[Bass&Trouble]

Petrol and diesel vehicles would both work fine with the battery disconnected once they have been started, provided the alternator is fit, and the alternator has the current capacity required for the electrical requirements of the petrol engine's ignition system. In the case of diesel, if not for an electrically operated fuel start/ stop system, the engine would work even without an alternator, since iginition is also mechanical.

Battery is not required to complete the circuit. The alternator, battery, and the electrical load posed by the car are all wired in parallel, electrically speaking. So if 'removing the battery' does not mean disconnecting the alternator terminals, then the circuit is always complete.

I'm not much of an auto guy, but weren't vintage cars an example of what LBM claims? Did they have batteries? If so, why would people crank it by hand with a lever? Or was it that they had a battery, but it was insufficient to crank, and meant only for ignition?

Edit: Please don't try what LBM already did.

I searched a bit after posting and realized that it's not such a good idea to keep engines running with an alternator connected, although it would be no problem if it was a dynamo. The alternator's electronics gets fooled into maxing the output, and the surge could damage some electricals.

[low_bass_makker]

Originally Posted by esteem_lover

LBM, i would ask you to try this in your car if it is a petrol & see for yourself. like sam said the battery sort of completes the circle. without the battery, the engine will stall. what you say is very true for a diesel engine. i have seen both happen.

Originally Posted by vikram_d

Any car with an ECU will not work without a battery. If you disconnect the battery when the engine is running then the engine will stall.All Non-ECU vehicles aka carbeuratted vehicles will stay on when the battery is disconnected.

I have try it on my swift which has a ECM and it keeps running....I agree with Sam Bhai the battery is required to complete the circuit when the engine is not running but when the engine has started the battery is not required.....

Guys everybody has a car anyone can try and post the result......

[tsk1979]

In Santro and indica when battery is down, if you push the car and start you can drive away. Know this from experience(Lots on the indica).

[vikram_d]

After push starting any car you can drive away. Once the engine is on what is to stop you from driving away?

[Vid6639]

Even in the lancer you can do this push and drive off. Although I noticed if the battery is low the engine finds it difficult to idle and the rpm goes below idle to the point of stalling.
If you start the car and remove the battery the lancer stalls unless you give a little gas then do that. then it stays fine.
Yet to try on Alto.

[jkdas]

Originally Posted by tsk1979

In Santro and indica when battery is down, if you push the car and start you can drive away. Know this from experience(Lots on the indica).

coz LBM confused me.... can this be done without battery for ecu and non-ecu cars!

[tsk1979]

Since Lancer and Santro both have ECU, I think this holds for ECU cars too. I guess you can try it out on your Santro. Start the engine and disconnect the battery. If car is stalling at idle try keeping the revs high and then disconnect the battery.

[low_bass_makker]

Originally Posted by Bass&Trouble

Edit: Please don't try what LBM already did.

I searched a bit after posting and realized that it's not such a good idea to keep engines running with an alternator connected, although it would be no problem if it was a dynamo. The alternator's electronics gets fooled into maxing the output, and the surge could damage some electricals.

I agree to it 100%...dont try it if the charging system is faulty it will definetly damage the car electricals.....but when the car is at ideal there is will me much harm.....as the alternater will be at low RPM.....

[s0uljah]

Originally Posted by tsk1979

Ask them to check your alternator regulator or the rectifier plate.

Yes they never check battery voltage while car is running at services

Thank you sir.

I think its a combination of the installation of powerful lamps + autocop recently that messed up my electricals.

Originally Posted by tsk1979

I use my ICE system as a reliable battery gauge(may not work for all).
1. Put the car on on : ICE starts
2. Crank engine : If ICE is still running while engine cranking battery charge good.

I avoid doing this as far as possible. But yeah its a quick way to figure if things are ok.

[superavi]

I used my uncle's Matiz, and the Battery had died (alternator belt snapped) and then the car went on for some time and left me stranded in the middle of the night. I guess this is because the alternator itself was not working. Theoretically, an FI car should work if the battery is removed after it's started.

As far as starting an ECU car (FI car) is concerned, do not push start. It will simply damage the ECU.

Carburretted cars - anything goes!

Superavi

[vikram_d]

How will push starting an MPFI car damage the ECU?

[sreenivass]

Originally Posted by jkdas

coz LBM confused me.... can this be done without battery for ecu and non-ecu cars!

Guys,

this is from my own experience. I had an alternator problem, it was not charging. The mechanics that came over start it on battery and check if it continues to run on after disconnecting the battery. When the alternator is fine it continues to function.

Per my knowledge Petra has an ECU.

[low_bass_makker]

Originally Posted by sreenivass

I had an alternator problem, it was not charging. The mechanics that came over start it on battery and check if it continues to run on after disconnecting the battery. When the alternator is fine it continues to function.

Exactly if the alternater is fine the engine will keep running if there is any fault the engine will stop.......

[Sam Kapasi]

Well, I used to have a Yamaha RX100 when I was younger. And Never really needed the battery and it was pretty much dead. (It was a 6V battery anyways)

So one day, I threw away the battery. Everything worked fine, but I kept losing bulbs. Made no sense to me initially till I realised 2 important things

1. A battery works like a capacitor, much like a capacitor works like a battery. Which means it also smoothens out the dirty spiky ac voltage generated by the alternator. ALTERNATor generates AC which is smoothed out by a rectifier and converts it to DC to charge your battery.

2. The electrical systems are designed to generate higher voltages than the designated battery (So that it may charge)
When there is a battery, even if it is a dud battery, it keeps the voltage in check. Without one, the electrical systems can go haywire.

Sort of what B&T said.

[rks]

Originally Posted by tsk1979

In Santro and indica when battery is down, if you push the car and start you can drive away. Know this from experience(Lots on the indica).

For what it is worth, this is what my Santro manual says:

Caution: If the engine does not start, no attempt should be made to push or tow start the vehicle. Vehicles with automatic transmission or fuel injection will not start in this manner since no drive is transmitted through the automatic transmission whilst the engine is not running and in the case of fuel injected derivatives, the fuel pump will not operate under tow start conditions. In addition, if the vehicle is equipped with an exhaust catalyst, damage to the catalyst may result if the vehicle is tow started.

Regarding battery life, it will be dependent on the total number of charge-discharge cycles. So heavy usage of ICE will bring down the battery life. But it is not as simple as this. My laptop guide advises that if the battery is not frequently used, then at least once a month it should be brought to a state of near-total discharge (less than 3% charge left) and then charged again. I think this applies to car batteries as well. Over-charging is bad for battery health.

What I do is once in about 2 weeks I run the air compressor on my car battery (off the cigarette lighter outlet) to top up air pressure in my 5 tyres. I do not keep the engine running, so this should provide a healthy discharge for the battery. If the battery does get drained by this procedure, I will know that it is time to change my battery (it is now more than 6 years old). My daily commute to the office (10 kms each way) plus my weekly Pune-Mumbai-Pune runs should keep the battery in a state of full charge most of the time (no ICE; Self-starter and to a lesser extent AC/headlights should be the main source of drainage). It is a maintenance-free battery, so distilled water levels are checked only once in about 3-4 months at the time of service.