Capacitors in Series

I did two (2) experiments with a 20V DC power supply and 4 capacitors in series. All series connections were checked to insure proper polarity.

Experiment with four (4) 22uF 16V tantalum capacitors:

20V-------(+) C1 (-) ----- (+) C2 (-) ----- (+) C3 (-) ----- (+) C4 (-) ----- GND
The voltage across each capacitor was 5 volts as expected.

However, when I did the same experiment with four (4) uxcell aluminum electrolytic capacitors 22uF 100V the results are different.
The voltage across the capacitors C1 through C4 respectively is 10.1, 6.6, 2.2, 1.2 volts. Looking for an explanation. Thanks.
 
The capacitors have different leakage current. The one with 1.2V is leaky.
Put a resistor across each cap. The resistors will make a voltage divider so each has 1/4 of the voltage.

There is also a chance the capacitance is not equal. If the bottom cap=47uF and the top cap = 10uF the circuit will not power up with a balance on the caps.
 
Ron thanks for the reply. Adding the resistors was going to be my next step but I wanted to avoid the power loss. I did test the capacitors with my ELC prior to the experiment and didn't notice any leakage problems but I will double check and try again. Just curious to see if I can get a more reasonable result. Thanks for the quick response.
 
The capacitors have different leakage current. The one with 1.2V is leaky.
Put a resistor across each cap. The resistors will make a voltage divider so each has 1/4 of the voltage.

There is also a chance the capacitance is not equal. If the bottom cap=47uF and the top cap = 10uF the circuit will not power up with a balance on the caps.
Thanks for the advice. Yes all the capacitors were of the same value. However I did get 4 new capacitors from the same bin; same values, manu., etc and did the experiment again. Much better results. I then started replacing C4 with the 4 capacitors from the previous experiment and found 2 that do appear to be significantly different in leakage. Thanks for the advice.
 
Top