[DML] Re: power drains....

["David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>]

A battery does not know the difference between a resistive load that
it is dumping into be it a carbon pile or a bank of resistors. As long
as it is a pure resistive load so no power is reflected back (like an
inductive load such as a coil). You CANNOT just measure voltage. You
measure the voltage WITH THE BATTERY UNDER A KNOWN LOAD. I can show
you a battery with 12.6 volts but with no capacity. Once you put a
load on it (like cranking the motor) it very quickly falls flat. Till
you put the load on the battery a voltmeter will tell you it is good.
Once you put the load on the voltage drops fast and far! That is how
you know if the battery is any good.
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@...> wrote:
>
> David, 
> If you have old equipment and your going to test an alternator the
> professional way was to use one type of equipment with a carbon pile
tester
> that will go up to 500 amps. That's what we had till we bought the
new load
> tester that doesn't have the carbon pile. 
> The professional way to test a battery is also with a carbon pile
tester, we
> have that also in the shop. It's the best and true way. 
> But if you want a quick and easy way to tell the State of Charge of a
> battery you can do it with a Digital Multi Meter at home. Yes, you
need to
> know what your doing, but professionals teach this way all the time.
Go on
> Arco's site. They build alternators and starters for very extreme
> applications and they teach this also.  
> But what do I know, I'm just a parts man that build's the best DeLorean
> alternators brand new and starters.
> John Hervey'
> www.specialtauto.com
>        
> 
> -----Original Message-----
> From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On
Behalf Of
> David Teitelbaum
> Sent: Sunday, August 05, 2007 9:25 PM
> To: dmcnews@xxxxxxxxxxxxxxx
> Subject: [DML] Re: power drains....
> 
> To test an alternator you use a carbon pile. To load test a battery
> all you need is a variable resistance load. Most service stations have
> such a device. To test a battery's state-of-charge you MUST put a load
> on it to remove any surface charge and to see how fast the voltage
> drops in relation to the load. What you are really measuring is
> amp/hours referencing the voltage to a known ampere load. You cannot
> just stick a voltmeter on a battery and from that reading tell if it
> is any good.
> David Teitelbaum
> vin 10757
> 
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@> wrote:
> >
> > David, 
> > Did I say anything about Amp's. I was talking about battery
> condition and
> > it's state of charge. 
> > If you want to test the current / amps condition of the battery the
> correct
> > way you need to find someone that has a carbon pile tester. There
> expensive
> > so you may have to call around to find someone that has it.
> > John Hervey
> > www.specialtauto.com
> > 
> > 
> > 
> > -----Original Message-----
> > From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On
> Behalf Of
> > David Teitelbaum
> > Sent: Thursday, August 02, 2007 8:34 PM
> > To: dmcnews@xxxxxxxxxxxxxxx
> > Subject: Re: [DML] power drains....
> > 
> > You cannot infer from a simple voltage reading what the ampere
> > capacity of a battery is. It takes a load test to determine that. Most
> > places will do it for free in the hopes of selling you a battery. If
> > you let a new battery go completly dead several times you may have
> > killed it. Lead-Acid batteries do not take kindly to being completely
> > discharged.
> > Pull all of the fuses. Put an ammeter in series with the battery.
> > Install the fuses one-at-a-time and watch the ammeter. When it jumps
> > up you will know which circuit is the problem. A battery Master Switch
> > is also useful.
> > David Teitelbaum
> > vin 10757
> > 
> > 
> > 
> > --- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@> wrote:
> > >
> > > Andy, 
> > > 12.66 volts the battery is at 100%, 12.5 volts the battery is at
> > 80%, 12.2
> > > volts the battery is at 40%. That's why at 12.2 volts it most likely
> > won't
> > > start.
> > > John Hervey
> > > www.specialtauto.com
> > > www.deloreanautoparts.com
> > > 
> > > 
> > [moderator snip]
> > 
> > 
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> 
> 
> 
> To address comments privately to the moderating team, please address:
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