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ML disconnect relay:
product number 7702B, rated 500A. I have one for each of the 2 batteries. The relays draw no current in ON or OFF state. There are wires to set the relay states depending on what the default state should be. In our setup, the wiring to the battery’s BMS ports is specified explicitly in the documentation so there is no head scratching to do.
We have produced about 100KWh a month historically (~140Ah@24V a day). We are having very good sun at the moment so I’ll measure a max production day today. The max Amps I saw going in was 36A in Curaçao last summer. Our production during the Pacific crossing, Gambier and southern Tuamotus in April-July was pretty poor with cloudy conditions and relatively low sun elevation.
Our wet locker doesn’t get wet. We are lucky to cruise in places were we don’t need foul weather clothes. We quickly vacuum packed and stowed those away. And the Amel cockpit helps with that.
Yes, breakfast toasts, 2mins of microwave here and there to reheat food, boiling water in 60s or cooking smelly food outside on the portable induction stove. All good examples of how it changes life onboard.
Long term storage or dock:
I would say, if we are aboard at the dock, I would let the solar deal with the batteries and use shore power for the others appliances of required. If we are off the boat for a long time, we would just switch everything off and not keep the shore power on. We left the boat in Curaçao for 2months last year and with everything off, the batteries lost less than 5% SOC.
Rangiroa, French Polynesia
Thanks for the reply!
Regarding your ML disconnect relay, which model are you using? For their disconnect relays, I only see 120amp max
Or did you use this charge disconnect? If so, any idea how I could use it with my system? 500amps may just be enough! The VE.BUS BMS load disconnect sends out 27v (more or less) when all is good and goes to open circuit when there is a problem with the batteries and the load needs to be disconnected. The other option, as someone suggested, is to buy THREE Victron BP-220 and attach one to each 25.8v pair. I presume that would give me 660 amps total?
Regarding your solar setup, any idea how many AH per day you average? Curious how that compares to our setup. We have a bit more rated capacity and we're doing parallel as noted before. Also, do you have any concerns with your MPPT getting wet? We definitely use that wet locker for...wet items.
The Victron Quattro also allows you to limit the input on both the 230v inputs. I leave the genset at 50amps but adjust the shore power as appropriate. That was very useful in Greece when we were "plugged into" someone's house circuit. Limiting it to 8 amps prevented constantly tripping their circuit breaker. :)
Regarding your shop vac'ing the engine room, we all get our kicks from somewhere I guess! My joy is in using the electric kettle and the microwave when I'm too lazy to do a proper meal and not having to fire up the genset.
To figure out SOC and charging voltage, I just played around. For example, my Mastervolt Alpha Pro2 set at 27.5v absorption will stop charging at about 90-93% SOC as reported on the Victron BMV-712 monitor. As you probably know, lifepo4 has very stable voltage until you hit the "knees" at near 0% SOC and 100% SOC. So you just have to play with it. I bet at 26.8v absorption, it'd be just about right for long term storage/docking.
I probably sound like a Victron rep, too, but like you, I just continued with choices made prior. My ecosystem lock-in with Victron started with the BlueSolar MPPT, which ironically I don't love!
2007 A54 #69