14-02-12, 01:31 PM
Batteries are very odd things...
First ... the chatter from under the seat is indeed a sign that at the the battery couldn't hold more than about 6V when the starter motor inrush current happened (70 amps or so). That's either a sign that all the 6 cells were discharged or that ONE of your cells is shagged.
As a rough guide ... starter motors are designed using the "Max Power Theorem" which says that you need half EMF of the battery (EMF = Electro-Motive-Force) to appear on the starter motor to get max cranking power. That usually means that they are designed to loose 3V in the battery (so its a 9V battery when cranking) and 3V in the cable so that 6V appears on the starter motor. You can see that if the battery goes slightly high-resistance then it will drop 4-6V and you will get 6V on the battery and 3V on the motor and the relay will drop out (and then immediately re-engage as the battery voltage rises - and then do it all over again, hence the 'machine-gun' noise).
Second ... lead-acid batteries (of any sort) don't like to be fully discharged - they like to be at full capacity 99% of the time and have 1/2 an amp hour (5% of capacity) taken out to start the engine and then be immediately recharged. they seem to last 10 years if that's what happens all the time.
The worst thing you can do to a battery (aside from dropping it) is to discharge it to 10 percent and then attempt to crank the engine... they REALLY don't like that and it quite often damages the first cell that goes to 0%. Then you end up with a 10V battery and experience suggests that a 10V battery will JUST ABOUT start a fazer on a nice warm day if its fully charged. In winter it will cause the 'machine-gun' noise from under the seat.
The OTHER worst thing you can do to a battery is to attempt to charge it beyond 100% (14.3V)- it just makes Hydrogen and Oxygen and grows spongy oxide on the plates and reduces its capacity.
Gel batteries(OEM fit for FZS600) are especially fragile. AGM batteries now sold as replacements are better and hold their charge longer but they have slightly less capacity.
Its supposed to have a 10 Amp Hour capacity - so a fully charged battery should last about 1.5 hours driving 2X headlights. If it only lasted 15 mins then I suspect that you have either a 10V battery or one that is just simply "almost shagged".
On the other hand, it may just have been partly charged.
First ... the chatter from under the seat is indeed a sign that at the the battery couldn't hold more than about 6V when the starter motor inrush current happened (70 amps or so). That's either a sign that all the 6 cells were discharged or that ONE of your cells is shagged.
As a rough guide ... starter motors are designed using the "Max Power Theorem" which says that you need half EMF of the battery (EMF = Electro-Motive-Force) to appear on the starter motor to get max cranking power. That usually means that they are designed to loose 3V in the battery (so its a 9V battery when cranking) and 3V in the cable so that 6V appears on the starter motor. You can see that if the battery goes slightly high-resistance then it will drop 4-6V and you will get 6V on the battery and 3V on the motor and the relay will drop out (and then immediately re-engage as the battery voltage rises - and then do it all over again, hence the 'machine-gun' noise).
Second ... lead-acid batteries (of any sort) don't like to be fully discharged - they like to be at full capacity 99% of the time and have 1/2 an amp hour (5% of capacity) taken out to start the engine and then be immediately recharged. they seem to last 10 years if that's what happens all the time.
The worst thing you can do to a battery (aside from dropping it) is to discharge it to 10 percent and then attempt to crank the engine... they REALLY don't like that and it quite often damages the first cell that goes to 0%. Then you end up with a 10V battery and experience suggests that a 10V battery will JUST ABOUT start a fazer on a nice warm day if its fully charged. In winter it will cause the 'machine-gun' noise from under the seat.
The OTHER worst thing you can do to a battery is to attempt to charge it beyond 100% (14.3V)- it just makes Hydrogen and Oxygen and grows spongy oxide on the plates and reduces its capacity.
Gel batteries(OEM fit for FZS600) are especially fragile. AGM batteries now sold as replacements are better and hold their charge longer but they have slightly less capacity.
Its supposed to have a 10 Amp Hour capacity - so a fully charged battery should last about 1.5 hours driving 2X headlights. If it only lasted 15 mins then I suspect that you have either a 10V battery or one that is just simply "almost shagged".
On the other hand, it may just have been partly charged.