Battery fail or something else..

[A100man]

Last Sunday (not yesterday) I took the FZ 750 out for a quick jaunt. Picked up form storage started fine. traveled for petrol (3 miles) started again fine after, rode to my mates house 30 miles all good (switch light on to dip as others seems to have). Chatted for 1.5 hours went to start the bike - zippo fuel pump ticked but not enough juice to turn the motor even a little

Initially thought I'd left the light on but I don't think its possible with key removed.

Jumped it to get going rode home fine. Tried again when home after another 30 miles (light off this time) still zippo. Jump started again and measured the charge volts - 13.9..

Hmm Took battery off and into work for a regulated charge using a PSU. Seemed to take the right amount of current - back on bike zippo again.

On the face of it battery seems fuked, but how come it happened so quick? With ignition on current draw is about 2.5 A which seems a lot but I guess could be just what the coils draw?

No problem with buying another batt but curious to know why it failed
and if there an issue cure it first('twas Yuasa Lead acid topped up between lines so not run dry)
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Polo]

Yeah I believe batteries like regular charging cycles. Had the same issue with my dad's car that he drove a couple of times a year. Get a voltmeter across the battery and if you have around 14v going in at a few thousand revs, time for a new battery.

[WD Forte]

Try charging it while ensuring its getting at least 13.5v
(chargers can fail y'know)
and leave it over night to settle indoors circa 20C
Read the standing voltage next day
Healthy batteries tend to show around 12.7V
12.4V ailing, 12V bad
It could also be a sulphated, broken or distorted plate inside which can give a voltage that looks ok but have no real discharge power when put to work, ie starting.
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bikers smell of wee

[A100man]

[A100man]

[steve the grease]

Funny things batteries, they either fail in the summer when its hot, or they fail in winter, which is when you would expect them to go .

Your experience mirriors my Mrs car .
Was a bit flat
charged all day
started fine next morning
went20 miles to the shops
2 hours later dead as fuck.
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All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of.....

[doggone]

A couple of weeks back my CRF250 just stopped dead it could only run with larger car battery attached by jump leads even on charge was no good.
I suspected all sorts of issues mainly due the near instantaneous total failure but it was just the battery has been fine with it replaced.

[Robby]

Could also be reg/rec starting to fail. They don't always fail totally. They may work until they get hot, or they make still work a bit at low revs but not high if one of the shunts has failed.

You can try diagnosing with a multimeter, check the charging system hot and cold. Or if you are relying on the bike or don't mind spending the money, I would go for a new battery and a MOSFET reg/rec.

Cheap aftermarket reg/recs on ebay are very hit and miss. If you have another bike, you could borrow the reg/rec off that for testing.

[MCN]

[GettinBetter]

Measure The specific gravity with hydrometer. It should by your description show it to be flat.

Stick it in a trickle charge of about 1A no more (that bit is important), and check with hydrometer daily. After a coupe of days to a week, you should see it start to come up the scale of the hydrometer, after two weeks you should see a healthy reading, leave it charging till it shows fully charged. If nothing happens after two weeks, bin it.

This is where a 30V 4A voltage/current controlled PSU comes in handy, although I have used a 3 pin 12v accessory charger rated at 1500mA before.

[Islander]

Batteries can and do fail that way. Measuring the off load voltage will show fairly normal readings but as soon as it's on load it'll drop drastically. It's caused by one or more cells failing high resistance. I had one on the GSF1200 a couple of years ago. I started it to warm it up, switched it off because I needed the key to get under the seat. The next press of the starter, nothing at all. Dead battery.

It's worth checking the charging output of course - just in case there's an underlying problem.

[A100man]