In that case, I'd probably take the easy way and just string enough 1N4001 diodes in series to drop the excess voltage.
With wall warts, the poor regulation of the old iron cored type is better for charging lead acid - a tight regulated SMPSU type will either give too much voltage or too little.
With wall warts, the poor regulation of the old iron cored type is better for charging lead acid - a tight regulated SMPSU type will either give too much voltage or too little.