[Geo_Ipe]

Noob Questions!

When idling and running the AC, where is the power drawn for the compressor from? I'm assuming that if the AC runs in the ignition on position without the engine running, it's drawn from the battery directly.

Also, does fan speed have a great effect on battery current drawn?

These have been questions asked to me in the past, to which I wasn't able to answer to the point! In my defence, I'm not an engineer!

[hillsnrains]

Originally Posted by Geo_Ipe

Noob Questions!

When idling and running the AC, where is the power drawn for the compressor from? I'm assuming that if the AC runs in the ignition on position without the engine running, it's drawn from the battery directly.

Also, does fan speed have a great effect on battery current drawn?

These have been questions asked to me in the past, to which I wasn't able to answer to the point! In my defence, I'm not an engineer!

1. Compressor is always powered by engine (there is a belt drive connecting engine and compressor)
2. Only fan can be driven by battery but not AC compressor
3. More power will be drawn from battery as the fan speed increases. Running fan for a while may be ok but not too long that to at high speed. Engine may refuse to crank if the battery is weak (read towards the end of it's life)

Hope this answers your queries.

[Geo_Ipe]

Originally Posted by hillsnrains

2. Only fan can be driven by battery but not AC compressor

If so, how does cooling happen in the 'Ignition On' position?

Edit: Quite a lot of useful information in this thread: http://www.team-bhp.com/forum/techni...-starts-3.html

I was always under the impression that cooling happens when just the ignition turned on! However, I think I was being on that. Gotta check it out today itself.

[hillsnrains]

Originally Posted by Geo_Ipe

If so, how does cooling happen in the 'Ignition On' position?

You will get this effect only when the AC compressor was run for a while before you put ignition on position.
Try to run the fan or switch on AC in a parked car w/o cranking the engine (parked ~1hr or so in hot sun).

You simply can't cool the cabin without cranking the engine, as simple as that.

[R2D2]

Originally Posted by Geo_Ipe

If so, how does cooling happen in the 'Ignition On' position?

It's not cooling, it's just the blower fan in action. And yes, fan speed does have an effect on current draw.

Primary source of power in a vehicle is the alternator/generator (NOT the battery as many believe) which provides electricity to ALL circuits and charges the battery. The primary function of a battery is to "store" electricity and discharge to the power the load when required.

Take an e.g. If power draw by a component, let's say AC blower is 10 A, and alternator is providing only 3 A, the balance 7 A will come from the battery.

Which means the blower keeps running but drains the battery at the same time. The alternator is not generating sufficient current to charge the battery.

The compressor is directly driven by the engine via a belt that is shared with other components like the water pump. So the AC compressor needs a running engine to actually perform its function.

Hope this answers your questions.

[benew]

Does anyone know who makes the OEM battery for VW Polo 1.2? My wife’s car has lasted for 10 years and 30k kilometres

The car doesn’t start until jump started which makes me think it’s a battery trouble and of course the age makes it obvious.

There were at least two instances where it got accidentally stopped while running but would not start. Maybe it’s completely lost the ability to retain charge or there is some other problem in the charging circuit!

I’m thinking of replacing the battery as the first step, would like to replace it with same battery since it gave such longevity. Appreciate other thoughts around possible causes.

Regards

Binu

[TheRajput]

Stuck up in a live situation
Switched off my Vento Petrol on a 3 minute signal. As the timer subsided, cranked the car with the AC and Headlights off and bang comes an exploding sound. Opened the bonnet to see my battery ripped from the middle with acid leaking. Have towed the car to the side of the road with the help of police. The battery guy is on his way with a new battery.
What are the do's and don'ts before installing the new battery.
Attached pic for reference.

[lapis_lazuli]

Originally Posted by TheRajput

Stuck up in a live situation...
What are the do's and don'ts before installing the new battery.
Attached pic for reference.

You should be worried about the acid spill more than anything else. I hope you got the entire under hood neutralised with some alkaline wash!! You might want to do that many times over and keep a close watch for emerging signs of corrosion even at "unlikely" locations. An explosion can cause the droplets to travel to nooks and corners. You might also want to also escalate this to the manufacturer of the battery... it may have caused significant damage. However the situation is entirely recoverable with multiple washes and neutralisation. Wish you all the best and please update.

[Miyata]

Originally Posted by TheRajput

Opened the bonnet to see my battery ripped from the middle with acid leaking.

I think you were very lucky there was no fire! Looks like only the battery casing got ripped apart there. A fire would have caused much more grief.

I think you should evaluate a few things -

1) Where did you purchase that battery? Any history that place might have? If so, you'd be doing a great service to others by reporting it here and else where.

2) Is there any electrical issue with your car that might have caused this? Would be good to get some expert evaluation lest it happens again and they discover something faulty in the electrical regulations.

Any further update on the situation?

[TheRajput]

Originally Posted by TheRajput

Stuck up in a live situation
Switched off my Vento Petrol on a 3 minute signal. As the timer subsided, cranked the car with the AC and Headlights off and bang comes an exploding sound. Opened the bonnet to see my battery ripped from the middle with acid leaking. Have towed the car to the side of the road with the help of police. The battery guy is on his way with a new battery.
What are the do's and don'ts before installing the new battery.
Attached pic for reference.

So an update after a week. The battery was three years old and under warranty. The culprit was found out to be a fault with the Alternator which was overcharging the battery and caused it to explode. Got the battery replaced and alternator fixed. The car is working fine now after multiple readings from the alternator.

Want your advice as to how can I neutralise the acid spill in the bonnet.

[Miyata]

Originally Posted by TheRajput

how can I neutralise the acid spill in the bonnet.

Few weeks or so back there was a mini discussion in one of them threads/posts about this very topic - acid neutralization. Don't recall exactly where it was - a brief search should bring it out.

That case had to do with someone that had put a battery in the trunk and the acid found it's way all the way to the rear seat and floor eating and corroding its way along.

The fundamental principle for acid cleaning is pretty much the same every place - do not touch with bare hands; do not inhale any fumes; let any wash through not spill on anyone's skin/eye etc; use a weak base to neutralize the acid; wash is thoroughly to dilute down or wash down any remnants.

I presume the service center guys have done something? After all, an accident from a faulty alternator ought to have been their complete responsibility. If not done already, you should also check/follow-up with them.

[lapis_lazuli]

Originally Posted by TheRajput

So an update after a week. The battery was three years old and under warranty. The culprit was found out to be a fault with the Alternator which was overcharging the battery and caused it to explode. Got the battery replaced and alternator fixed. The car is working fine now after multiple readings from the alternator.

Want your advice as to how can I neutralise the acid spill in the bonnet.

I HEARD from someone knowledgeable, that commercial "laundry soda and soap" diluted with water and pressure wash of the engine bay is what is usually followed. The "soda" part is important! He had a similar case, where the battery filler cap had cracked/leaked/cross thread, and there was spillage over days....from the earlier generation batteries. Car was a Qualis.

[Jaggu]

Originally Posted by TheRajput

Want your advice as to how can I neutralise the acid spill in the bonnet.

A good wash with regular water and maybe some soap and rinse should take care of this. Do it ASAP and ideally don't use too much of pressure and a top-down wash. Once done dry it off with compressed air and leave the hood open for a day you might want to do two wash cycle if the spill is bad.

[supremeBaleno]

Originally Posted by TheRajput

Switched off my Vento Petrol on a 3 minute signal. As the timer subsided, cranked the car with the AC and Headlights off and bang comes an exploding sound. Opened the bonnet to see my battery ripped from the middle with acid leaking.

I had never heard of car battery exploding till it happened to a friend few weeks ago. A quick search on tbhp showed a similar explosion.

Friend in his Scorpio with a 15-month (in warranty) Amaron battery had gone on a 75-km drive out from Chennai. After 1.5hours, when he returns to the car & starts the car, there is a loud sound. Photos of the engine bay post-explosion.

[iamswift]

Any comments on this video?
No explanation of "why" or "what" in the video.

https://www.youtube.com/watch?v=TYXx70MqJ-0