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Just wondering what the worst-case power consumption is on the 5V inputs for the GEM and Dashbox units and whether there are any specific concerns (ground loop on the serial?) with running them from the same supply. I note that both are 5V/2A supplies so 5V/4A should do it, but if it's more like 2A total then that makes a PCB mounted SMPS much smaller/nicer.

Rather than going with a UPS, I'd prefer to use a trick I used to do for remote-deployed telemetry gear and just run it from a 12V SLA battery, a wide input 5V SMPS and a float-mode SLA charger. Much safer and more reliable than some of the cheap UPSs that are available.

The other question I had was whether the PT needs to be 14Vac or could it be 12Vac without losing too much resolution on the voltage measurement and power calcs? Being in NZ, none of the supplied wall warts end up being a very good solution for NZ style plugs, so getting hold of a local replacement would be preferable.

JonoNZ wrote:Just wondering what the worst-case power consumption is on the 5V inputs for the GEM and Dashbox units and whether there are any specific concerns (ground loop on the serial?) with running them from the same supply. I note that both are 5V/2A supplies so 5V/4A should do it, but if it's more like 2A total then that makes a PCB mounted SMPS much smaller/nicer.

Rather than going with a UPS, I'd prefer to use a trick I used to do for remote-deployed telemetry gear and just run it from a 12V SLA battery, a wide input 5V SMPS and a float-mode SLA charger. Much safer and more reliable than some of the cheap UPSs that are available.

The other question I had was whether the PT needs to be 14Vac or could it be 12Vac without losing too much resolution on the voltage measurement and power calcs? Being in NZ, none of the supplied wall warts end up being a very good solution for NZ style plugs, so getting hold of a local replacement would be preferable.

DashBox is typically less than 5W, GEM is typically less than 1W.

The GEM needs 1A supply or less (depending on comm. module), the DashBox needs around 1.5A if using WiFi (1A if not).

Hi Ben,

Great, thanks for that info.

Any thoughts on the 14Vac vs 12Vac PT issue? Out of interest, why was a 14Vac PT chosen instead of 12Vac? They seem to be much rarer, at least for 240V input, anyway.

- Jono

JonoNZ wrote:Hi Ben,

Great, thanks for that info.

Any thoughts on the 14Vac vs 12Vac PT issue? Out of interest, why was a 14Vac PT chosen instead of 12Vac? They seem to be much rarer, at least for 240V input, anyway.

- Jono

The PT can't be swapped out. Our units are calibrated specifically to the PT we use. the 14Vac vs 12Vac may have been due to availability when they were sourced (we've been using that PT since the ECM-1240).