There are newer Lithium Ion Capacitor (LICs), with higher voltage than the 3.8V LICs I had tested before. Manufacturer Cda calls the 4V variant the LIB series and it ranges from 200 to 1100F. And I recently ordered 4.2V LICs that are 350F and an 1300F. I compared capacity, ESR and leakage current of 5 large LICs. To test capacitance I used my electronic load to discharge them at a constant 750mA down to 2.5V and I could read the capacity (mAh) from the display. I converted LIC specified capacitance (farad) to capacity (mAh) using the formula Q= C * V / 3.6. 

To measure the leakage I measured the voltage decay over the days with a bench multimeter. After 72 hours I calculated leakage using the formula I(A)=C(farad)*(yesterdaysvoltage[V]-todaysvoltage[V])/t[s]

	BT LIC-H-1840	Cda LIB1840Q4R0118	Cda LIB1330Q4R0357	Cda LIC1840Q3R8757	Vinatech VEL13353R8257G
Capacitance  specified (F)	1300F 4.2V	1100F 4.0V	350F 4.0V	750F 3.8V	250F 3.8V
Calculated capacity (mAh)	613mAh	458 mAh	145 mAh	270 mAh	90 mAh
Measured capacity (mAh)	668 mAh	550 mAh	136 mAh	273 mAh	96 mAh
diameter, length (mm)	18,40	18,40	13,30	18,40	13,35
ESR specified	90 milliohm	65 milliohm	100 milliohm	60 milliohm	100 milliohm
leakage specified	-	23 uA	4uA	23 uA	5 uA
leakage measured >72h	31uA	11uA	4uA	13uA	5uA
Price	€10.29 qty1	€8.61 qty1	€5.67 qty1	€8.46 qty1	€6.76 qty1

Conclusion: The capacitance is amazing and the leakage of the Cda and Vinatech is low enough for very low power applications. I definitely recommend using these.