Two different MPPT controllers together?





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  1. #1
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    Default Two different MPPT controllers together?

    Seeking a power setup with alternator charging and battery balancing, already flattened batteries once - my old Mercedes 508d allows you to pull the key from the ignition without turning it to "off"! (lights etc. stay on)



    • 3 x400W panels through 1 Victron BlueSolar MPPT150/85
    • 1 x400W panel through 1 WRND since it contains 20A MPPT anyway.
    • ...and you get battery balancing and alternator charging cheaply from the WRND.

    Will this work, 2 separate MPPT controllers?



    Looking 300-400Ah of use a day on a 600Ah battery bank. Should easily charge full in a typical day, even do well on overcast days.


    Cheers for any advice offered.

  2. #2
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    Default Re: Two different MPPT controllers together?

    Mercedes 508d...had to Google that

    I can see no problem using two different controllers.

    Many home systems have added windpower (see alternator) to charge batteries

    I have two Victron MPPT's on my home system and plan to change one to an Outback MPPT (larger capacity) and add more panels.
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  3. #3
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    Default Re: Two different MPPT controllers together?

    Quote Originally Posted by Prof View Post
    Mercedes 508d...had to Google that
    They're not young But they are very sturdy.

    Quote Originally Posted by Prof View Post
    I have two Victron MPPT's on my home system and plan to change one to an Outback MPPT (larger capacity) and add more panels.
    Hmm... did you do that without using the Victron networking feature (in mobile app)? Sommer so?

  4. #4
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    Default Re: Two different MPPT controllers together?

    The current two Victrons are not networked or synched.
    One just gets to float quicker than other.
    When load required and one can’t handle it by itself the other comes ‘online’
    Each MPPT connected to battery bank directly

    ’Sommer so’
    Last edited by Prof; 2020/05/18 at 06:06 PM.
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  5. #5
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    Default Re: Two different MPPT controllers together?

    Quote Originally Posted by Wick View Post
    Will this work, 2 separate MPPT controllers?

    I the solar panels cant be match then this is the alternative, thus yes .
    Johan Kriel

  6. #6
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    Default Re: Two different MPPT controllers together?

    Quote Originally Posted by Wick View Post
    Seeking a power setup with alternator charging and battery balancing, already flattened batteries once - my old Mercedes 508d allows you to pull the key from the ignition without turning it to "off"! (lights etc. stay on)



    • 3 x400W panels through 1 Victron BlueSolar MPPT150/85
    • 1 x400W panel through 1 WRND since it contains 20A MPPT anyway.
    • ...and you get battery balancing and alternator charging cheaply from the WRND.

    Will this work, 2 separate MPPT controllers?



    Looking 300-400Ah of use a day on a 600Ah battery bank. Should easily charge full in a typical day, even do well on overcast days.


    Cheers for any advice offered.
    I use 3 mppts to one battery bank, to rectify previous mistakes. Works perfect only thing you will see because nothing is equal
    they will not stop charging at once when the battery is full so what then it is full.
    You got yourself a power station sell the left overs to Eskom

  7. #7
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    Default Re: Two different MPPT controllers together?

    There should not be a problem if it is all the same battery. Main is risk is the potential high charge current visible to the battery when in a discharged state, but this quickly tapers off once the boost and float voltages are reached. The stronger charger will typically determine what this effective battery voltage will be (alternator, when running, MPPTs when stationary)

    Remember, all the chargers, alternators, AC chargers, MPPTs, PWMs etc. connected to the same battery can only "see" the same battery voltage.

    It can only "see" and respond, with current, to the battery voltage. It is unaware of the other chargers.

    The battery do see the the sum of currents though, and the main risks (if so considered) are potential high current charging rates for the battery, which is only really applicable on low state of charge batteries.

    On my own PV setup,I have yet to blow something up by running a 10 amp AC charger in combination with a 60 amp MPPT connected on the same battery bank

    Perhaps someone knows of a scenario where multiple chargers (within reason), connected to the same battery, can develop a equipment damage condition ( apart from the high charge currents)

    Thing is: Most chargers respond to low and high battery voltage, system loads, surplus or shortage inputs (Solar Pv) in similar ways, if the end goal is to charge the battery to a set voltage
    Last edited by vlakkie; 2020/05/18 at 07:44 PM.
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  8. #8
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    Default Re: Two different MPPT controllers together?

    Ideally the controllers must be identical and program settings on both must be identical, if they cannot be connected as one.

    For the nitpickers ... note I used the word: Ideally ...

    If they are not identical, the one MPPT would always "all the work", the other one seeing that all "appears" fine, would idle.

    Only under heavy loads would both non-identical controllers start preforming.

    If the above is not an issue, then one can go ahead and mix and match to one hearts content.
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  9. #9
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    Default Re: Two different MPPT controllers together?

    Quote Originally Posted by Wick View Post
    Seeking a power setup with alternator charging and battery balancing, already flattened batteries once - my old Mercedes 508d allows you to pull the key from the ignition without turning it to "off"! (lights etc. stay on)



    • 3 x400W panels through 1 Victron BlueSolar MPPT150/85
    • 1 x400W panel through 1 WRND since it contains 20A MPPT anyway.
    • ...and you get battery balancing and alternator charging cheaply from the WRND.

    Will this work, 2 separate MPPT controllers?



    Looking 300-400Ah of use a day on a 600Ah battery bank. Should easily charge full in a typical day, even do well on overcast days.


    Cheers for any advice offered.


    Just check your specs, as far as I know the WRND can't handle 400W solar, max it can handle is 300W with a max VOC of 40V.

    What's the voltage of your 400W panels, can't all 4 fit on the Victron?
    I'm thinking here to maybe just put all 4 big panels on the Victron for your aux bank and then just add a small 50W or so panel on the WRND to keep your starting battery topped up.
    Last edited by bigboy529; 2020/05/20 at 12:39 PM.
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  10. #10
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    Default Re: Two different MPPT controllers together?

    With a 20A max for the WRND at 12V gives 240W. I know the previous model WRND could not handle a 400W panel as already indicated. Always best to 1st stick to the maximums provided in the specs when fault finding or using different controllers in ||.

  11. #11
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    Default Re: Two different MPPT controllers together?

    Thanks guys. This was obviated this week when Victron released the 1.49 firmware and the V.E. Connect Software (?) upgrade which allows most of their devices to sync MPPT electronically. I'm going for 2 of these. It keeps things simple.
    Last edited by Wick; 2020/05/21 at 10:39 PM.

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