MPPT Charge Controller Solar and Auto Alternator hook up.

Psychowolff
Psychowolff Registered Users Posts: 4
Hi Everyone!

I'm rather new to the solar world and have a 'simple' question that I'm hoping some of you might be able to answer!

OK, I'm looking at using something like the MorningStar TS-60 MPPT controller in my RV to charge my coach batteries from 2 - 300W panels. (~600 Total) I currently have a pair of 170AHr 12V batteries that i would like to use in series and I might be getting another pair to make a 170AHr 48V system. I know the Controller will feed a 12/24/48V Battery bank but I would also like to use the RV's Alternator (~65A@14V) to charge the batteries while driving.

Is it possible (and is it normal?) to hook both the Solar AND the Alternator output to the Controller to charge a 24V battery bank (or 48V) and then also have the bank Discharge through the controller into a 12V distribution panel in the RV? Would I need the TS-60 controller or would the TS-30 be enough due to the higher voltage/Lower Amps?

Thanks!
Mike

Comments

  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭

    Is it possible (and is it normal?) to hook both the Solar AND the Alternator output to the Controller to charge a 24V battery bank (or 48V) and then also have the bank Discharge through the controller into a 12V distribution panel in the RV? Would I need the TS-60 controller or would the TS-30 be enough due to the higher voltage/Lower Amps?

    Thanks!
    Mike
    Connect both to battery bank - yes, no problem
    Discharge through controller - no, your battery bank will generally go right to the 12V distribution panel.  If you want a separate LVD (low voltage disconnect) then that's OK but the TS-60 won't do that for you.  The old Trace/Xantrex C40 does a good job there.  Generally that gets attached to everything EXCEPT the inverter, which always goes as directly as possible to the battery.

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    So, using 600w of pv, to charge a 24v battery bank, you need only a 25A charge controller.   Small controllers may have low input voltage limits, but the TS-MPPT-60 is a bit of overkill (but it is a nice controller).  The vehicle alternator is 12V only for the vehicle starting battery, don't try to mod it to get 24V charging out of it.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Connect both to battery bank - yes, no problem
    Discharge through controller - no, your battery bank will generally go right to the 12V distribution panel.  If you want a separate LVD (low voltage disconnect) then that's OK but the TS-60 won't do that for you.  The old Trace/Xantrex C40 does a good job there.  Generally that gets attached to everything EXCEPT the inverter, which always goes as directly as possible to the battery.

    Note that the above only works for a 12V system, not a 24V.
  • Psychowolff
    Psychowolff Registered Users Posts: 4
    Mike - I am not modifying the RV charging system, it is designed to charge the Starting batteries and the Coach batteries. (through an isolator) I'd leave that stock but add Solar - feeding 12-15V in and the controller would up it to 24V. I was Hoping I could make a 24V bank to decrease the amps (and use a Smaller/Cheaper TS30 like you said) and also to put the batteries in series to be able to keep better control over their health; as in parallel one battery can suck the life out of the other before you really know it.

    Bill - Darn, I thought the 'Load Control' was for feeding the Battery to the Dist Panel through the Controller. If I rewire the bank to 12V, would I have to go with the larger TS-60 MPPT Controller? The Panels will put out about 45-50A and the Alternator is about the same. (Not used together!) 

    I appreciate your time and help guys. I'm familiar with Electronics, just haven't gotten into the Solar side of things too much yet...
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,036 ✭✭✭✭✭
    "I'd leave that stock but add Solar - feeding 12-15V in and the controller would up it to 24V."


    MPPT controllers won't "UP" the voltage. They will take Higher voltage and step it down to the battery bank voltage.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    but add Solar - feeding 12-15V in and the controller would up it to 24V. I was Hoping I could make a 24V bank to decrease the amps (and use a Smaller/Cheaper TS30 like you said) and also to put the batteries in series
    MPPT controllers won't "UP" the voltage. They will take Higher voltage and step it down to the battery bank voltage.
    Most, but certainly not all, controllers work as littleharbor2 wrote.  What you (Psychowolff) want is a buck-boost controller.  Genasun makes several.  They are often used in golf carts where a 24 or 30 volt panel is used to charge a 36 volt battery.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    12V alternators are a bit of a unfortunately reality in many RVs. I do prefer 24V house systems, and heres a few ideas for getting around this, most of which ive written about recently in similar threads.

    1. replace the vehicle with one with 24V start electrics, duh.
    2. add a second 24v alternator
    3. leave the house and start systems separate and do a 100% solar / shore power house system
    4. adopt creative house charging, for instance, use a custom current limiting boost converter to feed power into a charge controller (tricky), or use a small inverter and AC charger (inefficient).

    However if  it was me, and none of the first three options were workable, and the solar system was never going to be bigger then 1kW, then frankly sticking to 12V house bank is the least of all evils.


    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Bill - Darn, I thought the 'Load Control' was for feeding the Battery to the Dist Panel through the Controller. If I rewire the bank to 12V, would I have to go with the larger TS-60 MPPT Controller? The Panels will put out about 45-50A and the Alternator is about the same. (Not used together!)
    No.  In fact you could probably use a TS-30.  With 600 watts and a charge output of 14 volts you would see 42 amps in a perfect world; in the real world you will rarely see over 35.  (And the controller will prevent too much current from flowing in that case.)

    For RV-sized loads, 12 volt systems aren't the end of the world.  There are a lot of benefits (no alternator changes, wide availability of loads.)  The one big negatives are the larger conductors and fuses needed, but that's not a huge hit for most installations, since RV's are (usually) physically small compared to houses.
  • Psychowolff
    Psychowolff Registered Users Posts: 4
    Thanks for all the Info guys, not everything I 'wanted' to hear but what is needed. I think I'll stick with the 12V system/Battery Bank. As Bill said, the RV isn't all that big and the Bank is actually only about 2' from the Dist Panel and Inverter so it should be just fine.

    The Isolator on the Alternator is about 12 feet but I changed out the 10Ga wire for a 6Ga, Thats about the best I can do there. I Do appreciate the Help and I'm sure I'll be back with other questions! LOL