Battery disconnect

zozomike
zozomike Solar Expert Posts: 134 ✭✭✭
in Off Grid Solar & Battery Systems #1
Just dropped another 3K on panels and parts to try to get the gain up to the long term needs of the battery ( which I bought too big too prematurely but was up against the death of my first set). This refit will involve lots of reconfigurations and one I did not account for is a robust battery disconnect for two charge controllers and the inverter. Looking around at RV stuff nothing seems robust enough ( I could be easily corrected on this issue) For my mind just some sort of Knife switch mounted so responders could find it with connections for all the above would work. But do not find such at NA/Sun. I guess I could use two more of the Buss MRCB switched breakers but that does not seem elegant or simple.
Any simple ideas that would be self apparent for outsiders should emergency occur? As for me a simple twist of a wrench at the batt works fine:roll:
Thanks

Off grid, all solar, passive and active (winter wood heat supplements) PV DHW.

Array 1-- 12 Sunpower 250, Outback FM 100 3kw

Array 2-- 12 Sunpower 250, Outback FM 100 3kw

Well array 780w, 6 Kyocera 130 w with Grundfos sqflex 11 and cu200 to elevated storage, ( 2- 330 g tanks,) no battery storage at well

10 24 volt Battle Born Lithiums

Outback Flexpower Two, VFXR 3524A 7kw


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Battery disconnect

    Your best bet for a battery disconnect is a battery disconnect switch like these Blue Sea units:
    http://www.solar-electric.com/baacma.html

    Note they are rated up to 350 Amps, which should be enough for any system (since that is crazy current).
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  • zozomike
    zozomike Solar Expert Posts: 134 ✭✭✭
    #3
    Re: Battery disconnect
    Cariboocoot wrote: »
    Your best bet for a battery disconnect is a battery disconnect switch like these Blue Sea units:
    http://www.solar-electric.com/baacma.html

    Note they are rated up to 350 Amps, which should be enough for any system (since that is crazy current).
    Thanks yet again, I think you should put a PayPal donation button somewhere. I mean it. I have no idea how you compensate all the time and skill...
    Yes thats enough amps, But i guess I am still nonplussed, do you mean I can stack the two CC outputs and the 3524 input (assume positive?) all on that switch then send one possibly 2/0 positive ?to the battery ( do have a fuse there) ?

    Off grid, all solar, passive and active (winter wood heat supplements) PV DHW.

    Array 1-- 12 Sunpower 250, Outback FM 100 3kw

    Array 2-- 12 Sunpower 250, Outback FM 100 3kw

    Well array 780w, 6 Kyocera 130 w with Grundfos sqflex 11 and cu200 to elevated storage, ( 2- 330 g tanks,) no battery storage at well

    10 24 volt Battle Born Lithiums

    Outback Flexpower Two, VFXR 3524A 7kw


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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #4
    Re: Battery disconnect
    zozomike wrote: »
    I can stack the two CC outputs and the 3524 input (assume positive?) all on that switch then send one possibly 2/0 positive ?to the battery ( do have a fuse there) ?

    Why do you want to use a switch rather than a circuit breaker as your battery disconnect?

    Also, when you disconnect the battery, you may damage equipment... the voltage from the charge controllers to the inverter may spike very high. You must be sure to disconnect the PV input from the controllers BEFORE you disconnect the controllers from their battery.

    Also, you should NOT stack two controllers and an inverter on a switch lug. You need some bus bars. Take a look at some of the Midnite electrical boxes.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #5
    Re: Battery disconnect

    Id forget the battery switches and fuses. Midnites MNDC and its ilk, with its carling breakers comes to the rescue here. Cheap for gear's quality and peace of mind.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Battery disconnect
    zoneblue wrote: »
    Id forget the battery switches and fuses. Midnites MNDC and its ilk, with its carling breakers comes to the rescue here. Cheap for gear's quality and peace of mind.

    Good stuff, to be sure. But not always the solution for every application.
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  • zozomike
    zozomike Solar Expert Posts: 134 ✭✭✭
    #7
    Re: Battery disconnect

    Thanks for all the ideas guys, just ordered another Quad enclosure and the appropriate breakers. So will have matching enclosures, one for the PV shutoffs, one for the battery shut offs. Now to wait for all this stuff and then spend a few days taking everything apart and putting it back together. This started out as a minimal one occupant occasional use cabin system and should now be family supportable. Had I known I would need to grow this much I should have bought a complete kit.

    Off grid, all solar, passive and active (winter wood heat supplements) PV DHW.

    Array 1-- 12 Sunpower 250, Outback FM 100 3kw

    Array 2-- 12 Sunpower 250, Outback FM 100 3kw

    Well array 780w, 6 Kyocera 130 w with Grundfos sqflex 11 and cu200 to elevated storage, ( 2- 330 g tanks,) no battery storage at well

    10 24 volt Battle Born Lithiums

    Outback Flexpower Two, VFXR 3524A 7kw


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Battery disconnect
    zozomike wrote: »
    This started out as a minimal one occupant occasional use cabin system and should now be family supportable. Had I known I would need to grow this much I should have bought a complete kit.

    An oft told tale! :D
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  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    #9
    Re: Battery disconnect

    I use the really big DC breakers like NAWS carries. http://www.solar-electric.com/mnedc250.html
    I did find some surplus for about 1/4 of the cost with similar specs from the aerospace industry and they work every bit as well as the Midnite version. I think both are made by Carlon or something like that. Make SURE that they are rated for DC in the voltage you are going to be using them at. When using multiple strings of batteries, I use one breaker per string. It makes it protected and if I want to just use one string it is as easy as shutting off the correct breakers.

    Good luck and let us know how it works out
    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
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