On 11/04/20 14:18, The Natural Philosopher wrote:
On 11/04/2020 11:57, Jeff Layman wrote:
On 11/04/20 11:21, Dave Plowman (News) wrote:
In article ,
Â*Â*Â* Bert Coules wrote:
"The Natural Philosopher" wrote:

And how can I tell when the battery is sufficiently charged?

when the terminal voltage is over 13V

But how do I tell that?Â* There's no meter or any other indicator sort
of on
the charger.

Leave it on for 24 hours.

A simple 6 amp charger will only charge at 6 amps for a short period (if
ever - many are extremely optimistic) and as the battery volts come up,
the charge rate will fall.

If the car won't start after 24 hours and the charger was working,
chances
are the battery has had it.

You can check the charger is working with a simple DVM or other method of
measuring the volts. They will be higher on charge than off charge.

The OP said that he doesn't have any method of measurement,
unfortunately. Might be simplest to charge for 4 or 5 hours, then turn
off the charger and turn the headlights on for a minute:
1. Headlights don't come on - battery buggered. Replace asap.
2. Headlights come on and stay on - battery ok. Continue charging.
3. Headlights come on and slowly fade - battery on the way out. The car
might start and get you from A to B, but I wouldn't guarantee getting
back from B to A! Replace battery asap.

Depending on the motor it takes about 200A to start a car for about 5
seconds.

If a reasonable charge current once started is 5 A that needs 200
seconds to replace the charge.

Or about 3 1/2 minutes.

These figures are well within an order of magnitude. If you start a car
you should not routinely stop it within 5 minutes if you can avoid it

Nothing wrong with your figures, but I don't understand the relevance
here. All I was trying to point out is a battery which will charge -
sort of - but won't hold a charge for very long. It'll lose that charge
over a period of several minutes or maybe an hour, and so needs
replacing. If the OP stops for less than a minute after driving around
with that battery and then tries to restart the car he /might/ get away
with it. He might not. The headlight test should show if the battery is
dodgy enough that it could fail to restart the car.

--

Jeff