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My daughters back from Uni yesterday and her car's been sat idle for a week and a half since I last took it for a run. She went to use it today and it started just fine, did a short (1 mile) run to the petrol station on her way to an appointment, put some fuel in and then when she got back after paying, couldn't restart it.
She collared some workman and his mate who bump started it for her but it had no power steering or dashboard (rev counter, speedo, etc.) She started to drive it home and within a few yards the PS came back, and speedo, but not revs. Got home and parked up and then tried to restart and dead again.
Alternator? I'm thinking not battery otherwise it would have been flat from the start, could be starter motor but then why would the PS and dashboard be weird?
Booked into nearby indie tomorrow but trying to work out what I might be in for.
Is it diesel? If so it will run without constant power. So sounds very much like the alternator as the engine was running, but no accessories.
Maybe the cold has killed the battery and the last start just took the last of the juice
Battery would be my guess.
Low voltage so car cuts non essential items to save a few milliamps.
Elec power steering, possibly, depending on model.
Not long enough drive to replace drain from initial re start after sitting cold, hence the no start at the petrol station.
Take battery out, charge indoors overnight. Should be fine tomorrow. Modern batteries seem to suddenly die though, be fine one day and flat the next.
Is it diesel? If so it will run without constant power. So sounds very much like the alternator as the engine was running, but no accessories.
Not a modern one, although the ECU might still work down to quite a low voltage.
I'd say alternator, my car did exactly the same when it died (with bonus pulsing headlights as the regulator was letting spikes through).
Check the battery voltage, it should be 12.5-13V when it's 'cold', then start the engine and it should jump to 13.5-14.5V. But it can be deceptive as they can die intermittently.
Don't just charge the battery and go off on a long trip if it's possibly the alternator, it'll set off fine, then leave you stranded somewhere when it runs flat.
Yeah batteries are odd things... it not nessesarily the alternator, or a knackered battery, it may just be a flat battery.
Cold weather + short runs = flat battery, even if the battery isn't knackered, it's easy to flatten if its old.
EDIT, after a bump start, it will still need a good run to charge it properly, or you'll just face the same issue, assuming the alternator is ok.
Check the terminals on the battery are tight including any ground bolts.
Battery is my guess. Mine wouldn't start too after sitting idle for nearly 10 days. I just recharged the battery with slow trickle charger for an hour or so to get it started. I need to charge it again as the cold weather is not doing good for the battery. Mine is a petrol Toyota Corolla 2005 with old tech.
Is it diesel? If so it will run without constant power.
Car diesel technology has moved on quite a bit since the 90s, and even then they still needed 12v to keep the stop solenoid open.
3 cylinder petrol Mitsubishi Colt, same engine as a Smart I believe.
We checked terminals and it was OK, and lights and everything else are still coming on.
Just proves volts and not amps.
Got a multi meter? Stick it across the terminals to check.
Or just charge it on trickle overnight, indoors. As cold kills batteries.
But with modern cells and power hungry cars once you kill the battery they tend, ime, not to recover
buy a new battery from somewhere you can take it back to (halfords or eurocarparts). plug it in, see if it fixes the issue (probably will). If not, take it back.
But with modern cells and power hungry cars once you kill the battery they tend, ime, not to recover
^^^ This. Mine seems to be fine during the summer but during the cold days, if left idle for more than 7 days, the battery will struggle badly or not even start. Need to be on trickle charger almost every 3 days if I don't drive it.
My car battery is from Halfords (Halfords' brand or as cheap as possible for me) and about 4 years old.
Cold weather + short runs = flat battery, even if the battery isn’t knackered, it’s easy to flatten if its old.
Just to add, or reiterate, a jump start won't fix it, it will just get you going...assuming it's only a flat battery, the car will need a really good run to allow the alternator time to charge it properly.
And if the battery is old you'll have to be mindfull to make sure it gets a good run often in cold weather.
Car diesel technology has moved on quite a bit since the 90s, and even then they still needed 12v to keep the stop solenoid open.
Fair enough. I was basing that on 2008 ish 1.7 astra which happily ran as long as you want on a bump start when the alternator died. Pretty sure that engine came out a tractor or something though 🤣
If it was the alternator I'd expect a dash light indicating a fault.
Fair enough. I was basing that on 2008 ish 1.7 astra which happily ran as long as you want on a bump start when the alternator died. Pretty sure that engine came out a tractor or something though
1.7 of that era would have been an Isuzu CDTI lump which needs quite a bit of power to keep running.
You'll probably find the alternator hadn't completely died, and was still putting out enough power for the engine to limp along, but not enough to put any meaningful charge back in the battery.
If it was the alternator I’d expect a dash light indicating a fault.
Not always. For an olde charge warning lamp system, there are a few ways the alternator could fail without bringing the light on.
The generation of technology that replaced ye olde warning lights are a bit smarter, and will detect more failures.
The latest generation with smart charging can detect even more failures, but often won't bring on any warning lamp until battery voltage has dropped towards a critical level.
So, home now and have tried jumpstarting on my bigger diesel's battery, and nothing. But lights are good, windows are running normally, just not starting. So my neighbour towstarted me and it ran fine, revs, speedo, lights, fan, PS, all good. It's only half mile to the little garage unit so I've run it there and left it outside to avoid having to do it in the morning.
I'm thinking starter motor now more than battery or alternator. I had tried rocking it first in case sticky but that did nothing, so it's sounding like that, or a bad connection to it.
Try whacking the starter.
Headlights and ancillaries don't use anything like the current required to start it. Invest in a cheap multimeter from Screwfix and test the battery.
It could also be a bad earth strap that has high resistance under load. Connect a single jump lead from the battery negative to the engine block (find a lifting eye or other clean metal directly on the engine) and this will provide a temporary earth. Also, physically yank the negative battery cable and see if it just breaks off.
Poor earth but probably a duff battery
Need a multi meter or preferably a big drop tester
PS cheap jump leads are shit, I had a set that were always more trouble than they were worth, so much resistance under high amps you'd have to leave them connected for 10 minutes to have any chance of transferring charge and they'd get nice and warm on in the process. So unless they are heavy duty and flexible I would not consider the failed jump start to be a suggestion that the fault isn't battery related.
buy a new battery from somewhere you can take it back to (halfords or eurocarparts). plug it in, see if it fixes the issue (probably will). If not, take it back.
Halfords won't take back a battery that's been fitted, ask me how I know.
Cheers all - it's at the garage now so we'll find out soon enough.
I'm not disputing the knowledge of STW but I like to understand stuff when I can. Electricity isn't a strong point though...... Jump starting then - we used good leads, the neighbour has a massive american doublecab thing for work (Dodge I think) and these leads looked like they'd been removed from Drax. So let's assume they could carry the load OK.
I don't understand the running it for 10 mins to charge the battery - if we're connecting a second (good) battery to the car in parallel to the possibly duff one, when you go to start, the circuit's complete so isn't it the same as having a new battery in there? Even if the good battery was trying to simultaneously charge the duff one and run the circuit in the car to the starter motor, wouldn't you expect it to at least give the starter a turn even if it isn't strong enough to do both? What is actually happening.
The jump leads (assuming you're using the normal sort of clips at the end) only have a small surface area to transmit the power. The starter will require say 150 amps - pulling that across the small surface area will result in a lot of loses.
The battery has much bigger, securely clamped contacts. Pulling 150 amps is going to be much more efficient that way.
Race cars have proper large plug and socket arrangements to connect external batteries - jumping that way is the same as using an internal battery with clamped up terminals.
The jump leads (assuming you’re using the normal sort of clips at the end) only have a small surface area to transmit the power.
I've often wondered about that, why decent leads have big fat wires to transmit the power but rely on pointy little teeth on the clamp as a connection. There's got to be a more efficient method of attachment that could be designed.
There’s got to be a more efficient method of attachment that could be designed.
Anderson connectors
https://www.12voltplanet.co.uk/anderson-power-connectors.html
I think an empty battery will also draw current. You might have got somewhere if you haf left the pick up running with the leads connected to pour some electric into the flat battery
If the battery is knackered it won't pull a charge
Think filling a bath with the plug out
Plus now things like smart charge alternators are common to help with parasitic losses to again help the co2 figure
Thanks for all the comments and tips. Turns out, not battery or alternator at all, both are absolutely fine and it was simply starter motor.
Fixed and now back on the road, albeit with wallet £240 lighter.