Thanks
For the time being I cleaned the battery poles and clamp connectors with a bit of sandpaper.
Is there another way to test the battery and alternator instead clamping the tester directly to the battery ? Can I use the tested connected to the positive side of the battery and then the negative somewhere on the chassis in an attempt for the tester to register the voltage drop or resistance ?
If so where should I connect the negative clamp of the tester ?