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How to Extend Battery Life

  1. Mar 8, 2014 #1
    For a physics project, we have to increase power to an automated wheelchair.

    This wheelchair has:
    Battery Capacity 2x60AH
    Battery Needed (x2) GR 24

    I know that this means there are 2 batteries at 60 Ampere-hours. I don't know what a GR 24 is.

    Also, I don't know how to increase the output from these batteries to give more power. Increase the AH? If anybody had any suggestions, that would be greatly appreciate.

    I understand that changing the motor would probably be more beneficial, however, my part of the project is to worry about battery drain.
  2. jcsd
  3. Mar 8, 2014 #2


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    Staff: Mentor

    GR24 means "group 24" and it refers to the size of the battery case (and that it's a deep-cycle battery, which is of course what you need for this application).

    The way you increase the amp-hours is to use more or bigger batteries.
  4. Mar 9, 2014 #3


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    Gold Member

    Agarb, I see you expect more power.. but for how much time? What is the time period for which you are going to use the battery? Or if you talk about the total charge, Bigger the Better.
  5. Mar 9, 2014 #4

    I need to make the wheelchair accelerate for 5 m/s^2 for 5 seconds. Think of it as a little turbo-boost
  6. Mar 9, 2014 #5

    So using a GR 27 or GR 31 wouldn't necessarily be a bigger battery, just a bigger case? Or would these be bigger with more amp-hours? Or both?
  7. Mar 9, 2014 #6


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    Staff: Mentor

    Amphours determines how many hours you'll be able to sustain travel. It is not an indicator* of the speed capabilty or maximum power. Basically, the only way you can make the wheels turn faster is by supplying more volts to your motor, or by replacing the motor with a bigger one that can consume more amps. Hand-in-hand with this change there will need to be a new electronic controller installed (or the old one substantially modified).
  8. Mar 10, 2014 #7
    What about sticking some extra magnets on the [DC] motor ? ... http://youtu.be/UkKk7qSaKJY?t=45s
    Last edited: Mar 10, 2014
  9. Mar 10, 2014 #8
    For the short period of time your wanting the power changing to much smaller batteries (due to less weight) and going up in voltage is really about the only way it's going to happen. More voltage will give you the watt increase for power and using smaller batteries will solve the weight problem. Most wheel chair motors are in the 350-500 watt range. You can normally double the voltage and get 2X+ more power as long as you don't expect them to last very long. You will need another controller for the higher voltage. The batteries are not the holdup on power here. Even small 12 amp scooter batteries can supply the amps for the time you need. Higher wattage motors or higher voltage is required. Higher voltage is the easiest way to go.
  10. May 15, 2014 #9
    Could build a capacitor bank for 5 second power boost, protect back flow with diode parallel into motor input, reverse polarity protect with cutout relay and put a separate button to engage marked "never press this button".
  11. May 23, 2014 #10


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    That would get it up to 25m/s, which is just under 60mph. Why would you need to accelerate a wheelchair up to highway speed?
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