New alternator/starter for Perkins 7.5KW generator

[LeoKa]

My electrician has suggested to replace the existing starter/generator (15A) with a larger one, to have it as a backup. He installed a battery charger/combiner for my two battery banks, so they can be charged from the main engine's alternator (160A). He wants to have the generator's alternator as a backup charger. Anyone knows this old Perkins diesel generator and can suggest a new alternator for it?
See photos.

 

[LeoKa]

The pictures

 

[Ski in NC]

If you have the generator running, just charge the battery with AC powered charger. No need for an alternator.

 

[LeoKa]

If you have the generator running, just charge the battery with AC powered charger. No need for an alternator.

Understand. I do charge the batteries from the main engine, but I want to have an extra option (backup) from the generator for emergencies.

 

[dimer2]

What I think Ski means is that your generator is already producing 120V. Use a regular 120v charger on whatever 'emergency' that requires a charge. Leave the alternator as is to take care of the generator battery.