Quote:
Originally Posted by Isaac Zackary
First, why not hook the caps directly to the starter, but put some resistance between it and the alternator (and any battery). That way you get full power to your starter, but the caps don't put a strain on your alternator.
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I put a power resistor in series with a LiFePO4 battery and my supercap to prevent the cap from trying to charge it too quickly when the battery voltage drops relative to the cap. Essentially I was preventing the alternator from trying to charge it too quickly. I figured the small battery could drop as low as 10v after supplying a parasitic load for some time, and I didn't want the alternator exceeding the charging limits.
I'm still not convinced the alternator needs to be protected from the demands put on it by a supercap. I'll take some measurements and report back here, but it'll be a couple weeks since I'm working 12hr shifts the next 8 days.
In other news, the Acura sat for several weeks and the battery was dead when my wife went to start it. I'm kinda hoping it won't recover so I can replace it with supercaps! However, even with 5x 3400 Farad caps in series, my spreadsheet is telling me that the 21.5 mA parasitic draw will only allow me to park for 1.5 days before I risk no longer being able to start. That means I'll have to get a small battery of some sort. I'm certainly not buying another Pb battery.