It's been suggested to me recently that putting a bigger alternator on an Atomic 4 is asking for trouble because the crank is only supported by two main bearings (front and back with nothing in the middle), and the additional side load on the crank will cause stresses on it which will likely cause it to fail in the long unsupported middle section.

I've just put a 70A Balmar (the 621) on to support the bigger house bank required for a new refrigeration installation this past offseason, and I know I can jumper the temperature control on the regulator to reduce the alternator output, but that would be a shame, given that a major reason for putting it on (aside from 3-stage charging) is in response to the rule of thumb that alternator capacity should be 25% of the bank's Ah rating.

I haven't been able to find a cutaway drawing of the A4 to check out the bearing story.

Can you comment?

Thanks.