Is there any disadvantage using an 18V 2A transformer with an adjustable DC-DC buck converter(link below) to charge a 12v 7Ah battery ?
I know that the charging current must not exceed C/10 (700mA here) and maximum voltage per cell shouldn't exceed 2.4V .
I guess the amount of current flowing into the battery should be proportional to the voltage difference between the charger and the battery. So i am planning to charge with a lower voltage initially like 13.6 V and gradually increase the to 14.1 V during the course of charging.
The Reasons for considering DC-DC buck converter is it's low cost and high efficiency. Lead acid battery chargers available here cost anywhere around 4 to 10 times more than this setup.