Batteries

what's the difference main between 2ah and 3ah batteries?
Is it worth the extra cost?

The ah rating is the capacity of the battery. Thus a 3ah battery will have 1.5 times the capacity of a 2ah battery ( and last 1.5 times as long powering the same circuit before it goes dead).

Only you can determine if the extra capacity is worth the extra price.

Thanks Carl, perhaps obvious to some but the questions are only easy when you know the answer. Thanks again, Ian

And, due to Economy of Scale, 3 A-h should cost slightly less than 3/2 of 2 A-h.

If the current discharge is high and depending on the chemistry of the battery you're talking about a 3AH battery will last more than 1.5 times as long as a 2AH battery. It really depends on the battery chemistry you're using, how much current you're drawing, how long you need it to last, and what the cost per AH of the batteries are to determine if it's worth it or not.