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Replacing Rechargeable Battery with Wall-Wart Power Supply

  1. Sep 20, 2012 #1
    I have a LifeFitness exercise bike. It uses a Hawker Energy Sealed Lead Rechargeable Battery that is three cells with a rating of 6 volts at 2.5 AmpHours for 1019 Watts.

    The battery is recharged by usage of the bike. However, the bike is designed for commercial use and the battery discharges over time with just my personal use. If I don't use the bike for an extended period like in the summer when I get outside on my mountain bike, I have to replace the battery because of its prolonged discharge state.

    So, I would like to replace or supplement the battery with a wall-wart style power supply. I will have no problem physically connecting one -- I just need to make sure I purchase the right thing.

    Because the bike is not designed for a power supply, I assume I need a good one with well regulated power. I don't know if I need good filtering, but I am assuming one with good regulation will also have good noise filtering anyway.

    What type of unit do I need to purchase? Is there a particular kind of store/supplier I need to purchase it from? Do I want a supply with a set 6V 2.5A rating, or am I better with a variable output supply like a replacement power supply for a laptop?

    Complicating things could be the fact that the bike is meant to provide regenerative power. Should I leave the battery in the bike when I attach the supply, or should I take the battery out?

    I hope this was an appropriate question to ask here. Please excuse me if it was not. Google search brought be here and there appeared to be other similar questions.

    Thank you for any help. This seems like a great community.
  2. jcsd
  3. Sep 21, 2012 #2


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    Staff: Mentor

    Hi WmPitcher. Welcome to Physics Forums.

    To address a question you didn't ask, :smile: have you thought of using solar cells to trickle charge your battery?
  4. Sep 21, 2012 #3
    Sure, I'm open to using a solar trickle charger -- or the same thing plugged-in. I don't move the bike. So, I am not worried about cords and the like. I just want a cost effective solution that does the job. I thought a wall-wart was the simplest and cheapest solution, but I have just enough knowledge to be dangerous.
  5. Sep 21, 2012 #4


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    Staff: Mentor

    With a makeshift mains charger you'd have to remember to switch it on, and later off, to avoid overcharging the battery. A low current solar charger could probably be left continuously charging, providing its output was below the float charge the sealed cells can tolerate. I have a couple of the sealed lead acid D cells, and know they can withstand constant charging of a certain level.

    The only difficulty would be if your bike is a long distance from a bright window.
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