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gertjand asked

Cerbo & DC generator

Hi All,

A couple of questions. Today I hooked my fisher Panda dc generator onto the cerbo relais, works like a charm. (Not via a bus because of the age of the genset) The cerbo doesn’t have an option for a DC generator only AC, correct? Might be a future software upgrade? Nevertheless, it works.


The question is, do I need to connect it to the charge disconnect of the BMS or will the Cerbo pass that signal on to the generator via the relais (set to ‘no’ for off en ‘nc’ for start). It is set to operate within a certain SOG range. But does the cerbo switches it of in case of a bms charge disconnect? When the bms shuts down, the cerbo is down too so in that case the relais will be set to ‘no’ again.


Furthermore:

It could be usefull to have the generator as backup power supply for the vessel in case something happens at sea and the bms switched the load off or alternatively a (mayday only;) bypass for the load disconnect in case of a urgent situations at sea where safety is more urgent that the lifespan of the lithiums :).

Best,

Gert Jan

cerbo gxGenerator
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2 Answers
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jwfrary answered ·

You will have to use the charge disconnect function of the BMS. The two logics, are not linked.

I'm assuming your using the older AGT type DC Generator. In which case you will be wanting to only run it up to say 95% SOC otherwise the Genny will be to lightly loaded to be efficient. - IE bulk charge only

I assume you have multi or quattro. You might want to look at using the logic onboard there to start stop the generator as you can combine it with ignore ac and also BMS assistants so that the whole get up is smarter, you still use the Cerbo to ask the Genny to start, but the multi has some say in it, depending on how the assistants are configured. Not done it with DC but works well with AC gens. - If your in a low battery situation that logic might not work of course. - But you can always start manually in that case.

Agreed, it would be useful to have a more sophisticated official means of DC genset control however it is pretty niche at the moment, mainly marine and telecoms.

I'm 99 % sure you have to have a battery involved in order for the regulator to work correctly on the old AGT. - Best to take that up with Fisher Panda Support. - The German office are good with Victron integration. Fisher Panda UK favour the green boxes of power.

I have to say, while I'm a fan of generator auto start on motor boats, and employing it extensively on my installations, I'm not sure I'm so keen on sailing yachts, special considerations need to be made of the exhaust system and the intake system as in heavy seas, its not uncommon for generators to suffer the dreaded hydraulic lock due to water sloshing around in the water lock. Depends entirely on how your using it I suppose, something to be aware of.

5th engine replacement of the year came in with problems related to poor exhaust arrangements. I would say its the most common cause of engine/generator failure next to general neglect!

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gertjand answered ·

Wauw, Perfect answer. Thx. Will watch out with sailing and double check the exhaust installation.

It would be another feature request to have nmea2k data availabl back to the cerbo gr. Then I could use tilt and heel data in de genset parameters. I have it set between 30 and 80% for the run time.

I will hook it up to the bms. I can join it with the alternator setup (I have setup the bms to turn of the magnetic field)

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jwfrary avatar image jwfrary commented ·

Fisher panda can bus and n2k are not so simply unified, I read, haven't played with it though. - Like to keep the N2K networks as simple as possible sometimes more integration leads to less reliability.

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