What is a “sleeping” battery?
In layman’s terms, a sleeping battery is a battery that does not have any voltage coming out of the terminals on top. It is in a protection state that prevents discharge.
The batteries have a device inside called a BMS (battery management system) that is responsible for making sure that the battery pack does not reach a condition that damages the cells inside. This management system is what keeps things in check to ensure you can keep your battery in operation for a long time without excess wear or degradation. If the battery is being pushed outside of its safe operating parameters, the BMS will prevent charging or discharging to protect itself.
What causes a battery to go to sleep?
The most often occurring situation that cause a battery to go to sleep are: draining the battery too far and drawing too much current from the battery.
How to recover a battery that has gone to sleep?
Simple – just apply charge to the battery.
Not always so simple – some chargers require there be voltage on their battery connection terminals in order for them to start charging. This means some smart chargers may not be able to charge the battery. Read below for more info to help get out of this state.
If you can’t recover the battery, and have the bluetooth model battery and purchased after July 2022, then you can confirm the cause of shutdown by connecting to the bluetooth app.
- Click the menu in the top corner and navigate to the “PROT state” page.
- Check if “Cell Overdischarged”, “Total Overdischarged” and/or “Overdischarged” are illuminated green – if they are, then your only option for recovering is applying charge to the battery.
- If “Cell Overtemperature” or “MOS Overtemperature” is green, just wait for the battery to cool down and it will reset on its own.
- If “Discharging Overcurrent”, “Short Circuit” and/or “Overcurrent” are illuminated green, this means you drained too much current from the battery. Remove loads before proceeding.
- In the menu again, navigate to the “Basic Settings” page and type in password “200010”. Click on the “Recovery” button. You have 3 attempts with this button – if you haven’t removed the load the excessive loads on the 3rd try, then the battery will be locked out and the only way to recover it is by applying charge.
- If this button does not work on the first try, disconnect everything from the battery and do an idle calibration.
Which chargers can recover a sleeping battery?
If you commonly run into an issue where your batteries are shut down, and you want a charger that can just be plugged in, turned on and get you going, then this list is going to serve you well. This list is not exclusive, so if you have any suggestions feel free to let us know.
- Victron BlueSmart chargers – the IP22, IP65 and IP67 versions.
- Victron SmartSolar MPPT charge controllers (all models)
- Victron Multiplus inverter/chargers
- WFCO converter / battery chargers (all models)
- A simple bench power supply set at 14.6v
- Progressive Dynamics converter/chargers *
*Note: most models will work, but select SKUs are not able to recover the battery. If the charger does not output voltage until a battery has been connected, then it will not be able to reactivate the battery.
Which chargers CAN’T recover a sleeping battery?
- AIMS power 12/24v and 36/48v converter chargers
- AIMS Power inverter/chargers
- Magnum Inverter/charger units
- Midnite Solar charge controllers
- Outback FlexMax solar charge controllers
- Voltronic All-In-One inverter/charger units
What to do if you have a charger that can’t recover your battery?
Jump start it like a car! By connecting jumper cables to a partially charged or full battery, you can get enough voltage to the charger to get it started, and from there the charger outputs enough voltage to get the battery reactivated and charging like normal.
Our Distributor, Current Connected provided a video explaining how to recover an over-discharged battery with one of the AIMS chargers that is not designed to wake up a sleeping battery. This can be used as a visual reference to help you.