[T3] Batteries.

Thu Jul 5 13:32:59 PDT 2018

Thank you Jim for the explaination.

  I just want to bring up a few things.

1) I don't have the clock connected , it's the type that runs all the time 
( does not have the click wind deal older clocks have) . I know you wrote 
about a way to install a fuse to disable it if the car sits . Mine works yet 
trying to set it to keep proper time is not worth it to me , I have it 
close.

2) I checked for a parasitic draw and found 5 mA , isolated it between the 
battery + red/white lead to the voltage reg B+ I removed the other red/white 
to fuse box off reg B+  during test . It's not much of a drain and I can 
only determin it's the Bosch electronic regulator called Bosch they have no 
idea how it even works. Perhaps it's normal it does work I don't care.

3) I checked the battery the morning after the drive with the headlamps on 
and it read 12.32 volts. I didn't check it before that drive and as I said 
during that drive even @2500 engine rpm the voltage was a best was 12.2  at 
idle it was below 12 volts . I felt since I had not checked of charged the 
battey for at least 6 months of 3 to 4 starts during a 2 to 3 mile stop and 
go traffic drive. The reason i saw such low voltage readings with the 
heaplamps on is because the battery voltage was low to begin with . Once I 
charged the battery and had 12.54 say 12.6 then with the lights on 
everything was then working fine . You said "Once the engine is started, a 
properly
> working charging system recharges the battery; after that, all the car's
> electrical components are running off the generator, except when the 
> engine
> is at idle"
 That being said I had a low battery 12.32 Volt so the gen even though 
charging was only charging .it may not have been able to carry the 
componants and this would depend on actuall draw of all the light's and FI 
system , I do realise the gen puts out 30 amp yet never checked to see , I 
imagine 30 amp is dependant on rpm and load .I have an old analog Volt /amp 
meter I could connect in series to see how many amps it puts out with 
everything on as well as check how many amps the system draws eng off , This 
may be me over thinking this which I do tend to do . This is sort of 
ingrained in me from all the years working on customers cars , I always 
wanted to be certain it was fixed right .

 I haven't worked on a car witha gen in decades other than mine . I replaced 
the gen witha Bosch rebuilt in 2001 I have the one that came on this car and 
had an extra from the 72 parts car for the core. Trouble is the rebuilt one 
where the brush holders are riveted to the cover I can more both brush 
holders a small amout they seem to make good contact , I didn't notice it 
until I replaced the brushes, wanted to use the orig gen plate yet could not 
get it off . The one on the car now has always had holders that move a bit 
and it always worked I'd prefer to find a way to tighten them since to old 
gen field wire insulation to the brushes is fallen away I don't trust it.

 To add this night time drive was also stop and go traffic and the VDO volt 
meter was 1 volt to low so I adjusted it to read correct with my DVM engine 
running at 2000 rpm and re-check it at idle all the time with the DVM 
connected to battery also even though the headlamp on drive voltage was low 
the gen light never came on and it does work.

 Yes I tnd to over think things yet I do not want to be standing on the side 
of the road , not in this area.

 William

----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Thursday, July 05, 2018 4:53 AM
Subject: Re: [T3] Batteries.

> On 4 Jul 2018 at 20:43, William J wrote:
>
>>  When I brought up the issue with low voltage driving at night . I
>> charged the battery in 2 3 hour 2 amp charges in 2 days , 6 hours. it
>> came from 12.32 V to 12.57 V. Then after that I ran  the engine and
>> checked the battery voltgae with lamps all on and off. I only ran the
>> engine at most for 1 hour . I felt well this had to drain it some , I
>> gave it another 3 hour  2amp charge and read 12.66 volts .
>
> Those voltage readings are all perfectly normal. The person who told you
> that a resting battery should measure above 13 V didn't know what he was
> talking about. Voltages that high will only be achieved DURING, or right
> after, charging
>
>>  I wait at least 15 hours after a charge to check it.
>
> Not necessary to wait that long. In that time, the clock will have drawn 
> the
> voltage down very slightly. An hour is usually sufficient. What you're 
> waiting
> for is the battery acid to equilize. Right after charging, the sulfate ion
> concentration right next to the plate will be higher than normal, because
> those sulfate ions came from the plate during charging. Once the ions have
> diffused evenly throughout the acid, you will get an accurate measure of 
> the
> state of your battery.
>
> The battery voltage is proportional to the sulfate ion concentration. 
> Standard
> battery acid is supplied at a concentration that gives sufficient energy
> storage without being so concentrated (strongly acidic) that it can damage
> the battery. It's a compromise that was made and agreed to decades before
> our cars were built.
>
>>  I don't feel I need to charge it every day it sits. And certainly
>> don't feel I need to check battery voltage before every drive I make .
>> I would if I had a mounted voltmeter I could flip a switch and see or
>> spend the 5 minutes it takes to connect my DVOM and check .
>
> You're obsessing about this, as you've said you tend to do. If the battery
> starts the engine normally, it's good. Once the engine is started, a 
> properly
> working charging system recharges the battery; after that, all the car's
> electrical components are running off the generator, except when the 
> engine
> is at idle.
>
> At idle, the battery is supplying the power to keep things going, but it 
> gets
> recharged quickly once you get off idle. This all happens automatically
> without our intervention.
>
> So here's the short story.
>
> If you get in the car and the voltmeter reads above 12 V, your battery is
> PROBABLY okay. If it starts the engine, you know it IS okay.
>
> If you can see the voltmeter go above 13 V when driving, you know the
> charging system is working. It should get above 14 V after driving a bit.
>
> At idle, the voltage should be above 12 V. The actual voltage depends on 
> so
> many things that it's not important, so there's no point in measuring it
> accurately.
>
>
>
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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