Setting up a battery powered router for Start Sender

Start Sender is a convenient way to send the starting time from the start to Photo Finish at the finish line. The problem is that the direct communication between two devices has a limited range (30m-40m) and to cover, e.g. a 100 m race you need an external WiFi network. And that is not always available outdoors in a stadium. A solution could be to set up a temporary router, and since there might not be a power plug nearby, it should preferably be a battery powered one.

That might seem like a complicated task, but actually, it is not. Since the router doesn’t need to be connected to the internet, the configuration is pretty simple. And since many routers run on 5V you can use the very common 5V USB power banks. So what you need is:

  • A basic WiFi router that runs on 5V
  • A power bank/battery with USB
  • A USB to power plug cable

The router can be pretty simple, no need for 5 GHz or built-in modems. An external antenna or two, however, is beneficial for the range. If it is easy to set up or is preconfigured, so much better. I bought a basic Netgear N150 for less than $20 at a sale in my local electronics shop. But you can, of course, use other routers.

The cable should have a standard USB connector at one end and a power plug that fits the router in the other. In my case, it was a 5.5mm/2.1mm like this

The battery could preferable be the type of power bank that has become very popular as a backup battery for mobile phones etc. This means that buying one enables you to use it for other purposes as well. One (of many) examples.


On the bottom of my router, the label with the serial number also shows a default network name (SSID), in my case NETGEAR99, and a password. I plugged in the battery in the router and opened WiFi in the settings app on both the iPhone and the iPad. After a little while NETGEAR99 showed up as an available network, and I chose that and entered the password. That was it! I placed the router on a table and walked 100m in one direction to set up the iPhone and then 100m in the other direction with the iPad. With this set up I had no problem sending the start signal 200m with the router in the middle.

Some tips for best connection/range

  • Place the router in the middle between the two devices.
  • Place it a bit off the ground (1m-2m).
  • Try to achieve a free line of sight.
  • Run on 2.4 GHz rather than 5 GHz (range over speed).
  • Download Apples free AirPort app and turn on ”WiFi search” in the settings. You can then use it to check the strength of the network.

Note: There are some battery powered travel routers available on the market. They are NOT suitable for this purpose since their range usually is very short.