E-bike charger

Discussion in 'Tech/Mech General' started by SMB, Jul 8, 2016.

  1. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
    I have a Haibike Sduro e-bike which is powered by a Yamaha 36v 400wh battery, charging when on hookup is not a problem but when I tried charging it via the leisure batteries using my fitted 1000w inverter it sucked the power at an alarming rate, I was literally watching the battery levels going down even in full sunshine and with 230w of solar panels. I am looking at a 12v portable inverter now, I have a 150w Kensington 12v inverter but I don't think its rated high enough to charge the battery. Anyone have any advice/suggestions? Bosch supply a 12v charger for their e-bike batteries but not Yamaha, typical!
     
  2. NickNic

    NickNic Funster Life Member

    Joined:
    Jan 14, 2014
    Messages:
    5,425
    Likes Received:
    11,093
    Location:
    Kettering
    Using a different inverter isn't going to help. It will still be drawing the same power from the same batteries.

    Trying to charge anything of a higher voltage than 12v is always going to drain your batteries quickly.

    Have a look at the mains charger and it should have the current (amps) it uses at 230v, stamped on it. Basically you multiply that by 20 to find how much it will take from your batteries per hour.

    Even if you could find a dedicated 12v charger for it the same thing would happen.

    If you really have to charge it from your leisure batteries all you can do to improve things will be to add more of them to increase the size of the battery bank.

    It doesn't matter how you charge it - via this inverter, that inverter, a 12v charger or anything else - it is still going to take the same from your batteries. A 12v charger might be marginally more efficient because you eliminate the losses from the inverter but it won't be noticeable.
     
    • Like Like x 2
    • Useful Useful x 1
  3. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
    Thanks for that Nick, I thought that might be the case but, having no idea about electrical systems, I thought I would ask anyway. I have a b2b charger fitted so I might try charging it via the inverter whilst driving, do you think that might do the trick? Cheers, Paul
     
    • Like Like x 1
  4. Lenny HB

    Lenny HB Funster

    Joined:
    Oct 18, 2007
    Messages:
    5,213
    Likes Received:
    5,008
    Location:
    West Sussex
    I use a 1000 watt pure sine inverter to charge my Bosch 400 watt batteries, only time I have really hammered the batteries is when I charged both at the same time from nearly flat in the evening. Charging a 400 watt battery should only take about 35A/H out of your batteries.

    The Bosch 12v charger is £150 and it takes 6.5 hours to charge a 300 watt battery and would give no advantage over an inverter. A battery of X size needs X amount of power to charge it regardless of type of charger.
     
  5. NickNic

    NickNic Funster Life Member

    Joined:
    Jan 14, 2014
    Messages:
    5,425
    Likes Received:
    11,093
    Location:
    Kettering
    It would certainly be better.
     
  6. NickNic

    NickNic Funster Life Member

    Joined:
    Jan 14, 2014
    Messages:
    5,425
    Likes Received:
    11,093
    Location:
    Kettering
    Depending on the size of his battery bank that could be too much.
     
  7. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
    I will try it tomorrow when I move on, thanks again
     
  8. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
     
  9. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
    Sorry Lenny, I somehow managed to place my reply in between your reply!
     
  10. injebreck99

    injebreck99 Funster

    Joined:
    Dec 5, 2011
    Messages:
    1,113
    Likes Received:
    1,157
    Location:
    norfolk
    That's what we do, but we have 24V 250W motors on our bikes and a 700W inverter.
     
    • Like Like x 1
  11. Lenny HB

    Lenny HB Funster

    Joined:
    Oct 18, 2007
    Messages:
    5,213
    Likes Received:
    5,008
    Location:
    West Sussex
    Were you by any chance looking at your battery monitor while still under load? After a fairly heavy current load you need to let the batteries recover for an hour before taking readings, they should have only dropped by about 10% unless they are getting tired..
    With your battery bank and solar panels shouldn't be any problem at all charging the bike battery.
     
    • Like Like x 1
  12. jockaneezer

    jockaneezer Funster

    Joined:
    Dec 12, 2010
    Messages:
    1,586
    Likes Received:
    3,058
    Location:
    Cumbria
    We tend to charge ours via the inverter only when we're driving between sites.
     
    • Like Like x 1
  13. autorouter

    autorouter Funster

    Joined:
    Apr 27, 2016
    Messages:
    113
    Likes Received:
    43
    Location:
    Manchester
    400 watt-hours in 12V leisure battery speak is 400/12 = 33 amp-hours. This is a small chunk of 400 amp-hours of leisure battery, and should not cause the big problems you are describing.

    Indeed, if the solar input is 11 amps, that's 11x3 = 33 amp-hours over a 3-hour period, so in fact your leisure batteries shouldn't be discharging at all!

    I guess the charging period on hookup is 3 hours, then the wattage of the charger is about 400/3 = 133 watts, so it's near the limit of a 150 watt inverter. Have a look at the small print on the label on the charger. If there's no wattage figure, it will have the voltage and current, eg 230V 0.5A. So just multiply them, eg 230 x 0.5 = 115 watts.

    Is your 150 watt inverter a 'pure sine wave' type? Maybe it and the 1000 watt inverter are the cheaper 'modified sine wave' type, and it's causing problems for the charger.

    If you're going for a larger inverter, 300 watts should be more than adequate, but make sure it's a 'pure sine wave' type.
     
    • Like Like x 1
  14. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
    I thought there should hve been enough power coming in via the solar panels as well, strange. The batteries are only a year old and have never been discharged below 80% so they should be ok. Oh well, I'm moving on tomorrow so I will hook the battery up to the inverter before I set off, thanks again


     
  15. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields

    Thanks for that, I'm going to experiment with the 1000w inverter which is a Waeco modified sine wave model, you could be right! The charger itself doesn't have the wattage marked on it but it says the input is 220-240v and 1.3A, the output is 3.6A
     
    Last edited: Jul 8, 2016
  16. Robert Clark

    Robert Clark Funster Life Member

    Joined:
    Jul 12, 2014
    Messages:
    5,567
    Likes Received:
    9,662
    Location:
    East Sussex
    As Nick says a B2B charger would be the perfect solution
    Leave your existing inverter in place and simply put the bikes on charge only when travelling between stops.
    Disconnect the bikes on arrival and you won't waste any valuable battery power
    In simple terms you are increasing your on board batteries by adding the bike batteries when you're most able to charge them
     
    • Like Like x 2
  17. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields
     
  18. NickNic

    NickNic Funster Life Member

    Joined:
    Jan 14, 2014
    Messages:
    5,425
    Likes Received:
    11,093
    Location:
    Kettering

    The 1.3A is what you need to know. This is the current it draws

    230 x 1.3 = 299 watts, call it 300 for simplicity.

    This remains constant whatever the voltage so for the inverter to provide 300W at 230V it needs to draw in 300W at 12V.

    Do the sums: 300 / 12 = 25A.

    So, allowing a bit for inverter inefficiency you will be pulling 25 - 30 amps per hour from you batteries.
     
    • Like Like x 1
  19. jockaneezer

    jockaneezer Funster

    Joined:
    Dec 12, 2010
    Messages:
    1,586
    Likes Received:
    3,058
    Location:
    Cumbria
    I reckon my 18 year old nephew would be an ideal candidate for the Mars mission. He spends all day in bed or at least horizontal, on his xBox or pc and has almost become nocturnal :(
     
    • Useful Useful x 1
  20. SMB

    SMB Funster

    Joined:
    Apr 26, 2013
    Messages:
    663
    Likes Received:
    588
    Location:
    north shields

    Thanks for that Nick, I plugged it in this morning before there was any solar input and the monitor was showing 14.5 amps going out nbut the rate it was discharging the other day with 11-12 amps of solar power going in makes me think your figure is definitely closer to the mark! Anyway, I connected it to the inverter whilst travelling and I arrived with full leisure batteries and a fully charged bike battery. Its a pity Yamaha only do a fast charger for the battery, a normal speed charger would be better for me as I would rather it took twice as long to charge at half the power! When I go out on the bike I probably do around 30-40 miles and use anywhere from 30% to 70% of the battery power, the problem will be when I am staying somewhere without EHU for more than a couple of days. Guess I will have to put more effort into the cycling manually and save the battry power for the steepest hills :( but thanks again for the advice its appreciated
     
    • Like Like x 1
Loading...

Share This Page