charging battery bank with an alternator

cockneybob2cockneybob2 Registered Users Posts: 18 ✭✭

hi , I have a used small 4 hp  diesel engine and a used 12 volt  60 amp car alternator both work fine , instead of connecting alternator cables straight to the battery bank to charge , is there any reason I can not connect the alternator cables into a totally separate stand alone mppt or pwm charge controller , would this work like a wind turbine and charge the battery bank .



  • EstragonEstragon Registered Users Posts: 3,043 ✭✭✭✭✭
    I suspect the output voltage would be too low for an mppt controller.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • cockneybob2cockneybob2 Registered Users Posts: 18 ✭✭
    ok , what if I purchased say a 24 volt alternator , would that work in principle
  • mcgivormcgivor Solar Expert Posts: 2,423 ✭✭✭✭✭
    Without a voltage regulator, the alternator would probably produce enough voltage to work with  MPPT, with  a regulator it would have too low a voltage and even with a 24V regulated alternator, it would more than likely confuse the tracking of the MPPT, with each trying to take control. You could of course use the regulated 12V alternator without a controller to add current, but it's not the most efficient use of fuel, this includes the theroy with a charge controller, as the battery becomes close to fully charged the more fuel is wasted and this is the reason generators are used as backup, rather than prime charging sources.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    900W  3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system. 
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
  • cockneybob2cockneybob2 Registered Users Posts: 18 ✭✭
    thanks mcgivor , this charging procedure is only for an  emergency ,  in case all else fails , have seen an economically priced solar and wind turbine charge controller , so guess that's the way to go , not bothered about the efficiency or economics of charging the battery bank as will only use is system once in a blue noon  if at all , as I have most of the gear , I just wondered if it would work , thanks
  • mike95490mike95490 Solar Expert Posts: 8,030 ✭✭✭✭
    Not all MPPT controllers are rated to work with a non-solar power source.  They depend on the "source" following solar PV rules, generators & chargers have vastly different impedance response
    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

    gen: ,

  • jonrjonr Solar Expert Posts: 1,135 ✭✭✭✭
    If the MPPT controller has a higher amp rating than the alternator, it will draw too much (unless the alternator has current limiting or a fuse).  Plus alternators require voltage to start producing power.   I agree - connect the regulated alternator directly to the batteries. 
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