I am thinking of switching out my factory alternator on my Perkins 4-108 for a high output Balmar to increase my charging efficiency. I have a decent refrig/freezer and but not a lot of other energy hogs on board and was wondering if anyone has any experience with mounting issues, pulley problems or engine issues.

I'm very late to this but I'll comment anyway, someone might find it useful. I put a 140amp (non-balmar) alternator in about 10 years ago and I've been thinking of replacing it with something smaller. I cannot keep belts on it, they're chewed up in less than an oil change interval. I have tried all sorts of high power belts but nothing has worked. I have a 2kw honda generator and am putting in a 60amp charger to recharge on the hook rather than using the engine. For weekending the engine driven charger works best but for long stays it's a poor use of engine hours.

That said, TAD Diesels has a serpentine belt retrofit for Perkins engines that sells for about $500 and includes new fresh water pump, crank pulley and alternator pulley. http://www.tadiesels.com/serpentine_4108.html