Battery-powered access points are typically used for site surveys. The engineer uses a professional battery pack with 802.3at/802.3bt PoE output which delivers power to the AP via Ethernet. I do love professional battery packs. Accelerator and VenVolt are your friends. I haven’t had a chance to test either one, but I’ve seen them in very capable hands of others.
Now, when you don’t have a PoE battery pack by hand and want to achieve a similar outcome, this tip might help you.
Use case and requirements
I am building a compact pocket-sized package consisting of an AP, small battery pack and I want to achieve at least 2-3 hours of battery life.
What am I going to use it for? I need to temporary install (and hide) an AP which we will then locate during my presentation using WLAN Pi Go – a mobile Wi-Fi tool which snaps magnetically to iPhone.
In the coming weeks, I am going to use the same setup for point-to-point Wi-Fi testing. So, this will help us kill two birds with one … battery pack I guess 😊
Solution
Cisco Meraki APs do have 12V DC input via barrel jack 5.5 mm x 2.5 mm connector. I then researched USB-C battery packs with USB Power Delivery 12V output. This part is important! Not all USB-C packs support this output voltage.
Finally, I found a USB-C PD cable which negotiates 12V with the battery pack, and outputs 12V DC to the AP’s barrel jack input.
I run the APs in Site Survey mode. To enable this mode connect to this AP’s SSID in normal cloud-managed mode, and browse to the Local Status Page (LSP). It is powered by a web server running locally on the AP. Access LSP via http://10.128.128.126/ while associated to the AP. I do recommend MR32 or newer software release which has some great survey mode enhancements.
Now, it is time to test and see if we can break things. How long does the battery last for? We get 6+ hours of battery life.
Let’s appreciate that the battery pack is nearly 7x smaller in volume than the already compact access point.
Kit list
- Cisco Meraki MR20, MR78, or other AP which accepts 12V barrel jack input. Newer Cisco Wireless APs do have a barrel jack connector but they require 54V input. This approach won’t work.
- USB-C PD cable with 5.5 mm x 2.5 mm barrel jack connector
- Anker 533 Power Bank PowerCore 30W or any other battery pack – just make sure it supports USB PD 12V output, not all do
It doesn’t stop there
Many other devices like routers, modems, home automation hubs use the same barrel jack connector and take 12V input. The main fact to keep in mind is that this Anker battery pack can output up to 12 Volts at 1.5 Amps on its USB-C port. We don’t want to overshoot these 18 Watts.