No decent alarm will activate with the engine on. The battery could
have been drained because the alternator wasn't charging it (at least
not sufficienctly). In that case the battery's reserve capacity was
used up and your engine stopped right then. The charging system should
keep the car running after starting, so that's the primary suspect.

If the charging system isn't working, you'll be replacing the battery
again or get stranded somewhere you don't want. Also, you should not
charge a drained battery by driving around because this stresses the
alternator too much and can cause it to fail early ($$$). Always
charge up a drained battery offline. Autozone can perform a free
battery test (don't know if they'll charge it up for you).

Repeated deep discharges are not good for either the battery or the
alternator. The battery will have a sulfate deposit on the plates that
it can't recover from; the alternator will overheat trying to charge
up a weak battery. That's why I change out the battery every 5 years
no questions asked. At ~$45 (Walmart, made by Johnson Controls
although the ~$80 AC Delco maintenance free is my preferred battery)
it's cheaper than doing my own oil changes in as little as 2 years.

So it's the usual suspects in an electrical system test. You need to
find out if the alternator failed (given that your engine quit while
running), all the cable connections are clean and tight, no excessive
current drain (>300ma?) when off, the alternator belt is properly
tensioned, and that the battery can still hold a charge.

On May 26, 7:28 pm, DrEdG...@gmail.com wrote:

On May 26, 10:28 pm, DrEdG...@gmail.com wrote:

I have had the same problem with other cars although opening the hood
and having the car die isnt one of them

It sounds to me like the battery may have a shorted cell(internally )
a build up of sulphides is usualy the reason, usually caused by old
age .

You dont say if the battery connections are clean and you have a good
clean solid ground ?This is paramount to having a trouble free
electrical system.

That would be the first thing to check.

I`m guessing here but you need to check out the alternator output with
a DC voltage tester (cheap at any auto parts store )

When running ,the alternator should be putting out around 13.5 -13.8
volts DC.

Measure across the + and - negative terminals.Be sure to keep the
polarity of the tester correct (red +, black - )

If it isnt you probably have blown a diode in the alternator .

Having an alternator try to charge an almost dead battery  will stress
the alternator to a point of no return(been there done that)and having
to replace the alternator with a new one or rebuilt one.

The battery when tested with the car NOT running should read at least
12 volts DC.

If it doesnt then your batery is due for replacement.

But FIRST,? charge your battery with an outside source battery charger
and see if it holds a charge .

If the battery wont hold a charge ? you can tell , because it will
never come up to full charge , no matter how long you leave it on the
charger.

Leave it on charge over night and if it doesnt come up to charge(less
than 1/2 an amp by morning ) you have a dead cell in your battery and
it needs replacing.

When replacing the battery make sure ALL connections are free and
clean of sulphates ( the green stuff that collects on terminals)

Baking soda and a scrub brush work fine for this

<Make sure ALL connections are tight after cleaning and start the
car ,put the tester across the positive and negative terminals on the
battery.

If the tester reads 13.5-13.8 volts everything is ok .

If it reads LESS than this you probably have an alternator problem as
well.

Hope this helps
Ed