A double request on this one, wondering if anyone can help?

First the problem, and what I believe it to be. I'll try to keep it simple but as detailed as I can.

54 plate, Vauxhall Astra H Elite, 1.7 Diesel.

Driving along, stereo starts cutting out, the factory stereo is awful and is temperamental to say the least, so not surprised. Driving later on, the heater blower starts cutting in/out. Got my attention now, potentially an electrical problem, will see how it plays out. 3rd driving outing, ABS warning light comes on, then goes out. Then the Engine warning light comes on, then goes out. Then both lights come on and stay on, along with a couple of others. Dashboard display starts to dim and the wipers go sluggish, finally ending in the power steering going. Engine still running at this point.

Limped home (was only very local at the time), switched the engine off. Tried to switch it on, nothing, dead.

So, my conclusion; either the battery, alternator or associated (belt, cable, etc) has gone down. Which after research, the alternator is a common problem with these.

This morning tried to start the car, it was not happy about it, but it did start. Checked the voltage at the battery terminals, 7 volts and rapidly dropping, indicating to me that it is a problem with the alternator and the engine is running entirely off battery power, or the voltage would be around the 14 volts mark, so the battery is not at fault. Checked all the fuses, nothing wrong there.

Thus leaving the alternator, alternator belt, or related wiring being the fault.

So, question 1 being, does anyone agree/not agree with my rudimentary diagnosis?

Question 2, does anyone know of a good, affordable mobile mechanic that would be able to fix the problem at a good price?(worst time of year financially *sad face*)

And question 3, what kind of prices are we looking at for this work?

Any help/suggestions would be greatly appreciated.

How old is the battery? If its old and failing it may not be holding the charge. Correct me if I'm wrong but I think on modern cars the car draws power from the battery when running, and the alternator keeps it topped up. Not like the old days when you could start a car then remove the battery!

Ste or Turnip would be my first choice if you want a second professional opinion.

They might even have a good spare battery to test on your car first. That way they can get it started and check if the alternator is ok.

I'm pretty sure we have a charged up battery in the garage if you wanted to pop that on and see if it fixes the issue. The alternators on them are quite common to go and they have a vacuum pump bolted on the back of them which of course adds to the cost.

Not the most difficult of jobs but probably still looking at a couple of hours as access is fairly limited and some things can be a little tight. Give me a shout if you want me to pop this battery on and see what it does.

So many faults seem to point to an electrical problem, how many amps the battery is putting out is more critical than volts.Could be as simple as a bad earth.A technical diagnostic is the best route if you find nothing obvious.

First thing I would check are ALL the earth straps. Make sure you find them all. Remove, clean up the end of the strap and the bit of engine/chassis it connects to back to bright metal, then try again.

If your mileage is above 90,000 then its probably alternator brushes (regulator) worn out. Unfortunately when it gets to that state the arcing has often damaged the armature slip rings as well so it might not just be a case of replacing the regulator.

Auto electrican's at top of green lane (Tranmere) will refurbish the alternator if you take it off.

In the meantime, do not leave the battery in a discharged state, it will destroy it if you do, get it charged.

Last time I had a load of dodgy electrical happenings (although didn't affect starting) was several split wires shorting out, Common problem on some vehicles either where wiring harness is in rubber gaiter by door hinge or passes into tailgate.

A failing coil pack also gave some dodgy electrics and driving before finally causing total electrical failure and starting

Thanks to all for the responses, and to DD for recommending the auto electrician by Green Lane station. All sorted now, it was the alternator. Refurbed with 12 months warranty for £75. Not bad at all.

Removal was a pain, as it was in an awkward place, the bolts had rounded, and the vacuum pump is attached to the alternator. Fitting was a lot quicker, and with a new bolt (£9 from Vauxhalls!) the car is back up and running. The battery has been charged and seems to be working fine, time will tell if is dying or not.

Thanks to all.