A dynamo??? I am sort of a novice, how is this different from an alternator?
14.5 amps seems kinda low. Most tractor manufacturers have 40 amp alternators for this horsepower range. Then again, the "dynamo" may be altogether different.
Kubota B2710, IH TD6-62 dozer with Drott 4n1 bucket loader
Technically, a dynamo (or generator) works just a like a motor in reverse. A coil is made to rotate in a magnetic field. A voltage is induced in the coil. The induced voltage produces a current in the coil. Slip rings and brushes are used to carry the current from the coil to an external circuit which charges the battery. An external voltage regulator is also used.
They are inexpensive to produce and for the range of output needed for small CUTs it is the perfect solution. Kubota uses them on all B and BX series tractors. Grand-L and L-series tractors and above have alternators. 14.5 amps is enough to operate two 55w lights with a little left over to spare.
The alternator upgrade essentially removes the dynamo and disconnects the voltage regulator (it's under the dash and hard to get at) and replaces them with an alternator.