72v motorcycle charger?

garynappi
garynappi Registered Users Posts: 105 ✭✭
edited October 2019 in Advanced Solar Electric Technical Forum #1
I've been riding for over 50 years, and now I'm looking at electric crotch rocket type bikes. All operate at 72 volts so naturally I'm looking at a solar charge station for my bike. 

But... I'm way out of my league when it comes to panel and CC selection. 

The mainstream makers are not forthcoming on battery specs, but smaller shops are more open about the batteries. 

One gives these details...
  • Battery: 72v 60ah Lithium
  • Charger: 72V 10A
  • Charging Time: 6-8 hours
That said, looking at various panels and controllers and the specs are not encouraging. Every CC seems to max out at 48 volts, and the specs on the panels needed for the CC are less than clear to me. 

The only CC I found to date that "may" work is the MIDNITE CLASSIC CP250 but while it claims to support 72 volt systems, it only has listing a VOC / VMP for 48 volt systems. Are there any CC's that specify 72volt support for a 72v lithium battery?

So, if I get an electric motorcycle I'll assume that most any series pair of 300+/- watt panels with a VMP or VOC of over 70-80 volts will work assuming I can find a suitable MPPT CC.

TIA for any advice, especially from any who are charging electric motorcycles.




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Comments

  • sawmill
    sawmill Solar Expert Posts: 93 ✭✭✭
    #2
    I assume the electric motorcycle would have an on board AC charger.  If the solar system is to only be used for the MC charging, would not PV panels with their own micro-inverters be a possible solution?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #3
    AFAIK, all MN Classic versions charge up to 72v banks.  The Vmp/Voc showing 48v in the sizing tool would be to;  make sure string voltage has enough overhead for bank voltage, and to make sure string voltage is under max (150v/200v/250v) operating, plus nominal bank voltage.  I'm not sure if a (eg) 150v Classic would be okay (in "hyperVoc") with 150+72=222v max Voc.  Probably, but I'd confirm if it might be an issue.

    As Sawmill suggests though, the bike may be designed for AC charging, with some of the charging control functions done in the AC charger.  Before charging directly with DC, I'd want to know more about what, if any, BMS is embedded in the battery pack, and the maximum bulk charge voltage for the specific lithium chemistry and pack configuration.
    Off-grid.  
    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
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  • papab
    papab Registered Users Posts: 66 ✭✭
    #4
    As they said, the simple solution is to just use the AC charger that comes with the bike, a cheap lead-acid battery and a properly sized inverter.   I have 2 e-bikes and that's what I do.   I would be nice to eliminate the inverter and have a DC-DC charger but there is significant work and risk involved to make that work.   It would probably void your warranty too.
    Also consider when you're going to ride and when you're going to be able to charge.   When it's sunny for both, right?   I haven't camped much with the e-bikes yet, but my plan is to charge up the bikes in the morning from the house battery in the van, then charge up the house battery while I'm riding.  If the days are long and warm I could ride earlier & charge up the bikes in the afternoon which would obviously be better for the van battery.
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  • garynappi
    garynappi Registered Users Posts: 105 ✭✭
    #5
    papab said:
    As they said, the simple solution is to just use the AC charger that comes with the bike, a cheap lead-acid battery and a properly sized inverter.   I have 2 e-bikes and that's what I do.   I would be nice to eliminate the inverter and have a DC-DC charger but there is significant work and risk involved to make that work.   It would probably void your warranty too.
    Also consider when you're going to ride and when you're going to be able to charge.   When it's sunny for both, right?   I haven't camped much with the e-bikes yet, but my plan is to charge up the bikes in the morning from the house battery in the van, then charge up the house battery while I'm riding.  If the days are long and warm I could ride earlier & charge up the bikes in the afternoon which would obviously be better for the van battery.
    Yeah, part of the purpose would be wilderness style camping, while I could use the truck for going and coming a bike would be a hoot.

    I've written a few of the manufacturers about whether the charger is internal (undesirable) or external and as yet have not received a reply. 


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