Just travelled down from Yorkshire to a 5 caravan site in Cheshire. Half way here on the motorway the battery light came on. Didn't want to stop, continued to site. Checked battery voltage 11.6v - clearly not being charged. Being on site with power, took the battery off and connected it to the caravan's charge system. Brought the battery up to 12.7v, started the engine, battery light went off. Checked input to battery whilst running - clearly being charged. Now my question is, I know that switching on and switching off again clears a multitude of problems, but surely not in a case like this? Is there an external component that is connected to the alternator that could somehow overheat and cause the problem and then cool down, or is it in the alternator? Connection here is a bit hit and miss so thank you in anticipation of your replies. The car by the way is a 61 reg HSE.

My first thought would be the caravan systems dragging the voltage down - flat/knackered battery / fridge ??? maybe worthwhile hooking up and watching the voltage (although may not show anything if you've successfully charged teh van battery)

Not sure about the alternator / charging - if I have my waeco fridge in the car it sometimes cuts off on low battery voltage even whilst driving - the wonders of intelligent systems!

Might be worth getting the battery tested too... 2000 Xei 1.8 gone
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not had that myself, but i have had similar to the reply, the car happily towing along and come to a junction and the cars been fine, now dash lights but the powersave which turns off my dashcam/headrest DVD has tripped and the screens have turned off, but by the time the kids have thought WTF they lights back on and they are quiet again, the weaco fridge was still on when i arrived too (so not sure if that had tripped and the beer was still cold)

Might be worth having a battery test, and run a meter over the car when running, and maybe do the same for the towing electrics as a old car (vaux Vectra) turn its self off when towing with ECU lights blazing and it turned out the electric plug on the caravan was shorting and was melted inside Former Mod/Member, with the most post & Chicken George Arch nemesis