I have some 6v / 4 AH rechargeable batteries. I'm asking about the proper specifications that should exist in an electrical generator to recharge them.
See if you can find a datasheet from the battery manufacturer, they should have some charging spec. especially for the maximum initial current.
Typically the recharge current is 0.1x discharge spec. (4ah/10 =400ma), you could recharge at a higher rate but this would assume some loss in battery life may occur.
I'm asking about the proper specifications that should exist in an electrical generator to recharge them.
Do you want to recharge these with a small rotating generator/alternator.
To recharge properly you need to:...
Not exceed maximum recharge current spec.
Monitor battery voltage & terminate recharge when battery voltage reaches that specified by the manufacturer (typically 7.1V for 6V) This is for cyclic use ie: charge, use, recharge....
For float use, the battery voltage should be typically 6.75V