Daisy Chaining Device To USB Ports For Power


I am a licensed amateur radio operator in the United States. In my pickup, I use a portable amateur radio to connect to a Rugged Spot digital hotspot. The digital hotspot gets a cellular connection from a cellular hotspot in my vehicle. Right now I run separate power cables to each device. I have noticed that the Rugged Spot has four USB ports and the cellular hotspot has one USB port. Can I, or should I , "daisy-chain" one device to the other for power? If so, does it matter what order I connect them in? I have read varying numbers as far as how much power the Rugged Spot needs. I think it is somewhere between 0.5 amp idle and closer to 1 amp when transmitting or receiving. I think the recommendations is to have a source that gives at least 1.5 amp.

I am having difficulty finding numbers on the MR1100, too. I am assuming that when the device is charging the internal battery and having multiple devices connected, that it would draw the most power. The technical specifications mention that it has a USB-A port, but perhaps the intended use is more for USB tethering, than charging/powering additional devices. I can't seem to find any specific numbers on the amount of power needed.

Another thought I have had is to simply try it and see if it works. I am assuming that by not supplying enough power I won't damage anything, but who knows.





If you are planning

If you are planning to do this and are involved in amateur radio you have a concept of loss. Connecting items in series will reduce the available current by both the device requirements and any voltage drop from connections and resistance to current flow in the wire itself.

Illiterate? Write for free help.

Current capability of USB ports

I’m not certain how strictly this applies to automotive applications but in the USB 1.0 and 2.0 specs, a standard downstream port is capable of delivering up to 500mA (0.5A); with USB 3.0, it moves up to 900mA (0.9A). The charging downstream and dedicated charging ports provide up to 1,500mA (1.5A). USB 3.0 and 3.1 ports can be distinguished by a blue plastic guidance piece in the connector.

John from PA