NEED ADVICE

I have a problem when I starting my car the battery light is on until I do not increase the revolutions even if the batteries have just been charged!  :dontknow: I have Mk1 with Corrado engine 1.8 16v and 45ah battery. Maybe I need bigger batteries 60Ah? As well I have a problem to starting it when is cold! THANKS.

Sounds to me like your battery doesn't have the power to start the car, or it struggles when the car is running, like you said.

Is the battery new? Because if a battery is old, it may not hold charge very well.

You havn't hade it that clear what the problem is,does the engine swing over o.k ? does it swing over but slowly ?does the light stay on ?does it start easy?
If I can understand your problem I'd be glad to try and help.

The engine swing ok but its does start with the first time. With the second or third time but battery light stay on unless I increase the revolution! Also I have a new battery now!

If the light stays on when the engine is running you have probably got a problem with the charging circuit. Most likely the alternator or wiring/connections.

Measure the volts across the battery with the engine running. Should be around 13.5+ volts.

new brushes on the alternator should cure any battery light staying on issues providing the battery is a good one,   its a nice easy fix,  if the alternator is a bosch one then its 2 screws to remove the reg from the alternator and the brushes are in there

Voltage regulator on the alternator?
i had the same fault and replaced my alternator. regulTor didnt cure fault