Lights dim when i brake-alternator tested OK

[Jdace]

Hi guys, lately when im driving at night I notice my lights dim when i brake, indicate, etc etc. I have taken it to an auto store and they tested it and battery came up low capacity, but starting and charging were OK. Ive been told to add an earth cable from chassis-engine. I know the battery ground cable splits;one to transmission, the other to chassis. I want to know if there is a cable already from chassis to engine (i couldnt find one), and if this is the right direction.

Thanks

 

[dac69er]

I would think about changing your battery. As you brake engine rpm drops, the power generated by the alternator will drop. The regulator in the alternator should control this, but the battery is there as a buffer to take up the 'slack' when the voltages vary slightly.

I would replace the battery if it is low capacity. No harm in check your earth points and/or adding a few more. As standard off the top of my head there should go from the battery to the chassis and gearbox front mount. Then there as a small one from the chassis to the top of the box and one from the chassis to the drivers side engine mount.

Try checking the ground points for the lights, these are tucked near the front lights.


What voltages do you get at the battery at idle speed and then a constant 3000rpm?