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Replacement Battery

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Add a bigger battery to increase range and ride time.


These batteries, also known as Reention Dorado batteries, fit into the downtube frame of your Biktrix eBike. Made with top-of-the-line Samsung and Panasonic cells, it doesn't get much better than this.

  • Juggernaut Classic
  • Juggernaut Ultra 1000 & 1000 Pro
  • Juggernaut Ultra FS
  • Stunner LT
  • Stunner X
  • Stunner Step-Thru
  • Stunner Step-Over
  • Swift Step-Over
  • Swift Step-Thru
  • Skycap


These replacement batteries are enclosed within the frame of:

  • Juggernaut Ultra Beast (48V 15Ah)
  • Challenger (48V 14Ah)
  • Juggernaut Ultra FS Pro
  • Juggernaut Duos (52V 17Ah)
  • Swift Lite (36V 10Ah)

Range Extender

These Range Extender replacement batteries are compatible with the following eBikes:

  • Juggernaut Ultra Eagle (52V 21Ah only fits the large frame Eagle)
  • Juggernaut Duos** (additional battery)


**The following are NOT compatible with the 21Ah downtube batteries (if you are unsure of the fit, please email us):

  • 18.5" Ultra Duo 2 Step-Over
  • Classic Duo Step-Over
  • Ultra Duo 3 Step-Over

Charger included in each battery purchase.

Customer Reviews
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Filter Reviews:
    Mathieu P.

    Expensive replacment

    Very expensive.

    Greg O.
    Canada Canada

    Large capacity battery

    I have installed the larger capacity battery, and tried it out for about a half hour ride, it certainly has a nice ride range, didn't drop hardly at all, for a number 2 power assist at crank....very very impresssed at this point....the original medium capacity battery that came with the bike still works as good as the day I bought the bike, 3 years ago....all round, the whole experience has been fantastic, with Biktrix. Great products from Biktrix.... Thanks to all Greg O

    Matthews R.
    United States

    Amazing battery.

    I am getting about 42 miles of travel on 35v 17ah battery on my 250w ebike at 18mph in vero beach Florida USA. Great battery . Definitely will buy another when needed. THANKS biketrix

    Mike A.

    Battery purchased

    Wow what customer service they went and measured one of there 48v short battery’s for me. it worked perfect on my other brand fat bike which only sold a 10.4amp battery but the bike comes with a 20 amp controller so 17amp is great almost double the range

    Pete W.
    United States

    Excellent owner and product

    Rashan is always available when I had questions and followed up with what he said right away.. Very happy products and my backup batteries

    joseph e.
    United States

    battery purchase far...I bought this as a spare because the battey that came with the bike was defective

    James G.
    United States

    Well, sometimes bigger IS actually better!

    I received the new 20 Ah battery for my Juggernaut Ultra, and suddenly worrying about having enough battery power for the return trip is not longer an issue. I did my best to see how long it would take me to run it down to a 50% charge by using throttle-only while in Level 5 sport mode. I rode for more than 2 hours, but only managed to get the battery down to 83%. I clearly did not set aside enough time for that little experiment, but it sure proved to me that I made a wise choice getting the big battery. I also have an 11.6 Ah battery that came with the bike, but I'll just use that as a backup - not sure I'll ever need it though. Get the biggest battery you can afford - you'll be glad you did.

    Carl T.
    United States

    Extra Battery

    This is a perfect replacement or extra battery in my Biktrix bike. It also fits another brand electric bike I own that needed more range and wasn't supported by that company.

    Gary A.
    United States

    Spare 19.4 AH 48 volt battery

    It was a pleasure dealing with Roshan as a person and Biktix as a company. I contact Roshan about a spare battery and he followed up with dimensional information so I could verify the unit would work in my "other brand" bike. I ordered and received the unit, it fit perfectly and gave me increased range. The only mistake was my own in that I should have originally bought a Biktrix bike! Good service and honest answers and good value!