Hi D,
This Should I use the AGM mode of my Bosch C3 charger? - Technical Area / Electrics & ICE - MX-5 Owners Club Forum (mx5oc.co.uk) has lots on charging.
This Service Information (kuppol.ru) is particularly interesting.
I and a friend are using older smart chargers without any apparent problem. I suspect that if the battery became discharged you would have trouble reviving it without the fancy Mazda chargers that are specifically designed for these and charge the battery with constant current and high voltage.
