Two charge controllers on one battery bank?

Options
foolios
foolios Solar Expert Posts: 53 ✭✭
in Solar Beginners Corner #1
I have two 30 amp charge controllers and I am wondering if I could make use of both of them to get to 40 amps input to one battery/bank or if I have to upgrade to one larger charge controller?

Thanks in advance.
· Share on Twitter

Comments

  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Options
    Re: Two charge controllers on one battery bank?

    Hi "foolios", welcome to the forum.
    In answer to your question:
    As long as they are fed from two separate, solar panel arrays. You can't connect two controllers to the same solar array.
    If you have only one large solar array, split it apart electrically and feed each half to it's own controller.
    · Share on Twitter
  • foolios
    foolios Solar Expert Posts: 53 ✭✭
    #3
    Options
    Re: Two charge controllers on one battery bank?

    Excellent, thank you.
    I was afraid that they would somehow interfere with each other's voltage output. Like one controller would see the +14v charge coming from the other charge controller and think the batteries were fully charged thus shutting each other off.
    · Share on Twitter
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Options
    Re: Two charge controllers on one battery bank?
    foolios wrote: »
    Excellent, thank you.
    I was afraid that they would somehow interfere with each other's voltage output. Like one controller would see the +14v charge coming from the other charge controller and think the batteries were fully charged thus shutting each other off.

    The controllers monitor battery voltage and hopefully battery temperature only, if that is, they are properly installed, so no worries there. They'll just enjoy the "help" they're receiving from each other getting the batteries charged.
    · Share on Twitter
  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #5
    Options
    Re: Two charge controllers on one battery bank?

    Are the controllers the same ?? like KIDS ?? Daisy them but as Wayne posted keep the supply PV to them , separate .

    VT

    EDit : I said "Kids" from the 30 amp post 1 .
    · Share on Twitter
  • foolios
    foolios Solar Expert Posts: 53 ✭✭
    #6
    Options
    Re: Two charge controllers on one battery bank?

    Nope, they aren't the same. I take it that may be a problem. They are rated to 14.4v max. Is that what the concern is?
    · Share on Twitter
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
    Options
    Re: Two charge controllers on one battery bank?
    foolios wrote: »
    Nope, they aren't the same. I take it that may be a problem. They are rated to 14.4v max. Is that what the concern is?
    The only concerns, if they are not identical, is that:
    1. They will not share the charging load equally when they are in Absorb or Float because of slight voltage differences. This should not hurt either the CCs or the batteries though.
    2. When both CCs are in Bulk stage, the combined maximum current will be more than the recommended upper limit current for the batteries. This can be avoided by making both CCs small, using limited size panel arrays on each, or more generally, by having the two CCs coordinate to produce the maximum charge current. Only the latter generally requires same manufacturer's CC units, and one which have communication capability built in.
    SMA SB 3000, old BP panels.
    · Share on Twitter
  • foolios
    foolios Solar Expert Posts: 53 ✭✭
    #8
    Options
    Re: Two charge controllers on one battery bank?

    Thank you for that information.
    I will consider those concerns if I do decide to follow that route.
    · Share on Twitter
  • jimindenver
    jimindenver Solar Expert Posts: 59 ✭✭
    #9
    Options
    Re: Two charge controllers on one battery bank?

    Can you set both controllers to the same float and absorb voltage?
    · Share on Twitter
  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #10
    Options
    Re: Two charge controllers on one battery bank?

    I wouldn't want to cause a hunting fight . I would set the lesser panel CC to higher float .
    Kinda like a Zero droop setup.
    · Share on Twitter
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #11
    Options
    Re: Two charge controllers on one battery bank?

    I have two separate PV arrays, one feeding a Midnight Classic and the other a Morningstar MPPT 60, which is also fed from a tiny micro hydro. The Midnight is very adjustable, so was able to closely match it to the Morningstar. Do they always agree? No, but they don't fight or even have serious arguments, and the single battery bank they feed is happy. The Midnight sometimes switches to Float while the Morningstar is still in Bulk, but by the end of the day the batteries are where they need to be, and that's while running two freezers, a converted fridge, and sometimes much more.
    · Share on Twitter

Categories