Originally Posted by salim
If the alternator puts out 220amps, and the van's engine uses 30amps. Then the Cabin's battery can take up to 190amps from the alternator. These numbers are from Fitz' posts a few years ago. The engine's battery has a 150amp fuse to the BIM for charging the cabin's battery. This was the fuse that I photographed earlier in the posts. I should be blowing this fuse every time I charge with the alternator. So what am I missing?
Thanks again for the collective wisdom.
So the chances of your alternator actually putting out the full load would be unusual, it would be dependent on a large battery bank, and high depth of discharge. The area where most damage is done to the alternator is at idle conditions, particularly start and stop in hot conditions. The output of alternator at idle with Lithium is more current than it was designed to cool.
The bigger issue, is over charging your lithium battery, especially if your alternator has a high voltage output. Once charged fully Lithium needs to have the charge turned off, or go down to a reasonable float voltage. So the BIM will ensure that you don't overcharge the battery, and also disconnects periodically during it's charge cycle. The other common method would be to use a DC to DC charger, that again monitor voltage, the current can be regulated ( either programmatically or by size of the unit).
Another method that is being used is to use an inverter hooked up to alternator Van battery and provide a secondary AC input to your Shore power charger. So you would supply enough AC power to run the charger in your inverter/charger such as a Magnum which is fully capable of being programmed for lithium batteries. This method can work really well with larger output alternators, where you are not worried about conversion lose. This is used a lot in the Transit world, commonly referred to as the Orton method.