How to wire relay outputs on cerbo gx

Q&A and troubleshooting
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Hi

I have a 48v lithium system in my campervan and i have want to wire a relay to power an 48v immersion heater as a dump load.
my question is

Can the relay outputs on the cerbo gx use a different voltage than the cerbo gx?
can i put 12v through the relay output to power a solid state relay the requires 12v on the control side?

12v is supplied from 48-12 convertor.
I have read the manual but it doesn’'t show whether this is possible

Thank you
Josh

1 Like
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Ho Josh,

The 2 relays on the Cerbo GX are potential-free contacts with a general NO/COM/NC combination.
It’s possible to connect the same 12V both to the Cerbo GX, and to the COM of the relay(s), to power an external 12V relay. Although you need to take care that the load of the external relay coil does not interfere the 12V power in general. This can cause a voltage drop, causing the Cerbo GX to reboot. In this case the external 12V power supply needs to be powerfull enough, or you better use an external second 12V supply.

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Hi,
Thanks for the reply.
Cerbo is powered from the 48v battery.
I was told that the relay is separate and can have a different voltage pass through.

I will have 48-12 converter running through cerbo relay and into control side of solid state relay and 48v on load side of relay from battery out to my immersion heater.

I really just needed to know if the relay contacts on cerbo are separate from the power for cerbo.

I need to do this as finding a 48v rated relay is proving very difficult.

4

@Josh_atkins yes the relay contacts have nothing to do with the power used by the CerboGX. That is what Theo was saying by describing them as potential free contacts.

5

Thank you,
I know enough about electronics to get by but don’t know all the correct terminology.

Thank you both.

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The Cerbo GX relays are not connected to anything, their contacts are therefore potential free.
The Cerbo GX relays can switch max. 30VDC at 6A/70VDC at 1A, and max. 125VAC at 6A.
I would preferably stay quite a bit below those values, just to prevent the relays from overload.

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