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Voltage stability in old truck

G

gothika

(The main reason the industry switch to 12v systems, 6v batteries just
could not hold up under constant use and the variable charge rates as
well as being limited in the amount of loads from the ever increasing
number of system accessories that were being added to cars.)

Actually, the underlying reason is that you need more
current to do the same amount of work at low voltage.
It was taking like 2 ga. wire for starter motors on
some of the larger engines, but at 12V you can do the
job with 4 or 6 ga. All the connectors had to be
beefier at 6V, corrosion and wire/connector resistance
were more problematic.

Copper wire being an expensive and [potentially] short
supply strategic material, the military bumped most of
their systems on up to 24/28 Volts.

And we may have not heard the last of it. There has
been talk of going to 42 Volts to power the increasing
demand of proliferating electronics in automotives.
It is unclear how this might be implemented, as this
is above what is normally considered "consumer safe"
low voltage. Check one of *those* with your tongue!
There was a time when a solid state 6v regulator could be
had, as well as a decent 6v altenator.

Check the rebuilders, like Jebco and Triodiode. You can
still get 6V regulators, reverse polarity diode packs, etc.
Yes NOW, but at one time, especially in the late 70's and most of the
80's you'd have to go service that specialized in parts restoration
for antiques. 6v regulators couldn't be had at you're local auto parts
store.
and yes you could find a cross at your local farm implement and
tractor shop, maybe.
Now here you are just dead wrong. Nearly all automotive
alternators since the early 70's are equipped with remote
sensing so that the alternator will maintain a nearly
constant voltage at some point other than the battery.
This is done both to reduce the amount of charge/discharge
cycling on the battery, thereby improving longevity, and
to minimize dimming of lights and similar problems that
would be associated with running from a battery in varying
states of charge. Turn something on, the alternator picks
it up right away. The only times significant current is
drawn from the battery is for starting, or at idle if you
have so much stuff turned on that the alternator won't
carry it all. Watch your ammeter if you don't believe me
(if you have one - ammeters are becoming extinct as modern
electronically regulated alternators do such a good job
you don't have to worry about it). The battery still acts
as a huge water dielectric capacitor to smooth alternator
ripple, but this is AC which has no net effect on charge
and is not hard on the battery.
Well.. if I'm so wrong try and jump off any auto with a computer/solid
state ignition and see what happens.
You HAVE to leave the jumpers on long enough to get a base charge on
the battery. i.e. you can't just jump it off and disconnect the
jumpers and have the motor run. The car being jumped IS running off
the battery of the other car, period.
In autos going back as late as the 70's the regulator acted as the
trap isolating the charging circuit from the secondary electrics, in
later models with computers they took over this function.
As for load sensing that too is a function of the computer, unless
you're referring to some of the altenators with internal electronics
for load balancing and timing. Just talk to any other mechanic about
these and you'll get the same consensus, total crap.
I mod alot of electrical systems and when I run across these, mostly
mitsubishi or nippondenso altenators, I either cross reference them to
a good marine grade non-electronic alt. with matching solid state
regulator or modify the exsisting alt. and put in an after market
brain box to match.
There are one-wire alternators made for simpler electrical
systems, like tractors, where charging the starting battery
is about all it has to do. These are not well-suited for
automotive applications, but a lot of backyard mechanics
use them in error because they are easy to hook up without
having to understand how the electrical system works.
Performance varies from fair to poor. Don't even think
about using one of these with a high-power sound system,
you won't get good results. They are disappearing even
from agricultural use as more high-demand electronics
make inroads.
You need to get up to date on your training, virtually all autos now
run on "isolated charging" electrical systems.
Don't believe me, rip out the dash board electrics of anything made in
the past 20-25 years. All low value solid state components that would
fry in a New York minute if you wired them into the charging circuit.
Smoke and mirrors and fuzzy thinking. Nothing in those
sentences solid enough even to poke at.
Nothing fuzzy about it, just standard design in todays auto electrics.
That's a bit misleading. Modern engine systems have
built-in filtering and regulation where needed. They
are well hardened against anything even a poor charging
system is likely to throw at them. They may perform a
little *better* with clean power, but it usually takes
some kind of major deficiency to bring them down, and
most of the time they don't even seem to care.

Dead wrong. I've seen injector manifolds blown clean off when when
things go horribly wrong.
You have an computer it runs the injector pump, controls timing and in
the more sophisticated engine controls valve timing.
Get any of this out of sync more than a bit and you start blowing
seals.
Even more and you'll have alot more flying off.
I run Bosch Jetronic "J" type on one of my current autos, the standard
pump pressure is 85psi, however the pump I run can range as high as
150psi. You get the valve timing off or have the computer go
haywire(OR set it up wrong) on this all you'll have left is so much
scrap metal.
Seen it happen time after time.
As for most of the stock oem stuff, you're incorrect they're very
touchy when it comes to having clean power.
In fact most of the GM, Ford or Chryslers out today have safety
interlocks to prevent the engine from running on low batteries.

I Stopped just the other day to help a lady with her 04 model
Cadillac.
Her battery went down and someone was trying to help her jump it off.
Neither new what they were doing.
I had them leave the jumpers on for about thirty minutes and she
finally got it to start.(The Caddy wouldn't even start with the jumper
cables on, the computer locked the system down entirely.)
 
J

James Sweet

gothika said:
(The main reason the industry switch to 12v systems, 6v batteries just
could not hold up under constant use and the variable charge rates as
well as being limited in the amount of loads from the ever increasing
number of system accessories that were being added to cars.)

Actually, the underlying reason is that you need more
current to do the same amount of work at low voltage.
It was taking like 2 ga. wire for starter motors on
some of the larger engines, but at 12V you can do the
job with 4 or 6 ga. All the connectors had to be
beefier at 6V, corrosion and wire/connector resistance
were more problematic.

Copper wire being an expensive and [potentially] short
supply strategic material, the military bumped most of
their systems on up to 24/28 Volts.

And we may have not heard the last of it. There has
been talk of going to 42 Volts to power the increasing
demand of proliferating electronics in automotives.
It is unclear how this might be implemented, as this
is above what is normally considered "consumer safe"
low voltage. Check one of *those* with your tongue!
There was a time when a solid state 6v regulator could be
had, as well as a decent 6v altenator.

Check the rebuilders, like Jebco and Triodiode. You can
still get 6V regulators, reverse polarity diode packs, etc.
Yes NOW, but at one time, especially in the late 70's and most of the
80's you'd have to go service that specialized in parts restoration
for antiques. 6v regulators couldn't be had at you're local auto parts
store.
and yes you could find a cross at your local farm implement and
tractor shop, maybe.
Now here you are just dead wrong. Nearly all automotive
alternators since the early 70's are equipped with remote
sensing so that the alternator will maintain a nearly
constant voltage at some point other than the battery.
This is done both to reduce the amount of charge/discharge
cycling on the battery, thereby improving longevity, and
to minimize dimming of lights and similar problems that
would be associated with running from a battery in varying
states of charge. Turn something on, the alternator picks
it up right away. The only times significant current is
drawn from the battery is for starting, or at idle if you
have so much stuff turned on that the alternator won't
carry it all. Watch your ammeter if you don't believe me
(if you have one - ammeters are becoming extinct as modern
electronically regulated alternators do such a good job
you don't have to worry about it). The battery still acts
as a huge water dielectric capacitor to smooth alternator
ripple, but this is AC which has no net effect on charge
and is not hard on the battery.
Well.. if I'm so wrong try and jump off any auto with a computer/solid
state ignition and see what happens.
You HAVE to leave the jumpers on long enough to get a base charge on
the battery. i.e. you can't just jump it off and disconnect the
jumpers and have the motor run. The car being jumped IS running off
the battery of the other car, period.
In autos going back as late as the 70's the regulator acted as the
trap isolating the charging circuit from the secondary electrics, in
later models with computers they took over this function.
As for load sensing that too is a function of the computer, unless
you're referring to some of the altenators with internal electronics
for load balancing and timing. Just talk to any other mechanic about
these and you'll get the same consensus, total crap.
I mod alot of electrical systems and when I run across these, mostly
mitsubishi or nippondenso altenators, I either cross reference them to
a good marine grade non-electronic alt. with matching solid state
regulator or modify the exsisting alt. and put in an after market
brain box to match.
There are one-wire alternators made for simpler electrical
systems, like tractors, where charging the starting battery
is about all it has to do. These are not well-suited for
automotive applications, but a lot of backyard mechanics
use them in error because they are easy to hook up without
having to understand how the electrical system works.
Performance varies from fair to poor. Don't even think
about using one of these with a high-power sound system,
you won't get good results. They are disappearing even
from agricultural use as more high-demand electronics
make inroads.
You need to get up to date on your training, virtually all autos now
run on "isolated charging" electrical systems.
Don't believe me, rip out the dash board electrics of anything made in
the past 20-25 years. All low value solid state components that would
fry in a New York minute if you wired them into the charging circuit.
Smoke and mirrors and fuzzy thinking. Nothing in those
sentences solid enough even to poke at.
Nothing fuzzy about it, just standard design in todays auto electrics.
That's a bit misleading. Modern engine systems have
built-in filtering and regulation where needed. They
are well hardened against anything even a poor charging
system is likely to throw at them. They may perform a
little *better* with clean power, but it usually takes
some kind of major deficiency to bring them down, and
most of the time they don't even seem to care.

Dead wrong. I've seen injector manifolds blown clean off when when
things go horribly wrong.
You have an computer it runs the injector pump, controls timing and in
the more sophisticated engine controls valve timing.
Get any of this out of sync more than a bit and you start blowing
seals.
Even more and you'll have alot more flying off.
I run Bosch Jetronic "J" type on one of my current autos, the standard
pump pressure is 85psi, however the pump I run can range as high as
150psi. You get the valve timing off or have the computer go
haywire(OR set it up wrong) on this all you'll have left is so much
scrap metal.
Seen it happen time after time.
As for most of the stock oem stuff, you're incorrect they're very
touchy when it comes to having clean power.
In fact most of the GM, Ford or Chryslers out today have safety
interlocks to prevent the engine from running on low batteries.

I Stopped just the other day to help a lady with her 04 model
Cadillac.
Her battery went down and someone was trying to help her jump it off.
Neither new what they were doing.
I had them leave the jumpers on for about thirty minutes and she
finally got it to start.(The Caddy wouldn't even start with the jumper
cables on, the computer locked the system down entirely.)

Well this argument is turning into a flame war, however I checked earlier
today on my own car just to make sure I wasn't full of it. The car is
equipped with Bosch LH JetTronic injection which is the only system I'm
fully familiar with. The battery with the car off was sitting at about
12.5v, measured about 12.3v at one of the accessory fuses. Turned the key on
and the voltage sagged slightly to around 11.9 at the fuse. Started up the
car, alternator is an internally regulated Bosch 100A unit, voltage at the
battery jumped up to 13.6v at idle, voltage at the fuse box was just a few
points below that. Rev the engine just slightly and it goes right up to a
rock solid 13.9v, shut off the car and it drops to 12.8v immediately and
then slowly settles a few points lower. The voltage at the fuse box which is
connected directly to the ignition and injection computers, instruments, etc
directly followed the voltage increase with the engine running, it was
higher than the idle voltage of the battery, therefore it's obvious that the
alternator is running things. Yes the battery needs to have a bit of a
charge in order for the engine to start but it's because otherwise the heavy
load of the starter will drop the voltage down too low for the electronics
to function. You can measure this yourself, if you jump a car with a
completely flat battery the voltage will drop down to 6-8v when the starter
cranks, this will cause the computer to not function, something that isn't a
problem on older cars. You've got some valid points but the information
behind them is somewhat lacking and the know it all attitude is far from
helpful.

Come to think of it, I've jumped my other car when the battery was
completely flat by dropping in the good battery from the other car, once
running I was able to disconnect the good battery and put the flat one back
in, engine kept running fine, this is also electronically injected with a
computer. So yes, the alternator will definitly run the car's electrical
system on it's own and it's just basic electrical principal that if
something is drawing power from a battery and something else is pumping
power back into the battery through the very same terminals at the same
time, then the source of energy keeping the battery up is also powering
anything drawing from it.
 
O

Ol' Duffer

Well this argument is turning into a flame war,

That was not my intention, but misinformation deserves
to be shot down. I'm satisfied with a single poke at
the nest, and the bees can buzz angrily around as long
as they want...
 
J

Jack

Holy Shit, Batman. All that stuff is expensive. I got this old truck years
ago so I could do the work on it myself ..fabricate if need be.. and not
have to be obliged to buy ready-made stuff ..and there is plenty of it out
there.
I was just at a local Show and Shine classic car show and most everyone
there had either someone else build their vehicle or maintain if for them or
bought ready-made stuff and hired someone to put it in. Seemed the main
thing was bragging rights: "nice demo and how much I spent". Strickly a
short term investment and "club rights". Hense, I shied away from sticking
my truck in the show as I found very few (there were some) owners that had
any commonality with my experience.

I degress.. Topic at hand, original post: suffice to say, Fred was very
gratious in lending his help in getting my tunes back into the truck. I
ended up using a 6.2 volt zener and 8.2 resistor combo that did the trick
just fine. No problems.

Thanks for the thread guys!

Jack
 
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