Sluggish power IET F Goblin Car

Recently encountered sluggish power on Goblin car. Battery fully charged and only a year old. All electrical connections seem solid.

Has anyone got any ideas on what the problem could be?

Any help would be appreciated.


  • Does the motor turn freely and smoothly by hand with the belt off? Any grinding or untoward noise?
    Likewise, does the rear axle run smoothly when disconnected? Brake releasing correctly?
  • Rear axle runs as expected. No undue noises. Fully charged battery operates at normal power and then suddenly starts running slowly as it loses power rapidly. Could it be overcharging? Could the batteries be damaged?
  • What charger are you using on the batteries to determine that it is fully charged?

    I have seen some chargers that apply 14.7V when using "boost" or "rapid" mode, which is a bit too high for the AGM batteries as there is very little electrolyte to start with which can easily boil away when overcharged. Does the battery get warm when charging? Can you hear "bubbling" noises from whilst charging?

    How long does it take for the car to become sluggish from fully charged? Are you able to get a reading of voltage at open circuit, you might have a dead cell?

  • The batteries need quite specific care in order to last and can degrade rapidly if they are not kept warm and charged. Could it be that you're using an old battery which has had to fend for its self over winter?
  • When charging the battery does not make any noises and it does not get warm. It appears that one of the batteries are not charging. Both batteries were brand new last year and have been kept indoors at all times. After charging the car lost power within 10-15 minutes. Is there a way of getting the battery to hold charge again?
  • Unfortunately the greenpower batteries are sealed to prevent nasty acid leaks and it can't be replaced/topped up like with a traditional car battery. There are "battery desulfators" which claim to restore the full capacity by pulsing the battery with higher voltages to "break up" the oxide and sulphate layers on the plates, but there is some debate about whether or not they are effective or not.

    If you've double checked and ruled out mechanical/wiring problems, then see if you can borrow a different make of battery charger and try it out using that, there isn't much more that can be done with the battery itself and you'll want to look at replacing it.

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