Capacitors

Brooke Clarke 2010

Background
Examples of Bad Caps
Super Capacitors
    Memory
    Industrial/Commercial
    Automotive Sound
    Measuring the Capacity of a Super Capacitor
Table
Related
Links

Background

These were purchased at test subjects for the ESR Micro combined Effective Series Resistance and Capacitance meter.  I was going to put this data on that page but way too large so is here as a separate page.

The first choice was to get leaded parts to allow insertion in the ESR MIcro and the SR715.  Parts that are a few cents were ordered on tape at 100 each so in some photos you will see the tape.  The photos have been scaled so they are all 200 pixels wide, so the scale factor varies a lot, i.e. they are NOT shown in relative size.

The photos will help ID different types of caps.  More photos on the Capacitor Failure paragraph on the Hints & Tips web page.
Wiki page Capacitor plague about the bad electrolytic caps (Wiki) made around 1999 but still being used up to about 2007 and failing in 2010.

Examples of Bad Caps

These are related to using the ESR-Cap meter.

Heathkit GC-1000 Most Accurate Clock

This had nearly all the electrolytic caps bad.  It's now working great on the built-in whip antenna. 

Oven Controller

See Hints and Tips: Cold Oven Robertshaw Controller in GE Electric Oven
Two caps in the analog temperature control circuitry, both marked 4.7 uF 35 V, tested C: 000 ESR: ---.  The interesting thing is that the replacement caps, rated 4.7 uF 25 V, are larger.  This means the capacitors the factory used were faulty in that you can't get that much capacitance in that small a package with that voltage rating.

I didn't determine the working voltage of the 4-bit micro controller but expect it runs on 5 volts.  The LM324 op amp might be running as high as 32 V, but I very much doubt it, +/- 15 would be the max expected, so getting 25 V replacement caps seems to be conservative.
Bad & Good caps from Robertshaw
                GE Oven controller
The bad C1 and C17 caps were punched into a copy of the board photograph to keep track of them and then bare wires were soldered on to allow them to fit in the SR LCR meter or HP LCR fixture.  You can see that the new caps are much bigger.


Cap
WVDC
dia
mm
height
mm
pitch
mm
Old
4.7
35
4
6
1.5
New
4.7
25
5
11
2

The height needs to be short in order to allow for the relay board that's mounted directly above this board (see the Hints and Tips web page).  The replacement parts were installed laying on their sides out of general principles.   But it turned out it was required for vertical clearnace.

The volume of an electrylytic capacitor depends on both the capacitance and on the working voltage and since the new part has a lower working voltage there's a huge difference in volume. 
The SR 715 (1 kHz & 1V drive) shows the bad caps as about 20 nF (0.02 uF) not the 4.7 uF they should be and with a series resistance of about 40 k Ohms.  This is consistant with the electrolyte evaporating.  Note that total hours of use this oven has seen is probably under 10 so the problem was not heat.  But the controler board (clock) is powered 24/7/365 minus the occasional power failure.

Super Capacitors

There are three general types of super capacitors (Wiki: Capacitor).  They are also known as Double Layer Capacitors (Wiki)

Memory Hold Up Super Caps

These typically have an internal resistance that's 10 or more Ohms.  Because of the high internal resistance they're good for very low current applications, but can not be used for powering motors or other high energy applications.
See 24 and 25 below.

Commercial/Industrial Super Caps

20 Farad 2.7 Volt Kamcap
20 Farad 2.7 Volt Kamcap
Miller Solar Engine 0.35 F, 2.7V
Miller Solar
                  Engine by Solarbotics


These are typically single units and so have a breakdown voltage under three volts.
Measuring (see below) a 20 Farad 2.7 Volt capacitor by setting the HP E3617A bench top power supply for 2.5 Volts (below the 2.7 V max) and with the clip leads shorted setting the current to 0.5 Amps.

Connecting the second clip lead when the clock is at the top of a minute (23:32:00) and watching the voltage on the power supply climb.
It gets to 2.0 volts at 23:33:25, i.e. after 85 seconds.
So the total Coulombs moved is I (Amp)* t (sec)= 0.5A * 85 seconds = 42.5 CoulC = Q / V = 42.5 Coul / 2 Volts = 21.25 Farads

Automotive Audio Super Caps

These start at about 1 Farad and are rated for "12 Volt" automotive electrical systems and so can be charged.
The built-in voltmeter shows Lo from about 5 volts to 8.34 Volts then shows the voltage up to 15.9 Volts, and above that shows Hi.
The meter draws 17 ma at 16 volts, which is a large part of 100 ma, which I'm using to measure the capacitance, so for measuring the capacitance it's best to remove the meter.

It's probably also a good idea for automotive users to remove the voltmeter so that the battery will hold it's charge for a longer time.  With the voltmeter connected the cap drains very quickly, but without the meter the battery takes a few days to discharge to 9 Volts.  If the cap discharges too far it may blow a fuse in an automotive application.


1 Farad Super
                  Capacitor
1 Farad Cap
with Voltmeter removed
1 Farad Cap with Voltmeter removed



Measuring the Capacity of a Super Capacitor

The method is knows as Coulomb (Wiki) counting and is commonly used to measure battery State Of Charge (Wiki: SOC Coulomb counting).

For example for the 1 Farad Truconnex super capacitor above I started with the terminals shorted for a little while so the voltage was zero.

Then setup an HP/Agilent E3617A bench top power supply for 16.0 Volts open circuit and with the leads shorted together set the current to 100 mA.
Agilent E3617 DC Power Supply 0-60V, 0-1A
At the top of a minute I connected the power supply to the super capacitor and watched the voltage meter on the supply climb up to 14 Volts and noted the time again (it was right at 2 minutes.

The number of coulombs delivered to the capacitor is 0.1 Amps * 120 Seconds = 12 coulombs

Note:  The reason for using a current source rather than a common power supply that's close to a constant voltage source is that if a voltage source is used the current will be constantly changing to reflect the voltage difference between the fixed power supply voltage and the increasing capacitor voltage.  That makes it very hard to count the charge transfer (coulombs).

C = Q / V = 12 / 14 = 0.857 Farad

Plotting in Excell time vs. voltage and fitting a straight line that goes through 0, 0 gives the following slope & quality of fit:
Volts on the Y axis and Seconds on the X axis.

C = dQ / dV
dQ is the change in one second and since the current is 0.1 Amp that's 0.1 coulomb.
dV is the slope of the line and that's 0.0776 so:

C = 0.1 / 0.0776 = 1.288 Farads
This may be a little more accurate than basing the capacitance on a single measurement, like above.
There is a little curvature in the actual data compared to the straight line, not sure why.

Next try this with a different current to see if it results in a similar answer.


Table


Tested in # order using all the testers, then the next #.  A Lazy Susan helped.
SR 715 at left then counter clockwise Micro ESR-Cap meter, EVB ESR (only) meter, Fluke 87 DMM
Lazy Susan
        Capacitor ESR Testing setup

#
Photo Mouser p/n Type Cap Voltage $ ESR Micro  Fluke 87
EVB
SR715  HP4328
ESR Cap uf
Cap uf
ESR
R C uf
ESR
1
 Cap 01 647-UVR1C101MDD1TD Al Electrolytic
100 uf


116
102


92.65


16 0.03 1.2


1.0
1.85

1.45
2
 Cap 02 647-UVZ0J153MHD Al Electrolytic
15,000 uf

   14750 OL

   13670

6.3 1.40 0.06


0.06
.036

0.043
3
 Cap 03 647-UHM0J272MPD Al Electrolytic
2,700 uf

  2750
2944

   2594

6.3 0.34 0.06


0.07
0.018

0.025
4
 Cap 04 647-UVR1H220MDD1TA Al Electrolytic
22 uf

  23.5
20.7

   19.8

50 0.02 1.5


1.1
4.3

2.4
5
 Cap 5 647-UHD1A471MPD1TD Al Electrolytic
470 uf

  495
490

  490


10 0.08 0.09


0
0.14

0.096
6
 Cap 06 661-PSA10VB100M Al Organic Polymer 100 uf

  105
106

  103


10 0.72 0.06


0
0.34

0.078
7
 Cap 07 75-94SA226X0020CBP Al Organic Polymer 22 uf

  28.3
24.9


 24

20 1.55 0.3


0.06 1.0
0.263
8
 Cap 08 647-PLF0J471MC06 Al Organic Polymer 470 uf

  496
492

   480

6.3 1.15 0.2


0
0.02

0.0160
9
 Cap 09 598-CD15ED270J03F Mica 27 pf

  0
Note1

   27.8pf

500 0.75 ----

19.5
OL
93k

OL
10
 Cap 10 810-FK26Y5V1A226Z Multi Layer Ceramic 22 uf

  15


   14.7

10 0.34 0.22


0.01 4 Note 3
0.08
11
 Cap 11 810-FK22X7R1C226M Multi Layer Ceramic 22 uf

  25
23.3

   24.6

16 1.06 0.13


0.01
2.3

0.248
12
 Cap 12 581-NOJC107M006RWJ Niobium Oxide 100 uf

  106.8
95.0

   

6 0.67 0.16


0.24
Note2 Note2 Note2
13
 Cap 13 581-NOJB226M006 Niobium Oxide 22 uf

  32.1
27.1

 Note2  Note2

6 0.42 0.46


0.46
Note2
14
 Cap 14 581-NOJE477M004 Niobium Oxide 470 uf

  441
452

   

4 4.30 0.08


0.01
Note2 Note2 Note2
15
 Cap 15 140-PF2A472F Polyester Film 0.0047

  0
5mf

   4.78mf

100 0.51 ----


OL
368

OL
16
 Cap 16 80-MMK37.5226K250R06 Polyester Film 22 uf

  25.4
22.0

   21.9

250 5.98 0.39


0.24
0.14

0.1
17
 Cap 17 80-T520B107M4ATE35 Polymer Tantalum 100 uf

  111.8
96.5

 Note2  Note2

4
ESD
0.94 0.07


0.06
Note2
18
 Cap 18 80-T520A226M6ATE100 Polymer Tantalum 22 uf

   25.4 22.6

 Note2  Note2

6.3
ESD
0.72 0.14


0.13
Note2
19
 Cap 19 80-T520D477M004 Polymer Tantalum 470 uf

  441
439

 Note2  Note2

4
ESD
1.31 0.05


0.08
Note2
20
 Cap 20 871-B32676E3226K Polypropylene 22 uf

  25.6
22.23

   22.12

300 10.85 0.12


0.03
-0.004

0.14
21
 Cap 21 505-FKP233/1000/5 Polypropylene 33 pf

  0
Note1
 Note2  Note2

1000 0.49 ----


OL
OL
22
 Cap 22 581-TAP226K016CRW Solid Tantalum 22 uf

  26.1
22.6

   22.1

16 0.53 0.48


0.43
1.4

0.76
23
 Cap 23 71-597D477X0004V2T Solid Tantalum 470 uf

  495
486

 Note2  Note2

4
ESD
1.45 0.05


0.15
Note2
24
 Cap 24 598-EDLSG105V5R5C Supercapacitor 1 f

 
OL

 Note2  Note2

5.5 2.94 6.5


7.5
7.2
25
 Cap 25
581-BZ015B603ZLB Supercapacitor 60 mf

  R ONLY
OL

 Note2  Note2

5.5 14.42 0.12


0.29
0.097
26
Cap 26
FRS CGC-10
Computer Grade
90,000



R ONLY OL

98030




10
1.75
0.03


0.02
.
-0.0025
0.0165
27
Cap 27
FRS MC-3.3
Polypropylene
3.3



3.9
3.41

3.4108




400
2.00
0.51


0.52

0.050
0.78
28
Cap 28
FRS OMB1MFD
Orange Coating
1.0



1.2
1.006

1.0040




630
1.96
2.0


1.7

2.77
4.2

Cap29
647-UKL1E4R7KDDANA Al Electrolytic
4.7







4.7



25





3.3


Note 1 The Fluke 87 has trouble measuring the capactiance of parts in the pf range because it's difficult to get a repeatable delta to zero the meter.  A plug in axial capacitor fixture might solve that problem.
Note 2 the Stanford Research 715 is fixtured for axial lead parts only, SMT and supercaps do not fit.
Note 3 Multi Layer Ceramic Caps (MLCC) have frequency dependent capacitance and series resistance on the SR 715.
Note 4 FRS is Fair Radio Sales

Related


ESR-Cap meter -
EVB ESR Meter - Modified for testing Batteries
Fluke 87V DMM -has Capactiance test capability
HP 4260A Universal Bridge
HP 4328A Milliohmmeter
HP 4332 LCR Meter
Marconi TF-2700 Universal Bridge
Stanford Research 715 LCR Meter
ZM-11/U Capactance-Inductance-Resistance Bridge
Test Equipment

Links

Back to Brooke's Home, Test Equipment, Products for Sale, Military Information web pages.
[an error occurred while processing this directive] Page created 11 Mar 2010.