E-bike query on charging battery

Discussion in 'Tech/Mech General' started by sciac2001, Aug 15, 2015.

  1. sciac2001

    sciac2001 Funster

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    Thinking about getting 'er indoors (actually mostly outdoors now that we travel for 11 months of the year, but hey!) an electric bike because she has knee issues and cannot pedal properly.
    We tend to spend most of the touring year off-grid and charge our leisure battery through the marvel that is the solar panel.
    A question that I have on e-bikes is whether it would be possible to charge up the battery from the power of my leisure battery. I have a 200w portable inverter but am assuming that the charger might require a higher wattage, which in turn may drain my leisure battery too severely.
    Any advice please?
    Thanks
     
  2. Munchie

    Munchie Funster Life Member

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    I would like to know too! We have a 300watt pure sine wave invertor
     
  3. Lenny HB

    Lenny HB Funster

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    I have just fitted a 1000 watt pure sine wave inverter for charging the e-bikes, works fine, but to charge both batteries fully takes over a 100 A/H out of the leisure batteries and with only 200 watts of solar they take days to recover. Pondering weather to fit another solar panel or don't let the bike batteries get too flat before recharging not always possible if you for a long ride.

    Our batteries are 400 watt Bosch, each charger takes a max of 1.5 amps on mains.
    Also found if both of the switch mode chargers have not been used for a while if I plug both in it trips the inverter overload, easy solution, plug one in leave a minute or 2 unplug plug, the other one in then after another couple of mins can plug the first one back in.

    If you are looking at charging 2 bike batteries you need at least a 1000 Watt inverter, I would also get a pure sine wave one, a bit more expensive but a lot cheaper than new chargers if a cheap one blows them, not worth the risk.
     
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  4. Allanm

    Allanm Funster

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  5. Glandwr

    Glandwr Funster

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    Touring off grid you will drive fairly often. An inverter on when the engine is going should be your aim.

    Dick
     
  6. Forestboy

    Forestboy Funster Life Member

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    We have twin solar panels (don't know power) topping up our 400 a/h of deep cycle traction batteries. We charge both bike batteries together with a 1500 watt pure sine inverter never got close to flattening the batteries but it does take a hell of a lot out of them.
     
  7. Jaws

    Jaws Funster Life Member

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    The bike battery chargers are quite low wattage.. I have eben used a 300w inverter to do the job.

    Aint got one of the chargers to hand but doubt they will draw more than an amp or so which equates to an absolute maximum of 450 watts
     
  8. hilldweller

    hilldweller Funster Life Member

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    300W inverter works fine for us. The problem being how much an ebike battery needs. They are usually 36V now so every amp into the bike is 3 amps out of the leisure battery.

    The way to work it out is 36V x 10Ah is 360 watt hours. A common 12V 100Ah has 600 watt hours available so two flat bike batteries and you've emptied the leisure battery.
     
  9. Scattycat

    Scattycat Funster

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    We have a 300watt inverter and charge our 2 bike batteries while driving.
     
  10. Lenny HB

    Lenny HB Funster

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    Depends on the batteries and chargers ours 1.5 amp which is 360 watts, allowing for 90% efficiency of the inverters, that's 800 watts or 67 amps at 12v (for both) and takes 2.5 - hours to fully charge the batteries that's 134 A/H.
     
  11. Judge Mental

    Judge Mental Funster Deceased RIP

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    Plus bosch 400 Ah batteries fully charge from empty in 3.5....partial charge in a lot less ( recommended)

    Cheap batteries can take a day
     
  12. hilldweller

    hilldweller Funster Life Member

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    Hell of a battery.
     
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  13. Judge Mental

    Judge Mental Funster Deceased RIP

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    Yes they are preety good H! They do a 12v car charger for them as well but think they are expensive....
     
  14. Don Quixote

    Don Quixote Funster

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    So to get 134 amps out you will need a battery bank of no less than 270 amps - why because you should never discharge ANY battery less than 50% as it will get damaged and DIE......
     
  15. chaser

    chaser Funster

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    Not done much with bikes yet but when we got them , I charged one battery up with one of those inverter that you plug into a cig lighter, 150 watts, didn't notice it running the battery down too much but then we travel every day.
     
  16. Lenny HB

    Lenny HB Funster

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    £143 and takes 6 hours for a full chage compared to 2.5 hours for the mains charger.
     
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  17. Lenny HB

    Lenny HB Funster

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    Your statement of "ANY" battery is is totally untrue, Gel and traction batteries are perfectly OK with 80% DOD and most AGM are fine with 75% DOD. Even some good quality wet cells are often OK to 60-70% DOD .
     
  18. Don Quixote

    Don Quixote Funster

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    Your are right GEL can be fine the rest as I state 50% or less and your are starting to damage them. Why do they sell so many replacement batteries if it "OK" to discharge them past 50%........ at the end of the day I have posted here many times ( as others have as well ) about keeping batteries in a good state ( they last longer ) and as mine are fine the way I treat them. Other than passing on what I know it's a case of "it's your batteries do as you please."
    I will no longer post any help here on the forum or advise about batteries / solar or otherwise as many know better than me............ so wasting my time typing.
     
    Last edited: Aug 16, 2015
  19. Bartyfixedit

    Bartyfixedit Funster

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    We have woosh bikes and our system has a pure sine wave inverter running continuously. When charging the Bike the inverter draws an extra 7A off the battery bank for up to a maximum of 5 hours. Once the battery is charged the draw is minimal.
    To summarise, our 300 amp/hr bank would charge each bike from flat around 5 times before reaching 50 percent charge.
     
  20. Judge Mental

    Judge Mental Funster Deceased RIP

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    Don't be silly...keep posting:)

    Bosch batteries BMS
    If you do a top up charge say 20% it will not count as a full charge.... so 5 @ 20% equals a charge life....
     
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