My plan is now to disconnect the broken 24VDC alternator to ensure that it cannot cause any problems to my new battery bank. Then I’ll use a 12VDC to 24VDC charger to use my small 200Ah 12VDC house bank to charge the big 700Ah 24VDC bank. The 12V alternator will supply the power when the engine is running.
The downside is that my 24V system has the fridge, freezer and inverter hooked up to it, so the charging current isn’t much more than the normal demands during the day; but it will be enough to allow me to get to St. Lucia without draining the system.
It was hot and humid when I worked on accessing the back of the alternator, but I’ve got practice in removing the galley contents and shelving, so the job went relatively quickly.
I already had a 24V – 12V Orion charger in place and wired up, so it was a quick job to replace the original unit with the new to make the charge go the other direction.
By the early afternoon I’d gotten everything finished and fired up the engine to assist in charging. It worked right away, but as expected the net effect was just a small charge. At least it will stop excessive battery drain while underway.