Starting your car with jumper
leads is simple: get another car alongside, connect up, start the engine and
you're away.
Right? Wrong! Because I now know the downside.
A recent jump-start started a fire that could have killed me, wrecked my
Aston Martin DB7 and BMW 730i and burned down my garage.
As it was, C$5,000 of damage was done to the Aston and I now appreciate
the need for adequate jumper cables, the correct procedure
and the potential for damage to both cars.
Many Astons have starting problems. Their electrical systems drain a 12-volt
battery if left for more than a few days, and only the newest
ones have a sleep mode. In four years of DB7 ownership I have got through
three batteries.
I already had a trickle charger to plug into the cigarette lighter, which
was fine except that I had to feed the lead through the window, which entailed
leaving the alarm off. Aston Martin has now supplied a charger that feeds
a socket in the trunk and exits under the lid so the alarm
can stay on.
Last winter, however, I was without this device and my Astons battery was
dead just a day after a 200-mile run. With the car in the garage, I reversed
the BMW up and took out my "heavy duty" jumper cables. I connected them
to both batteries, started the BMW, went into the
garage and switched on the Aston.
It didn't start, but flames and acrid smoke shot from its trunk toward
the BMW as the cables' coating melted, scattering gobbets of flaming
plastic. The fire hazard was somewhat intensified by the paint store on
one side of the garage and a shed full of dry firewood on the other.
I was stuck at the back of the garage and to escape I would need to squeeze
past both vehicles.
I killed the DB7's ignition, broke the jumper-lead connection (the clips
were coming away from the wires) and ran past the Aston.
I then drove the BMW clear, smothered the fire and shakily rang the CAA.
The driver looked tearful as I explained how close two prized cars had
come to destruction; he said I was lucky to get out alive.
He reassured me I had connected the jumper cables correctly, then diagnosed
the causes of the fire.
The cables might have looked superficially sturdy, but their aluminum cores
could not handle the amps generated by a modern alternator.
He also said the Astons battery was too dead to cope with a hefty charge-up
generated by the BMW which had detected a dead battery and
was belting out the amps to charge it up. He said that I should have connected
everything without the cars started, then gone for a cup of
tea while the battery acclimatised.
I rang the CAAs technical department to find out more. They first advised
me the safe order to attach jumper cables:
clip the positive/red jumper lead to the positive/red terminal of the dead
battery, then the other end to the positive/red terminal on the
good battery. After that clip the negative/black jumper lead to the negative/black
terminal on the good battery and the other end to the negative/black terminal
on the dead battery.
To be absolutely safe and avoid the very small risk of an explosion caused
by a spark igniting the hydrogen coming off the charging
dead battery, don't attach jumper cables to that battery, but instead
clip the red lead to a distributor box under the hood and the black
to the engine. If you are trying to jumper start an old, classic car, be
very careful that you are dealing with the same wiring polarities,
as many of them have positive ground. The CAA also said that it is best
to connect up, run the engine of the donor car, switch off after 10 minutes,
disconnect the cables and then try to start the car with the poor battery.
Remember to keep the jumper cables clear of rotating engine parts and hot
exhausts.
The CAA said it is best policy not to try to start the car with jumper
cables still connected and also to keep both ignition keys in your pocket,
as occasionally, when systems kick in, they can activate the central locking.
My BMW was almost unscathed, but the DB7 was taken away for evaluation
and repairs. The damage was superficial, except to the
CD stack, but the fire had knocked out the electrics, so a new radio was
needed, too.
Aston Martin also fitted the beefiest battery it could find.
I now have my DB7 back and I shall now use my trickle charger religiously
- but I also have a set of very expensive copper-cored jumper
cables and two fire extinguishers in the garage.
Better safe than sorry.
