Date: 29-03-24  Time: 11:40 am

Author Topic: Battery dies but then comes back again, all a bit weird?  (Read 1745 times)

ProdigalSon

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Battery dies but then comes back again, all a bit weird?
« on: 04 November 2018, 08:52:45 pm »
So i got my bike out today to go for a ride with my friends having last ridden it last Saturday, as usual the bike fires straight up, I go to the garage again the same thing hop on fires straight up, get to meeting point have a coffee and leave and again it starts straight up. So a little further up the road we pull over and stop while one of the others fills up with petrol and bike doesn't fire and second push on the button the engine is slow to turn over, third push and barely turns one revolution.


Fortunately as it was warm it only took a brief push to bump start it and for the rest of the day no further problems, I checked the batter when I got home and these were the figures I got. Static ignition off 13.4 volts, engine running no lights 14.4 volts, engine running lights on 13.8 volts, these were all at tick over as I couldn't hold the multi meter on the battery and twist the throttle at the same time.


The bike doesn't have an alarm fitted so no rain on the battery whilst the bike is not in use and in the week prior to last Saturday it sat connected to my Optimate, any ideas peeps? :)

celticbiker

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #1 on: 05 November 2018, 07:46:36 am »
Could be the starter relay.
As they make contact there is a small arc created between the two plates, over time this causes a build up of carbon on their surface which in turn creates a high resistance preventing enough current being passed to turn the starter. Other times the relay will fire (click, click, click....) as you push the button but the starter won't turn at all.
There is a simple test for this but wouldn't want to suggest it if you are not mechanically or electrically competent.
Simple solution is to replace it, it's a £6 part and takes about 10 minutes to do.
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ProdigalSon

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #2 on: 05 November 2018, 07:35:33 pm »
Could be the starter relay.
As they make contact there is a small arc created between the two plates, over time this causes a build up of carbon on their surface which in turn creates a high resistance preventing enough current being passed to turn the starter. Other times the relay will fire (click, click, click....) as you push the button but the starter won't turn at all.
There is a simple test for this but wouldn't want to suggest it if you are not mechanically or electrically competent.
Simple solution is to replace it, it's a £6 part and takes about 10 minutes to do.


Thanks for that, for £6.00 I'll change it just as a precaution but there was no clicking on the relay it was literally as if it had a flat battery even though it had started without a hitch three times already yesterday morning? :(

celticbiker

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #3 on: 05 November 2018, 07:47:53 pm »
A similar thing could have also happened in the starter button so it's worth cleaning the contacts in there too.
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Falcon 269

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #4 on: 05 November 2018, 09:03:58 pm »
As always, check your earth connections before doing any further troubleshooting with electrical faults. :)

ProdigalSon

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #5 on: 06 November 2018, 11:31:56 am »
As always, check your earth connections before doing any further troubleshooting with electrical faults. :)


Good shout, thanks Mike, I checked the battery last night and at rest it's 12.88, now I know it's a 12 volt battery but I'm thinking that's possibly a little low with no load on it?

Dynspud

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #6 on: 06 November 2018, 01:38:41 pm »
That sounds about right for the battery voltage mate.


My understanding is:-
Cold voltage = 12.5 v (minimum)
Cranking voltage = 10 v (minimum)
4000 RPM voltage = 14v (minimum)


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PieEater

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #7 on: 06 November 2018, 03:11:00 pm »
Someone will correct me if I'm wrong but you will still get at least the expected cold voltage readings even if you have a dead cell in the battery as the other cells will still be outputting the volts but not the amps. This was explained to me by a battery specialist when I couldn't understand why my battery optimiser was saying the battery voltage was OK but the battery still wouldn't crank over the engine. Needless to say a new battery resolved the issue.
« Last Edit: 06 November 2018, 03:11:40 pm by PieEater »

ProdigalSon

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Re: Battery dies but then comes back again, all a bit weird?
« Reply #8 on: 06 November 2018, 04:19:35 pm »
Thanks for the replies guys, I have a proper full size charger which I believe can test the battery and see if there are any dead cells.