What is the alternator pulley ratio ? If it is 2:1, that will give you 1300rpm on the alternator at the 650 engine rpm. A 3:1 ratio would be 1950 rpm.
I haven't received my alternator yet (it looks like it's going to be delivered today but DHL is handling it so even though it's at the facility 10 miles away from my house, I should proably get it by mid April sometime) and it doesn't come with a pulley.
I was trying to figure out what size pully to put on it.
Using the equation: generator pully size = (engine pully size * engine RPM)/generator RPM
I can change the pully size by determining what RPM the engine and the alternator should run at.
Originally, my uneducated instincts told me to max the RPM of the alternator to its highest comfortable RPM (6000 RPM) to output the 175 Amps. I wanted the largest pulley I could put on it (to avoid slippage) so using the engine stats of RPM = 650 (that's highest comfortable engine RPM) and Flywheel = 24" and alternator RPM of 6000, my pulley size is 2.6 inches (pretty small don't you think?).
You said you planned charging from 50 percent to 80 percent on a daily basis. That would be about 252AH daily, or 4.2 hours at a 60amp rate.
I can see where you got the 4.2 hours (252/60) but I'm not sure where you got the 252AH. I plan on using 4 Trojan 420AH batteries which is a total of 1680AH. I discharge to 50% (when the batteries reach 840AH). I need to bring the batteries up to 80% of their capacity (1344AH). To do so means that I need to charge 1344 - 840 AH = 504AH. 504/60 is 8.4 hours.
Please let me know if I'm way off the mark here or if I've misunderstood where you are coming from.
Acutally this is all very encouraging because this means I can significantly increase my pulley size along with my comfort level. If I drop the alternator RPM's down to 2000 (which, according to the specs, generates 140 Amps), I can put about an 8" pulley on the alternator (and have the engine run at 650RPM).
This also means that I can charge 540AH in slightly less than 4 hours. Or, up the alternator RPMS to 3000, put a 5.2" pulley on it and generate 160 Amps which would charge the 540AH in around 3 hours. I'm getting the alternater RPM's and Amp output from the Leece Neville spec chart for that alternator.
I would set the engine at a good rpm (to deliver the bulk amperage I wanted) and let it run until the amps start dropping off, then you can lower the engine rpm.
OK. Now here is where I hit a roadblock -- what instrument would I use to monitor the the amperage going into the battery pack? Also, what instrument would I use to monitor the battery usage (an e-meter?)?
If I were going to hook up a charge controller, I would want to disable or remove the electronic regulator on the alternator. I would probably use a rheostat to let me control the alternator output.
Now this is kind of beyond my knowlege and abilities. I'd like to learn how to do something like this, but it looks like I'd need to spend more time learning electronics.
So let's say I go the route of alternator direct to the battery pack. How would I equalize the battery pack and bring it up to 100%? Would that simply be running the engine alternator for a longer period of time until the pack came up to 100%?
Thanks so much for spending time answering my questions. I really appreciate it.
Phil