Battery Charger and Full Sun at the same time

Coach Dad
Coach Dad Solar Expert Posts: 154 ✭✭
in Off Grid Solar & Battery Systems #1
I have a question for the experts…
I’m installing a Magnum Energy MS4024PAE inverter and a Tri-Star MPPT 60 charge controller to a 24v battery bank.
The inverter has a built-in 105A battery charger which comes on automatically when the generator is running. The Charge Controller can provide about 50A from the Solar Panels for charging the batteries if the PV’s are getting full sun.

I was just wondering….What happens if I’m running my generator (to power other things) while there is full sun on the Solar Panels. Will both the Inverter and the Charge controller provide charge current to the Battery bank? Are the charge currents combined for a faster charge time?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Battery Charger and Full Sun at the same time

    i'm guessing this is an off grid install. when running the generator the charger in the magnum will be active. hopefully the generator will be large enough to handle the huge current draw that will be presented by both the loads and the charger, but charge rates can usually be tailored with the remote. anyway, the controller with the pvs is a separate charging source and both the generator through the magnum and the solar will try to charge your battery bank. the combined current will be around 155a and is a sizable charging current, but you should already know what your batteries can take. if both sources are too much then shut off the generator or limit the charge from the generator with the remote.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #3
    Re: Battery Charger and Full Sun at the same time

    I have this problem quite often. I have shop tools that require more current than my batteries can handle even with the sun shining, so I run the generator. The combined charging of sun and generator is too much for the batteries. I do what Niel suggests above... turn off the charger function of my inverter/charger.

    Niel did not mention, though, that this is only necessary during bulk charging. Once you reach absorb (or float) stage there is no need to turn off (or throttle back) the charger. The two (or even more) charging sources will self regulate.

    Both my charge controller and my inverter/charger are Outback products and its a shame that during bulk stage they cannot coordinate their charging.

    This issue has been discussed in a previous thread and someone pointed out that the sunny island products can regulate the charging current.
    --vtMaps

    EDIT: here is the link to the previous thread:
    http://forum.solar-electric.com/showthread.php?14524-Could-cheap-panels-alter-the-panel-battery-ratio&p=108889#post108889
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Coach Dad
    Coach Dad Solar Expert Posts: 154 ✭✭
    #4
    Re: Battery Charger and Full Sun at the same time

    Thanks for the quick reply...
    According the Sun Extender the AGM batteries can handle up to 500A per 100AH of batteries... I so my 305AH batteries will be fine.
    I'm just making sure I don't ruin my batteries...
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Battery Charger and Full Sun at the same time

    yes, according to concorde they will be able to take that much current. they still need the time to go through the absorb charge stage too so it won't necessarily be as quick as you think either.

    not sure of what you are looking at for your loads, but i figure you are good to about 3kwh of usable storage in those batteries. that accounts for a 25% temp derating and 50% dod.
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  • Coach Dad
    Coach Dad Solar Expert Posts: 154 ✭✭
    #6
    Re: Battery Charger and Full Sun at the same time

    Niel- You raise another question in my mind..
    I need 2 hours of absorb charge... So what happens in the winter when there is only 2 1/2 hours of sun per day?
    I've got enough PV to finish the bulk in about an hour... Could the absorb finish the next day or will the partial sun be enough to handle the absorb?
    niel wrote: »
    yes, according to concorde they will be able to take that much current. they still need the time to go through the absorb charge stage too so it won't necessarily be as quick as you think either.

    not sure of what you are looking at for your loads, but i figure you are good to about 3kwh of usable storage in those batteries. that accounts for a 25% temp derating and 50% dod.
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  • SolaRevolution
    SolaRevolution Solar Expert Posts: 410 ✭✭
    #7
    Re: Battery Charger and Full Sun at the same time

    There is a quirk you should know about for the Magnums.

    From the manual:

    "3.2.1 Battery Charging
    ...After Charge Mode begins, the DC voltage is monitored to determine the charging
    stage. If the DC voltage is low (≤ 25.6 / 24-volt models or ≤ 51.2 / 48-volt models), the charger
    begins Bulk Charging. If the DC voltage is high (>25.6 / 24-volt models or >51.2 / 48-volt models),
    the charger will skip the Bulk and Absorb charging stages and go directly to Float Charging."

    If you have good sun on your PV array, your generator will not contribute to battery charging once the voltage exceeds the float set point.

    If your Magnum control panel is the ME-RC50 you cannot start a bulk charge from the generator if the battery voltage is already elevated from another charging source.
    If you are using the ME-ARC50 you can choose to force it into a Bulk cycle.

    If you have the ME-RC50 and you need to start a generator powered bulk cycle you may have to briefly shut off the PV and/or briefly pull the battery voltage down with a heavy load so it will be low enough to allow a bulk cycle. I've had calls where people can't understand why their system will not bulk charge from their generator.


    The TS-MPPT 60 will still do a bulk and then absorption based on time.
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  • Coach Dad
    Coach Dad Solar Expert Posts: 154 ✭✭
    #8
    Re: Battery Charger and Full Sun at the same time

    SolaRevolution... Thanks for the heads up.
    SolaRevolution wrote: »
    There is a quirk you should know about for the Magnums..

    Do you know if I can change that by programing the AC In-VDC settings using the ME-ARC?
    This is what the ME-ARC manual says...
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  • SolaRevolution
    SolaRevolution Solar Expert Posts: 410 ✭✭
    #9
    Re: Battery Charger and Full Sun at the same time

    Coach Dad-

    From how I read it, that "AC In-VDC" setting is intended to prioritize charging from the alternatative (DC) energy source. I don't think you could set it in a way that would force it to use the available AC power (generator) if the battery voltage was already elevated.

    Alex
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