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Re: [ST] Flat Battery



I had always thought of amperage as an "on demand" thing, i.e. amperage
isn't pushed, it's drawn.  Am I wrong?  It seems that I am.

Electrical has always cornfused me.

David

On 3/8/07, drbrant@xxxxxxxxxxxxxx <drbrant@xxxxxxxxxxxxxx> wrote:
>
> Chris,
>
> You are correct that I errored in confusing cold cranking amps with
> amperage in an automotive battery.
>
> The point remains that an automotive charging system is capable of
> producing many more amps than a motorcycle electrical system can
> handle.  The result is damaged components, typically the regulator rectifier
> is the first to fail.
>
> Rick
>
>
>
> -----Original Message-----
> >From: Chris Harwood <Chris@xxxxxxxxxxxxxxxxxx>
> >Sent: Mar 7, 2007 7:48 PM
> >To: ST@xxxxxxxxxxxxxx
> >Subject: Re: [ST] Flat Battery
> >
> >Rick
> >
> >I've studied electricity for over 40 years including at university and
> some of your comments there make me cringe.  You could connect a billion-amp
> charger to your battery and the charging current will be determined by the
> battery's internal resistance and the difference in voltage between the
> open-circuit battery and the open-circuit charger.  That could be milliamps.
> >
> >Incidentally, we dispensed with amp-hours over here some years ago and we
> rate lead/acid car batteries in cranking amps now.  It's all part of
> progress and we are clearly more advanced than the rest of the world (not).
> >
> >Chris Harwood
> >00 RS UK
> >
> >>>> drbrant@xxxxxxxxxxxxxx 08/03/2007 00:05:06 >>>
> >Neil,
> >
> >Actually Kevin explanation is a rather good.  As a basic rule you can
> divided a batteries amp hours, the rating on the battery, by the charging
> amps to determine the maximum total time to charge the battery.  Note
> typical car batteries range from 500 amp hours to 800 amp hours.  Most
> motorcycle batteries are in the 10-20 amp hours range.  I think the amp the
> middle numbers on a Yuasa Battery.
> >
> >The major risk associated with using an running automobile to charge a
> motorcycle battery is too many amps over heating the electrical system and
> damaging components.  I sold a GS650 to an in-law many years ago who was an
> automotive mechanic.  He attempted to charge the battery with an 8-0 amp
> hour automotive charger and destroyed the regulator rectified in the
> bike.  An alternator in a car will produce similar results.  It is also
> possible to short a battery out by exposing it to too many amps.
> >
> >If you don't believe us you can either study electricity some or go and
> hook a high amperage charger to you motorcycles electrical system.
> >
> >Rick B
> >Pfafftown, NC
> >-----Original Message-----
> >>From: Neil Lindsey <Neil.Lindsey@xxxxxxx>
> >>Sent: Mar 7, 2007 6:42 PM
> >>To: ST@xxxxxxxxxxxxxx
> >>Subject: Re: [ST] Flat Battery
> >>
> >>Kevin --
> >>
> >>sorry, but you have no idea what you are talking about
> >>
> >>----- Original Message -----
> >>From: "Kevin Dicks" <kdicks@xxxxxxxxxx>
> >>To: <ST@xxxxxxxxxxxxxx>
> >>Sent: Wednesday, March 07, 2007 12:14 PM
> >>Subject: Re: [ST] Flat Battery
> >>
> >>
> >>> Agreed.  What I should have said is that a car battery needs more
> current
> >>> to
> >>> charge it compared to a bike battery given the same time period -
> another
> >>> effect of this is, as you point out, it has a higher AH.  If you leave
> a
> >>> battery on a 20mA charger for long enough, given the correct voltage,
> it
> >>> will probably eventually charge (as long as the battery is in good
> >>> condition
> >>> etc).  The point I was trying to make was that even though a car
> battery
> >>> and
> >>> a bike battery have the same voltage, they are very different when it
> >>> comes
> >>> to current (and therefore the AH each can provide).  Given this
> >>> difference,
> >>> the charging system of a car can (because it has to) provide far more
> >>> power
> >>> (Volts *  Current) than a bike charging system can.  Given that,
> >>> jump-starting a bike from a car with the car engine running, 'may'
> lead to
> >>> problems with the bike due to the higher current the car charging
> system
> >>> provides.
> >>>
> >>> -----Original Message-----
> >>> From: st-bounces@xxxxxxxxxxxxxxxxxxxx
> >>> [mailto:st-bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Eoin Kirwan
> >>> Sent: Wednesday, March 07, 2007 3:08 PM
> >>> To: ST@xxxxxxxxxxxxxx
> >>> Subject: Re: [ST] Flat Battery
> >>>
> >>>
> >>> On Wednesday 07 March 2007 03:23, Kevin Dicks wrote:
> >>>> Current is not the same as Voltage. Just look at the size of a car's
> >>>> battery in comparison to a bike's.
> >>>
> >>> But it's the same voltage. The larger size means more amp-hours, so it
> can
> >>> power a given load for a longer time - or a larger load for the same
> >>> length
> >>> of time - before it becomes discharged.
> >>>
> >>>> The car battery needs more current to
> >>>> charge it - even though the voltage is the same as the bike's (give
> or
> >>>> take).
> >>>
> >>> It doesn't need more current to charge it, it needs more amp-hours to
> >>> charge
> >>>
> >>> it. Whether you do that by using a larger charge current in the same
> time,
> >>> or
> >>> use the same charging current for a longer time, is up to you. The
> >>> *maximum*
> >>>
> >>> recommended charging current will be larger, but you don't have to
> charge
> >>> it
> >>>
> >>> at the maximum rate, it'll just take longer.
> >>>
> >>>
> >>> Eoin
> >>>
> >>> '04 ST955i
> >>>
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> >>
> >>
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