[changzuki]

Originally Posted by BobS

CrazyJerry,
Wow, what a great part-by-part system analysis. Are you retired or just don't bother with sleep, anymore? If you don't mind, a couple of questions:
1. With an alternator cutoff switch, the alternator rotor is still engine-driven. Could a switch-driven clutch like the AC compressor clutch reduce the load on the belt even further (and the relays then could be replaced by a diode bank)? Would this be of advantage?
2. Have you seen Lasersaber on Youtube? He has replaced his car battery with 6 supercapacitors and a very small battery. With your minimal draw, you may be able to
get by with an even lighter setup than his, maybe 1/2 lb. If you haven't seen his video, Youtube the words "boost pack".
Looking forward to much more of your analysis.
BobS

@ BobS,
From the lengthy reply to your earlier question about the above, I wanted to add another thought.
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Lithium (lifepo4 such as what I have) would lend itself better to your suggestion of the AC clutch/alternator on/off setup than lead-acid chemistry. Reason being is lead acid prefers a bulk charge to a point, then a float charge to fully charge. Failure to do this over time can result in shorter battery life.. Lithium has greater charge efficiency and lends itself well to accepting a steady charge - or pulse for x-minutes charge cycles - until full, then the charge unit can and should be shut off.
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Also, the Lithium discharge voltage is more stable over time than lead acid. So generally speaking there's less fluctuation between the highs voltages and the low voltages. Some of the more sensitive electronics that are less tolerant to voltage swings will fare better over the long haul from the steadier flat discharge voltage of the lithiums...
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Ok, that's a bit off course but is relevant to supporting the idea of an on-off type system where an AC compressor clutch might be used to engage an alternator to charge a battery, then disconnect it in light of fuel savings while at the same time, preserving the lifespan of a battery,. System will be disappointing if it means replacing a lead acid battery prematurely due to sulfation; inadequate charging of a lead acid battery...
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~CrazyJerry