Fully charged battery won't turn the starter motor

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oldbiker
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Joined: Sun Apr 26, 2020 6:54 pm

Re: Fully charged battery won't turn the starter motor

Post by oldbiker »

I dont really check the voltage before charging. During the winter months I just plonk the charger on each bike for a day (about every 6 weeks(ish)). I dont bother charging the bat if the bikes are being used. Since the charger is supposed to stop charging when battery full I just put it on and test before removing - usually about 14.5+ volts.

An easy test for your bike is to put the main headlight on full beam and then hit the starter button. On a good motobatt the lights should stay on and motor spin ok - on a gt750.
On my xs650 the engine now is spinning over more slowly than in the past even when fully charged - it might be a duff connection or the bat going. Its tough on bats is the xs650.
With spare bat its a simple test. With 10 bikes I can nick one from another bike.
I find these motobats do give good performance for longer than a standard lead acid battery.

I tend to use cheap batteries on bikes withOUT electric starting. They still seem to last well.
teazer
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Re: Fully charged battery won't turn the starter motor

Post by teazer »

As per normal, this thread is bouncing all over the place and some good points have been raised.

The issue sounds like the battery is dead and a replacement will fix that. If it turns over fast again, that was the issue.

If it is still hard to turn over, the issue is likely to be the starter brushes or corroded connections.

If the battery replacement works, then the next thing to check is the charging system to ensure that the battery is being charged properly when the bike is running.

Just as an aside, I set up my old bikes so that the lights are OFF when I start the bike and I fit a relay into the circuits to ensure full power to all systems. If There's no OFF position for lights, I fit a NC relay so that when I press the starter button, it cuts power to the lights as the starter solenoid is engaged. That is basically how most modern bikes are wired.

On a GT750 the starter is more or less the same as a 550 or a GSXR1000 or TL1000 and should spin the engine over pretty fast.

BTW, MotoBatt I believe are AGM which are generally very good and reliable batteries. I would never fit a traditional lead acid battery in a motorcycle. They are cheap but at what cost?
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Dutch
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Re: Fully charged battery won't turn the starter motor

Post by Dutch »

stevewharton wrote: Sun Jan 02, 2022 1:02 pm Hi Jeff, had my Motobatt battery on the kettle for over six years now and it's still going strong. When parked in the garage it's always connected to the "Babybatt" charger (as advised by the seller) that I bought with the battery. Not sure whether there's any difference between the way a Babybatt and an Optimate works, but with my battery and charger both designed and made by the same company, perhaps that's why it's lasted a lot longer?
All the best for the new year mate, Steve.

P.S. the Babybatt charger only puts a trickle charge into the battery when needed, otherwise it's on standby and I thought the Optimate did the same?
As for the Yuasa type lead acid batteries, I never had one on the kettle that lasted much more than two year

Steve/Old Biker - Is this the charger that you use - https://www.tayna.co.uk/battery-charger ... /baby-boy/

Teazer The bike starts ok with the kickstart and today I did some checks.

1st - I always ensure the lights are turned off before hitting the start button especially when cold starting

2nd - The voltage when it's on idle is approx 11.0 v and 14.2v at 4000rmp

3rd - When I increase the revs the headlight goes much brighter so I assume the bike is charging when out on a run but
not been out since early Nov

My new Motobatt Battery should arrive tomorrow so will up update you then

Thanks again for your help
Jeff
GT750A
oldbiker
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Re: Fully charged battery won't turn the starter motor

Post by oldbiker »

Dutch wrote: Tue Jan 04, 2022 7:30 pm
Steve/Old Biker - Is this the charger that you use - https://www.tayna.co.uk/battery-charger ... /baby-boy/
Opps only just spotted the question.

Same charger as mine. Same manufacturer. Mine states a max charging rate of 500mA@12v. So it should be ok for big or smaller batts.
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Dutch
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Re: Fully charged battery won't turn the starter motor

Post by Dutch »

Hi guys,

New battery arrived today and checked the voltage before I did anything and for me it was a little on the low side @12.33v so fitted it and it started the bike within seconds. Took a reading of it ticking over (Idle)and it was 11.8v so all is well again

Took a reading when I switched the engine off and it was 12.30v so would you connect the charger? as the weather's not looking too good the next few days so not likely to be taking it for a spin.

Thanks again
Regards Jeff
GT750A
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stevewharton
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Re: Fully charged battery won't turn the starter motor

Post by stevewharton »

Dutch wrote: Tue Jan 04, 2022 7:30 pm
stevewharton wrote: Sun Jan 02, 2022 1:02 pm Hi Jeff, had my Motobatt battery on the kettle for over six years now and it's still going strong. When parked in the garage it's always connected to the "Babybatt" charger (as advised by the seller) that I bought with the battery. Not sure whether there's any difference between the way a Babybatt and an Optimate works, but with my battery and charger both designed and made by the same company, perhaps that's why it's lasted a lot longer?
All the best for the new year mate, Steve.

P.S. the Babybatt charger only puts a trickle charge into the battery when needed, otherwise it's on standby and I thought the Optimate did the same?
As for the Yuasa type lead acid batteries, I never had one on the kettle that lasted much more than two year

Steve/Old Biker - Is this the charger that you use - https://www.tayna.co.uk/battery-charger ... /baby-boy/
Hi Jeff, yep that's the one and a similar price to what I paid about six years ago when I bought the "yellow brick" battery.
Look, my paintwork hasn't got "Fish scales" :x they're "Dragon scales" right!!! However, after some thought, I will accept "Black Marlin" or "Swordfish", but definitely not "Haddock" or "Cod".
bigrocketrider
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Location: Cornwall

Re: Fully charged battery won't turn the starter motor

Post by bigrocketrider »

For what its worth, I have a collection of bikes and would only buy Motobats. I also leave them on trickle chargers (optimates) continually when not in use - my kettle one has been on 11 years and still works absolutely fine!!
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