Old fashioned car battery charger technology


Z

zikkimalambo

Hi all,

Just an academic question.

What used to be used in Car Battery charger to convert the AC - DC
before silicon diodes/bridge rectifiers came along?

And did they do full rectification or just half wave?
 
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M

manatbandq

Hi all,

Just an academic question.

What used to be used in Car Battery charger to convert the AC - DC
before silicon diodes/bridge rectifiers came along?
Not sure about battery chargers in particular but older rectifiers
were either a vacuum tube or a selenium rectifier.

MBQ
 
B

Bob Eager

Hi all,

Just an academic question.

What used to be used in Car Battery charger to convert the AC - DC
before silicon diodes/bridge rectifiers came along?
Supplementary:

What used to be used in car battery chargers to convery 240v to 12v when
the mains was DC?

(my train set used a small rotary converter)
 
Z

zikkimalambo

Supplementary:

What used to be used in car battery chargers to convery 240v to 12v when
the mains was DC?

(my train set used a small rotary converter)
Explain please

Thinking about it, I think I still have the "Transformer" that my
parents bought for the family train set in my loft C 1966 or so, and I
remember it having bugger all in it apart from a transformer and some
kind of overcurrent trip. I wonder what is in there?

I did have a look at the wikipaedia article mentioed earlier and also
followed the link to Bridge Rectifiers and the later link to vibrators
(electrical). Fascinating stuff!

I think my friend's late uncle's battery charger probably had a centre
tapped transformer and a couple of metal diodes (centre tapped so as
to get full wave rectification with just of two diodes) thus saving
the cost of two diodes. I suppose this made sense in the olden days
when diodes were relatively expensive compared with an extra tapping
on the transformer.
 
C

Cicero

Not sure about battery chargers in particular but older rectifiers were
either a vacuum tube or a selenium rectifier.

MBQ
==================================
As far as I know the vacuum tube type ('valve') was used in radios
etc. The plate type 'selenium plate' were used in more rugged
environments such as battery chargers. Picture here:

http://images.google.co.uk/images?gbv=2&svnum=10&hl=en&q=selenium+rectifier&btnG=Search+Images

I think you would find plenty of this type of battery charger still in use
in older home workshops / garages.

Cic.
 
M

meow2222

Any of the following:
vibrator rectifier
synchronous motor with commutator rectifier
tungar mercury discharge diode
selenium rectifier stack

AFAIK the old electrolytic rectifiers werent used
in commercial car chargers, but quite possibly in home made ones.

Vacuum valves were no use for this task.


Any of the following:
series impedance, no transformation or isolation
vibrator & transformer with synchronous rectifier
motor generator


NT
 
D

Derek Geldard

Explain please

Thinking about it, I think I still have the "Transformer" that my
parents bought for the family train set in my loft C 1966 or so, and I
remember it having bugger all in it apart from a transformer and some
kind of overcurrent trip. I wonder what is in there?
I had one C1960. The transformer was a seperate unit to the "Train
controller" which had a miniature "Tram Controller" type handle
combining reversing and rheostatic speed control, smooth operation of
which was very poor and sticky. It also had a single red button which
functioned as a primitive (I think magnetic because it buzzed) circuit
breaker. I think all this adds up to a centre tapped rheostat and
bi-phase half wave rectification with germanium diodes.

The transformer also had a 1.25" fuse which blew very readily in case
of a derailment or just a short circuit both of which were quite
frequent in the days of Hornby 3 rail track. It was quite expensive to
keep on replacing fuses out of a 12 year old's pocket money. :-(
I did have a look at the wikipaedia article mentioed earlier and also
followed the link to Bridge Rectifiers and the later link to vibrators
(electrical). Fascinating stuff!

I think my friend's late uncle's battery charger probably had a centre
tapped transformer and a couple of metal diodes (centre tapped so as
to get full wave rectification with just of two diodes) thus saving
the cost of two diodes.
It's possible, but each diode would need 2x the current carrying
capacity for the same current output.
I suppose this made sense in the olden days
when diodes were relatively expensive compared with an extra tapping
on the transformer.
I'm sure some cheap low powered ones just had a single diode and half
wave rectification if the way they buzzed and the way the needle on
the ammeter used to vibrate was anything to go by.

DG
 
B

Bob Eager

Explain please
What I said. In the late 1950s our mains was DC at 240 volts.
Transformers don't work on DC. So what was used?

I had a Tri-Ang train set. It used 12 volts DC. I had a little
motor/generator combined (240v motor, 12v generator) in a perforated
metal case, about 12 inches by 6 by 6 (perhaps a little smaller).
Excitement when my dad came home with a small red box and said "We'll be
using this instead from next week". That was a transformer/rectifier box
to use when they changed our mains to AC.
 
H

Harry Bloomfield

Just an academic question.
What used to be used in Car Battery charger to convert the AC - DC
before silicon diodes/bridge rectifiers came along?
And did they do full rectification or just half wave?
Selenium rectifiers - easy to spot by the large metal cooling fins. Any
over heating in the selenium and they would be easily damaged. Once you
have smelt one failing, you could instantly recognise it the next time.
I think most were full wave, either using the two diode method or four.
 
H

Harry Bloomfield

(e-mail address removed) explained on 13/09/2007 :
Well, that was very quick! For a suplementry question (no extra
points i'm afraid) has technology moved on since the 70's? or are
todays chargers still a transformer, rectifier and a fuse in a box?
They have moved on. The older ones had to be watched to prevent them
over-charging and damaging batteries. The more modern ones at least
stop charging when a full charge has been put into the battery. Even
better modern ones use a three stage intelligent charging process.
 
S

Sam Farrell

DC in the 1950's surely they stopped using DC back in the 1930's

Sam Farrell
 
H

Harry Bloomfield

Harry Bloomfield was thinking very hard :
Selenium rectifiers - easy to spot by the large metal cooling fins. Any over
heating in the selenium and they would be easily damaged. Once you have smelt
one failing, you could instantly recognise it the next time. I think most
were full wave, either using the two diode method or four.
smelt = smelled :-(

There is an example of one on Ebay...

http://cgi.ebay.com/ebaymotors/Honda-CB100-CL100-SL100-CB125-CL125-Selenium-Rectifier_W0QQcmdZViewItemQQcategoryZ35594QQihZ007QQitemZ170147139355QQrdZ1QQsspagenameZWD2V
 
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C

clot

Dave said:
I thought they used AC - hence the convoluted reversing system?
Not my recollection, but it was a looong time agooo and I could be
wrong!
 

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