On Fri, 07 Aug 2015 11:45:37 +1000, Blano wrote:

"Dave Liquorice" wrote in message
ll.co.uk...
Power cut this afternoon about 1700, text from DNO saying High Voltage
fault off until 2030. Drag out generator, battery utterly flat. Pull
started the (diesel) generator and power came back about 1900. Even
after that couple of hours the battery didn't have enough umph to
engage with the starter ring. It sits at about 11.5 V, one end cell
looks a bit low one electrolyte and the case at that end is slighly
bulging. Battery is kept on genset in the unheated garage so may well
have got frozen. Perhaps not last winter but in 9/10 or 10/11 it got
below -10 C without much trouble.

Pretty sure the battery is a gonner and I'd not trust it anyway for a
semi-critical system. It'll be replaced but how to keep the new one in
good condition for years with it doing basically nothing. The genset
might called into service in anger once a year and occasionally if it's
"a while" since the last in anger run I'll fire it up for a couple
hours powering a fan heater to make sure it still works.

So how do you molly codle a lead acid battery that doesn't get much
use? Keep it somewhere a bit warmer? Would have to have an easy to use
plug/socket capable of carrying the starter current. I don't want to be
fiddling about reconnecting the battery in the middle of the night, by
torch light, whilst being battered by a gale and driving snow...

Don't fancy the idea of having it on a charger all the time, even one
of the clever ones that drop to a "float" charge. I suspect that rate
will still be too high and dry the cells out over the months.

Surely there must be really smart chargers around for just that
situation ?

I have got a small PV panel that I had used with it before but wasn't
convinced that the dark/low light leakage drained more from the battery
than was put in by the PV. The PV panel was in a north facing window so
not ideal. To get south facing wuld require a rather long cable run,
proably not far short of 50m by the time you've gone round things.

Any other suggestions?

I have two car batteries on the go.
Both have been abused in the past by being let go flat in the car whilst
we were on a long holiday abroad.
Both have been brought back to life by a trickle charger and at the moment
I have one on charge and the other in the car. When one battery starts to
lose charge due to infrequent short journeys (especially over winter) I
swap them over.

Been doing this for 2 or 3 years now and both batteries seem to be holding
up.

The charger is an AccuMate which is claimed to be good both for
maintenance charging and recovering deeply discharged batteries.

So perhaps a good quality maintenance charger, and a heating strip/pad
linked to a thermostat wrapped around the battery to prevent freezing,
could keep your battery alive.

Cheers

Dave R



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