What matters about Standby current in practice?

Individually these are milliamps; added up and multiplied by 24 hours, they become one of the biggest items in the daily balance. Over a winter lay-up, half an amp adds up to well over a hundred amp-hours.

If you want to monitor remotely, you need the standby current of monitor, interface and router combined — measured, not estimated. Monitoring that drains the battery itself is worse than none.

How do you measure standby current?

Switch off all loads, disconnect the negative cable at the battery and insert a multimeter on its current range. It is easier with a DC clamp meter or with a battery monitor and shunt that also shows small currents.

How much does standby current add up to?

  • 50 mA around the clock is 1.2 Ah a day.
  • Over 30 days of standstill that adds up to 36 Ah.
  • A small battery can be deeply discharged this way during winter storage.

What helps against high standby current?

Make devices with standby individually switchable, open the battery main switch during longer standstill and deliberately fuse loads that must stay powered ahead of the main switch. Include standby current in the daily balance, for example with the battery capacity calculator.

Related terms

All terms from A to Z

Still unclear?

We are happy to explain it for your specific case.

ContactTo the Academy