How do you buy a trickle charger---or a float charger---to match you battery? Mine is 12 v 520 A/100 min. Thanks

Doug

 

You don't or shouldn't need to match a trickle charger to a battery.
If you want to keep the battery charge maintained if the car sits for extended time then get a good quality trickle charger that will charge up to 4 amps and slow the charge when the battery is fully charged.