On Sun, 07 Jun 2009 20:13:54 +0100, Gareth wrote:

Eddie wrote:
My car battery is oversized for the car. The battery is a bit old
but usually works fine. The battery is flat (I left the lights
on).

My fancy new modern charger senses a poor battery and only puts in
very little charge.

I used to use a really old charger to charge this battery
successfully. I opened up the old charger and saw it was only a
transformer and a big rectifier. That's it. No soothing.

Is this ok for a car battery or is it way too crude?

Both; it is crude but it's ok for a car battery.

Modern "intelligent" chargers are much kinder to the battery and usually
have an automatic maintain mode, so you don't have to remove the charger as
soon as it's charged and can even use them to maintain the charge if the
vehicle is not used for some time. Old fashioned basic chargers will
sometimes recover batteries that an intelligent charger won't charge
though, but if you leave them on too long they'll boil the electrolyte off.
Personally, I use an intelligent charger, but have an old charger to start
the charge on any very flat battery, which I can then complete with the
modern one.

SteveW