On Fri, 04 Jan 2019 18:17:29 -0000, Dave Plowman (News) wrote:

In article ,
Commander Kinsey wrote:
Bull****. I've got a very basic 4A battery charger. Just a transformer
and rectifier. If the battery is flat, it'll give out 4A. Once the
battery gets full, it drops to a fraction of an amp. Basically it just
gives out 13.8V maximum - the trickle charge for a lead acid.

The output of a basic battery charger will vary a lot due to the
transformer regulation and so on. A basic one is very unlikely to produce
a constant voltage - unless specifically for SLA gel types.

Just been reading up on Li-Ion car batteries (I assume they have charging protection built into them so they can just be dropped into an existing car). They cost twice as much but should last 4 times as long. They're lighter, so motorcyclists love them, not sure the weight is important in a car though.