Car More Dead from Boosting a Dead Car Battery

[D from BC]

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.
Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that
the dead battery be charged. This is often impractical because
of where the vehicle is sitting so most people with a dead
battery boost their vehicle - but several important steps must
be followed to prevent damage.
}
Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

 

[Mike Monett]

Taken from

"Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting."

"Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that the
dead battery be charged. This is often impractical because of
where the vehicle is sitting so most people with a dead battery
boost their vehicle - but several important steps must be followed
to prevent damage."

Come 'on. Is it impossible to throw in some protection
electronics?

And what about this surge?. Wimpy car electronics?

Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads.

Would you buy a car that has a big sticker: "Contains sensitive
electronics. Do not boost"

Hi D,

There's a bit of a contradiction in this article. Reading further
down, we find:

"On many new vehicles, the battery is concealed under the rear
seat, in the trunk or beneath plastic covers in the engine
compartment. Fortunately, the manufacturers usually provide a
positive connector under the hood to provide a connection point
for boosting. Look for it under a bright red plastic cap marked
'battery' or with a + sign."

If the manufacturers provide a means of boosting the battery, they
are saying it won't damage the car (when done properly.)

Most tow trucks will boost a battery with no hesitation. A few
simple precautions helps avoid problems, like turning the ignition
off on the car before connecting the cables.

Once the cables are connected, it's difficult to see how a surge
could produce voltages high enough to destroy any electronics. The
two batteries in parallel would absorb the surge.

In cold weaather, it's important to keep a discharged battery from
freezing. This means getting it recharged, or removing it and taking
it inside to keep it warm.

Eventually the battery will fail to hold a charge, and the only
solution is to get a new one. If it's more than three years old, I'd
replace it before bad weather starts.

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm

 

[w_tom]

The term is load dump. SAE J1455 and ISO 7637/1 define load dump
with voltages up to 270V. SGS Thompson (who makes semiconductor
protection) defined it as peak voltage 80 to 100 volts. The SGS
Thompson application note then says:

 

[D from BC]

The term is load dump. SAE J1455 and ISO 7637/1 define load
dump
with voltages up to 270V. SGS Thompson (who makes semiconductor
protection) defined it as peak voltage 80 to 100 volts. The SGS
Thompson application note then says:

The protection at the alternator level [APC series] is a quite
new concept and all the technical problems do not seem to
be completely solved.

Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

..
----
mmmm... agencies defining voltages (>>12V) as a result of load
dump..SGS doing similiar.
It's evidence of overvoltage.

High currents + inductance = spiker? Somewhere I'm guessing.
But..it's a battery to battery circuit as one poster pointed
out. Isn't that dead battery a dead end? Kinda like creating a
surge past a parallel capacitor.

Without studying lead acid battery behavior...maybe a dead lead
battery is at it's highest internal impedance. I'm guessing that
first crappy connection with the gater clips pulses anything
heavy with inductance which spikes the auto electronics.
Dunno...

I wonder if there's a product out there.. call it.."Booster
Saver" that claims to protect the auto electronics during a
boost. $$$$
D
_---------------

 

[kell]

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.
Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that
the dead battery be charged. This is often impractical because
of where the vehicle is sitting so most people with a dead
battery boost their vehicle - but several important steps must
be followed to prevent damage.
}
Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

I guess what might happen is you get a load dump when you take the
cables off, if the battery is still dead.
You could use some kind of snubber to prevent this, I guess, but if it
means an extra clip on the booster nobody's going to use it.

 

[AndyS]

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.

Andy answers:
If the dead battery is completely dead, it will not provide a
stabilizer
to the system.
Assuming the jumper cables can start the dead car, when the
jumper cables are removed, the alternator in the dead car will not
be stabilized by the battery, and the output voltage will run high.
Some of the electronics in the dead car may not be protected against
this high voltage.

Note that ALL automobiles have manuals that warn the operator to
NEVER disconnect the battery with the engine running. That is exactly
the same problem as stated above.... It has nothing whatever to do
with the charging vehicle.

The storage battery is the primary voltage stabilizing device in
an alternator-battery system. It must be in good shape for the
electrical system to work as designed.....

Andy in Eureka, Texas

 

[Homer.Simpson]

D from BC said

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.
Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that
the dead battery be charged. This is often impractical because
of where the vehicle is sitting so most people with a dead
battery boost their vehicle - but several important steps must
be followed to prevent damage.
}
Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

Transients on the vehicle battery line can be a real pain for the
designer.

Load dump, as has been discussed, is normally the result of the battery
being disconnected while the alternator is at full charge. The
alternator generates a huge electrical transient as a result of the
"increased" load impedance. This transient is seen all over the
vehicle battery harness.

Most modern alternators are "centrally suppressed", in that they
incorporate a local zener to eat the overvoltage. Hence, the maximum
load dump is clamped at the source.

Some alternators are not centrally suppressed. Then the transient is
eaten by all the boxes on the harness. (or maybe the one with the
least series inductance, from the alternator). In any event, every box
usually has to be designed to eat the entire energy slug. Number and
location of such boxes vary from vehicle to vehicle.

These transients are not for sissies. A 12V system might be 70V
through 4 ohms. A 24V system might be 150V through 0.75 ohms.
Further, the spec might require a repetitive pulse for an extended
period of time.

The designer is forced to follow one of two paths:
1) Insure all circuits can handle the overvoltage.
2) Clamp it with a TVS

Solution 1 is the simplest. However, this means all MOSFETS might be
100V (or greater) - with increased RDSon. Hence they dissipate more
power under nominal conditions. Further, this decreased efficiency is
a real bummer with the controller in a 125`C environment. This means
larger packages, more substantial thermal designs, larger footprint,
etc. Any DC/DC converters must be able to maintain its V(o) of ~5V
under this transient. That's a Vin range of 4.5V (crank) to ~100V(load
dump).

Solution 2 is sometimes better. However, the TVS clamp cannot commence
until just above jump start voltage (typically 2x nominal). Further,
the worst case tolerance on the TVS might mean one can't start clamping
until ~40V for a 12V system. So, all MOSFETS are 50V - with their
reduced efficiency. The issue worsens at 24V when the jump start is
48V (or higher) and the currents are much more substantial.

Back to OP's comment..... I s'ppose the real risk is to the jumper's
car rather than the jumpee's car. His car is seeing the most
substantial impedance transient. The jumpee benefits from the load of
the dead battery. This is speculation on my part.

Cars are no longer dominated by mechanical systems - electronics is a
very major part.

 

[jasen]

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.
Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that
the dead battery be charged. This is often impractical because
of where the vehicle is sitting so most people with a dead
battery boost their vehicle - but several important steps must
be followed to prevent damage.
}
Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

users will connect devices up backwards, discharge freakish ammounts
of electrosytatic charge into sensitive electrics and do other unfortunate
things, manufacturers are covering their assets.

correct usage of booster cables isn't simply a matter of matching positive
and negative on both sides

 

[Mike Monett]

If the dead battery is completely dead, it will not provide a
stabilizer to the system.

Assuming the jumper cables can start the dead car, when the jumper
cables are removed, the alternator in the dead car will not be
stabilized by the battery, and the output voltage will run high.

Some of the electronics in the dead car may not be protected
against this high voltage.

Note that ALL automobiles have manuals that warn the operator to
NEVER disconnect the battery with the engine running. That is
exactly the same problem as stated above. It has nothing whatever
to do with the charging vehicle.

The storage battery is the primary voltage stabilizing device in
an alternator-battery system. It must be in good shape for the
electrical system to work as designed.

Nah. The alternator is the primary voltage stabilizing device in the
system. It sets the voltage to around 14.5V, depending on
temperature.

I have had plenty of occasions where I left the lights on or had
some other problem that drained the battery completely.

A discharged battery still has a specific gravity of around 1.130,
meaning it has plenty of sulfuric acid remaining. This means it will
have a low resistance. This will prevent the alternator from
developing a high output voltage.

When you boost the battery, you have one car with the engine
running, and one car cranking. The source alternator is putting out
as much current as it can, and the target battery is receiving some
charge.

When the target engine starts, its alternator starts developing
current to charge the battery. Now you let the throttle off the
source engine so it goes to idle, and remove the jumper cables.

Since the target battery is taking most of the current from the
alternator, there is no large reduction when the cables are removed,
so there is no load dump from the alternator.

The load dump occurs when there is a high current drain and the
battery is disconnected. That never happens during a boost, so there
is little cause for concern.

Just watch the tow trucks during a cold spell. They pop the cables
on, get the engine started, remove the cables, and get the owner to
sign the bill. Then they're on their way to the next poor victim.

About the only reason for a problem is poor connections to the
battery. If they suddenly open while the alternator is delivering
high current, it will cause a load dump and fry the electronics.

This could happen while removing the jumper cables, and people would
think it was caused by the boost.

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm

 

[Michael A. Terrell]

Mike Monett wrote:


That proportional spacing is a pain in the ass. I have vision
problems, and it is very hard to read with my vision problems. Its one
of the reasons I had to stop reading the local newspaper. I learned to
speed read 40 years ago, but it only works on properly laid out text.

"Pretty print" is a waste of time and energy, not to mention that it
takes longer to upload and download the files. You might as well be
using HTML with 6 pt type and a different color on every character.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Jon]

Taken fromhttp://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, ...

ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=148254
..
A relatively safe way to boost is to turn off the "dead" car's
ignition. Then connect the boost cables. Do not attempt to start the
"dead" car with the boost cables connected. Let the Booster car charge
the dead battery to the point where it is capable of starting the car.
This will take several minutes. Remove the boost cables. Start the
"dead" car using its own recharged battery.

 

[Rich Grise]

I wonder if there's a product out there.. call it.."Booster Saver"
that
claims to protect the auto electronics during a boost. $$$$

Yes, but I don't know what it's called - maybe "jump start battery"....
http://www.autobarn.net/kak990096.html is one example.

It's just a portable starting battery, about the size of a thick telephone
book. I think it'd be safe to just clip that across the battery. I had
that done once, and I was amazed at how "well" the car cranked - it seemed
like the jumper battery didn't even droop at all.

Good Luck!
Rich

 

[jasen]

Back to OP's comment..... I s'ppose the real risk is to the jumper's
car rather than the jumpee's car. His car is seeing the most
substantial impedance transient. The jumpee benefits from the load of
the dead battery. This is speculation on my part.

The jump cables have finite resistance, and are not disconnected until
the jumpee's car is running (so voltage has equalised somewhat)
add to that that the jumper typically has a better battery than the jumpee
and that it's fully charged.

Normally the battery will swallow any surges from the altenator that are
due to changing load.

Bye.
Jasen

 

[Jamie]

Taken from
http://www.canadiandriver.com/winter/050126.htm
{
Some car manufacturers do not recommend boosting a vehicle, They
state that damage to electronic controls can occur if voltage
surges flow through the electrical system during boosting.
Instead of boosting, the auto manufacturers prefer that a fully
charged battery be installed in place of the dead one or that
the dead battery be charged. This is often impractical because
of where the vehicle is sitting so most people with a dead
battery boost their vehicle - but several important steps must
be followed to prevent damage.
}
Come 'on... is it impossible to throw in some protection
electronics?
And what about this surge?...Wimpy car electronics?
Perhaps HV spikes from the booster wire inductance can zap the
computer and other loads..
Would you buy a car that has a big sticker: "Contains sensitive
electronics..do not boost"

One should always check to make sure there is no open cell/circuit
in the current battery that is mounted in the car otherwise, a boost
start will most likely cause damage as soon as you remove the external
source from it's own source..
Most of the time you should first clean your connector clamps before
jumping since, this maybe the original reason why your battery is
low/dead in the first place. If you do have a bad connection at the
cables and you boost start, your electrical system may become unstable
because the alternator is not seeing a constant voltage at it's output
terminal which causes it's own regulator to become unstable since it
treats the battery as if it was a capacitor also.
Many car's employ protection in this area, for example, if you get a
boost start and if the battery is completely shot or cable/clamps have
no connection, as soon as you disconnect the boost cables, the car will
stall.

 

[joseph2k]

The jump cables have finite resistance, and are not disconnected until
the jumpee's car is running (so voltage has equalised somewhat)
add to that that the jumper typically has a better battery than the jumpee
and that it's fully charged.

Normally the battery will swallow any surges from the altenator that are
due to changing load.

Bye.
Jasen

Some more items in the equation: More modern cars have more never off
electronics Alarms, keyless entry systems, etc., There is an additional
hazard in Jumping a car, "polarity reversal". very little auto electronics
is well protected for this.

 

[Jeff L]

Some more items in the equation: More modern cars have more never off
electronics Alarms, keyless entry systems, etc., There is an additional
hazard in Jumping a car, "polarity reversal". very little auto electronics
is well protected for this.

This is the big danger in boosting with someone who does not know what they
are doing. When a battery is dead, is it very easy to do a polarity
reversal.

 

[Rich Grise]

This is the big danger in boosting with someone who does not know what
they are doing. When a battery is dead, is it very easy to do a polarity
reversal.

I was doing just this one time, and the guy had no clue, and he started
to clip the cables onto his battery backwards. I said,
"NONONONONONONO!!!!!!", and luckily he stopped in time.

I 'splained to him, and said, "I didn't really know what to say..." and
he said, "Well, 'NONONONONONONO!!!!!!' seems to've worked pretty good."

Cheers!
Rich

 

[Ancient_Hacker]

On most cars the first sign that you've reversed the cables is smoke
coming from the alternator. The diodes in there keep the battery from
back-discharging into the stator windows. Reverse the jumper cables
and you have a few hundred amps going thru some #12 wires, which don't
take long to burn up.