My power to my motor is dropping after 5 miles rapidly

Discussion in 'Maintenance and Repairs' started by Wall1388, Jun 29, 2017.

  1. Wall1388

    Wall1388 New Member

    I have a 48 volt 1000 watt front hub wheel it's generic out of Hong Kong ....for the first month and a half it ran fine I'm experiencing going from Full to half to empty after 5 miles.... I have four batteries 12 volt 18 a h .acid....after this I put a multimeter on them and they readaround 12.5 volts each... the batteries always charge up to 13.5 volts when fully charged ....if anyone has a reason why this would be happening I would appreciate your input..... frustrated in Florida .....thanks
    Last edited: Jun 29, 2017

  2. Please support your local electric bike shop! These guys work hard offering test rides, sharing expertise and performing support.
    EBR strives to be impartial, we don't sell bikes ourselves and keep ads limited and relevant. Donations are greatly appreciated.

  3. JRA

    JRA Well-Known Member

    SLA batteries lose their effectiveness very quickly when charged/discharged repeatedly unless they are deep cells. Do yourself a favor and get a LiFePo4 battery or the equivalent and I bet that solves your problem and you will get way better performance and mileage along with a much lighter bike.
  4. Wall1388

    Wall1388 New Member

    Thanks for ur reply...what has me fusyrated
  5. Wall1388

    Wall1388 New Member

  6. emco5

    emco5 Active Member

    Maybe the hub's controller is programmed to work with Lithium batteries which have higher voltage and a narrower draw-down range than lead-acid.
    Ann M. likes this.
  7. Wall1388

    Wall1388 New Member

    Thanks for the answer... they said that I can use lithium battery or the acid but they had to be 17ah or up so I chose the 18 ah 12v 4 of them because of there warranty and they can last up to 3 yrs...and of course there much cheaper than lithium...this is my first time trying a ebike ...and I only use it to go about 25 miles a WK ... the longest trip I took was 25 miles.. most ly it's 12 and it's plugged in to recharge..'s like the motor is running off of 6 v instead of the 48 ..... because when the throttle reads empty the batteries are all reading around 12 v each.....
  8. J.R.

    J.R. Well-Known Member

    Not 6, but not 48 either. The batteries are tripping the low voltage cutoff. You are checking the voltage of the batteries after use, but not under load. If you could check the voltage after those 5 miles, while something was drawing 48 volts/15 amps, you would find the batteries are not 12.5 v. Find a battery supply that can test the batteries under load. Usually a free test.

    You'll need a lithium-ion pack to do your regular 12 mile ride in hot Florida. Or deep cycle SLA. Even expensive deep cycle batteries won't hold up nearly as long as lithium-ion.

    Good luck!
  9. Wall1388

    Wall1388 New Member

    Thanks I'll try that today...