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Discussion Starter · #1 ·
I’m putting my electrical system together and have a question about the relays in the Cerbo GX.
one of the items going in my system is a 24v-12v/70a converter. It has a built in on/off switch. Basically 2 wire connection, jumped and it is on, open and it is off. The load is 100ma. It looks like the relay can handle more than that. So can I use the Cerbo to turn this converter on and off? It is only going to be used to run the 12v AC unit.

Thanks for the help
 

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Not a definitive answer... but that is my understanding and plan as well. I have a few 12VDC relays - 40A and higher - that I expect to use with the Cerbo relay connections - for example to have an option to shut off the solar input or the fridge output at the wire level. By spec, you're in good shape.
 

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I’m putting my electrical system together and have a question about the relays in the Cerbo GX.
one of the items going in my system is a 24v-12v/70a converter. It has a built in on/off switch. Basically 2 wire connection, jumped and it is on, open and it is off. The load is 100ma. It looks like the relay can handle more than that. So can I use the Cerbo to turn this converter on and off? It is only going to be used to run the 12v AC unit.

Thanks for the help
You should be fine driving a bosch-style relay with the Cerbo, but more importantly, 12V x 70A = 840W. Are you sure your a/c doesn't ever draw more than that? From what I've heard they easily draw 750+, some even 1kW. Most DC converters require you to stay under 66% for continuous operation. You may want to check with the converter manufacturer about continuous load ratings.

Also, I would double check your a/c has soft-start and that it can't ever draw more than 70A. Typically exceeding a converter's capacity isn't like a battery. It'll blow a fuse on the converter (if it has one) or destroy it, unless you have an over current protection device (OCPD) like a breaker or a fuse, and even then it's a matter of how fast the OCPD acts.

Cheers.
 

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Discussion Starter · #4 ·
You should be fine driving a bosch-style relay with the Cerbo, but more importantly, 12V x 70A = 840W. Are you sure your a/c doesn't ever draw more than that? From what I've heard they easily draw 750+, some even 1kW. Most DC converters require you to stay under 66% for continuous operation. You may want to check with the converter manufacturer about continuous load ratings.

Also, I would double check your a/c has soft-start and that it can't ever draw more than 70A. Typically exceeding a converter's capacity isn't like a battery. It'll blow a fuse on the converter (if it has one) or destroy it, unless you have an over current protection device (OCPD) like a breaker or a fuse, and even then it's a matter of how fast the OCPD acts.

Cheers.
The converter is a Victron 24/12-70 and it has a max output of 85amps and continuous of 70amps.
The AC is a Dometic RTX 2000 and it has a amp draw of 19-59amps. So I think I have all the correct equipment.
I will be connecting it all on the bench and testing to see how it all works together.
 

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Discussion Starter · #5 ·
Not a definitive answer... but that is my understanding and plan as well. I have a few 12VDC relays - 40A and higher - that I expect to use with the Cerbo relay connections - for example to have an option to shut off the solar input or the fridge output at the wire level. By spec, you're in good shape.
So do I need to use an external relay or can the Cerbo be used as an on off switch. The converter has an on/off jumper that only pulls 100ma in the on position. I would like to just connect the 2 wires not have to connect to a relay and then to the converter to turn it on.
 

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So do I need to use an external relay or can the Cerbo be used as an on off switch. The converter has an on/off jumper that only pulls 100ma in the on position. I would like to just connect the 2 wires not have to connect to a relay and then to the converter to turn it on.
Sorry, I read your original post quickly and didn't realize you were just trying to switch a low amp low volt circuit. Specs for the gx relays are more than enough to switch your device. No need for a secondary power relay:
Rectangle Handwriting Font Parallel Circle


Cheers.
 

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So do I need to use an external relay or can the Cerbo be used as an on off switch. The converter has an on/off jumper that only pulls 100ma in the on position. I would like to just connect the 2 wires not have to connect to a relay and then to the converter to turn it on.
@Van Gogh pretty much answered it: if you're using an external relay and using the Cerbo to activate it, should be fine. But if you were trying to run more than a few amps directly, nope. So the device you're describing? Sounds fine.

Curious which device it is and why you'd want to turn off your 12VDC systems?
 

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Discussion Starter · #8 ·
@Van Gogh pretty much answered it: if you're using an external relay and using the Cerbo to activate it, should be fine. But if you were trying to run more than a few amps directly, nope. So the device you're describing? Sounds fine.

Curious which device it is and why you'd want to turn off your 12VDC systems?
The device is the Victron 24/12-70 converter. It will only be used to run my 12v air conditioner. So I only want it on when I need the AC on. The few other 12v items I have like lights and my Rixen heat will be on a much smaller converter that will stay on. Im trying to make as many systems as I can be on 24v.
 

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The device is the Victron 24/12-70 converter. It will only be used to run my 12v air conditioner. So I only want it on when I need the AC on. The few other 12v items I have like lights and my Rixen heat will be on a much smaller converter that will stay on. Im trying to make as many systems as I can be on 24v.
Ah. I have that same device running all my 12VDC stuff. Yeah, based on spec, you should be fine driving that. FWIW, the no-load draw is cited as <20mA for the converter. But if the AC unit is drawing more I guess that would be the easiest way to shut it all off.
 
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