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Old 22nd February 2009, 20:24   #226
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Originally Posted by DerAlte View Post
Could it be possible that the reason is something totally different? Like: how does one 'belt-drive' - with a transversely mounted engine - a fan whose axis is 90deg to the engine?
+1 to that - hit the nail on the head...
How?
High-amp continuous charging of a cell which is already fully charged will...Result: Boiling electrolyte, warped plates, and high risk of exploding batt. ...
... in conditions where the heat generated in its coils far exceeds the heat taken away - the insulation goes up in a puff of smoke.


And 55Ah is a discharge rating, not a 'current drawn' rating of a battery
The constant '70A' is a myth: as and when the voltage of the battery increases, the current drawn by it reduces (please draw an electrical schematic and do the maths).
The 55Ah and 70A were hypothetical figures...
... nor does it take the electrolyte to boiling point.
Never seen electrolyte boil inside a batt or that it explodes? Simple experiment. Dead-short the + and - terminals and go for a walk... you'll come back to realise that Pb-sulfate does have pseudo-explosive properties... BTW, don't sue me for damages.
You can charge it till the cows come home, but a dead cell does not hold charge any more - the damage is irreverseable
You missed the operating words "if you suspect..." I never said bench-charging a batt with a dead cell will bring it back to life.

Errr... what is the difference between dynamo and alternator (as far as the loads are concerned)?
Did I say there's any difference in terms of load? I just said I changed over to alt from dynamo then. Free country, my free choice, and HM followed suit almost 10 years later...
And finally, I'm glad R2D2 agrees to my opinion of removing battery wires when an engine's running. For the sake of hypothetical argument, all of us have run our cars for hundreds of miles with the wires removed. For all practical purposes, even anupmathur didn't remove the wires. Emergency situations plus mad mechanics = removed wires. Else leave the batt connected and enjoy lower repair bills...
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Old 22nd February 2009, 21:14   #227
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Originally Posted by SS-Traveller View Post
High-amp continuous charging of a cell which is already fully charged will..
Try it and measure the current. You will not be able to push high current through a fully charged battery. Not if you are using a charger/alternator giving 14.4V. What gets pushed = ((14.4-12.x)/internal resistance of battery)
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The 55Ah and 70A were hypothetical figures...
Even then, the rated alternator current will not flow from alternator to battery.
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Never seen electrolyte boil inside a batt or that it explodes? ...
No. Burnt shorting wire insulation, yes. Battery exploded = no! I've done my share of experimentation at DCE!
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Did I say there's any difference in terms of load? I just said I changed over to alt from dynamo then. Free country, my free choice, and HM followed suit almost 10 years later...
Give the devil his due! Dynamo is a DC generator. Alternator is an AC generator with a buit-in rectifier. DC generators became prohibitively expensive to produce in the '80s. Hence the switchover. Otherwise, there was no logical reason to give up on the higher efficiency of DC dynamos.
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... and enjoy lower repair bills...
Repair cost will not change whether you keep the wires connected or not!
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Old 22nd February 2009, 21:32   #228
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Dynamo is a DC generator. Alternator is an AC generator with a buit-in rectifier. DC generators became prohibitively expensive to produce in the '80s. Hence the switchover.
Sir, I think you are mistaken. The dynamo was not expensive to produce than an alternator.

I think its related to servicing costs of the dynamo and the charging characteristics.
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Old 22nd February 2009, 21:40   #229
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No. Burnt shorting wire insulation, yes. Battery exploded = no!
Go to my friendly neighbourhood batterywallah and he'll show you an exploded battery. It's sitting with him right now. Anyone interested to see it may PM me for this person's address and phone number.

And DerAlte, I'm going to quote your signature right back at you now about this...

Last edited by SS-Traveller : 22nd February 2009 at 21:42.
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Old 22nd February 2009, 21:57   #230
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Amit, the regulator is built into the alternator. It performs 2 functions 1) regulates the field current in the rotor windings which in turn determines the voltage/current induced in the stator coils. 2) It rectifies the 3 phase AC from the stator windings (3, each placed 120 deg apart), i.e converts AC to DC and supplies it to the battery and the rest of the car's electrical circuits.

P.S. - Modern cars have regulator/rectifier built into 1 unit, this unit is a part of the alt.

Rgds,

R2D2
Sir this does not answer anything , Car electrical are quite simple circuits and there is no great electronics involved as some people on this thread believe.

1. rectifier != Regulator : A regulated power supply is something which gives DC without ripples a 3 Phase rectifier gives output with ripples.
Many people asserted on this thread about regulator going bust , But there
is no centralized regulator to speak of.
First a regulator is not just resistance ( fan regulator ) as many people seem to believe , In electronics a regulator stage in a power supply is a circuit which gives out constant voltage irrespective of load ( current drawn) with in range. As alternator output varies with load and engine RPM it is obvious there is no regulator in place.

It is quite cheap to manufacture smaller RPS for ECU / ICE and other components and built them in the components rather then a centralized regulated PS, and this is the way commercial car electrical are made

2. Regulation of current in rotor windings can be done in a very simple manner with out any regulator.

3. Any regulator or rectifier can not be prevented from damage by a battery or any kind of capacitance placed in parallel at output.

I explained point 3 in great detail in one of my post may be you can go through that once more.

From my understanding of electrical / electronics based on my background and practical experience of driving a car once with out battery I can safely say , Nothing will go wrong.

@ SS-Traveller:

1 if a cell is dead in battery it will never give it original output whatever way you charge it as a number of cells are connected in series and parallel to give desired rating and one dead means a permanent loss.

2. A mechnical fan is more effiecient becuase out put is directly from engine and losses are only due to belt slip , in electrical fan there is mech -> electrical -> mechanical conversion involved
so energy loss is more
electrcial fan scores more on convinence point of view.

think of itw hy we has mechanical gears and tranismission in cars unlike diesel -electric engine similar to locomotive

Last edited by amitk26 : 22nd February 2009 at 22:06.
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Old 22nd February 2009, 22:45   #231
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Sir this does not answer anything
It should be seen in the context of what you asked. Actually it was the answer to your question in another post, "Can you please look at the alternator of you petrol car first and find if there is anything which can be called regulator ?" I could also show you the exploded diagram of my car's alternator (in the wk shop manual) to prove that there is actually something called a regulator/rectified built in to the alt.

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Originally Posted by amitk26 View Post
From my understanding of electrical / electronics based on my background and practical experience of driving a car once with out battery I can safely say , Nothing will go wrong.
No matter how experienced I may be, I believe it is best to go by the advice given by the manufacturer in the workshop manual. It is sane advice given the fact that the mfr knows the product the best. But then to each his own.

Cheers!

Last edited by R2D2 : 22nd February 2009 at 22:48.
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Old 22nd February 2009, 22:56   #232
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Originally Posted by amitk26 View Post
@ SS-Traveller:

1 if a cell is dead in battery it will never give it original output whatever way you charge it as a number of cells are connected in series and parallel to give desired rating and one dead means a permanent loss.

2. A mechnical fan is more effiecient becuase out put is directly from engine and losses are only due to belt slip , in electrical fan there is mech -> electrical -> mechanical conversion involved
so energy loss is more
electrcial fan scores more on convinence point of view.
1. Agreed that a batt with a dead cell is a batt totally gone. But some people still try to charge such a battery and see if it comes back to life, or maybe run a few weeks more. If at all an attempt is made to charge such a batt, I'd advise a bench charger to do the job. I wouldn't advise such a thing myself.
2. Rev for rev, yes, a mechanical fan is more energy efficient than an electrical fan. But the electrical fans switch off when not required, so save energy. So over a period of time electrical fans are more energy efficient.

I seem to remember that some mechanical fans in some cars used to come with an electric clutch to switch it off and let the pulley freewheel without turning the fan. Does such a thing exist still, and any idea of what cars such a system comes in? Members' inputs
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Old 22nd February 2009, 23:12   #233
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@amitk26,

mech->electrical->mech conversion runs above 90% of efficiency. the major loss is in thermal->mech which will happen in engine anyway (< 40% efficiency if i remember correctly). if u require any amount of control, it's best to switch to electrical.

and I thought batteries work with a few dead cells. how are they arranged?

diesel rail engines convert energy to electrical and then use series DC motor, only because of greater control and no mechanical parts needed which would add to operating costs.

Last edited by vivekiny2k : 22nd February 2009 at 23:13.
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Old 22nd February 2009, 23:23   #234
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Sir, I think you are mistaken...
Possible, @headers-anna. In fact, must be - if you say so!
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Originally Posted by SS-Traveller View Post
... I'm going to quote your signature right back at you now about this...
Apologies, yes, I could never make the battery explode - I am too much of a conventional technology person! Your neighborhood battery-wallah has achieved what possibly no one else has achieved. All the best, your battery is in good hands.
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Old 22nd February 2009, 23:49   #235
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It should be seen in the context of what you asked. Actually it was the answer to your question in another post, "Can you please look at the alternator of you petrol car first and find if there is anything which can be called regulator ?" I could also show you the exploded diagram of my car's alternator (in the wk shop manual) to prove that there is actually something called a regulator/rectified built in to the alt.
still the question remains unanswered if you earnestly believe that something will go bust in alternator then it needs to be explained what is that thing and why exactly should it go bust.

Please bear in mind I am not contesting claim of any electronics malfunctioning elsewhere due to absence of battery to serve peak loads which is incidentally primary and only purpose in a running car IMO

As some people are claiming that removing battery will cause something to go bust in alternator so I asked what is that thing and why exactly should it go bust.

As a corollary to above headers mentioned this for petrol and not diesel there is no fundamental design difference in alternators so I asked another question.

As this thread is in technical discussion forum may I request people answering them to back the claims made by appropriate theory
example
"The reverse voltage across diode reached more then .balh blah .. due to .blah blah... so diode will break and you will get open diode."
rather then just a claim that some thing will go bust inside alternator.

Last edited by amitk26 : 23rd February 2009 at 00:09.
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Old 22nd February 2009, 23:58   #236
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Originally Posted by vivekiny2k View Post
@amitk26,

mech->electrical->mech conversion runs above 90% of efficiency. the major loss is in thermal->mech which will happen in engine anyway (< 40% efficiency if i remember correctly). if u require any amount of control, it's best to switch to electrical.
So you say an alternator converts more then 90% of mechanical energy to electrical , very interesting any source or citation for this data ? then why don't they use same technology in larger turbines to give us more efficient power plants.
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and I thought batteries work with a few dead cells. how are they arranged?

diesel rail engines convert energy to electrical and then use series DC motor, only because of greater control and no mechanical parts needed which would add to operating costs.
Yes batteries do work , it was to answer that by using bench charger dead cell can be revived , spot on about diesel locomotive
as a corollary I would say there is some conversion loss so on smaller automobiles costly mechanical gears and transmissions are preferred over
simpler electrical moters.
Now in case alternator was running at 90 efficiency as mentioned by you above it would have been very easy to attach a bigger one directly to IC engine and drive the vehicle by electric moters just like a diesel locomotive. Think of it awsome accelaration , less noise , less consumables ( gearbox ,transmission oils ) , less moving parts so low wear and tear and maintainance cost. In fact due to all these advantages locomotives use diesel -electric powertrain the cost is losses in conversion IMHO
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Old 23rd February 2009, 00:11   #237
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You should not use regulator - rectifier interchangeably in any technical discussion. If anyone claims that car alternator has a regulator then I would like to see it and also what exactly it is regulating.
I have already explained what a regulator/rectifier (it is a single uinit in my car!) does in an alt does in another post (post 196). Please read it if possible. If you believe there is no component that rectifies and regulate the output from an alt so be it. As for proof that such a component does exist please see the relevant portion of a car's workshop manual or alternator repair manual. I for one believe what a workshop manual tells me.

Rgds,

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Old 23rd February 2009, 00:11   #238
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The electrolyte can boil in a Lead-Acid battery - I have seen that myself. This happened when A 6 V, 4.5 AH battery (not car battery) was being charged by a homemade charger. Guess something was wrong with the charger. We switched off the charger immediately, so no idea whether the battery would have exploded in the long run..
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Old 23rd February 2009, 00:28   #239
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I have already explained what a regulator/rectifier (it is a single uinit in my car!) does in an alt does in another post (post 196). Please read it if possible. If you believe there is no component that rectifies and regulate the output from an alt so be it. As for proof that such a component does exist please see the relevant portion of a car's workshop manual or alternator repair manual. I for one believe what a workshop manual tells me.

Rgds,
Sir the said voltage regulator inside alternator is a device which controls the battery charging and cuts off above 14.5 Volts ,This device is actually controlling charging of battery and It is not something which is regulating the power supply , So word regulator is little misleading here.
if you belive that power you get is regulated you can do a small experiment of putting a multimeter to measure voltage and the switch on all lights and turn music to full blast.

Again presence or absence of battery in a running alternator makes no difference to the switch which turns on/off the charging terminal ( regulator) or the rectifier, electrically the rectifier is a separate unit and some one published a baleno circuit diagram you can look for details in it.

Something being manufactured in a single pack and shown as one replaceable block in your service manual does not make it interchangeable functionally.
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Old 23rd February 2009, 00:39   #240
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Sir the said voltage regulator inside alternator is a device which controls the battery charging and cuts off above 14.5 Volts ,This device is actually controlling charging of battery and It is not something which is regulating the power supply , So word regulator is little misleading here..
Amit, the regulator controls the voltage to the field windings in the rotor which in turn determines the strength of the magnetic field. Stronger the magnetic field, stronger the current induced in the stator windings. The rectifier converts 3 phase AC from the stator windings to DC and supplies it to the all the electrical circuits and the battery.

The Japanese, masters at miniaturisation, have integrated both rectifier and regulator into one single component. This is in my car, a Toyota Corolla Altis and my previous car (Toyota Corolla).

The rectification and regulation functions may be in two separate units in other vehicles.

Thanks,

R2D2

Last edited by R2D2 : 23rd February 2009 at 00:42.
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