Do you remember what problems you heard about the restart batteries? They sell it as a direct replacement they guarantee to work with any unmodified charging system. I haven't had any issues at all yet and the car has started after just sitting for several days but I'm not sure what I would be looking for other than a no start condition. All the electronics in the car are working the same as they always have. Both batteries are class H6. Maybe some people weren't charging them before install per the directions or using the wrong charger damaging the battery. The owner's manual for both the battery and the car itself are very particular about the way this install is performed and I'm sure plenty of people skip the directions being it's just a battery swap. Some people buy smaller ones but then you need to build brackets or secure it in some other fashion. I'm keeping the lead acid battery to test other electronics and as a backup.
