Overvolting a currie from 24v to 36v

Discussion in 'Electric Bicycles' started by Jeff Winder, May 15, 2010.

  1. Jeff Winder

    Jeff Winder New Member

    I'm new to the forum, so 'Yes' I did search before posting and making a new thread.
    I want to up the voltage on my currie bike. I have a currie eZip Trailz. SLA 24v @ 10ah ,Brushed motor controller (standard setup).

    After searching on the web and in other forums, It appears that some currie owners can run 36v without changing the controller, while other cannot...
    On my controller is printed the following: DC Brushed Motor Controller
    Model No 24v 35A
    Control Voltage 1-4v
    Drawing No: JC08CN04RMB
    2008 03 20

    Anyone know if this controller will handle a 36v 10ah batt???? I would really like to know before spending $290.00 + for a Ping LiFePo4.

    My backup plan is to do the following:
    I do have a variable power supply that is adjustable up to 50v at 3amps, so if I do not hear back from anyone, I will hook up the supply to the terminals and test to see what the upper voltage limit is that I can use to supply my system. So, worse case scenario, I should be able to at least go up a few volts over the standard 24v without changing the controller.

    Jeff :grin5:
    Cincinnati, OH

  2. moondog

    moondog Member

    Hi , You could also add another battery and see.

    The motor on my bike at 24V gets a little warm and that's it. Controller too.

    That's good.

    Using 36v can make the motor hot.

    If the electric motor or controller gets hot that is not good because that heat is wasted battery energy and it can ruin the motor.
  3. safe

    safe Active Member

    If I have to I'll start pulling out all the charts to explain this more fully, but the short answer is that it's current that actually does most of the damage. Now with brushed motors there is the issue about maximum rpm too... the more you increase the voltage the faster the motor spins and that causes arching across the brush / commutator interface which wears the brushes faster.

    Going from 24 volts / 30 amps to 36 volts / 20 amps (or 10 amps) should be fine.

    The big problems come about when people increase the voltage, but leave the current limit the same. The effect isn't bad at high rpm, but at low rpm you get a doubling of heat. Low rpm (hills) become the thing that destroys the motor when you overvolt. But with a lower current limit it slows the heating.

    I bought one of those ebay Currie motors that are rated as 1.4 hp and I'm running mine at 48 volts / 20 amps (roughly, not sure exactly) and it runs really cool.

    If you blow up your stock motor you ought to buy the ebay motor with the Neodymium magnets. That motor is incredibly well built by comparison to stock.
  4. moondog

    moondog Member

    They make a 24v and 36v version of that motor, both rated at 450w.

    They are not the same. If they are both 450W then the 36V motor would flow less current than the 24V motor.

    A 24V motor is designed to work best at 24V.

    A 36V motor is designed to work best at 36V.

    You can make holes in the 24V motor , put a fan on it for cooling, rewind it or just buy a 36 v motor.
    Last edited: May 16, 2010
  5. moondog

    moondog Member

    Last edited: May 16, 2010
  6. Jeff Winder

    Jeff Winder New Member


    Just hooked up my variable power supply to the bike, and was able to run it up to 36/38 volts without any problem. See attached photos. All I did was connect the supply to the terminals , lift the rear tire and throttle it up. The meter in the picture is showing no amps as I couldn't operate both the camera and experiment at the same time.

    The initial throttle pegged the amp meter, then backed down and showed a steady 2.5a load at full throttle. Oh course, not much load with it freewheeling, but I am now confident that the Ping 36v LifePo4 will work. :)


    Attached Files:

  7. moondog

    moondog Member

    A lot of info here. http://endless-sphere.com/forums/viewtopic.php?f=6&t=3249

    The meter won't peg, the high current will cause the battery pack to cut off to help save it from damage.

    Ping has a good rep for building battery packs. That is something considering how easily people ignore his suggestions for their use.

    I have worked in electronics repair for over 25 years now.

    The best designed tv's are the ones that don't need a lot of big heatsinks and fans

    The worst designed tv's are the ones with a lot of big heatsinks and fans. They get hot and break down more.

    Keep this in mind. If your motor, controller, wires and batteries don't get hot then you have a motorized bike that is designed to put your power on the tire and not waste it by making things hot.
    Last edited: May 17, 2010
  8. safe

    safe Active Member

    No Load speed doesn't tell you anything about current draw under load.

    The controller current limit is your best way to control heat. Lower current limits tend to produce cooler running motors that are more efficient, but they lack the low end torque. High currents allow more low end torque, but this produces a lot of heat and lowers efficiency.

    In most cases when you simultaneously increase voltage and lower the current limit you get the best of both worlds. The increased voltage produces more power at higher rpm, but the lowered current tends to still do well in torque because the controllers operate in such a way that the actual current the motor "sees" is larger than the battery current. This concept is somewhat bizarre to people outside of the electric world, but the formula goes:

    Total Power = Battery Current * Battery Voltage

    "Current Multiplication" = Battery Voltage / Throttle (duty cycle)

    ...so you might have a situation like:

    1 / 50% (throttle) = 2

    ...which means that there are times when the lower the throttle setting you have (less than 100%) the HIGHER the current you get.


    If you aren't confused then you are probably lying, but the technical stuff on this is more complex than you probably realize. The "bottom line" is that the rated settings work well because they are conservative, but there is a whole world of "tuning" that you can do that allows you to achieve optimizations for whatever you want.

    The conservative settings are usually pretty good.


    In general if you increase voltage you should reduce the current limit if you want to retain a conservative heat profile. And too much voltage can be too much because it increases motor rpm excessively.
    Last edited: May 17, 2010
  9. moondog

    moondog Member

    I have a couple of evg mini ebikes. I studied the history of them.

    They used these batteries first.


    Then went to sla then to NiMH ? Mine have the NiMH batteries.

    Then back to sla ? http://www.nycewheels.com/ebike-mini-sla-conversion.html

    Batteries confused them too and they had some top people at that company.

    They both have http://www.heinzmannusa.com/how_it_works.html

    brushed motors that say 24V on them and use 36V battery packs but they do have 20" wheels.

    ebike history : http://blog.bradrourke.com/2009/02/16/electric-bicycles-their-time-never-came/


    That brings with it a host of issues. We had to create VIN numbers, meet Department of Transportation regulations, which included having headlights that were as powerful as car headlights, and riders had to wear motorcycle helmets and typically get special motorcycle licenses in order to ride the things. We’re talking bikes with little motors, here, and all this rigmarole just about killed the idea before it started.

    But that was my job. The helmet and license thing. Me and a colleague, transportation consultant Ryan Snyder, went around to state capitals trying to get the laws changed in order to allow people to actually ride these things. Ryan had more success than I did with his states, but together we were able to get the law changed in California and I went on to get the law changed in Oregon and Washington states. W00t! The basic idea was simple: we created a new “class” of vehicle called the “electric assisted bicycle.” This new class of vehicle could be ridden without a special license, only on streets (not sidewalks), and anyone under 16 had to wear a helmet — but a bike helmet, not a motorcycle helmet.


    Currie went with sla and sold them at Walmart. They are still in business.
    Last edited: May 17, 2010
  10. Jeff Winder

    Jeff Winder New Member

    Ping Battery box

    Just finished up my ping battery box. Fits the currie bike just like the factory battery.

    The photos show the box without the front and back mounted.

    Now just waiting for the Ping Batt !!


    Attached Files:

  11. moondog

    moondog Member

  12. libranskeptic

    libranskeptic Member

    A variant on this is a perhaps common scenario, where one has a boring, tired and lame 36v battery looking for a home. What better than use it as an upgrade for an even lamer battery on a 24v bike.

    Not sure how, but i gather its simple and efficient, lower the 36v battery output to ~24v +20%, ride a while & monitor heat etc., gradually crank up a bit more if comfortable.

    Me included. My target 24v bike is a 200-250 watt model, set to 200, so clearly there is a lot of spare meat there, and makers have to be conservative, to suit all conditions, not just yours. The midwest is not the outback e.g.

    i.e. you dont know what you dont know, so make safe assumptions, such as, surely 20% more is a no brainer. After that, slowly slowly.

    10 amps 24v = 240w, 28v=280, 32v=320w

    pick one you feel safe with and probably within motor/controller manufacturers tolerance ranges, having checked temperatures of components during daily use as u work your way up. Cool, you get to upgrade once a month :).
  13. DrkAngel

    DrkAngel Member

    OEM 24V 10Ah SLA supplied restricted range and deteriorated rapidly.
    Tried 6Ah then 12Ah NiCd with moderate improvement.
    Tried 36V SLA then finally converted to 36V 20.8Ah Li-ion ... from recycled laptop cells!

    Purchased a newer eZip that didn't support 10s 36V Li-ion so built 7s 25.9V 31.2Ah Li-ion that ran nicely on everything ... gave me a couple extra mph and tripled range!
    Moved up to recycling LiP0 25.9V 25.92Ah
    Found some good 18650 Li-ion cells and built 33.3V 31.2Ah pack that works with most of my eBikes

    Yes I did upgrade some eBikes with a 24V - 36V+ cheap controller
    With my "standard" LiPo 25.9V pack I was able to rig the multi-position switch so that in
    position 1 it ran from 7s 25.9V pack,
    position 2 runs 7s 25.9V pack in series with 3s 11.1V pack for an effective 10s 37V pack.
    My TURBO switch.
    "Legal" 20mph motor only "switched" to 25mph+ (near 30mph ... with substantial pedal assist)
    (Changed freewheel from 20T to 16T to provide motor only 20mph from 25.9V)
  14. View attachment 72550 View attachment 72551 View attachment 72550 These are my two controllers for my two ezip Currie bike, I seen a video on some guy name Sean putting four turnigy lipos on it and working. I tried it with four new lipos 5.0 in parallel and series but doesn't work. Does anyone knows why or have any info that can help me. I want to know if the stock controller & throttle works with 36v? HELP PLEASE