xena expressed precisely :
My horse is due to foal any day now, so I bought a wireless CCTV system so I
could keep an eye on her. I specifically needed one that could run off a
battery as there is no power in the stable.

I set it all up and it worked fine for a few minutes, then it stopped, and it
looks as though the camera battery has run out. It was also supplied with an
adaptor, which says Output 8V - 500mA. Well as the rechargeable batteries I
have are 160mAh, would I be right in thinking that these batteries will last
all of about 20 minutes?? If so, I'm absolutely seething, that's no good at
all. I'm waiting for a response off the company that sold me the kit (they
know exactly what it was being used for...)

Is there any way I can get the camera to run off a 12v leisure battery
instead?

20 minutes would be about right.

If the 8v needed is 8v DC, then you could run it from a 7808 series
regulator. Get a 1amp version of the 7808 from perhaps Maplin. It has
three terminals + in, ground, + output at 8v. Mount in on an heat sink
because it will need to be kept cool.

An 85amp hour battery will last around 130 hours continuous running.

Another solution might be to get hold of a long 240v extension and take
care where you place the cable.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk