On 18/06/2014 17:29, Dave Liquorice wrote:
On Wed, 18 Jun 2014 00:38:08 +0100, Johny B Good wrote:

Rescued mine from the garage, not a lot inside. Connected across
the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400?
diode
in series, that's the sum total of bits inside. Don't know what
the ?
is as that's against the tiny bit of PCB.

The diode is most likely a 1N4001, the lowest PIV rating of that
series, one or two hundred volts afair.

1N4001 is 50 V. B-) Well I just looked at th spec to get the
leakage.

An 1N5817 would be a better choice - much lower Vf at low currents.

http://www.fairchildsemi.com/ds/1N/1N5818.pdf

They are usually a fair bit better than the datasheet max ratings would
suggest in terms of reverse leakage.

The last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).

Car batteries really don't like any deep discharge and aren't that
keen on constant charging either. So I'm not surprised they died PDQ,
I'm also on the look out for 4 12 V deep discharge batteries for the
2 kVA UPS I have kicking about. Ideally things greater than 100 AHr
but then they'll probably be flooded and vented so not ideal for
being in the equipment cupboard. Back of the garage and run a
"maintained" mains feed in is probably the best option but I've heard
stories that UPS's might object to long output cables.

Old government surplus NiFe are incredibly robust if you can still find
them. They scrapped a fortunes worth of the things in the early 1990's
and then proceeded to destroy a complete batch of new replacement NiCd
by using the same top up 30% recharging regime for a couple of years.

After that they got wise and modified the SOP instructions...

--
Regards,
Martin Brown