On 27 Jun 2020 11:41:06 GMT, David wrote:

snip

Does anyone have any experience of these, perhaps enough to make a
recommendation?


Sort of.

Daughter had an electric fence around a rabbit hutch, powered by a 12V
17Ah sealed battery. On every night and if the area wasn't attended (=
my Mum was away g) and the battery would last (safely) over a week.

I added a 5W solar panel and one of the LCD / USB controllers you
mentioned and the battery would then last nearer 3 weeks.

The reason it wasn't more was mainly down to the fact the panel wasn't
anywhere near optimally mounted, in fact it would only be exposed to
any real sunlight for a couple of hours each day.

The real reason for adding the controller was it allowed the electric
fence to run automatically only dusk to dawn and protected the battery
from over discharge.

The 'problem' with any of these controllers and smaller panels is the
parasitic energy they draw to run themselves.

I could have re-orientated the panel, got a bigger panel or put
another panel at the other end of the building (to catch the sun later
in the day) but it was easier to just swap the battery for it's
partner and on an Optimate 2 charge / maintainer.

So, unless you know the overall balance of the system (worst case
energy in V typical energy out) is 'suitable' for your needs and so if
a controller is 'worth it', you may be better off with just an
anti-discharge protection diode.

Whilst a controller is a must to protect a battery from overcharge, if
the panel can deliver more current (and voltage) than the battery
should get once fully charged, the use of one with smaller panels
(where the ability of the panel is offset by the self discharge of the
controller) only really works to protect the battery from over
discharge, ironically, partially caused by the controller itself.

Cheers, T i m