Battery problem or Optimate problem...?

[Grahamm]

Going out for a ride yesterday on my FZ6 '04, it tried to crank the engine once, sluggishly, then I got the dreaded "buzz" of the solenoid indicating a flat battery

(Probably I should have put it on charge when I got back from my mother's after Xmas, but anyway...)

I managed to bump start it, rode fine and when I got back, got the Optimate III out to charge the battery up.

The problem is that, after plugging it in, I got the Green "power" light, but none of the others until after a few minutes the "desulphate" light came on which I thought only comes on if the battery is near dead.

As it was dark I couldn't do anything about it then (no light in the shed) and today I was out for another Observed ride, so I just hoped it would start today, which it did.

It was ok until we did some slow riding practice and at one point I thoughtlessly sat on it with the engine off, but the headlight still on, meaning that when I tried to start it... buzz....

So I bump start it again, ride ok, and at the next two stops, switch off promptly, restart, no problem.

I get home and again try to plug in the Optimate, but still get only the Power light.

I have the Optimate adapter (bolts to the battery and has a covered connector to go to the charger) and the contacts appear to be clean and seem to fit together ok, so I'm not sure what's going on. Is the Optimate buggered?  Is the battery shot (but if it was, surely it wouldn't start at all)?

Anyone got any ideas?

[Grahamm]

PS Oops, that's '04 model, '06 registration, ie it's just over 5 years old and currently just done 28,000 miles if it makes any difference...

[GrahamB]

I would guess it's your battery. Sounds like the optimate is doing its best to put some life in to it from very very dead which could be why you only get the green light initially. Riding the bike is giving it a bit of juice enough for a few starts but lights on with no engine is just killing it dead. Optimate "might" rescue it if you give it long enough but don't bank on it. 

[Fazerider]

You might have more success if the battery is off the bike. If there's any other circuitry connected to the battery the Optimate may detect that and restrict itself from applying the higher voltage the desulphation process requires.

[rustyrider]

Almost certainly one cell gone down.  Put a meter across the battery and I doubt you'll see more than 12V, dropping to under 10V when you try to crank it.

New battery time.

[Grahamm]

Almost certainly one cell gone down.  Put a meter across the battery and I doubt you'll see more than 12V,

So a reading of 5.5V would be a bad thing, then...? 

New battery time.

Certainly looks like it.

Oh well, I needed to get a new chain too, so at least I can get both done at the same time.