Batteries And Stuff

I'm 99% sure my battery is goosed. After a week on the Optimate while I
waited for some bits, the bike started fine 5 or 6 times while I was
checking bits and bobs worked as I put them back on. However inevitably
on the test ride (lights on) when I stopped to get some food for the SO
it wouldn't start. I managed to bump it and it was okay, once I'd found
a hill

Anyway I'm going to get a new battery tomorrow but I thought I'd check
the alternator first. I've seen people stick a voltmeter across the
battery with the bike running and check that there's 'stuff'. What
should this be, 12v or is it more if the alt is working properly?

As I said pretty sure it's the battery, but best to check before I get a
new one. As Ben said the other week running lights on all the time + a
Evo alarm + short journeys = dead battery in 3 years

Cheers

 

There do seem to be a lot of "my battery's dead" threads in 'ere and it got
me to wondering how much bike batteries cost these days? I haven't bought
one for *mumble* years but I'm sure that if, maybe, ~£30 worth of battery
was causing me hassle every day I'd be straight out to get the charging
system tested/buy a new battery. If they're ~£60, of course, it'd be a
different matter.

I know bikes are easier to bump than cars but you can only waddle away from
junctions and have the back wheel lock up after a few yards so many times
before it gets quite embarrassing.

Problem is, alternators can lie (or so it seems to me) and still show 12-14v
but not be charging properly. IANAE but it's to do with Amps too, I think.
Not enough of 'em.

....Or are bike batteries just not up to the job, generally speaking, coz
they have to be small and light?

Si

 

For my bike a cheap battery is £20 and a Yuasa £50. The reason I asked
is because I've bought a new one in the past and then still had
problems. If I can eliminate the risk of this I'll be happy.

Got some funny looks waddling down the pavement in the dark last night !

F*ck it then I'll just buy a new battery anyway and if it doesn't sort
it take it to the dealers.

 

I had the same problem. My Optimate went through a period of showing
the orange light in the morning - it's usually green after overnight
charge. My battery went dead on me one morning so I fixed[1] the
Optimate and everything seems sort of OK now. I'm still a bit suspect
that it's not quite fully functioning as if it were new. It may need
another fixing session.

[1] fixed = kicked & shook it, vigorously.

 

Oh yes, it's worth having it tested first if the shop's not going to charge
you for half an hour's labour, in which case it's probably cheaper to just
buy a new battery.

Si

 

Eeeek!

 

Steve P wrote on 07/05/2004 :

With the engine not running, nothing switched on and the battery fully
charged, the voltage across the battery should be around 12.5volts.
Much less than this could indicate a failed or shorted cell.

With the lights turned on and the engine running if the battery is
being charged correctly, the voltage across the battery should be 13.8
to 14.2 volts. It should initially start charging at around 14.2, then
drop back to 13.8 volts once the battery attains a full charge.

If it is not doing the above, the charging system is at fault otherwise
blame a failing battery.

 

Nice one, that's what I was after. I'm off to check at lunchtime since
there is a choice of battery (again) so I need to get the right one.
I'll dig the meter out and have a quick play.

As I said I suspect the battery as it was charged fully by the charger
but dies pretty quickly after.

 

And if you're going to test this, bear in mind the alternator on the
GSXR doesn't start charging unless the revs are over 5.5k[1] rpm.
This is why town riding with the lights on fucks the battery, it just
never gets charged.



[1] Around there, it's got the exact amount in the Haynes book
somewhere.

 

Ta muchly that's a big help. Mind you it's going to annoy my next door
neighbour who's on nights at the moment and will probably be asleep

Out of interest does anyone have a rough idea how long would the
alternator would take to charge a fairly flat battery? I ask because I
was out for about 40 minutes last night so thought the battery might
have been a bit charged. Mind you it was dark so lights were on!

 

How fast is 5.5k in first gear?

 

25ish I think. 6.5-7k was 30 IIRC.

 

According to http://www.pro-libertate.com/gsxr1000/cear-calc.xls, it is
36.8 mph.

BTW, I don't believe that 5.5k is the RPM at which the GSX-R1000
alternator output exceeds the electrical load on the system, it
sounds too high by at least 2k.

 

You might be right, but that doesn't mean that the system
will *allow* charging...

 

Stay in first then

 

Too noisy around town, don't want to be one of those 'noisy bikers' .
I don't think my neck could stand it either, nice jerky FI would give me
whiplash.

 

Steve has a 750.

 

Steve P wrote

It depends.

First of all will have to provide enough current to run the bike,
somewhere about 20-25% max revs. Once it has power to spare it can
charge the battery. A decent blat for an hour should see even a fully
flat one charged to it's max.