Flat Battery Confusion...

[Capt Kremin]

I know a flat battery is nothing new, but I wasn't expecting it after taking precautions.

I was off on holiday to the Canaries for 2 weeks, so my '97 900SS was tucked up in the garage in a nice blanket, and connected to it's Optimate 3.

When I got back the Optimate had a green light, and all was well with the world.
I took her out of the garage and expected to have to pay for my absence, maybe clean the plugs or adjust the chain as penance before she would fire up.... but no the engine turned over a couple of times and then stopped!

The battery cannot be flat I thought, and I noticed that when the choke was off the battery would spin the engine over no problem. As soon as the choke was engaged, or the throttle opened it was as if I was asking it to turn over the QE2 engine, it just stopped.

Plugs out, covered in fuel..... so it must be the battery. Jump leads to the rescue, and she was up and running no problem.

So a new battery is ready for pick up at Ducati Manchester on Tuesday, but I'm left confused by the way the choke affected the ability of the battery to turn the engine over.

With my basic mechanical knowledge I cannot make sense of it....any body care to enlighten me?

Thanks.:puzzled:

[Iconic944ss]

Its a bummer innit !!!

I had a slightly similar problem with a Gel battery that I bought fo rmy 93 900ss - the eventual diag was that the sprag clutch might be on the way out.

Hope it isnt this in your case but it sounds more mechanical than electrical

Good luck - Frank

[Derek]

Originally posted by Capt Kremin
I'm left confused by the way the choke affected the ability of the battery to turn the engine over.

With my basic mechanical knowledge I cannot make sense of it....any body care to enlighten me?


The engine is effectively a pump, when the throttle is closed and the choke is off the inlet is closed and very little air gets in so the starter can turn it over fairly easily. When the throttle is opened or the choke turned on (which opens an auxiliary air passage, more air is allowed in which has to be compressed to pump it through the engine. This extra work would appear to be beyond the capabilities of your worn out battery.

[Capt Kremin]

Thanks for the info guys, the pump analogy really works for me. Sorry for the delay in responding but had problems with the PC!

New battery installed and she fire's up like a dream, glad it appears that it was solely down to the 7 year old battery.

Cheers.

:D