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1
New update after 2 years and 5 months in Use.

I made today internal resistance measurements of four from eight batteries.
 
News are so and so.
Batteries when-new they did measure 19 to 20 milliohm its one.

Now batteries started aging and internal resistance this increased but differently from cell to cell, and imagine that those cells operate always as team of four.
This translates that any amount of use or abuse, this is equal to all.

According to my own batteries naming:
M8 = 28 Milli ohm     
M7 = 29 Milli ohm
M6 = 22 Milli ohm
M5 = 24 Milli ohm

Measurement was taken with cells fully charged.

Now according my experiences so at about 45 Milli ohm its cell would have lost 50% of capacity.
2
While arrival of my load PCB this can take several days, I am feeling allot of enthusiasm about this project !

In my planning this is to create one high quality enclosure for this PCB, and professional grade cables and connectors for it.
For example I just discovered one pair of Kelvin type clips designed for battery Lead Acid, this usable for very small ( 7Ah ) up to larger ones.
And interestingly enough front jaws design, are flat and look good even for LCR use and even components testing.

With such clips at hand, I will make one foolproof set of cables, this will use 4 wires connectivity, and will be 100% safe regarding short circuit accidents.
 
http://www.ebay.com/sch/m.html?_odkw=&_ssn=mxqtech&item=301697783899&_osacat=0&ssPageName=STRK%3AMEBIDX%3AIT&_from=R40&_trksid=p2046732.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=100A+Crocodile+Alligator&_sacat=0 

I liked them that much and got three pairs.  8)

Speaking of output connections :
No rule forbids having in your enclosure in parallel connections of  both.
Banana binding post ( 2 x 20A & 2 x 5A female) among with 4Pin Male & Female Panel Chassis ( for  battery type Kelvin clips ) 
 
3
Here I am starting to explore LED display components.

Three digits LED this is SP420361N   1534   0.56 inch

Four digits LED this is SR420361N 1549

http://www.arkled.net/

The all idea, this is if I can find compatible with a larger dimensions this to be replaced.
4
For DIY printed labels I just discovered A4 Self Adhesive Glossy Photo Inkjet Paper.

I did order some so to try it.

http://www.ebay.com/sch/m.html?_odkw=&_ssn=digiextras_uk&item=371201071186&_osacat=0&ssPageName=STRK%3AMEBIDX%3AIT&_from=R40&_trksid=p2046732.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=A4+Self+Adhesive+Glossy+Photo+Inkjet+&_sacat=0

It comes with hard to believe specifications: Anti Smudge and Water Resistant
5
New PSU this is now tested and ready for delivery.  :)
My own friend and customer he did fall in love with it, design and quality far from his own expectations. 8)

My first ever made one, I did it at age of 21 years old, with minimum use of specialized tools.
If recent version this looking significantly better as build, this is due advanced craftsmanship skills, that no copycat can have or buy.


Last pictures:
a) New 20Kg of electrical power
b) The artist ... with 30 Celsius indoor at night.  ;) (June 23 2017)
   

6
HIOKI RM3542A Resistance Meter this is a tool that I am aware that with out it I would be blind in the world of resistors.  ;)

Recently I made a power supply for a friend with eight power transistors connected in parallel.
Therefore I was forced to buy several 5W 0.1R ( we called them as cement type) in Greece.
By having around HIOKI RM3542A this become a great opportunity to actually measure and make a conclusion of specific resistors tolerance by %, as this is usually not labeled any more.
In past two decades most such resistors were  labeled as 5% or 10%.

Twenty years later that manufacturing technology supposedly become more precise, now they do not label in full such resistors.

Now lets see what I got speaking of measurements of twelve resistors.

HIOKI RM3542A set at measuring range of 100 milliohm , and comparator system set at 1% (+/_)

Resistor value  ......  comparator  Value
   
99.1073  ....   - 0.983
99.0805  ....   - 0.919
100.2165 ....  + 0.226
99.5548  ....   - 0.455

97.9256  ....  - 2.074
100.0870 .... + 0.087
99.2508   ....  - 0.749
97.6602  ....  - 2.340

100.0140 ....  + 0.014
98.1107  ....  -  1.889
99.9268  ....  - 0.073
99.7705  ....  - 0.229 

I do not know how to react speaking of conclusion.
Should I be happy ? That this factory aiming for  0.5% tolerance on average.
Should I get mad ?  Because production quality this is far from be stable.

Another mystery with specific resistors this is their wattage, version of 22 Ohm resistors from this factory was unable to tolerate equal wattage with resistors made at 90s,  and new resistors got up to 100 Celsius right away, and due wattage limitation they caused huge output voltage sag over load condition.

New resistors was indeed selected to match actual transistor specifications, and they do not get hot at all.

My thoughts now are that precision in resistance manufacturing this also influenced wattage, and this also become more precise,  this now translates that hobbyist makers are in higher risk of watching resistors to get in flames,  when they will do wrong parts selection.

Professional electronics engineers they have modern tools, and parts selection will be precise.
And in case that an electronic part this fails, then it is a manufacturer fault.

Conclusion
Within 2017 precision this is all around us.
And your measuring gear this must be equally precise according to electronic spare parts that you are going to work with.
Low Ohm measurements this is a job for measuring equipment which they have lower measuring range, this be close to measuring value.
   
 

   
7
DC voltage precision sources are expensive items.
When you are planning to use them with external power due a battery source, then reverse polarity protection this is a must have.

My choice this is LT1021-10 from Linear Technology Corporation.
Linear Technology does not mention what will happens to their chip in case of reverse polarity incident.

Better safe than sorry, and here is most simple solution as reverse polarity protection.
1) Fuse Box with 0.5A fuse
2) Any diode this can handle 5A load.

In case of accident 0.5A fuse this will be destroyed and voltage will be disrupted.  ;)
 
8
This is a very nice question that mostly hobbyists will ask when they come close to some sort of measuring secondary standard.

How do you measure drifts of the order of 1ppm/year?

First of a few glossary explanations.
Your new and made by high precision electronic part, this is called at it best as secondary standard.
True measuring standards are stored and locked in vaults.

ppm this translates to part per million. 

One secondary standard with 1ppm change per year this translate to:
1V
Displayed as 1.000.000 at the screen of a multimeter with one million counts resolution.
This will change to  0.999.999  or  1.000.001 

Therefore which out you having invest buying one such high counts multimeter or voltmeter, there is no chance so you to measure such low ppm differences.

Now lets assume that you do own one such high counts measuring device, and this is was not calibrated (inspected) in past two months, them again it is not possible the measurement that you will do to be spot on.
Measuring equipment they also drift internally,  and such meters they should pass calibration inspection more frequently (three times per year).   
 
In the world of handheld multimeter, with resolution of  30.000 or 50.000 counts there is no chance to see small ppm changes.

At 50.000 counts display, when change of ppm this is large enough to form a number of ppt ( part per thousands) then it could be measurable by a handheld multimeter.   
 
For safe measurements at the range of 1ppm, even one million counts DMM this is not enough.
DC Volt measurements or resistor measurements at over one million display resolution this is a huge challenge and a job for dedicated measuring equipment.   
This could be an ultra high resolution resistors meter, or alternatively one high resolution DC volt meter.


Now it is time for me to break down the cost of such equipment in relation to thousands of dollar or Euro, for you.

I am aware of three highest counts multimeter in the market.
Retail prices of 10.000E up to 12.000E

Dedicated DC volt meter at such high counts I assume retail price of 3.500E
Dedicated resistors meter also at such high counts this it does have also 3.500E retail price.

Now think of law of ohm and make a new calculation.
R + V + I = 3 x 3.500 Euro = 10.500 Euro  ....  here is your total to pay for getting an high precision + high resolution multimeter, at your home.   

Prices it could or not include VAT  ;D
9
Insulated  Terminals Crimp Connector this looking simple in product design, but there is a secret this separating "Good quality" ones from those made from inexperienced factories.

One picture equals to 1000 words, therefore take a good look of machined part this is inside the barrel, this formed with attention to detail, so this to prevent cable from moving.
Professional electricians are aware, that we do leave over the striped copper our own oil residue this produced by our own hands.
Such a well made type of Insulated  Terminals Crimp Connector, they are worth our money, if you do care for 100% perfect workmanship and materials.
10
I did a great find  8)   some one from Latin America he did a chart of  60W Electronic Load ZPB30A1 V2.6 and he record Ampere output per its volts setting.
I am going to do the same for this 110W product version, and this comparison will be of great interest for many people.  ;)


According to 60W Electronic Load ZPB30A1 V2.6 electrical accuracy specifications are:

Maximum capacity test error :
0.5A 2.5%
2A 1.5%
5A and above 1.2%

Voltage measurement error :
1% + - 0.02V

Changes Log for 110W :
New Delta high speed dual bearing fan
Higher cooling redundancy
More suitable for long hours !


I am professional electrician, I have the awareness that a better performing DC fan, this change it does also changing DC power supply requirements for the new 110W circuitry.
ZHIYU maker always advice PSU for 60W PCB circuit this to be at  0.5A of greater.
An higher performing DC fan will require higher energy consumption.
Therefore and possibly, for 110W model, required power supply this would be 1A as minimum requirement.
   
Best power supply for stable operation of ZPB30A1 in all conditions of operation, this is something that I am going to explore too.

According to DELTA DC fan website, AFB 50x50x20 series comes in four versions at 12V DC:

RPM  ---------- Consumption in Ampere

4000 = 0.06

4800 = 0.07

5600 = 0.10

6400 =  0.14

7400=  0.16

Inrush current this is triple at start up. 
Therefore just for correct operation of DC fan, 0.5 A this is required for the fan alone.   
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