Using Cerbo to control a heat pad under a lithium battery

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markblox asked Oct 16, '20

Using Cerbo to control a heat pad under a lithium battery

I am going to install a Victron lithium battery and intend to have a heat pad under the battery with a small air space between the two. It will be in a reasonably cold part of the boat and I would like to avoid the possibility of a situation where the smart lithium won't accept a charge.

The question is: can a Cerbo GX be used to automatically start and stop power to a heat mat. I know it has a couple of relays and I don't have a generator so relay one is avaliable and it has four thermometer inputs but I can't find any info as to see if it is possible or not.

cerbo gx Lithium Battery

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Answer 1 · 2020-10-23T18:41:35Z

bathnm answered · Oct 23, 2020 at 06:41 PM

The ability to trigger a relay via temperature is needed. This is not yet available within the GUI screen but could be coded. I suspect that the relay would need to control a second relay as the relay on the Cerbo will not have enough power to supply the heat mats.

I have heat mats installed under my batteries, but not yet wired, so have considered writing a script to pull the temperature from dBus and then change the state of the relay.

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Answer 2 · 2020-11-02T18:05:48Z

Eddy answered · Nov 02, 2020 at 06:05 PM

A couple of people are waiting for this extension/upgrade. Controlling something by temperature is asked for, but still missing. They want to work on it .. we have to be patient.

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Answer 3 · 2020-11-03T13:32:03Z

Guy Stewart (Victron Community Manager) answered · Nov 03, 2020 at 01:32 PM

It’s a much demanded feature, please have a read of these to understand the current situation, examples and some available workarounds until full support is developed.

https://community.victronenergy.com/questions/66045/measuring-and-switching-on-extraction-fan.html

https://community.victronenergy.com/questions/57187/curbo-gx-temperature-activation-of-relay.html

https://community.victronenergy.com/questions/9730/how-can-you-control-relays-using-temperature-data.html

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markblox commented · Nov 08, 2020 at 04:55 PM

Thanks very much, very interesting. I think I will install a temp probe to the battery and control a relay (for the heat pad) from relay two of the Cerbo GX, set up an alarm and VRM notification and as we are live-aboard will just manually turn the relay on until Victron revise the software which fingers crossed will allow the relay to talk to the temperature input.

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