whats wrong with my car?

[TEAK36]

Hi,
I have a Rover 75, and for the past 2 months I have had an intermittent problem. Somtimes when I try to start my car there is now power coming from the battery.If I keep trying, the car would eventually start, but it sounded like the battery was dying. 2 weks ago I went to Halfords and had a new battery fitted. When I tried to start the car with the new battery there was no power again. The guy at Halfords went and got a tube of copper coloured paste which it smeared over the battery connections.My car then started first time, and has done ever since, until last night. I was 150 miles up the M1 and stopped for some petrol, and when I tried to start my car I had the same problem as before. I got my tool kit out, undid the cable connectors are smeared around the copper paste that was still on them. My car then started first time. This problem kept happening evey time I stopped, all the way up to bloody Newcastle, but I think it was the moving of the connector rather than the paste that made things work.

I know almost zero about cars, but to me this sounds like there may be a loose connection somewhere.

Any advice would be most appreciated.

[Batman7070]

Examine closely the battery cable terminals where the cable enters the cable terminal. The crimp may be corroded inside the crimp or the cable even loose in its crimp. Examine too the batery negative earth connection to the car chassis.
If the battery terminals are of the round stud type check to see if the cable clamp on the battery stud is not loosening off the stud taper.