SuperCap PS
SuperCap
Using this cap: Nesscap 2.7V 360F PN ESHSR-0360C0-002R7A
Alternative is BCAP0360 P270 S18
https://www.tecategroup.com/products/ultracapacitors/ultracapacitor-FAQ.php
Passive Balancing: One technique to compensate for variations in parallel resistance is to place a same valued bypass resistor in parallel with each cell, sized to dominate the total cell leakage current. This effectively reduces the variation of equivalent parallel resistance between the cells which is responsible for the leakage current. For example, if the cells have an average leakage current of 10uA +/- 3uA, a 1% resistor which will bypass 100uA may be a good choice. By using this resistor in parallel to each cell the average leakage current is now 110uA +/- 4uA. Introduction of this resistor has now decreased the variation in leakage current from 30% to 3.6%.
Need to add a balancing resistor in parallel with each cap, so can put it across the terminals
Leakage is .75ma Note that alternate BCAP0360 P270 S18 has same leakage
Aim for around 7.5ma or 0.0075 a with balancing resistors
For a 3.3V power supply, each cap sees 3.3/2 = 1.65V
v=ir r =v/i = 1.65/.0075 = 220 ohm T
power =v*i = 0.0124w so can use any size resistor.
his is max recommended resistance. Can go smaller. Smaller will equalize voltage faster which is better. Disadvantage is higher power and higher current.
If use 1000 ohm resistor, i = 1.65/1000=.00165 a =1.65ma p = .0027w
If use 100 ohm resistor, i = 1.65/100=.0165 a =16.5ma p = .027w
if 75 ohm resistors, i = 1.65/75=.022 a = 22ma p = 0.036w
if 50 ohm resistors, i = 1.65/50=.033 a = 33ma p = 0.054w
For a 5V power supply, each cap sees 2.5V
r = 2.5/.0075=333 ohm
p = .019 w
5v ps for SBC
http://www.reuk.co.uk/wordpress/electric-circuit/lm317-current-calculator/
for 750ma, 1.7ohm 1w resistor
for 500ma, 2.5 Ohms >0.63 Watts
Using a Jameco linear walwart for +5VDC
168605 DDU050100H4660 TRANS,WALL,REG,LIN,5VDC/1000mA F2,2.5mm X 5.5mm,UL/CUL