Good chargers will cycle the charge to suit the depth of charge required. This is not 12V but more usually 13v or 14V for periods.
>
>Never heard of that, and never thought it necessary: the trick with
>lead-acid batteries is to charge them to a constant voltage, and -
snip
>
>> Yes, a car regulator keeps the volage just above 14volts during charging.
> 14.4V was the figure I remember from my days at collage Yes, that's about the top of the limit. (14.2 - 14.4)
>
>> The Haynes Carvan Manual states that a fully charged battery (with no load and charger disconnected) shows 12.7V on a meter.
Ah. Now there's a problem. If the battery has just come off charge,
(even a couple of hours ago) there's something called a surface charge
which gives a false reading You need to wait overnight, or remove this surface charge with a decent load (say a car headlamp for 20 seconds) before doing this check. PS DON'T just use a bulb and some wires, the spark
might ignite gasses (yes Gas comes out for hours) and you wouldn't
like the BANG (I've heard it once)
>
>again from memory, I think it's 13.8v for a car battery,
>but maybe a leisure battery is subtly different (must get out the meter one day!)
No, I would say 13.5 only on charge (at a low rate)
The difference between leisure batteries and car batteries are subtle,
but are as follows.
1. Leisure batteries have a different plate separator which keeps the
particles of lead (or lead something or other, I never did listen to
the chemistry bit) on the plates when the battery is flat. This means
you can run the battery flat, but can't take current out too fast to
start a car (the separator limits the flow of electrolyte around the
plates or something)
2. Low Maintainance Car batteries have calcium in the plates. This
reduces gassing and water loss, but means that if the cell drops below
a certain critical voltage, you can't recover the cell. Sometimes if
you catch it the same hour it went flat, you'll be OK. Basically a car
battery with 10.2volts is dead.
A Leisure battery doesn't have
this anti gassing property, so you have to be more careful not to let
it get hot when charging, charge it too quickly, too long, etc, but
it can go flat and survive.
More to follow when time permits
>
>
>--
>Jeff (Reflections)
