Internal combustion, 250cc fuel-injected motorcycle.

Original battery is 12V 6Ah (10 hr) CCA: 130A

The new battery is 12V 4Ah (10 hr) CCA: 70A

Should I worry for anything apart from the actual capacity (1/3 less time) of the battery?

  • Correct, 4Ah would equate to a shorter run time. Depending on how the cells are arranged it could even equate to less horse power.
    – MonkeyZeus
    Dec 30, 2019 at 19:52
  • Is this an internal combustion bike (with a gasoline engine, where the battery is used to start it) or an electric bike (with a motor that is powered by this battery)?
    – dwizum
    Dec 31, 2019 at 14:28
  • It's an internal combustion, 250cc fuel-injected motorcycle. Just edited original question to specify that.
    – azathoth
    Dec 31, 2019 at 15:52

1 Answer 1


Power = volts X amps. A smaller capacity battery will generally deliver less cold cranking amps (CCA) than a larger capacity battery. By reducing the amps delivered by the battery you are reducing the power it can deliver to crank your starter, so you could have problems starting up or running under a high electrical load.

If the 4Ah battery has the same CCA as the 6Ah then you might get away with it, however you'll have less overall capacity, your 4Ah battery will not be able to crank for as long as a 6Ah. There's a reason it came with a 6Ah battery, and you should replace it with a 6Ah one, not less.

Edit after CCAs were added into the question: The 4Ah battery has almost half the CCAs as the 6Ah battery, if your bike has a starter the 4Ah battery may have trouble cranking it as it has far less power.

  • Amp-hours is a rating of capacity, not current. Current for motorcycle batteries is rated in CCA (cold cranking amps) just as with automotive batteries. It is often the case that a battery with less capacity (amp hours) will also have a lower CCA rating, but that is not always true. In other words, a battery with a smaller AH rating will not inherently deliver less current.
    – dwizum
    Dec 31, 2019 at 14:27
  • 1
    I completely agree with you @dwizum, I've never seen a 4Ah battery with the same CCA as a 6Ah so I am making an assumption here. I will edit to make that assumption clear.
    – GdD
    Dec 31, 2019 at 14:35
  • Thank you, it's been two days since installed 4Ah battery, and engine starts with no problem.
    – azathoth
    Dec 31, 2019 at 15:38
  • Just updated with CCA ratings
    – azathoth
    Dec 31, 2019 at 15:58
  • Likewise, a higher Ah battery does NOT guarantee a higher CCA rating. Also, a battery with 30% less Ah will (assuming both batteries are healthy) be more susceptible to parasitic draw and will die from sitting faster. Dec 31, 2019 at 17:19

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