Push-starting an A/T

Preamble
So far, I’ve written about car electrics/batteries on four earlier occasions in these columns but going by the number of queries that I continue to receive on them, I find that they form a good percentage of car owners operating problems across the country.

So here are some recent QnA’s that stand out in my mind and archives – hoping that they’ll be of interest and use to most car owners. Incidentally, the first question was from a gentleman who’d been trying to get an answer to it for quite some time from leading auto magazines and other websites but none responded…

Question
When a car battery has run down, why is it difficult or even impossible to push-start an automatic transmission car as against manual transmission car, which easily starts on pushing? In absence of a jump-switch, how does one start an A/T car anyway?

Answer
An A/T has to have a ‘fluid coupling’ to enable it work the way it does, instead of the conventional clutch in an M/T. As a result, there’s no ‘coupling’ at all between the engine and the GB when the engine is not spinning above its minimum/idling rpm. Consequently, when attempted to push start, the ‘reverse torque’ from the road wheels doesn’t get transmitted to the engine coz of the fluid coupling in between and therefore, the engine doesn’t ‘crank’ the way a starter motor does it.

In other words, a battery-stalled A/T can only be ‘jump-started’ from another car/healthy battery and these days, all OEM ‘on-road-service’ vehicles are equipped to do so. Btw, an M/T Mpfi/Crdi vehicle with a flat battery may not push-start either, depending upon the state of charge on the seemingly dead battery. Therefore, such vehicles are also advised only to be jump-started, like A/T’s, so as not to damage their ‘ECUs’ in the process.

This QnA reminded me of a saying that ‘never buy a car that you can’t push’!

Question
I am a Bullet enthusiast. I want to know what is the use of the ‘Amp’ in my Bullet and why should it be brought to ‘0’ before starting? Why is it not present in other bikes?

Answer
The ‘Amp’ or the ‘Ammeter’ is an old British automotive tradition, like the engine oil pressure gauge, where cars as well as bikes that have a battery/charging system were provided with it on the dash, so as to give an easy indication of the state of the battery and its charging system at a glance. Over a period of time, as the vehicles’ cruising speeds went up, the philosophy of ‘minimum instrumentation on the dash’ took over, so as not to distract a driver’s attention to the extent possible - besides cost cutting of course. So instead, only warning lights are provided nowadays for such purposes.

As far as a Bullet is concerned, it has a battery driven ignition coil, quite like cars, unlike a ‘magneto-driven’ one on most other 2-wheelers AND a powerful headlamp on top of that, though its battery is relatively smaller in capacity due to space constraints. Therefore, to ensure that full battery power is available for the ignition to kick-start, recommending one to bring the ‘Amp’ to ‘0’/zero is a way to tell the rider to ensure that all the lights etc are switched off before attempting to kick-start.

On the other hand in present day cars, the battery is relatively of larger capacity and in any case, their starter motors draw such a heavy current, of the order of a few hundred amps, that even if the head lamps that draw 10-15 amps only are on at the time of cranking the starter motor, it’d make no difference – provided the battery is not already dying of age or whatever other reason.