Quote:
Originally Posted by cts_casemod
Why not use the ubiquitous TL431 with a 100Ohm series resistor for the same effort/cost, and much better regulation?
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I wasn't familiar with this low cost solution as I rarely tinker with electronics. Seems a superior solution to me. No satisfying light though! I've had LEDs stay lit for months on a fully charged cap bank.
What package TL431 would you recommend? If I wanted the activation voltage at 2.9v, what would I need to do?
Quote:
Originally Posted by freddyzdead
...the reason red LEDs aren't much good is a typical red one will start conducting at about 1.7 volts and less than 1 milliamp, which is negligible for this purpose...
Looks like I don't really need the capacitors, but I will put them in anyway. It has to make life easier for the battery, I think. I will update when they arrive.
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I used LEDs because I already had a bunch on hand, along with the diodes necessary to solder in series to get the activation voltage close to where it needs to be. This is a proven effective solution, and common due to how cheap and easy it is to implement.
You probably don't need the caps, but what is the burst (short duration) C rating for your battery? I've thought about wiring in a low ohm power resistor to limit battery output. It would put the demands of starting on the caps, but allow the battery to keep them topped up when the vehicle is off.
Perhaps not an issue in Australia, but LiFePO4 is not rated to accept a charge below 0 C. The LiFePO4 in my Prius is inside the cabin where it is significantly protected from freezing.