On 12/03/2015 10:18, Another John wrote:
In article ,
Martin Brown wrote:

Your least worst option now is to charge it for a couple of hours with a
dumb as a rock simple lead acid battery charger to see if you can get
any charge to stick (ie. enough to start the mower). If it won't hold
charge for at least a week you are stuck with replacing it.

Ideally an initial charge rate of C/10 to C/5 but keep an eye on it.

Smart chargers will sense battery parameters and do a safety cutout if
the battery has gone high impedance or has one cell reverse polarised.
The lifetime of the SLA has been compromised - possibly to zero.

Thanks Martin ... yerrrsss: my charger is "dumb as a rock": just has
lights (no dials or meters), and very little in the way of controls (in
fact just one switch: 6V or 12V?!)

Putting a multimeter in series on the amps range to see what current is
flowing might be informative. Or just look for the spark when you make
the connection to show that there really is some output.

I regretted buying it as soon as I got it, but it cost about 35 quid and
was reluctant to spend more, especially as I myself know almost nothing
about electrics/electronics.

I find dumb as a rock ones OK provided you remember to either charge at
C/10 or religiously set a timer/alarm to switch off when fully charged.

I'll see what happens next time I go across and give it another charge.
I'll report back, as I really do appreciate the help you've all supplied.

John

Rapidonline have a reasonable selection of SLA batteries at fairly
decent prices. The official lawnmower spare will be overpriced though
probably not by as much as wheelchair batteries. It does have to be
pretty rugged and robust to stand up to the vibration on a lawnmower.

--
Regards,
Martin Brown