[Sutripta]

^^^
We can discuss all these in detail if we have a dedicated alternator thread. As I have said before, there are things to discuss, debate, and differ on! But to do it now will take us off rail. So we'll keep these for another day. Otherwise I feel we are in agreement enough to proceed.

To continue:
So the alternator will have a I-V curve. In fact a family of curves, if we step some parameter, like say RPM.
Now where on the curve will the operating point lie? This will be determined by the load. In case of a simple resistive load, the operating point can be found quite easily, either analytically, or graphically. It will be easier for others to visualise it graphically: the load line will be a straight line. The operating point will be the point of intersection of the two lines.
The battery most certainly is not a simple resistive load.

To emphasise how the nature of the load determines operating point, and its importance, let me use a (very bad) analogy, but which people are familiar with: audio systems. No matter how powerful your amplifier, load (speaker impedence) along with amplifier determines how much power is actually delivered.

Are we still more or less in agreement?

Regards
Sutripta

[Sutripta]

I thought we would be having a lively give and take interactive session here. Looks like that that is not going to be, so let me put down my thoughts in one final post. More so because I'll be off the grid for sometime now.

Let us start with something all of us on this forum is familiar with: the push start because of a dead battery. Immediately on starting, if one revs the engine, one gets more output (in the form of current) from the alternator than when idling. Substantially more. (To those who think that that is not the case, may I suggest you actually measure, not go by it has to this or that, and so no need to measure etc. And a word about measurement: if one is using one of those el cheapo digital tong tester, make sure you have an AC/DC (Hall effect) instrument. And see to it that the setup gives consistent reproducible readings. It is not as simple as it sounds, given that these meters will give a different reading everytime one snaps shut the jaws. Or how one places the wire in the ~25 sq cm window. And yes, I know wire placement should not matter as long as it is enclosed (Gauss's law) but it does with these meters.)

Now let's come to another part: what happens when one connects a healthy battery in parallel with a dead one.(The situation is the same whether the two batteries are physically in one car, or in two.) There will be substantial current flow from the healthy battery to the dead one, as the healthy one gets discharged trying to charge the dead one.
What happens to the common voltage (Let us call the common voltage the Bus Voltage.) Logically it should be in between that of the two batteries. (Where it actually is depends on the characteristics of the two batteries, esp if one of these is near EoL (which is different from SoC). In fact it can dip so low that the engine will not crank. As the dead battery accepts some charge, the bus voltage rises (even though the healthy battery gets discharged). Hopefully it will rise enough so that the engine cranks. (This phenomenon has been noted and alluded to by some people earlier.)

Now apart from the two batteries, there is another power source connected to the same bus:- the alternator. Its primary purpose is to keep batteries charged. To have it and not use, would in my philosophy, be ridiculous. And its output is more when it is revved!

Jump starting a car is not just about cranking the helpee car. It is about connecting (parallelling) two power sources, which at that point of time have different characteristics, which is never recommended, and hoping for the best.
We do not know the condition of the helpee vehicle. Keeping the engine on of the helper car is insurance, so that the helper does not land up needing help itself. Revving the engine of the helper is to bring into play the third source of power, the alternator, to help in charging the discharged battery, and thereby help with the bus voltage. Not really to supply power to the self starter.

Others might have different philosophies. Including praying to God while cranking, or pummelling the steering wheel while mouthing obscenities. Whatever works for that person!

One point which can give rise to a lot of esoteric hairsplitting: What is a dead battery? I think we'll go with a commonsense* approach: Ïn the not so distant past, this battery was cranking/ starting the car. Now it is not.

* As we have seen just a few posts back, not everything can be answered with just commonsense. Some amount of extra knowledge is needed. But in this particular case, I think this commonsense definition of a "dead battery" will suffice.

Regards
Sutripta

[TheTeacher]

Most interesting, thank you gentlemen for your erudition!

Somewhat OT: alternators put out alternating current. How / where is it rectified? The AVR?

More OT: Timeline: 1960s, '70s, early '80s. We were always Ambassador owners and did long trips quite often. Batteries would die quickly. There was one auto electrical specialist in Chennai those days, and batteries were sourced from them. They suggested turning on the headlights when on the highway to reduce charge into the battery from the dynamo. This didn't help. They then took to fiddling with the cut-out etc; if I remember right, those were the "esoteric Lucas CV regulators". The driver would take the car to the auto electrical place before the trip; they would make some adjustments; after the trip, the driver would go there again to get things set back to "normal". We never had problems with batteries or dynamos after following this practice.

[Sutripta]

Originally Posted by TheTeacher

Somewhat OT: alternators put out alternating current. How / where is it rectified? The AVR?

By two sets of three diodes commoned together (diode trio).

More OT: Timeline: 1960s, '70s, early '80s. We were always Ambassador owners and did long trips quite often. Batteries would die quickly. There was one auto electrical specialist in Chennai those days, and batteries were sourced from them. They suggested turning on the headlights when on the highway to reduce charge into the battery from the dynamo. This didn't help. They then took to fiddling with the cut-out etc; if I remember right, those were the "esoteric Lucas CV regulators". The driver would take the car to the auto electrical place before the trip; they would make some adjustments; after the trip, the driver would go there again to get things set back to "normal". We never had problems with batteries or dynamos after following this practice.

Discussions about dynamos and its regulators should belong in the vintage and classic car section! However a few point:

The "esoteric cutout" was phased out around the late 60s. It was easily identified by its two coil internal structure, and externally by its rounded cover being held with a wire clamp. It was replaced by the (much better) three coil design.

The "switch on headlights on long runs" was another piece of widely repeated misinformation based on misconception. It had to do with how the ammeter was wired in the Ambassador.

Regards
Sutripta

[sourabhzen]

Help needed - the connectors that are attached to cables and connected to the battery are corroded are are about to break. How do I change them? is it required to take the car to authorized service center for the job?

[Mortis]

Originally Posted by sourabhzen

Help needed - the connectors that are attached to cables and connected to the battery are corroded are are about to break. How do I change them? is it required to take the car to authorized service center for the job?

If you take it to a battery shop, they will have the necessary connectors and will do the job for you. no need to go to the SC.

[R2D2]

Originally Posted by sourabhzen

Help needed - the connectors that are attached to cables and connected to the battery are corroded are are about to break. How do I change them? is it required to take the car to authorized service center for the job?

If I were you I'd take the car to the ASC and get them replaced. Battery cables are not very expensive. And believe me, OEM cables last heck of a lot longer than the cheapskate cables the roadside battery dealers use.

[KALSANKRPAI]

Originally Posted by saket77

Good points, in short, you need to cut down on everything that draw battery power when the engine is not up. You may include this in the list too:

What does a maintenance free battery means?

[saket77]

Originally Posted by KALSANKRPAI

What does a maintenance free battery means?

Well, if you are talking about wet cell batteries used in most cars, then I would say it is more of a marketing gimmick! At the most, an improvement over old technology.

See it like this: if you compare it with older generation wet cell batteries of the 80s and upto mid-90s which were mostly used in Ambys and Premier Padminis of the times, then they required to be topped up with distilled or demineralized water frequently. The water which was used to dilute the sulphuric acid inside was frequently lost during recharge cycles as they were either converted to gases as a chemical reaction, by means of evaporation and by boiling off. Due to these, topping up of water was a frequent affair.
However, the current gen batteries require less frequent top ups as some of the evaporation and boiling off situations are now controlled with better designs, materials and better engineering.
Due to this, they were pitched as 'maintenance free', mainly against the older gen batteries.
Gel/ AGM/ Non spillable etc batteries which do not have liquid electrolytes may be better examples of being 'maintenance-free'.

Regards,
Saket.

[aaggoswami]

In one of my earlier posts, I mentioned that my setup with Philips Rally 90/100W works well. Seems like a rough patch has hit me this month.

I visited Rajkot on 16th, and had to use headlight for a good 3+hours on return journey. Used Wagon R since then for city duties and today when I was to start my Swift to bring it in my compound for washing, the battery was barely able to provide any juice. Car didn't start, the cranking was slow and it took longer than usual to start. Somehow, after 3 attempts, engine came to life. Let it idle for 5 mins, brought car in compound, gave it a wash. Switched off and tried to start again. Barely enough power from battery but it did start the machine. Great I thought.

But then I switched on my lights to take car out and park in front of my home. Its barely a 30ft total movement of car. After parking, switched off the car. Tried to switch on and it just wont crank.

My question :

1) With only 3 hours of driving that too mostly on highway, can the battery die down due to higher wattage bulbs ?

2) Could there be anything wrong with wiring kit ? Its not Philips or Hella, but Lucas or Lumax, has separate fuses for each bulb.

3) Can adulterated fuel cause this ? Like fuel pump working harder and drawing more current due to bad fuel ? I filled up petrol worth Rs.1000/- at Tarapur, reliance bunk. But today, when I revved the motor, it was all good. Know this is far stretched, but this doubt cropped after one of my neighbour told me this. Most unlikely reason.

Should I go back to 55/60W or try 90/100W Osram which were there earlier ?

Is there any method to check if my wiring kit is OK ?
The alternator shouldn't fail, and wiring should be good are two assumptions I am making.

Confused.

I have kept battery on charging at home (I've two battery chargers, thanks to dad who kept them handy due to Premier President we had).

[condor]

Originally Posted by aaggoswami

1) With only 3 hours of driving that too mostly on highway, can the battery die down due to higher wattage bulbs ?

Using the lights when driving will normally not cause any problems to the battery.

Irrespective of the cause, you started the car 3 times. Each time you have not let the battery charge up to replenish the diminished charge levels. If you had left the car to idle for at least 15 minutes in one go, it should have been fine. Esp when you had seen the difficulty in starting.

Having said that, pls get battery checked ( it is possibly already weak).

Originally Posted by MileCruncher

I have projector +HID setup on my car but not sure why, but they are not bright enough to light the road ahead.

What is the color temperature of the bulbs. Are the lights focussing well ?

[aaggoswami]

Originally Posted by condor

Using the lights when driving will normally not cause any problems to the battery.

Irrespective of the cause, y.. had left the car to idle for at least 15 minutes in one go, it should have been fine. Esp when you had seen the difficulty in starting.

Having said that, pls get battery checked ( it is possibly already weak).

Car was left to idle for 20+ mins. 5 mins outside compound, and then inside compound when I gave the car a full wash + interior mat dusting. I switched off the car after washing/dusting, engine was on till then. Infact, it did reach the normal operating temperate. But the start stop cycle+high watt bulbs would have drained whatever was left in battery. In the last attempt, the crank just didn't happen.

Thankfully this did not happen while traveling out of station.

I think that battery could be weak (Its stock : Tata Green). Shall get it checked on Monday if by Sunday the battery isn't charged.

[aaggoswami]

Update :

Yesterday I checked the voltage at home while putting battery for charging. It was 10.6.
Today morning it was same, and in late evening I tried to put battery in car and if car started, take the car to battery shop owner who is known to us. The car didn't crank one bit. Took battery to shop, they checked and told me that battery is gone. One cell was completely lost, and water had turned black. Thats the reason why I could not get the battery charged further than 10.6V. And probably due to this reason that long idling didn't help.

Got Amaron Flo, 35Ah, for Rs. 3500/- and installed it. Car is back to life. Amaron Flo is working in my K10 Wagon R since last two years, 22K kms. and has seen tough life, like repeated start/stop (read urban cycle).

The bulb+wiring does not seem to be the culprit; light set up remains as it is. Just back from a nice 30 km. drive and all is well.

[sgiitk]

@aagoswami; As I was reading your post, a dead cell is what immediately struck me. Contrary to what I thought, due to a higher compression when hot, cars do tend to want a higher current for starting when hot. I had a classic case of a Santro AT. It would crank normally when cold, or after half an hour. Was baulking whenever we tried to start a hot engine almost immediately. I went to my battery supplier, a bad cell about to die. Also. then I discovered that a long warranty on the battery may not help. Reason is that all warranty stuff is on the MRP, so you may end up shelling out more for a warranty replacement (after the pro-rata depreciation) than on a new one.

[techcoze]

What's the applicable warranty on batteries which came with the new car (VW polo in my case)? Is it same 1 year just like whole car warranty or 2-3 years (depending on battery manufacturer) like we get for aftermarket batteries. My brothers VW polo was purchased approx 2 years ago and now OEM battery is dead. Service advisor says warranty only 1 year. What are my options for this issue?