On Fri, 13 Jun 2014 08:28:01 +0000 (UTC),
(Andrew Gabriel) wrote:

In article o.uk,
"Dave Liquorice" writes:
On Thu, 12 Jun 2014 23:49:52 +0000 (UTC), Andrew Gabriel wrote:

I must rescue it from the garage and "get at it". B-)

ISTR the circuit was embedded in a lump of silicone, or some such.

Wouldn't be surprised but just bunging in a schotty diode to stop the
leakage would be an improvement. I doubt it'll ever generate enough
umpf, even in direct sunlight, to damage a wet lead acid battery.

Don't know about current technology wet batteries, but charging them
really slowly use to cause the generation of large crystals on the
plates, which were much more prone to fall off (losing their storage
capacity), and build up a sediment at the bottom of the cell, where
they eventually short the plates out.

Which explanation rather neatly accounts for why a bank of 4 12v 36AH
car batteries used in place of the originally specified 17AH SLAs on
my SmartUPS 2000 only lasted 6 months or so at a time before they
started going 'leaky'!

Sadly, I did this 'experiment' _twice_ before realising the futility
of such an 'economic' solution' to the lack of the battery box that
normally would have come with my 'Bargain Purchase' at a radioham
rally a decade or so back.

The worst of this was this wasn't the first time I'd experienced this
problem a decade or so earlier. However, it was a 'one off' which I
put down to it being a defective battery I'd used with a 13.8v 4A CB
power pack to endow my PSU with low duty cycle high current output. A
common solution for the majority of the CBers running "100W Burners".

I've run out of suitable SLAs for the UPS and don't care too much for
the extortionate pricing of replacements so it's sat in the basement
in bypass. The "Protected Sockets" are no longer 'protected'.

However, I suppose I could use a very low output voltage mains
transformer to impose a 50Hz half volt peak to peak ripple on the
charging supply and try another set of 'cheap car batteries' but I
suspect I'd need something a little more sophisticated to maximise
battery life without confusing the UPS's original 'charging circuit'.

Luckily, I've downloaded several dozen APC UPS manuals and circuit
diagrams, including the all important SmartUPS 2000 one so I do have
some chance of being able to achieve this happy state of affairs.

The UPS manufacturers could have so easily addressed this issue but
it simply wasn't in their interest to do so (UPS supplied SLA
batteries are their equivilent to the inkjet printer manufacturer's
cash cow of inkjet refill cartridges).
--
J B Good