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JUV wrote:Great, thanks for all the advice. Will try a decent new battery (from somewhere cheaper than Halfords) and see where we go from there - certainly the existing one looks to be down on its charge (dark green indicator) so a replacement isn't going to hurt.

Good to know the alternator and voltage regulator are one in the same too - takes some of the uncertainty out of things, even if it does inevitably put the price of a new one up. Thanks again.

I'd still get a good battery depot to load test your battery, it certainly will not be 100% compared with when it was new, but might not be the route cause of your problems. The green indicator thing, is I think, more of a liquid level indicator with a built in hydrometer for good measure, the reason that they go darkish tends to be that the electrolite ends up with debris in it as the battery runs out of life, plus the liquid level drops a bit so the green turns to black.