cerbo analog input specification

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pmolettiere asked Oct 14, '22

cerbo analog input specification

I see in the manual that the Cerbo analog inputs are 12v resistive, and can be configured to use US, European or custom resistance ranges, all within 0Ω to 264Ω.

Does the Cerbo apply any sensing voltage to the inputs itself? ie., if I put a volt meter across the terminals for an analog input, will I read any input? Likewise, if I put a resistor, say, 180Ω across the terminals, will I read any voltage on the input?

If any voltage is applied by the Cerbo, what is the max current the Cerbo will allow to flow in the resistor example above?

Thanks for any help!

cerbo gx input current analog

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Kevin Windrem answered · Oct 14, 2022 at 04:02 PM

There is a resistive pull-up to 5 volts inside Cerbo. So you'll read 5 volts with nothing connected to the input.

Victron also sells the GX Tank 140 which is a voltage or current input. There's a pull-up on these inputs but it's a much higher resistance unless you put it in current mode.

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pmolettiere commented · Oct 14, 2022 at 04:46 PM

Thanks for the response. I'm looking to design a small circuit to connect a voltage based capacitive tank sensor to the cerbo. It looks like maybe the GX Tank would work, although it would be nice to be able to just use what's already installed.

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Answer 1 · 2022-10-14T16:42:44Z

pmolettiere answered · Oct 14, 2022 at 04:42 PM

OK, so I took my own measurements. With the tank configured as custom from 0Ω to 264Ω, I took the following measurements:

Resistance	Voltage
open	4.84v
10Ω	4.5mV
100Ω	0.6v
220Ω	1.2v
330Ω	"Disconnected"

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