On Sat, 04 Mar 2017 13:53:56 +0000 (GMT), Dave Plowman (News) wrote:

I bought myself an ACT battery tester ages ago. Not cheap, but does test
a battery quickly and easily. I'd hope any place claiming to test
batteries would have something similar.

I think our local garage's battery tester is BFO wire wound resistor
(foot long 1" dia) attached to a frame with a couple of hefty hinged
probes. A volt meter is wired across the resistor. Firmly push one
probe onto one terminal, whack the other onto the other hold for a
few seconds as 100 odd amps flow and watch the voltage... Hopefully
the first probe on doesn't weld itself to the terminal, the other
might if you are a bit slow whacking it on and pulling it off. B-)

--
Cheers
Dave.