[xj] Starter/ballast resistor

I just noticed for the first time that my starter coil
(a Jaguar part) has something like these words printed on it:

‘‘Do not operate without a ballast resistor’’

and I’m pretty sure there is none attached to it -

it should be on the passenger’s side,
just below the starter, correct?–
Travis Fields 1986 XJ6 Series III
Los Angeles, United States
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In reply to a message from calitrav sent Mon 18 Feb 2008:

Starter coil ?
Do you mean ignition coil ?
If your starter solenoid has a ‘‘do not operate without a ballast
resistor’’ label stuck on it someone has peeled it off the ignition
coil.
The general consensus on the forum is that the series 3 ignition
is improved by by-passing the ignition coil ballast resistor, and
the ignition amp can handle the extra load.
But then again, the general consensus is also that the ignition
amp is prone to unexpected failure…

:slight_smile:

Dave–
The original message included these comments:

I just noticed for the first time that my starter coil
(a Jaguar part) has something like these words printed on it:
‘‘Do not operate without a ballast resistor’’
and I’m pretty sure there is none attached to it -
it should be on the passenger’s side,
just below the starter, correct?


Dave Collishaw '79 S2 Daimler Sov '92 xj40
Peterborough, United Kingdom
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No, it’s a lie Travis. The EI system needs no ballast to limit coil current.
The ballast would be right on the coil’s + terminal, if present. Maybe
you’tr thinking of the aluminum box under the air cleaner that’s got the
resistors for the injectors?–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

calitrav wrote:

I just noticed for the first time that my starter coil
(a Jaguar part) has something like these words printed on it:

‘‘Do not operate without a ballast resistor’’

and I’m pretty sure there is none attached to it -

it should be on the passenger’s side,
just below the starter, correct?

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Dave, I must to confess to never having had an ignition-amp failure in the
XJs, or in any other EI car! Maybe in the XJs it’s because their boots each
have one in the spares box.
:]
Actually, the ignition amps used are integrated circuits and have considerable
complexity, which includes coil-current sensing/limiting.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

sparx wrote:

In reply to a message from calitrav sent Mon 18 Feb 2008:

Starter coil ?
Do you mean ignition coil ?
If your starter solenoid has a ‘‘do not operate without a ballast
resistor’’ label stuck on it someone has peeled it off the ignition
coil.
The general consensus on the forum is that the series 3 ignition
is improved by by-passing the ignition coil ballast resistor, and
the ignition amp can handle the extra load.
But then again, the general consensus is also that the ignition
amp is prone to unexpected failure…

:slight_smile:

Dave

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In reply to a message from sparx sent Mon 18 Feb 2008:

Whoops, yes, I meant the ignition coil.

So running it with a ballast resistor could help or hurt eh?

Hmm…–
The original message included these comments:

Starter coil ?
Do you mean ignition coil ?


Travis Fields 1986 XJ6 Series III
Los Angeles, United States
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In reply to a message from calitrav sent Tue 19 Feb 2008:

The coil needs a ballast resistor for the electronic ignition,
or a coil with internal resistor built in.

                                      Walter--

The original message included these comments:

Whoops, yes, I meant the ignition coil.
So running it with a ballast resistor could help or hurt eh?


Walter Schuster 78XJ6 FI Ser.II, 69E Ser.II 2+2original
Albuquerque/New Mexico, United States
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In reply to a message from W. Schuster sent Tue 19 Feb 2008:

And not having one would only be an issue on start-up?

I’m sure it doesn’t have a ballst resistor now -
found a pic of a Jag that has one: mine doesn’t.–
Travis Fields 1986 XJ6 Series III
Los Angeles, United States
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Travis, all a ballast does is waste energy, so, in fact, early cars with
points had a bypass circuit for starting that shorted the ballast out of the
picture. You can simply forget ballasts ever existed!–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

calitrav wrote:

In reply to a message from W. Schuster sent Tue 19 Feb 2008:

And not having one would only be an issue on start-up?

I’m sure it doesn’t have a ballst resistor now -
found a pic of a Jag that has one: mine doesn’t.

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Walter, that’s simply not true. The whole idea of a fancy ignition amplifier
is to control the energy stored in the coil during the dwell period and to
deliver it to spark by stopping the coil current faster and better than an old
points system, at all rpm. That’s in fact why these are called Constant
Energy ignitions.

I don’t get where all these ballast myths come from! Both our XJs had no
ballasts before I changed coils, and they still have none, despite the fact
that both coils have 1 Ohm primaries, for performance systems. The GM amp is
just fine with that.

If anyone would like to see what’s actually in a modern ignition amp, I’ll be
happy to send the PDF of Motorola’s equivalent to ours. It’s by no means a
simple device.

Please let’s stop this ballast stuff & nonsense – none of our XJs with
ignition amps need one.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

W. Schuster wrote:

In reply to a message from calitrav sent Tue 19 Feb 2008:

The coil needs a ballast resistor for the electronic ignition,
or a coil with internal resistor built in.

                                      Walter

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calitrav wrote:

I just noticed for the first time that my starter coil
(a Jaguar part) has something like these words printed on it:

‘‘Do not operate without a ballast resistor’’

and I’m pretty sure there is none attached to it -

They are just protecting their asses, Travis…:slight_smile:

The use of a ballast resistor is principally unrelated to the coil
itself - it’s depending on the ignition system the coil is used for.
It’s likely meant as a multipurpose coil and if used by a points system,
or other systems permitting coil to be grounded with the engine
stationary, an external coil is required to protect the coil from
burning out…

On the Jaguar CE system the ballast resistor is not necessary - and may
be counterproductive…

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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Travis,
You post here to get accurate information I am sure, so here is a quick
statement from a vendor who has stood the test of time and peer review on
ballast resistors. The ballast resistor is needed with many different OEM
coils independent of their ignition type (points or electronic) The ballast
resistor was used with some coils on these Jags due to their internal
structure. High voltage CHARGING systems are the reason to step the coil
voltage down during operation to avoid coil overheating and subsequent
failure. Your coil may be the one designed for 12v at the primary and your
charging system provides 14.2v while the engine is running. If your coil
calls for a ballast resistor it needs it, period. If you have such a coil I
suggest you replace it with the type shown in the article and discard the
resistor.

http://www.hot-spark.com/HS13BR.htm
Good Luck
Gregory McCord
“Scotlander”
90 VDP Majestic
00 XJ8
94 Sovereign
63 MK II 3.8----- Original Message -----
From: “calitrav” calitrav@gmail.com
To: xj@jag-lovers.org
Sent: Monday, February 18, 2008 8:43 PM
Subject: Re: [xj] Starter/ballast resistor

In reply to a message from sparx sent Mon 18 Feb 2008:

Whoops, yes, I meant the ignition coil.

So running it with a ballast resistor could help or hurt eh?

Hmm…


The original message included these comments:

Starter coil ?
Do you mean ignition coil ?


Travis Fields 1986 XJ6 Series III

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In reply to a message from Frank Andersen sent Tue 19 Feb 2008:

If I could throw in my $.02 on the ballast resistor discussion:

A short history of the balast resistor.

In the old days of point type ignitions and carburetors with
chokes to start cold engines, manufacturers found that they
needed a really hot spark to fire a cold engine with a
really rich mixture turning slowly with the starter. On top
of this, the starter was drawing a lot of current and
dropping the voltage to the coil (Note how your lights dim
when you crank your engine over) making the spark even
weaker. So, they used a coil with a very low primary
winding so they got a really strong spark. Problem was,
this really strong spark wreaked havok on the rotor and
distributor cap and the low primary winding on the coil made
a really big spark when the points contacted and seperated,
burning out points rather quickly.

So, they used these low proimary winding coils to make
engines start better, but put a ballast resistor in series
with the primary winding to make them play nice with the
points, cap, and rotor. Then in order to get the hot spark
they needed to start the car, they ran a second wire to the
primary winding on thhe coil, usually from the starter relay.

So, when you turn the key to start and crank the engine, the
starter solenoid sends the full 12V to the coil and you get
a hot spark to start the engine. Once the engine starts and
the starter is disengaged, the 12V to the coil is attenuated
through the ballast resistor and the current flow is reduced
to save the points, cap & rotor.

In a car with electronic ignition, you may or may not have a
ballast resistor depending in what the manufacturer designs.
As a general rule of thumb, bypassing the ballast resistor
will give you a stronger spark at the expense of more rapid
cap & rotor wear unless the EI compensates and reduces the
voltage to the primary side of the coil. Whether the Jag’s
module actually does this, I don’t know.–
Wild Bill
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In reply to a message from Wild Bill sent Tue 19 Feb 2008:

I’m getting a feeling of deja vu here :slight_smile:

Dave–
Dave Collishaw '79 S2 Daimler Sov '92 xj40
Peterborough, United Kingdom
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To clarify, with respect to our Jaguars specifically…

On the Ser III XJ6s with the 4.2 and CEI, the ballast resistor…when
used…was not wired as a “bypass resistor” to aid in starting. It was wired
in line.
The 3.4 engine versions, which still used points ignition, used the bypass
wiring/resistor scheme.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJR
1990 T-Bird SCFrom: “Wild Bill” wbeau@yahoo.com

So, when you turn the key to start and crank the engine, the
starter solenoid sends the full 12V to the coil and you get
a hot spark to start the engine. Once the engine starts and
the starter is disengaged, the 12V to the coil is attenuated
through the ballast resistor and the current flow is reduced
to save the points, cap & rotor.

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In reply to a message from Doug Dwyer sent Tue 19 Feb 2008:

Correct, Doug. That’s what I said. The ballast resistor is
wired in line so that the voltage is attenuated when the car
is running. The starter bypassed the ballast resistor to
get more current through the coil to aid in starting. i.e.
The ballast resistor is out of the circuit only during the
time the starter is engaged. The ballast resistor only
helped in starting because it was bypassed. Not using the
ballast resistor helps in starting.–
Wild Bill
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In reply to a message from calitrav sent Mon 18 Feb 2008:

Should have exploded into a billion pieces by now! Ah well
it’s still winter here - nothing else to do but stir a little.
But please don’t get us into … well you all know!–
The original message included these comments:

I just noticed for the first time that my starter coil
‘‘Do not operate without a ballast resistor’’


Rolph XJ6 C Manual/SU’s/: Alicante(Spain) Tampere(Finland)
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In reply to a message from Rolph sent Tue 19 Feb 2008:

rolph,

i’m more interested in knowing what tires you’re running on and
whether you mount the white stripes in or out, what weight of oil
you’re topping up with and whether it’s synthetic or not. :slight_smile:

ken

ps. it’s still winter here too but the car is clean and the roads
are dry (not that either of those things keep the car housebound
when they’re not true).–
Ken Cantor, 1992 Series III V12 Vanden Plas
Edmonton/Alberta, Canada
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Another good scammer there. You can indeed increase point life by reducing
coil current, which is what any resistor will do. In doing so, you
proportionally decrease energy available for spark. This was an old, known
tradeoff in points systems.

It’s, of course, irrelevant to us. And, to proffer ballasts for electronic
ignitions, whose modules have extremely complex, well-engineered circuitry to
in fact dynamically control coil current, is to simply show ignorance or
exploitation of the unsuspecting.

The fact that they charge $3.95 to mail a 2 oz. resistor they also charge
$7.95 for should be a hint. Then too, so should their charge of over $32 for
an ordinary coil with overly high primary resistance and nothing special about
the secondary.

Greg, since you claim sensitivity to truthiness, how about reading the
technical data for one of the manufacturers’ ignition modules? You know, the
ones actually used in modern cars, even those being built today. Even ones
with coil-per-plug. You’re welcome to the Motorola one from me.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

kcscotlander@sbcglobal.net wrote:

Travis,
You post here to get accurate information I am sure, so here is a
quick statement from a vendor who has stood the test of time and peer
review on ballast resistors. The ballast resistor is needed with many
different OEM coils independent of their ignition type (points or
electronic) The ballast resistor was used with some coils on these Jags
due to their internal structure. High voltage CHARGING systems are the
reason to step the coil voltage down during operation to avoid coil
overheating and subsequent failure. Your coil may be the one designed
for 12v at the primary and your charging system provides 14.2v while the
engine is running. If your coil calls for a ballast resistor it needs
it, period. If you have such a coil I suggest you replace it with the
type shown in the article and discard the resistor.

http://www.hot-spark.com/HS13BR.htm

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Good Bill, but it’s actually not that “the EI compensates and reduces the
voltage to the primary side of the coil”. It controls the current during
dwell time to guarantee the proper energy storage in the coil’s magnetic
field. Remember the energy in the coil is 1/2 times its inductance times the
current squared. Directly analogous to 1/2 mass times velocity squared, etc.

Storing “constant energy” regardless of rpm, is what EI modules do. I really
suggest getting the design data that folks at GM, etc. use to implement an EI
system. As I’ve long said, I happen to have one of Motorola’s, that someone
else passed to me, and anyone else is welcome to. It may be eye opening just
to see how much circuitry is inside the modules and see the functions
performed by the different circuits within them.

Also, remember that the ballast was added to protect points & coil from
overheating when the ignition was left on, but the engine had stopped with
points closed. And we know that some Hall-Effect & other EI pickups can do
similar, just having only the coil to overheat. For our case, there’s no
possibility of this because our EIs depend on the rotor turning.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Wild Bill wrote:

In reply to a message from Frank Andersen sent Tue 19 Feb 2008:

If I could throw in my $.02 on the ballast resistor discussion:

A short history of the balast resistor.

In the old days of point type ignitions and carburetors with
chokes to start cold engines, manufacturers found that they
needed a really hot spark to fire a cold engine with a
really rich mixture turning slowly with the starter. On top
of this, the starter was drawing a lot of current and
dropping the voltage to the coil (Note how your lights dim
when you crank your engine over) making the spark even
weaker. So, they used a coil with a very low primary
winding so they got a really strong spark. Problem was,
this really strong spark wreaked havok on the rotor and
distributor cap and the low primary winding on the coil made
a really big spark when the points contacted and seperated,
burning out points rather quickly.

So, they used these low primary winding coils to make
engines start better, but put a ballast resistor in series
with the primary winding to make them play nice with the
points, cap, and rotor. Then in order to get the hot spark
they needed to start the car, they ran a second wire to the
primary winding on thhe coil, usually from the starter relay.

So, when you turn the key to start and crank the engine, the
starter solenoid sends the full 12V to the coil and you get
a hot spark to start the engine. Once the engine starts and
the starter is disengaged, the 12V to the coil is attenuated
through the ballast resistor and the current flow is reduced
to save the points, cap & rotor.

In a car with electronic ignition, you may or may not have a
ballast resistor depending in what the manufacturer designs.
As a general rule of thumb, bypassing the ballast resistor
will give you a stronger spark at the expense of more rapid
cap & rotor wear unless the EI compensates and reduces the
voltage to the primary side of the coil. Whether the Jag’s
module actually does this, I don’t know.

Wild Bill

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Right ! Except on a Ser III XJ6 with CEI ignition, where the ballast is
not on a bypass at all, regardless if the starter motor is in use ! It is
always in use, at all times.

:slight_smile:

Doug Dwyer
Longview Washington USA
1995 XJR
1990 T-Bird SCFrom: “Wild Bill” wbeau@yahoo.com

The ballast resistor is
wired in line so that the voltage is attenuated when the car
is running. The starter bypassed the ballast resistor to
get more current through the coil to aid in starting. i.e.
The ballast resistor is out of the circuit only during the
time the starter is engaged. The ballast resistor only
helped in starting because it was bypassed. Not using the
ballast resistor helps in starting.

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