2AWG cables into Morningstar TS-MPPT-60

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Iceni John
Iceni John Solar Expert Posts: 103 ✭✭
in Off Grid Solar & Battery Systems #1
Morningstar says that cables as large as 2AWG can be used with this charge controller - coarse-stranded THHN would probably work OK in its four clamp-down cable terminals, medium-stranded battery cable only just fits, but forget about even trying to put 2AWG fine-stranded welding cable in them! I toyed with several ideas how to connect 2AWG welding cable into the terminals, including making my own adapters (way too much work, and one more joint to add resistance and voltage loss) or buying the QuickCable MagnaLug connectors for inverters (probably not cheap). I finally had a flash of inspiration when walking through the plumbing aisle at Home Despot. Nibco 1/4" copper tube couplings are slightly larger ID than a 2AWG lug, and cost only $0.71 each: http://www.homedepot.com/p/NIBCO-1-4...2Z12kxZ1z114xd I first crimped them square with my FTZ crimper using its 2AWG dies, then used the Harbor Fright hydraulic crimper and its "0 AWG" hexagonal dies to get a rough hex shape, then finished it off with the HF's "2 AWG" dies to produce a perfect hex end to the cable, with the cable strands and Nibco coupling all fused nicely together into one solid mass of copper. This hex end to the cable now fits perfectly in the Morningstar's clamp-down terminals.

However, why doesn't Morningstar use threaded studs instead of those hokey clamp-down terminals? One could then use proper lugs without needing to faff about doing what I did. It really bugs me when manufacturers make me have to reengineer what they should have done right in the first place. Hrumph.

John

40' Crown bus with 2kW of tiltable panels on the roof:

Eight Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries, and maybe a small Exeltech inverter for the fridger.

Southern California

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  • unseenone
    unseenone Solar Expert Posts: 61 ✭
    #2
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    You can crimp a lug to the fine stranded cable ends, and fit it that way. I used Anderson ends, and modified them.
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  • froggersix
    froggersix Solar Expert Posts: 35 ✭
    #3
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    why would you need 2 wire in or out of 60 amp controller? sounds like bad system not controller fault.
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  • Iceni John
    Iceni John Solar Expert Posts: 103 ✭✭
    #4
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    froggersix wrote: »
    why would you need 2 wire in or out of 60 amp controller? sounds like bad system not controller fault.

    Because I had the 2AWG cable already! I'm just using what I already have. Besides, too large is better than too small. Also, it is the largest size recommended by Morningstar.

    John

    40' Crown bus with 2kW of tiltable panels on the roof:

    Eight Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries, and maybe a small Exeltech inverter for the fridger.

    Southern California

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  • cupcake
    cupcake Solar Expert Posts: 254 ✭✭✭
    #5
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    Why in CandyLand are you using 2/0 cable on this 60amp charge controller...??

    A plain old 8 guage wire works for the solar input.
    A plain old 6 or 4 guage works on the battery output...


    jamming 2/0 cable on this controller is just wanton overkill cubed. bigger is not better... better is better...

    the 8,6,and4 guage wire will carry ALL the amps this little controller can handle....

    2/0 wire is INSANITY to bend and shape and workwith anyway....


    -- cake cake cake


















    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #6
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    I am actually quite happy that they are supporting larger AWG wire for their controller. Ideally, you want around 0.05 to 0.10 maximum voltage drop from controller to battery bank for a 12 volt battery bank (you wan the controller to "accurately" measure the battery bank voltage for fast charging and accurate absorb/float settings).

    Using a generic voltage drop calculator, 2 awg wire, and 60 amps, what is the longest cable run (one way run) that it could support with a maximum of 0.10 volt drop?

    http://www.calculator.net/voltage-drop-calculator.html

    Turns out, that 5 feet (one way run) of #2 cable gives 0.94 volt drop:

    Voltage drop: 0.094
    Voltage drop percentage: 0.65%
    Voltage at the end: 14.406

    That is actually a good "fit" for a typical system design...

    Personally, I would like if more charge controllers used remote voltage sense leads, or if not that, you could program in the wire length+gauge or resistance--And the controller can then measure/estimate the voltage at the battery terminals (battery bus).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Iceni John
    Iceni John Solar Expert Posts: 103 ✭✭
    #7
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    cupcake wrote: »
    Why in CandyLand are you using 2/0 cable on this 60amp charge controller...??

    A plain old 8 guage wire works for the solar input.
    A plain old 6 or 4 guage works on the battery output...


    jamming 2/0 cable on this controller is just wanton overkill cubed. bigger is not better... better is better...

    the 8,6,and4 guage wire will carry ALL the amps this little controller can handle....

    2/0 wire is INSANITY to bend and shape and workwith anyway....


    -- cake cake cake


















    Er, no, I'm not! I'm using 2 gauge, not 2/0. Obviously even I know better than to use 2/0 for a 60A controller! As I explained, I'm using it because I had it, but 4 gauge would have been OK as well. I keep the 2/0 for each house battery bank's cabling, and use 4/0 for the inverter and for the starter interconnection from the house batteries (my 42MT starter draws 900A or more, so only 4/0 is good there).

    OK?

    John

    40' Crown bus with 2kW of tiltable panels on the roof:

    Eight Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries, and maybe a small Exeltech inverter for the fridger.

    Southern California

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  • cupcake
    cupcake Solar Expert Posts: 254 ✭✭✭
    #8
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    Iceni John wrote: »

    Er, no, I'm not! I'm using 2 gauge, not 2/0. Obviously even I know better than to use 2/0 for a 60A controller! As I explained, I'm using it because I had it, but 4 gauge would have been OK as well. I keep the 2/0 for each house battery bank's cabling, and use 4/0 for the inverter and for the starter interconnection from the house batteries (my 42MT starter draws 900A or more, so only 4/0 is good there).

    OK?

    John


    Lawdy... I musta been drinkin last night... I thought you wrote 2/0 wire! LOL my bad! I have the same controller 4 guage is just perfect...

    cheers


    cake

    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


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  • Imurphy
    Imurphy Registered Users Posts: 16 ✭✭
    #9
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    I'd have to pull up a book for the mppt 60 but the pwm versions do use remote sensing leads, and I always recommend they be used, even with properly sized feed cables.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #10
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    The MorningStar TS family does have sense leads (small wires from controller to battery terminals to directly measure battery voltage).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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