On 06/04/2018 14:25, T i m wrote:
On Fri, 6 Apr 2018 12:34:24 +0100, newshound
wrote:

snip

Going slightly OT, pulled an apparently dead 105 AH leisure battery out
of a caravan yesterday (hadn't been used for months and the charging
circuit claimed it was dead when on mains hookup).

Gave it best part of a pint of demin water and stuck it on charge on a
traditional charger, this morning all the cells are bubbling nicely and
it's showing over 14 volts immediately after disconnection. Will stick
it on a smart charger for a few days but I'm quite hopeful.

I get given and collect myself many batteries in various states of
charge and whilst some appear the be ok (in that they show a
reasonable terminal voltage pre charging, come up to full charge and
cut-off / test as 'ok' etc) most have a much reduced capacity, both as
seen on my instant capacity tester and a monitored discharge (down to
~50% DOD etc).

So, typically a car (SLI) battery that was generally good in the
summer but failed in the winter may be down to 20Ah from it's 60Ah
when new.

If it's not too big and comes with a built in handle I might keep it
to use as a portable jump-start battery and if not it goes down the
scrappy (I try to take them in reasonably sized batches as it
minimises the 'loss' from stuff being sub 1kg increments). ;-)

Similar to my experience, but such things are often recoverable enough
to use for electric fencers and lighting.

If a battery looks 'tired' (dirty, writing worn off, damaged
terminals, bulging case etc) I'm happy to weigh it in. It's when they
look brand new (like the 2 x 12V x 17Ah GEL batteries I recently took
out of Dads old mobility scooter) but are completely shot it pains me
a little (such a waste etc).

Looking upon these things as 'consumables' helps (a bit [1]). ;-)

Cheers, T i m

[1] During my role as a 'Field Tech' I have visited many industrial
premises and often got the chance of a quick 'personal tour' (don't
ask you don't get etc). ;-)

One process that was probably the most 'messy' and potentially fairly
dangerous (for all sorts of reasons) was one of the big lead acid
manufacturers (running various EV's I was particularly interested).

I was fairly used to the smell of hydrogen (my own EV's and wet LA in
general etc) but it was all the hot machinery (lead casting) other
chemistry and acid knocking about that made one want to look but keep
it all at a safe distance (especially from my eyes and suit)! ;-)

Went round a hard chrome plating and grinding plant the other day. A
fine collection of near antique planetary grinders, the baths looked
fairly evil. Apparently they fabricate their own "custom" electrodes
from lead bars about 10 mm square. They melt down old electrodes and
re-cast them, but I didn't see them doing that.