Lead-acid charger/starter...

D

Don Y

Guest
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
<https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg>
 
On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg
Click to expand...

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
 
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Click to expand...

Shoemaker, unless you\'re in Europe.

RL
 
On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL
Click to expand...

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.
 
On Wed, 2 Nov 2022 05:07:36 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.
Click to expand...

Lots of cool occupation names:

Shepherd
Baker
Plumber/plummer
Weaver
Mason
Bailey
Fletcher
Carpenter
Fisher

I think Larkin means groundskeeper or steward.

Bloggs?
 
On Wed, 02 Nov 2022 08:05:22 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Wed, 2 Nov 2022 05:07:36 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.

Lots of cool occupation names:

Shepherd
Baker
Plumber/plummer
Weaver
Mason
Bailey
Fletcher
Carpenter
Fisher

I think Larkin means groundskeeper or steward.

Bloggs?
Click to expand...

..<https://en.wikipedia.org/wiki/Joe_Bloggs>


Joe Gwinn (whose surname means white (the color) in Welsh)
 
On Wed, 02 Nov 2022 11:23:09 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Wed, 02 Nov 2022 08:05:22 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Wed, 2 Nov 2022 05:07:36 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.

Lots of cool occupation names:

Shepherd
Baker
Plumber/plummer
Weaver
Mason
Bailey
Fletcher
Carpenter
Fisher

I think Larkin means groundskeeper or steward.

Bloggs?


.<https://en.wikipedia.org/wiki/Joe_Bloggs
Click to expand...

OK, he is Mr Baggy Jeans.

>Joe Gwinn (whose surname means white (the color) in Welsh)

In the USA, a few common surnames are White, Black, Green, and Grey.
Not many Pink or Violet.

It\'s too late for Diode, Cap, and Chip, I guess. Choke is sorta weird.

Varicap Diode would be a good girl\'s name.
 
On 02/11/2022 16:02, John Larkin wrote:

<snip>
In the USA, a few common surnames are White, Black, Green, and Grey.
Not many Pink or Violet.

It\'s too late for Diode, Cap, and Chip, I guess. Choke is sorta weird.

Varicap Diode would be a good girl\'s name.
Click to expand...

Elsie Dee and her sister Ellie.

--
Cheers
Clive
 
On 11/2/2022 4:16 AM, Fred Bloggs wrote:
On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not the smaller 50A;
something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a
natural filter. When energy is applied at 60-120 Hz, it looks like the DC
average to the battery, which doesn\'t respond to those frequencies. If the
charger/ starter is built into a wheeled cart and is heavy, that\'s a clue
it\'s based on a line powered stepdown transformer. From what I can see from
the few diagrams available, they all use a center tapped transformer, tap is
common ( from there to battery NEG clamp) and the hot legs go to individual
high current diodes (anodes), the cathodes are connected together to provide
current to the battery POS clamp. Depending on diode packaging that
orientation could be reversed for heat sinking purposes- as with
interference fitted stud packages. They can add stuff in POS clamp lead like
current limiting resistor and circuit breaker and maybe other things like an
over-duty timer in starter mode for idiot proofing. The center tapped
xformer makes sense by minimizing number of expensive high current
semiconductors required, reducing voltage loss, and minimizing the iron
stack required. Interestingly DieHard was ( at least at one time)
manufactured by Schumacher, one of the best available.
Click to expand...

That\'s how they WERE designed -- 60 years ago.

But, back then, there were no \"electronics\" that had to continue
operating with the \"battery\" dropping to 0V between \"cycles\".
Rather, the \"electrics\" just had to tolerate battery dropping to
~6V -- and the starter relay continuing to \"hold\".

With a completely flat (or removed/disconnected) battery, the
\"charger/starter\" is the sole source of current.

Would they design ECUs with the ability to carryover when powered
by rectified AC? Or, would they just have enough bulk decoupling
to even out the *DC* that they expect on their inputs?

[I\'m actually looking at 24V starters]

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER or 2:SHOO-MAH-SHER
Click to expand...

smith
 
John Larkin wrote:
On Wed, 2 Nov 2022 05:07:36 -0700 (PDT), Fred Bloggs
bloggs.fredbloggs.fred@gmail.com> wrote:

On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg>

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.

Lots of cool occupation names:

Shepherd
Baker
Plumber/plummer
Weaver
Mason
Bailey
Fletcher
Carpenter
Fisher
Click to expand...

Not to mention Smith, Reeve, Groome, Tanner, Fuller, Singer, Piper,
Miner, Tinker, Cook, Carver, Potter, and so forth.
I think Larkin means groundskeeper or steward.
Click to expand...

\'Larrikin\' or \'Larrykin\' is an unruly youngster. (\"Hobbs\" is a Robert
derivative, I think.)

> Bloggs?

\"Fred Bloggs\" is roughly an English equivalent to \"Larry Lunchbucket\".

(\'s a nym, see?)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com


 
On Wednesday, November 2, 2022 at 11:05:32 AM UTC-4, John Larkin wrote:
On Wed, 2 Nov 2022 05:07:36 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 8:03:56 AM UTC-4, legg wrote:
On Wed, 2 Nov 2022 04:16:41 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not
the smaller 50A; something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a natural filter. When energy is applied at 60-120 Hz, it looks like the DC average to the battery, which doesn\'t respond to those frequencies. If the charger/ starter is built into a wheeled cart and is heavy, that\'s a clue it\'s based on a line powered stepdown transformer. From what I can see from the few diagrams available, they all use a center tapped transformer, tap is common ( from there to battery NEG clamp) and the hot legs go to individual high current diodes (anodes), the cathodes are connected together to provide current to the battery POS clamp. Depending on diode packaging that orientation could be reversed for heat sinking purposes- as with interference fitted stud packages. They can add stuff in POS clamp lead like current limiting resistor and circuit breaker and maybe other things like an over-duty timer in starter mode for idiot proofing. The center tapped xformer makes sense by minimizing
number of expensive high current semiconductors required, reducing voltage loss, and minimizing the iron stack required.
Interestingly DieHard was ( at least at one time) manufactured by Schumacher, one of the best available.

The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER
or
2:SHOO-MAH-SHER
Shoemaker, unless you\'re in Europe.

RL

Thanks - was wondering. Ever since I heard a French national use pronunciation #2 I haven\'t been able to shake it.
Lots of cool occupation names:

Shepherd
Baker
Plumber/plummer
Weaver
Mason
Bailey
Fletcher
Carpenter
Fisher

I think Larkin means groundskeeper or steward.

Bloggs?
Click to expand...

They think it meant bookbinder.
They have a family crest with what looks like some of those hunting hawks and a tree stump with something or another stuck in it.
https://www.houseofnames.com/bloggs-family-crest#:~:text=The%20origins%20of%20the%20Bloggs,as%20a%20shoemaker%20or%20bookbinder.
 
On Wednesday, November 2, 2022 at 2:42:08 PM UTC-4, Don Y wrote:
On 11/2/2022 4:16 AM, Fred Bloggs wrote:
On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not the smaller 50A;
something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a
natural filter. When energy is applied at 60-120 Hz, it looks like the DC
average to the battery, which doesn\'t respond to those frequencies. If the
charger/ starter is built into a wheeled cart and is heavy, that\'s a clue
it\'s based on a line powered stepdown transformer. From what I can see from
the few diagrams available, they all use a center tapped transformer, tap is
common ( from there to battery NEG clamp) and the hot legs go to individual
high current diodes (anodes), the cathodes are connected together to provide
current to the battery POS clamp. Depending on diode packaging that
orientation could be reversed for heat sinking purposes- as with
interference fitted stud packages. They can add stuff in POS clamp lead like
current limiting resistor and circuit breaker and maybe other things like an
over-duty timer in starter mode for idiot proofing. The center tapped
xformer makes sense by minimizing number of expensive high current
semiconductors required, reducing voltage loss, and minimizing the iron
stack required. Interestingly DieHard was ( at least at one time)
manufactured by Schumacher, one of the best available.
That\'s how they WERE designed -- 60 years ago.

But, back then, there were no \"electronics\" that had to continue
operating with the \"battery\" dropping to 0V between \"cycles\".
Rather, the \"electrics\" just had to tolerate battery dropping to
~6V -- and the starter relay continuing to \"hold\".

With a completely flat (or removed/disconnected) battery, the
\"charger/starter\" is the sole source of current.

Would they design ECUs with the ability to carryover when powered
by rectified AC? Or, would they just have enough bulk decoupling
to even out the *DC* that they expect on their inputs?
Click to expand...

I doubt it. The SAE requirement last I looked was everything operate down to 8V - to get through starting.


[I\'m actually looking at 24V starters]
The question is do Americans pronounce Schumacher as:

1: SHOO- MACH-ER or 2:SHOO-MAH-SHER
smith
Click to expand...
 
On 11/2/2022 6:31 PM, Fred Bloggs wrote:
On Wednesday, November 2, 2022 at 2:42:08 PM UTC-4, Don Y wrote:
On 11/2/2022 4:16 AM, Fred Bloggs wrote:
On Wednesday, November 2, 2022 at 5:39:41 AM UTC-4, Don Y wrote:
The \"charge\" functions are pretty easily understood.

But, is the \"engine start\" function just a whopping big
transformer-rectifier-filter sitting behind the clamps?

I\'m speaking of the ~200A load current devices, not the smaller 50A;
something along the lines of:
https://dygtyjqp7pi0m.cloudfront.net/i/40360/34822921_1m.jpg

Lead acid charger/ starters don\'t need or use a filter. The battery is a
natural filter. When energy is applied at 60-120 Hz, it looks like the DC
average to the battery, which doesn\'t respond to those frequencies. If the
charger/ starter is built into a wheeled cart and is heavy, that\'s a clue
it\'s based on a line powered stepdown transformer. From what I can see from
the few diagrams available, they all use a center tapped transformer, tap is
common ( from there to battery NEG clamp) and the hot legs go to individual
high current diodes (anodes), the cathodes are connected together to provide
current to the battery POS clamp. Depending on diode packaging that
orientation could be reversed for heat sinking purposes- as with
interference fitted stud packages. They can add stuff in POS clamp lead like
current limiting resistor and circuit breaker and maybe other things like an
over-duty timer in starter mode for idiot proofing. The center tapped
xformer makes sense by minimizing number of expensive high current
semiconductors required, reducing voltage loss, and minimizing the iron
stack required. Interestingly DieHard was ( at least at one time)
manufactured by Schumacher, one of the best available.
That\'s how they WERE designed -- 60 years ago.

But, back then, there were no \"electronics\" that had to continue
operating with the \"battery\" dropping to 0V between \"cycles\".
Rather, the \"electrics\" just had to tolerate battery dropping to
~6V -- and the starter relay continuing to \"hold\".

With a completely flat (or removed/disconnected) battery, the
\"charger/starter\" is the sole source of current.

Would they design ECUs with the ability to carryover when powered
by rectified AC? Or, would they just have enough bulk decoupling
to even out the *DC* that they expect on their inputs?

I doubt it. The SAE requirement last I looked was everything operate down to 8V - to get through starting.
Click to expand...

So, you\'d not *expect* \"rectified AC\" on your \"DC In\" pin.
Rather, you\'d expect the battery to provide a floor of at least
8V with the \"ripple\" appearing above that.
 
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