On Monday, 22 April 2019 22:12:55 UTC+1, Roger Mills wrote:
On 22/04/2019 18:45, tabbypurr wrote:
On Monday, 22 April 2019 13:48:22 UTC+1, Roger Mills wrote:

Could that be caused by discharging it too deeply? If not, by what else?
Is there any fix other than replacing the battery?

Battery knackered, obviously. Sitting around discharged is fatal to lead acids. It might be worth a go discharging it to about 3.5v then immediately pulse charging it. A variant of that method was used a fair bit back in the 50s to get car batteries good enough to sell the car. You need a charger with recondition mode of course - or could do it the old way, but those setups tended to be a hazard.


NT

Could be worth a try. The only charger I have is the wallwart which came
with it.

that certainly won't do it.

What is the 'old' way - manually switching it on and off? If
so, at what frequency?

Connecting to the mains via a rectifier & current limiting lightbulb. It's not safe, don't do it. The basic idea is that excess voltage can break down some of the sulphation, which insulates & blocks ion flow. Of course that can only be applied in pulses, otherwise the battery would overheat grossly..


NT