Hi guys,

I'm brand new to the forum, and to riding having only passed my Mod 2 last Friday

I have a 2002 FS which apparently has a new battery, yet doesn't seem to hold any charge. I'm having to hook it up to a charger to start it up. Took it out for a ride for last night, only half hour or so but as soon as I turned it off and tried to start it up again was completely flat :-(

Its now at home going on a 24hour charge to see if that helps but not too optimistic.

Any ideas of what could be going on? I'll have to apologise in advance I am not technically or mechanically minded so please keep it simple for me :-)

Help please

 

Hi and welcome to the club! If the 24hr charge doesn't work then it looks like your battery is on its way out. If however the bike starts ok after you've charged the battery overnight, connect a multi-meter across the battery terminals, start the engine and increase the revs to around 3500-5000 rpm. You should see an increase in battery voltage on the meter of 13.5-14.2 volts. This would indicate that the battery is being charged. If you don't see an increase in voltage you could have a problem with either the alternator or rectifier. A quicker way to check if the charging system is ok is to start the engine, switch on your headlight and rev the engine. If the headlight brightens up as you rev it and goes dimmer as you close the throttle, then all should be ok and a new battery may be all you need. Get it checked out at a decent electrical shop, which they'll usually do for free! Of course if it turns out it is dead they'll probably expect you to buy a new battery from them! Lol!

 

Perfect,

Thanks for your reply.

I will give it a go tonight, fingers crossed its just a battery :-)

 

So just tested it with a meter and the light dimming test...

The lights do brighten and dim when I throttle on and off..

The meter at idol with no lights was reading about 14.6 when revved up to about 14.8
With lights on, meter read around 13 - when revved to 5,000 read around 14.8..

Turned the bike off 5 mins ago and is reading around 12.8.

So can I assume that if the battery reading doesn't drop much further then the 24hr charge has worked and if its dead again in the morning it's just a new battery?

 

Keep the meter on it and watch it as you crank it. If it drops into the 10s, its getting weak. If it goes below 10, its new battery time. It should bounce back to around 12.6 after cranking. Do it a few times.

 

Sorry, dumb question time...

What's cranking?

If what you meant by cranking was to start it up, turn off then start up again.. Done that.. The volts dropped to around 10.1 ish once dropping to 9.9....

 

Yes, just cranking the engine over. If you can keep it from starting, even better. If it starts, just shut it off and start it again. What your doing is using the starter to load test the battery. It's not as good as a real load test, but it's the best you can do at home.

10.1 and 9.9 is low. You probably could use a new battery. You said it "apparently" has a new battery. How do you know this? There may be a date code on the battery somewhere of when it was made to be sure. If it is newish, you may have a warranty from somewhere, but without a receipt the date code better be recent.

 

Thanks for that, I only bought the bike last weekend so the new battery part night be rubbish.

Sounds like I might need a new battery. At least it's nothing major!