Author Topic: Flat battery?  (Read 1525 times)

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Offline Shed

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Re: Flat battery?
Reply #10 on: 24 February, 2020, 08:53:10 PM
Piss poor.  :025:


Offline ToonCBF

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Re: Flat battery?
Reply #11 on: 25 February, 2020, 09:39:47 AM
I just plug mine in to an optimate when I am going to leave it for more than a few weeks, it always turns over and fires first time. The optimate is 8 years old and I have never had a battery die on me on any previous bikes whilst using it. A worthwhile investment!!!
I have the body of an 18 year old...... I keep it in the freezer!!!! (Spike Milligan)


Offline Greenfingers

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Re: Flat battery?
Reply #12 on: 02 March, 2020, 10:24:44 PM
Well, after fully charging the battery, I left it disconnected on the bench for a good few days. I checked the voltage each day afterwards, and after a couple of days, it was down to 12.7volts. Then it seemed to lose a tiny bit each day, going to 12.69,.68,.67,.67,.66,.66 and then I got fed up with the experiment and put it back on the bike.
It still had plenty of beans left to start the bike, so now I'm just going to leave it and see what happens.


Offline Art

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Re: Flat battery?
Reply #13 on: 03 March, 2020, 08:09:41 AM
Nowt wrong with that. Expect a fully charged battery to show a reading of between 12.6v and 12.8v across the terminals, rarely any more. These batteries are made up of six 2.2v cells giving a theoretical maximum voltage of 13.2v but you'll never get that, not even from a brand spanking new straight off the production line battery. If you have too much time on your hands the real battery condition tests now would be to see what the voltage drops are.

1) CCA (cold cranking amps) test - Disable the fuel system and turn the engine over on the starter motor for 15 seconds while checking the voltage across the battery terminals. Anything above 9.5v is acceptable, the nearer to 12v the better.

2) Electrical load test - With the engine running at a fast idle (1500 rpm) and all electrical equipment turned on, don't forget to beep the horn. Check the battery voltage for a minimum of a 0.5v voltage increase above the battery’s initial level of charge, that's 13.2v in your case (12.7v + 0.5v). Note if you get test results of less than 13v or more than 14.5v on this test you'll need to carry out an alternator output test.

and for completeness here it is

3) Alternator output voltage test - With the headlamp on high beam and the engine running at 5,000 RPM check the voltage across the alternator terminals (the large red cable to the battery and an engine earth point will do). An output voltage reading of between 13.2v – 14.2v is OK. If the output voltage is less than 13v suspect a stator fault, if the output voltage is more than 15.5v suspect a regulator/rectifier fault.