Voltage query

I've just been out with a multi-tester, as I have a couple of concerns about
the bike batteries and charging. Temperature at the time of testing was
about -2°C. I checked the battery voltage for each bike across the battery
terminals, and then again with the engine running at a fast idle.

XT600E - newish battery, bike not touched for 10 days:
Engine off, battery voltage 12.8V
Fast idle, battery voltage 13.7V

ST1300A - battery age unknown, on Optimate for a week, rested 30 mins before
test:
Engine off, battery voltage 12.5V
Fast idle, battery voltage 14.4V.

The way I interpret this is -

XT - healthy battery, poor charging
ST - dying battery, healthy charging.

Additional info: put the XT on the Optimate a while ago, kept reporting
battery fault, sulphation etc before settling down to charge. Pan battery
totally discharges after 2 weeks in the garage if not charged.

Am I on the right lines?

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

Mark Olson typed:

I always understood that alternator voltage at fast idle should be around
14.4V - 13.7 seems rather low.

The ST battery is of unknown age, and may well be the 2003 original for all
I know. It'll get replaced; you have confirmed my thoughts. There is no
alarm - the only drain is the usual always-on ECU stuff. Thanks for the
link - I'll chase it up.

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

No. Both charge rates sound fine to me, but yes, the ST battery is
dying.

 

Both are fine. The ST may have a slightly higher charge rate to allow
for accessories.

 

The message <>

I had an accumulator which was discharging, and a garage owner told me
to charge it (or was it not charge it? can't remember now! Someone will
know.), empty it out, wash it out with distilled water, then refill it
with acid.

Worked a treat.

The plates were discharging through the sediment.

 

Plus, a) what sort of multimeter?, and b) when you say "engine off"
do you mean just that or ignition off as well? A lead-acid cell gives
2.1 V at no-load. A digital multimeter imposes essentially no load
so a 12 V battery should read 13.2 V -- with no other load -- pretty much
independently of its charge state. A moving-coil meter imposes some load,
but probably little enough to ignore. Anything below 13.2 V implies that
there is a load on the battery; in the case of the ST this is almost
certainly self-discharge through sediments, possibly compounded by reduced
capacity. I'm less sure about the XT as I'm not certain if there were
other loads involved.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Dr Ivan D. Reid typed:

It is a digital multimeter. Both were tested with ignition off, just probes
to the battery terminals, and then at fast idle of about 2000 (and also
8000, purely in the interests of research - stayed dead on 14.4V) rpm for
the ST, and "running nicely, but not caning it yet" for the XT (rev counters
only came on those in 1996). Sorry, should have made that clearer.

Looks like a new battery for the Pan (not unexpected), and forget about the
rest. Many thanks to all for replies.

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

Wot ee said, plus, get yerself a hygrometer!

I find it's not wonderfully easy to suck up enough acid to test on a
bike battery, but it should be do-able. Ignore the measurements on the
float unless it's really well made (test the calibration in distilled
water): look for one or two cells giving a very different reading to the
others and for the liquid level being obviously different when you have
all the caps off.

Broadly, high float = well charged cell, low float = discharged. If
there's a difference between cells the battery is dying. You can keep it
going for a bit by topping up with distilled water, otherwise flush out
and refill or replace.

A hygrometer is the only way to check individual cells for anything
other than a lorry battery.

HTH,

Regards,

S.

PS: Should be dirt cheap and has a whole one moving part.

 

SpamTrapSeeSig typed:

I used to have one of these many moons ago, when most batteries had screw
caps and you needed to top them up every week or so. I think I inherited it
from my Dad. ISTR having several pairs of Levis with holes down both legs
because of all the dribbles from the hygrometer. I haven't used (or seen)
one in years, as all the batteries I have bought in recent memory have been
sealed. I'll have a look at the battery and, if I can find a way of getting
into it, I'll give that a go. I love low-tech.

I've just looked up the price of a new battery for the Pan, and I've had to
sit down. I think I may keep the old one going for a while yet.

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

ITYM Hydrometer.

 

typed:

Hehe. Caught me, it did.

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

it's not unusual to see under 13V on a battery in cold weather, but the
self-discharge (if it does it when disconnected from the bike, see comment
about alarms) is a sure indication of flakiness.

charging wise, the bets way to test it is at about 3000 revs or so with the
headlight on, if you're still getting 13.8V plus it's OK.

fully charged nominal for a 12V lead-acid is 13.8V and if it's not
exceeeding that an on-vehicle charging system can do with checking. Most of
the car ones run at about 14-14.5V, you should see that at moderate revs
with no loads. With loads on (e.g. headlamp) it shouldn't go below 13.8V at
revs, but will probably at idle or near-idle, as the alternator is only
rated for full output at a fair lot of revs, although alternators are better
in this respect than the old dynamos we used to have.

 

Oops. Will try to engage brain next time. You'm right, course.

Amusingly, my electronic desk hyGrometer is claiming 30% (they're not
very good really). At a guess, the real value is nearer 0-20% ATM, coz
it's so cold.



eBay Item #: 180313560733 looks like a decent one, and not expensive.
It's similar to the one I currently have, and doesn't have a rubber bulb
etc., so shouldn't rot.

I wouldn't touch anything labelled 'Silverline' any more, as I just
think 'snails'.

 

It's possible on re-reading that I'm wrong and that 13.8V is float charge
voltage for a 6-cell lead-acid. However, the charging system on a motor
should be doing better than that as it's not a float-charge application.

 

[snip]

Did you take any alarm/imobiliser into account? What's the voltage with
the battery disconnected rather than "ignition off"?

 

Tim typed:

There's no alarm - just the standard HISS immobiliser. I didn't check with
the battery disconnected (too much faff resetting all the clock functions,
losing the trip setting etc.).

--
Rich B

1971 S2a
1995 XT600E
2003 ST1300 Pan European
Oh, and a Ford

Take out the obvious to email me.

 

OK, it was just a thought that there may be something draining the
battery.

 

erm, 6 (cells) x 2.1 (V) = 12.6 V

If the battery has been recently charged, it will be necessary to
remove the surface charge before taking a voltage reading - switch the
headlight on for a minute or two, then let the battery voltage
stabilise and take the reading.

 

Nominal Cell Voltage is 2.105 =x6 12.63 volt
Anything between 12.6 (low) and 13v (v-good) with 24 hours standing after
charging indicates a good battery.
Accurately of your DVM is of some importance in making a voltage only
assessment ;(



-

 

Thus spake Kim Bolton () unto the assembled multitudes:

Is this the reason why, whenever I try to hook up my battery to my Optimate
immediately after a run, the Optimate gives a red light ('battery f*cked')
indication? If I leave it for 15 minutes and then hook it up, it's fine
and goes into the normal charging sequence.