On Fri, 10 Apr 2020 17:37:24 +0100, Fredxx wrote:

On 10/04/2020 17:20:09, Bert Coules wrote:
I just discovered that my car's battery is flat.* I won't need the car
until around the middle of next week: will it damage the battery at all
to leave it uncharged until then?

Yes. It's probably buggered already.

Agreed, depending on how 'flat' (and to some degree, the chemistry of
the battery [1]).

If Bert tried to start the car and it was *just* sluggish, he may be
in with a better chance than if it wouldn't even bring up the dash
lights, for example.

Never let a lead-acid go flat.

If we are talking about real flat then I agree 100%, but it can depend
on how long it then stays flat for as to how much damage it suffers.

eg, When I designed, built and raced an electric motorbike, it wasn't
unknown for the batteries to be at well below the desired maximum of
50% discharge (so 'flat' by battery terms) but as long as I got them
back on charge again quickly, they didn't seem to suffer (I used them
all season and won the last race). ;-)

It might work afterwards but most of its
capacity will have been destroyed.

Given the above caveats, I might go as far as 'some of it's capacity
can be lost'.

And are the home rescue services operating at the moment anyway?

Yes, best tell them you need to go shopping!

I wonder if that could be covered under the vehicle maintenance
exemption?

Now might be the time to investigate battery isolator connectors or
solar chargers? I also have one of the very portable LiPo battery jump
starters that are amazing.

Cheers, T i m