How far would a car run on the battery ?

[Dave Plowman (News)]

All the baulk ring boxes I've had apart are very similar regardless of maker. Plain cone synchromesh was found on the early Midget.

[bert]

When I had an Austin 1100 auto you could tow start it but all my more recent autos said it's a no-no. Don't know about DSGs or the type of auto fitted on small cars theses days. Suspect you could as they are essentially a normal box with a robot lugged on the side.

[Bodgit]

I managed to drive from Prague to Leicester in my 1981 Honda Civic with the charging light on all the way. I stopped (and restarted the engne) 5 times in total. I crossed the channel at Calais and had to switch the lights on on the other side, which seemed a bit dim, so I drove 10 miles or so, found a layby and parked up until the next morning when it was light and continu ed. The battery voltage was 10v when I finished the journey so I don't thin k it would have gone much further. I make that nearly 1000 miles, including 5 engine starts and 10-15 minutes with the lights on.

That car had a carb engine with an engine management system. I guess in mod ern cars you wouldn't get quite that far!

[Dave Plowman (News)]

An auto needs hydraulic pressure to work (to engage the various clutches) This is supplied by an engine driven pump. So engine not running, no pressure. Some older boxes had a second pump driven off the output shaft which supplied pressure if the car was towed. Mainly to prevent damage to the box if the car was towed a long distance - but also allowed a bump start. Snag with doing a tow start is the very real chance of the towed car running into the one in front when it starts. Hence the US way which you see in old movies of pushing the car with another.

I'd be surprised if any modern auto including the robot controlled synchromesh types can be bump started.

[SteveW]

My Sierra happily ran a couple of hundred miles, with at least 3 starts, use of wipers and for part of the time lights - it would still start the next day. My Focus TDCI managed 3 miles after the charge light came on, a start, 2 miles home, a start, 2 miles to garage and was then completely dead.

SteveW

[SteveW]

I have vague memories that the 4 & 5 did. The replacement Sierra (same engine and gearbox) certainly did - as I had to replace it with two wheels on the kerb and me lying in the gutter (and it was raining too!)

SteveW

[Grimly Curmudgeon]

The angle on the synchro cones and the depth/number of oil grooves makes a difference.

[Alan Braggins]

Years ago I was told that if you stall on a level crossing and can't start the car and the lights start flashing, you can get clear using just the starter motor faster than you can abandon the car to be hit by the train, especially if you have e.g. small kids strapped in child seats. Fortunately I've never seen it tested though.

just say you can try it if there is time.

[SteveW]

I have moved my car out of a car-wash that way, when the underbody wash was a bit overenthusiastic and soaked the HT leads. I was also a passenger when we moved another car out of the way when stalled in a ford - we thought the ignition was soaked, but it was actually the impact switch had cut off the fuel pump when the towbar drop plate bottomed out.

SteveW

[Tim+]

An increasing number of cars (like mine) have a clutch interlock preventing the starter working without the clutch pedal depressed. Guess I just die horribly. ;-)

Tim

[Jim Hawkins]

Well, asuming it had a 12 volt 50 Amp battery that was fully charged, and you could convert all that electrical energy to useful mechanical work, you could expect to get about 0.8 horsepower - and that for only the hour before the battery went flat. What distance that might move the average car I leave to others to guess !

Jim Hawkins

[Charles Ellson]

If you're stuck on a level crossing then it is what can be delivered in the next ten seconds or so that matters, the other 55m 50s are comparatively irrelevant. About 200A from a fully charged battery should not be that unusual when starting so you're probably looking at at least 3hp. Short circuit currents for lead acid cells of car battery size and above are typically measured in thousands of amps.

[SteveW]

Purely out of interest, the construction and uses regs (I think it was there that I saw it last week) only require vehicles to have a power of

4.4 kW per tonne (not going anywhere fast there either!), so a boot full of batteries, an oversized starter motor and plenty of spare time to get there and you could go zero emissions ;)

SteveW

[Dave Plowman (News)]

More or less what was done over 100 years ago.