If your car's instrument panel includes an
, it will tell you how well the charging system is working - the difference between the
going into the
and the power being used from it.
are powerful enough to cope with the demand for
a modern car's electrics, but dynamos often are not. So if your car has a
dynamo, and its output is inadequate, it makes sense to swap a dynamo for an
When you have tested the charging system of a car fitted with an
, and the checks in
How to test a car battery
point to a fault in the
, make sure that you need to replace it. The fault may be elsewhere.