New battery goes flat FZ1n

[sidewaysid]

I put a new battery on my bike FZ1 every year, and if I don't keep it on the optimiser, it flattens within a week, it is now un rideable really for fear of getting caught out. I think there is a bad earth or a leak to earth, but recently I have seen a lot of stuff with the Alternator/generator falling to bits, does anyone have a clue as to what it might be. Thanks guys

[unfazed]

Sounds like it is not charging. These bike are notorious for the rotor magnets falling and can cause untold damage. The rotor should be changed regardless of condition for safety. Only true way of checking it is to remove the generator cover. You just need to replace the gasket.

[Wallace]

If you or someone you know has a mutimeter, set it to amps, disconnect the battery earth lead and measure between it and the battery earth terminal.
This should tell you if something's dragging the battery down.

[sidewaysid]

WallaceThanks for the reply, I did do that with the multimeter on DC volts. I got a reading of -3.2 v and I wasn't sure of what that would relate to. I did read somewhere that the reading sgould show zero, what do you say, maybe I have the meter on the wrong setting.

[Wallace]

Sorry for the late reply, between work and building an extension I haven't had much time for anything else.


If the meter is set to amps that would show if it's drawing current which would flatten the battery. Just be aware that with a lot of meters you have to change which hole the positive probe plugs into to measure current.

[Gnasher]

Sounds like it is not charging. These bike are notorious for the rotor magnets falling and can cause untold damage. The rotor should be changed regardless of condition for safety. Only true way of checking it is to remove the generator cover. You just need to replace the gasket.

The above is very likely.  Simple test, but you need to start the bike, jump start it from another battery, once running check the voltage across the battery at 6500 it should be reading 14v.  Even at idle it should read around 12.8 - 13v, if it isn't there's a changing issue, possibly the magneto or the rectifier.

Is there an alarm fitted, heated grips, or any other extras?  These can fail and drain the battery in hours!