Seemingly dead, so put it on a charger. This suggested it was ok and holding its charge, but need a little charging for half an hour.

Put it back on the bike last night, 12.75v showing on the multimeter.

This morning voltage read 12.69 and briefly turned over. 2nd start failed immediately and battery note down to 12.24v

I had the bike started yesterday and it was showing 14.5v ish, so the charging should be ok on the bike.

Is this just a dead battery?

12.24 isn’t terrible by any stretch…. especially after an attempted start. 12.69 after overnight is perfectly fine and you’ll never really get more than that generally.

That doesn’t necessarily mean it’s NOT the battery that’s the issue… but IMO it’s not top of the list from them figures both last night and when running.

Last night, straight off the charger it started easily and strongly. Before being topped off on the charger again. Hence pointing the finger at the battery.

I guess it could be something that’s causing a problem when starting, and drawing current that means there’s not enough to start.

Depends on what you are trying to start too – big V Twins eat batteries at an alarming rate!  I had a pile of dead ones in the garage before I could keep the thing on a charger!  Italian electrics weren’t really helping either mind…..

If it starts up nice and sharp then I wouldn’t worry about it.  If you find that it is struggling get a new battery (I switched to LiPo jobs which always sound like they are struggling when you press the button… that sinking feeling that you are stranded a long way from home… but then they pick up some enthusiasm and get the job done… always fun!)

I’d change it – there’s nothing worse than that lingering doubt in the back of your mind, though at least bikes are easier to bump start than cars!

It’s a street triple 675. Current battery is a MottoBat AGM, which has been fine until now.

It’s a couple of years old, but I let it get flat a year ago by leaving the lights on, and then zapped it last week with a multi-meter accident (I accidentally tried to measure current instead of voltage across an indicator and drew lots of amps!).  So it’s had a couple of heavy discharges in its life.   Last week (before owning a proper charger) I jump started the bike and rode it to charge.  Seemed ok, and I’ve ridden several times since.

What symptoms do you get? On my KTM if the battery is shafted, then the starter solenoid makes a half-hearted click, front light will flicker and the fuel pump cycles really slowly.

Pretty much the same symptoms.  Half hearted turn over, then just the solenoid click.

12.2ish volts is 50% dead and below 12 volts is classed as discharged.

Sam, have you had the bike out for a ride as I’m assuming like most of us it has been stood idle over winter. If the voltage was dropping down to 11v I’d be worried but not whilst still showing 12v.

Capt. Kornos, I use a LiPo battery too. On cold mornings you are best leaving the lights on two or three minutes, which warms the battery and it starts much better. I’ve had my KTM start at -2C on first push of the button

What happens to the voltage when you try cranking?

It’s most likely the battery, as their internal resistance increases as they age, so although the voltage appears OK when unloaded, it drops when loaded i.e. when cranking.

Putting it on a trickle charge for a couple days may resurrect it for a while. It all depends on whether you prefer reliability or delaying spending money.

Could it have dried out,can you refill/top up then trickle charge?

Not sure about voltage when cranking, but as it sounds weak, that seems to tally with it having a higher resistance due to age / use.

It lives outside (albeit under a cover) and has been used over winter, just not as regularly.

Seems like a new battery wouldn’t hurt, I’d rather it was reliable rather then just limping it on for a but longer.

Fasthaggis: they’re a gel cell, so you can’t top up.

Does sound like you need a new one. 2 years is pretty good going for a motorbike battery, especially one that lives outside.

IME AGM batteries hate a full discharge. I’ve had a couple of car ones die that way.

IdI say it’s time for a new one.

Coincidentally I’ve just had a very similar issue with my Street Triple last week which resulted in me getting stuck with a bike that wouldn’t start.

My battery and charging voltage readings were similar to yours so I just stuck a new battery on it. It’s been perfect ever since.

The new battery was a like for like replacement of the original Yaesu one and it was only about £30 from Halfords with a trade Club card and they had them on the shelf.

Fasthaggis: they’re a gel cell, so you can’t top up.

Ah right,looks like they need a proper smart charger and don’t like full discharges.

AGM batteries can be a bit problematic if they become fully discharged, as then then either need a high voltage to force a charge into them to start charging quickly, or a prolonged lower voltage charge. Usually putting them on an unregulated charger overnight will recover them well enough to become serviceable again.

I say unregulated, because digital staged chargers typically only work on voltage, so you connect a flat battery, it enters constant current mode, voltage rises quickly due to the battery having high internal resistance, it reaches the charge cut-off voltage, the charger then thinks the battery is charged, so it then drops to trickle charge mode, which the voltage generally isn’t high enough to force the battery to start charging.

AGMs are not an ideal drop in replacement for a conventional lead acid battery, but they can work well. The major benefit of AGM is they accept charge far faster than wet batteries, however that means on a non-smart charge system, they will push alternators to their limit.
Without a smart charging system, jump start a wet battery system and the alternator voltage will quite quickly rise to above 14V and the battery will gradually accept charge. With an AGM battery, the alternator voltage won’t rise until the battery is charged. I’ve seen AGM battery voltages sit below 13V while only gradually creeping up with the alternator belt screeching and the alternator itself starting to smoulder after being jump started because they’re absorbing that much charge the alternator is being pushed beyond it’s limit.
Smart charging/battery monitoring systems will handle those conditions, and ensure the alternator is never pushed any harder than it needs to be.

Thanks folks, I’m convinced enough that a new battery is certainly worth the experiment.

I chose the current AGM battery as I thought it might be better at living outside, and better at cold cranking.  Is all of this just BS and so I’m better off buying a more reputable company’s regular lead acid battery?

What age Street Triple? I have a 2009, and had no end of electrical issues for a while.

Reg Rec failed, then the generator, then the battery.

Touch wood, all good now.

Worth investigating the reg rec if you haven’t.

he wouldn’t be getting 14.5v running if Reg-rec.

I used to leave both my bikes on Optimates 24/7, the lead acid battery on my Ducati was well into its fourth year and still going strong.

They’re old new now, but if it needs a replacement I’m still amazed by the Yuasa’s High Performance series- I put a YTZ12S in my SV650 back in 2006, purely for the higher CCA, since it makes such a difference on cold starts… but since then it’s spent years on end completely flat as a pancake and not even able to light up a dash bulb, but it still recharges every time. It’s lost some capacity but what a trooper.

My money’s on the battery being shagged. Had the very same thing with my bike. Charge the battery and it’d start OK. Leave it overnight and you’d be greeted by the click of death. It was charging when running so new battery time.

I got a Motoatt one on the rcommendation of my local motorbike shop. Seems OK, so far. I usually go for a Yusa one, but we’ll see how this one goes.

Thanks peeps.

Halfords on the way home I think.  The original Yuasa battery on the bike lasted 4 years, this Motobatt AGM lasted just 2 (albeit with some deep discharge cycles).  As I now have a charger to leave on the battery I may as well just go for a  Yuasa as that seems to be the sensible and easy option.

Update: New Yuasa battery bought.  Carefully filled and gently charged with a bike battery charger.  Bike now seems to be back to normal, strong starting and the battery is clearly charging on the bike.

Thanks for all the helpful info.