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VK3ABK > TECHNI 13.08.04 03:45l 77 Lines 3360 Bytes #999 (0) @ WW
BID : 32073_VK3KAY
Read: GUEST OE7FMI
Subj: Car Battery Confusion.
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<7M3TJZ<JE7YGF<LU6DTS<ZL2TZE<VK3KAY
Sent: 040813/0138Z @:VK3KAY.#WEV.VIC.AUS.OC #:32073 [Wendouree] $:32073_VK3KAY
From: VK3ABK@VK3KAY.#WEV.VIC.AUS.OC
To : TECHNI@WW
Hello all.
I was just about to send a thankyou to all who commented on car battery
charging. So many, 23 bulletins, from 15 callsigns, and 7 countries!
And all interesting and helpful, without animosity, which shows the truth
in our purpose, to stick to technical topics in Amateur Radio.
But then the I read a bunch of bulletins sent by the great commentator
who has been mysteriously missing from the the debate. Yes, the one and
only, 'The Jersey Jackass', had to add his confabulations and confusion.
JJ wrote... (After the usual 'wise-guy put-down' introduction)
"As for those voltage spikes coming out of a battery charger, there aren't
any.....spikes and transients are stepped down proportionally by the
transformer's winding ratio."
A good try, but I was interested in the capacitive coupling from the primary
to the secondary winding. A quality transformer would have an electrostatic
shield between windings, but not a $20 battery charger transformer.
JJ added...
"....anything that may be present simply is smoothed out (by the battery)
along with the ripple voltage."
The ripple voltage is at 100Hz. Noise spikes include a spectrum of radio
frequencies which may bypass a battery, especially in poor condition.
My experience, and that of other writers, shows high voltage, not current,
as a likely cause of alternator diode and transistor failure.
JJ comments on 'sulfating' and the life of a car battery benefiting from an
occasional "flat and charge from scratch".
More information needed there. This is not what the 'experts' say.
JJ includes in his bulletins to others some strange waffle that reads like
he made it up as he went. Even gets confused when he includes a 'reference
voltage' as part of a servo loop. Actually the alternator regulator includes
a zener diode to provide an independant 'reference voltage'.
There is more for the reading in these random words of the master magician,
but the one comment (directed to Barry, VK2AAB) will cause much angst among
the 'common' motorist.
JJ tells us that the "...charging a flat battery with the engine alternator
can easily overheat and destroy the alternator. It was never designed for
prolonged high output.
That's rubbish!
A car alternator is designed to run the entire car electrical system, and
to do this hours on end. The rated output, typically 40-45 Amp, is more than
adequate to run the car electrics, and the battery is only used for cranking
and running lights etc when stationary. Once the car is running, the battery
only serves as a circuit control device.
I have just returned from a short trip through the busy 8am-9am traffic.
The day is cold, and rain was falling with early dawn light making visibility
a hazard. But about 1 in 5 cars had no lights showing. On the return run,
a majority had no lights, or just the parkers on. This is the usual way the
average motorist tries to conserve his battery, falsely thinking his lights
may flatten it! No advice from qualified people can stop this dangerous way
of driving. Thankfully, motorcyclists are now required by law to have lights
on whenever the bike is being ridden. Maybe this should be a universal law
and there are signs of some action on this in Australia.
Any comments?
73. Dick. VK3ABK.
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