CTEK 25000 is a better choice if you need to float charge all three connected parallel. It is better to charge them individually until they are fully charged and then maintain with float charging on parallel connection. The reason for not to bulk charge them together is, it can cause high energy transfer from the battery with higher residual voltage to the battery with low voltage. This is detrimental to all batteries with differing pre-charge voltages. The exception is when all three are connected permanently in your application. 7002 will max out at 225ah, for float charging and therefore fall short of charging all three together (330ah). I hope this will answer your concern.