# Battery Backup for the AC41

Verkada door controllers bring plug-and-play simplicity to enterprise-grade access control. The [Verkada AC41 Door Controller](https://www.verkada.com/access-control/ac41/) supports existing door hardware and card readers while enabling cloud-based access to a limitless number of doors and events across your organization.

Verkada offers the **ACC-BAT-4AH** for use with the AC41, where it can be powered by a 12V 4.5Ah, sealed lead-acid (SLA) battery as a backup power source.

![](/files/BY8S1fPM8KQyRaqRNS1Y)

## Install a backup battery to your AC41

In case of a power outage, or situations where your Verkada [Access Controller](https://docs.verkada.com/docs/access-controllers-series-overview.pdf) is powering locks, or being used in critical safety applications, we strongly recommend that you to consider a battery backup plan.

Connect the **red** lead with the positive (**+**) connector on the battery and the **black** one to the negative (**-**). The battery pack can then sit inside the Verkada AC41 case.

**Example**: Ready-to-connect red and black leads

![](/files/lWu7LZdenkCNrIaYnPbh)

**Example**: Completed installation

![](/files/y22SljF6La99Ln2yBNvi)

## Wire backup batteries to the AC41

To get double the amp hours (capacity), while maintaining the same voltage, you can connect 2 batteries in parallel (**not in series**) to provide twice as much battery capacity.

**Example**: Connecting 2 batteries in parallel

![](/files/b7QjS2wa4lw1CB85yyV0)


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