Balmar High Output Alternators
We installed two large, 100A Balmar alternators on the engine, both for redundancy and for maximum output and minimum engine run time.
If you are going to run a 40HP engine at anchor, you might as well let it do as much work as possible.
The refrigerator compressor is mounted in place of the standard Perkins alternator and the two alternators are mounted on custom brackets above and below. The bottom alternator mounts to the engine mount bracket.
Each alternator has a separate regulator. One connects directly to battery bank 2 which runs the inverter, and the other connects to the battery selector switch so that I can direct the charge current to bank one or two or both.
The separate engine start battery trickle charges though both a battery combiner and a battery isolator.
One of the biggest challenges with the dual alternator installation is making sure that the belts are perfectly aligned to avoid belt wear, and making sure that there is enough belt to pulley contact to avoid slippage.
Belt dressing spray is only a very temporary solution and belt slippage is the most common alternator charging problem under heavy loads.
It is important to use the best quality belts. I purchased the better quality type from Napa Truck and Auto Parts.
I purchased a second power take off pulley for the Perkins 4.108 from Foley marine.
Currently one belt drives the fresh water pump and both alternators. The second belt drives the refrigerator compressor and one alternator.
It might have been better to have one belt run the waterpump and fridge, and have the second belt run off the fridge to the two alternators. This would give better belt-pulley contact and reduce side loading on the power take off pulley and thus the front bearings and seals.
Howard [ Just Imagine ] 01-Jan-2008
Just Imagine Alternators (Technical)