Robbob2112 Answer thread

[robbob2112]

Anatomy of a MCCB - this one was $36 on aliexpress


With the cover off.


The arc chutes, 1/2" wide and 1.25" tall




Where the arc chutes go.


Very good quality and I wouldn't hesitate to trust it as a switch.

Below are some additional brands

Top quality is TOMZN closely followed by TAIXI.... then the ZOII but it doesn't have lubricant at the moving points... and the BAOYI in a distant last place.... CHINTZ comes in below the TAIXI and TOMZN but higher than the ZOII





All of the ones I have in my possession are marked for line/load in one way or the other --- they are polarized..... This tracks with only having arc chutes at one end...

the big 4-pole breaker on the left also includes a 24v remote trip relay so it can be controlled by a dry contact off an inverter or code red or cerbo GX box....

The Baoyi seems to be made from much lower quality parts, the top/bottom shell don't mate up totally evenly and it wouldn't surprise me if it came from the reject pile and was sold then relabeled.
The ZoII seems a bit better quality but lacks lubricant inside it so to me that means it might not trip at the rated current if there is corrosion present.

The Taixi and the TOMZN are both really good quality inside and out -- DiH00l (note that is zero zero verse 'o' 'o') -- is the same parent company as Taixi ...

I checked with a file and all of them have tin plated copper where the bolts go in.... I went deep enough to get through the plating when checking since a lot of the fake bus bars out there are brass that is copper then nickel plated. When plating brass nickel makes a dull pitted finish if you don't first plate it with copper.

I got the Taixi and TOMNZ off AliExpress and the other two came from Temu -- which tracks because a lot of the stuff I have gotten from Temu is marginal quality where from Aliexpress I seem to get exactly what I order.

My preferred brand is the TOMZN black version -- it has the highest AIC of the bunch

 

[robbob2112]

Seems like I am always looking these up to answer questions

NEC Ampacity table
Wire ampacity tables -- original PDFs attached where possible






Windy Nation ampacity table for welding wire - NOT UL listed





DLO cable - fine stranded - UL listed




abyc cable chart attached

 

[robbob2112]

Design for backup of an oxygen concentrator - 400w draw


The math - note this excludes conversion losses -

Here is some more math and a very reliable but self built unit design with links - The total cost is around $2200 without the MPPT.

NOTE - this can be done with cheaper components and cut $600ish - but reliability may be affected. Cheaper batteries save $300, Cheaper inverter save $200, $100ish


400w * 12hr = 4800Whrs * 1.25 for extra just in case = 6000Whrs - that is an expensive solar generator.


12.8v * 300ah = 3840 -- so need two of them
12.8v * 300ah * 2 = 7680Whrs

7680Whrs / 400watts = 19.2hrs runtime without power

With the 60amp charger -
7680Whrs / (60amps * 14.4) = 8.9 hours to recharge from empty after a power outage.

Parts list -
the Pheonix inverter has very very low idle draw.
I have some of the bus bars so I know they are pure copper and rated as such.
I have a battery of that type using it for my UPS on the computer so I know the quality.
I have the 20amp version of the litime charger and it run for more than a year reliably -


All of this can be installed into a box to cover the wires and stuff... BUT the charger needs to have ventilation so either outside the box or with holes and baffles cut to allow it to intake fresh air and blow the hot out.

If you want to know state of charge it takes a second set of bus bars so we have a set of battery bus bars and a set of load bus bars.

2 sets

https://www.amazon.com/AMOMD-Current-Terminal-Battery-Distribution/dp/B0BVBHF1KJ

2 batteries

https://www.amazon.com/Wattcycle-LiFePO4-Lithium-Temperature-Protection/dp/B0DGGQ53GR

4 fuse block

Blue Sea Systems 5191 MRBF Terminal Fuse Block 30-300A

MRBF Terminal Fuse Block: 30-300A, Max Amperage: 300A, Max Voltage: 58V DC, Accepts 5/16" ring terminals, Mounts on 3/8” terminal studs.

www.currentconnected.com

4 fuses - 2 - 250amp, 1 x 75amp, and 1 x 150amp --- may want to get extras of each

Cooper Bussmann MRBF Terminal Fuse 30A - 250A

MRBF Terminal Fuse: meets the ABYC requirements for DC main circuit protection, ignition protected, IP66 rated, 58V DC max voltage

www.currentconnected.com

1 switch

Victron Battery Switch ON/OFF 275A

Effortless Power Control with the Victron Battery Switch - Customizable, ISO8846 Compliant, and Easy to Install. Discover Peak Performance Now!

www.currentconnected.com

1 inverter

Victron 12V Phoenix 1.2kVA 120V Inverter VE.Direct

Stay connected and power up confidently with the Victron Phoenix Inverter. Advanced features for a customizable and efficient power solution.

www.currentconnected.com

1 charger - 60amps

https://www.litime.com/products/litime-12v14-6v-60a-lifepo4-lithium-deep-cycle-smart-battery-charger

1 class T fuseblock (225amp + size)

Blue Sea Systems 5502100 Ignition Protected Class-T Fuse Block 225-400A

1 class T fuse 250amp - get a spare

Blue Sea Systems 5118 Fuse A3T (Class T) 250 Amp

Battery monitor

https://www.amazon.com/CHINS-Battery-Monitor-Multimeter-Voltmeter/dp/B0DJ54SFDZ/

IF you want to add solar - (not required)
this is the MPPT - and you need some panels you can pick up locally - at 12v it will put 500w in the battery - if you get the 150/45 it puts 600w into the battery ... or you can get others - but the solar aspect is not required

Victron SmartSolar Charge Controller - MPPT VE.Direct

Optimize solar energy harvest and extend battery life with the SmartSolar Charge Controller. Remote monitoring and intelligent battery management included.

www.currentconnected.com

Battery cables the same length to the bus bars - so they are evenly used.
Also, use no-ox-id special A on alll the connections - just thin coating

Amazon.com

Need a torque wrench for proper tightening everything


View attachment 262270






As an alternative to the switch - I actually like this better - The moulded case circuit breaker (MCCB) can be switched with load on it, and it breaks both lines.

https://www.amazon.com/PPOZYLPC-Circuit-Overload-Protection-Protector/dp/B0DC2VBNCR/

 

[robbob2112]

Wind and snow load hazard calculation tool

ASCE Hazard Tool

Quickly retrieve site structural design parameters specified by ASCE 7-10, ASCE 7-16, and ASCE 7-20, including wind, seismic, snow, ice, rain, flood, tsunami, and tornado.

ascehazardtool.org

 

[robbob2112]

My wind and snow loads from ASCE

ASCE Hazard Tool

Quickly retrieve site structural design parameters specified by ASCE 7-10, ASCE 7-16, and ASCE 7-20, including wind, seismic, snow, ice, rain, flood, tsunami, and tornado.

ascehazardtool.org

 

[robbob2112]

Here is my novel - thinking out loud a bit.

If you use the MRBF get the 58v rated version -

I don't use ANL for anything that has much current passing through it... they have a higher internal resistance than the Mega fuse so they get hotter. The 70v mega fuses are 3.5ka at 12v, 2.5k at 70v....

There are other fuses with ceramic bodies that fit the ANL mounts and inside a victron in place of the Mega fuse - but be careful when using them to make sure the mount can take the generated heat... a lot of ANL and Mega mounts are just common ABS and will melt if you pass high currents through the fuse. This is true of all fuses that were originated in the car audio market where they have highly variable current so the mounts are not designed for constant high current.


For the MRBF





My choices of fuses has evolved over time as I have been learning more

For single 12.8v200ah or less - MRBF on the post
For up to 4 12v200ah batteries in parallel - MRBF on each post, paralleled with bus bars - class T to the inverter/charger

For single 12.8v300ah - MRBF on the post - class T to the inverter - see note below

For anything 48v - class T or BS88 or NH00 or EF3

For any parallel set of any size batteries that exceeds 4 in parallel - class T on each battery

For cables to small MPPT -
30amp or less - the small cartridge fuse holder - make sure they are rated for the amps - some are 15a and some are 20a
Breakers - DC rated with arc shunts - simpler - check AIC is 20k or more at the voltage
Mega fuse
MRBF

For cables to DC load panels 50a or less -
Mega fuse
ANL fuse ** I don't like them, but they do work for this

For cables to inverter -
DC rated breaker - simpler - check AIC is 20k or more at the voltage
Class T fuse
Mega fuse - only for 1500w or less and only on 24v or more - for 12v the class T or breaker will waste less energy as heat.
MRBF fuse - same as the Mega fuse




NOTE: on battery internal resistance
I measured the internal resistance of the 12.8v300ah battery now that I have one in hand and the short circuit current is 8000amps ... This assumes the MOSFETs on the BMS fail short as they do, then there is a short across the battery posts. Not very likely but it could happen if a battery BMS has been damaged in some way.... probably by running for max current to long, running hot then hard cutoff from over-volt, or other ways that stress the MOSFETs... and the bargin battery vendors are almost certainly using cheaper mosfets and the no-name vendors that are here today and gone tomorrow may be using reclaimed components.


Ohm's Law: I=V/RI = V / R


For a Wattcycle 12.8v300ah battery with 304ah prismatic cells - 200amp BMS






For a LiTime 12.8v200ah plus - 200ah prismatic cells - 200amp BMS.

​

 

[HarryN]

Came up today - labeling requirements for NEC inspections - Original PDF attached

View attachment 260135

Building Inspector-s Guide - NEC 690 PV Labeling Requirements | HellermannTyton

www.hellermanntyton.us

What happens when english majors are asked to help with electricity.....

 

[robbob2112]

What happens when english majors are asked to help with electricity.....

Hahaha..l practical failed english... but i do a bunch of technical writing in my job

 

[robbob2112]

Project - automatic pre-charge circuit

WORK IN PROGRESS - don't take it and make it without understanding it


Once the contactor closes it takes 7w to keep it closed, and there will be no current flow through the pre-charge part of the circuit once the contactor closes because the ends are at the same potential. Open the switch that powers the timer and it will de-energize the relay coil which will open the contactor.


Time delay relay - https://www.amazon.com/dp/B081N5NG8Q
Contactor - https://batteryhookup.com/products/te-connectivity-ev200aaana-500a-0-900vdc - datasheet attached
Resistor - https://www.amazon.com/dp/B07RTTSC2V
Fuse holder - https://www.amazon.com/dp/B0BF9LDW1P

NOTES -
The timer I picked is only for 12v/24v - if you use that one with 48v it will require a buck converter to step the voltage down, or pick a different timer.

The LED I picked is packaged and includes a resistor for 12-24v - the LED + 620Ω resistor is all packed inside

Amazon.com

 

[robbob2112]

Standard Blurb

Don't spend any money, until you have planned out the entire system. An eraser is cheap, but returns can be costly.

Planning

1. Energy Audit - what do you have to power?
2. Size the inverter for your maximum instantaneous demand (including surges).
3. Size the battery for how long you want power, when the sun isn't shining.
4. Size the PV to cover the loads and recharge the battery, when the sun is shining for your area - most in the US use 4hrs or 5 hours a day of sun
5. Trying to use old equipment you already have usually costs more in design compromises than just selling it and doing it right.
6. READ the site - every question you have has probably already been asked - if you have special circumstance - start your own thread.

Design planning

1. Use drawio to design your system if the instructions didn't include a design you can use. https://www.drawio.com/
2. Tilt angle - your latitude is your year round tilt angle - in my case the 5/12 roof pitch is around 22 degrees so is a summer time tilt. My winter tilt is somewhere around 42 degrees - but they would act like a sail and tear my roof off if tilted that far.
3. Don't forget temperature when calculating panel voltage - my 335w panels mounted at 42degrees on the side of the house deliver 408w in winter at 36 degrees.... at 9 degrees it delivers 430w... The voltage increase is similar with an increase in current.

Installing

1. Use https://pvwatts.nrel.gov/pvwatts.php - put in your address and the rest to see how many hours a day of sun
2. Use this when you mount your panels to get the wind and snow loads - https://ascehazardtool.org/
3. Buy quality tool when you do - the cheap stuff is generally inferior and will make bad connections
4. Remember you are dealing with lethal current and voltage - use safety equipment
5. If you are unsure about anything ASK - there are many experts in different fields willing to answer your questions

 

[robbob2112]

Distributing Power from many batteries - this is my take on things - Others have different ideas on how to do it. Ideally both positive and negative come together off the large bus bar into a 2-pole MCCB to be able to shut everything off with one switch. The current involved might not let that happen without getting into recicu-stupid prices.

Fuse/breaker sizes depend on the batteries and the load. The batteries determine the size to the smaller bus bars - they should be 125% of what the battery BMS continuous rating is.... typically for a 100ah battery that is 100amps so the fuse/breaker would be 125amps.

The fuse between the bus bars can be smaller than the total capacity of all the batteries added. If you say have a 10kW inverter and all the batteries are 48v100ah ...

10000kW/51.2v = 195amps

if you have 2 of the inverters that doubles to 390amps.

So If I want each set of batteries to be able to run both inverters
390as * 1.25 = 488amps - so use 500amp fuses or MCCB breakers.

If you want to have the ability to loose one set of batteries and still run then fuse them to 250amps each -

In either case the fuse/breaker to the inverter will be 500amps

 

[robbob2112]

Breaker trip curves and meanings

Tripping Curves of Circuit Breaker. B, C, D, K & Z Trip Curve

Types of Circuit Breaker Based on its Tripping Curves. What is a Trip Curve & How to Read it? Why We Need Different Tripping Curves for MCB?

www.electricaltechnology.org

What does B,C,D curve mean for Acti 9 MCB? | Schneider Electric Australia

And this (copy/pasted because things disappear and links go dead)

Circuit breakers curves

Circuit breakers are critical components of electrical systems. They are designed to protect electrical equipment from damage due to overcurrent or short circuits.

www.linkedin.com

 

[Brucey]

Feel free to delete, but here's the carlingtech f frame breaker trip curves, commonly known as the midnite MNEDC 175A and 250A panel mount DC breakers. My 250s have a trip curve of 16 and a trip rating of 313A.

 

[robbob2112]

Bus bar ampacity table

Electrical: Bus Bar - Table 1: Ampacities

Ampacities in the table below are for bus bars having an emissivity of 0.4.

www.copper.org

 

[HRTKD]

Busbars can be stacked for greater ampacity. But there appear to be limits on directly stacking busbars together. The ampacity gain is not linear. Meaning that a busbar rated for 1100 amps won't provide 2200 amps when two of them are stacked together.

Note in the table linked below that the specification provided is when there is 1/4" of spacing between "stacked" busbars.

Bus Bar Emissivity Ampacity Chart

Table of effects of emissivity and number of copper busses on ampacity

stormpowercomponents.com

I am not an expert in this. It's just something that I found on the Internet a few years ago when I started making my own busbars from Copper flat bar stock.

 

[robbob2112]

Why is the negative post of a battery hotter than the positive post

Followup to this
https://diysolarforum.com/threads/wattcycle-12v-300ah-mini-inside-look.95913/post-1336147


Evidence to support my theory

The positive is 4 x 8awg and the negative is 3 x 6awg

Black wire from BMS to terminal is 13" long
Black wire from BMS to B- is 11" long'
Positive red wire is 11.5" long


0.25MΩ for just the positive cable
1.10mΩ for the B- through the BMS to the P-

more resistance for the same current means more heat generated.

In theory they need to keep the negative wires as short as practical to keep the waste watts as low as possible. My 24" of wires is completely unnecessary. Looks like they increased the wire AWG size to drop the resistance a bit, but maybe they should have gone to 4awg X 3 to get it lower...







At 280amps - wasted power at the terminals from inside the battery

Positive - 19.6W
Negative 86.2W


In 5 minutes - open air - 4/0 wire x 2ft long attached -- accounting for convective cooling


And it steadies out at
Positive terminal 146c
negative terminal 443c

insane and to small a wire apparently

at 100amps
Positive 61c
Negative 123c

Calculation shows the best would be 2 x 2awg wires... or 3 x 4awg wires... --

for 2 x 2awg the negative temp is 72c - for 100amps
for 2 x 2awg the negative temp is 147c - for 200amps
for 2 x 2awg the negative temp is 258x - for 280amps


Non-linear curve because P = I^2 * R ... .


So this must play into the battery design as well...

Larger wire, larger terminal .. balancing act

and the solution is to operate at the least current possible to waste the least heat possible.


So,

conclusion - keep the positive and negative wires as short and as large as possible.
Making the wires larger is better than making them shorter since the resistance per foot decreases non-linear by cross-sectional area where it is a linear relationship for for length ---

A temp difference between positive and negative is expected and negative will be hotter... and can be ignored.

 

[HRTKD]

The positive is 4 x 8awg and the negative is 3 x 6awg

The effective gauge of these two are 2 awg and 1 awg, respectively.

This is according to the Combined Wire Gauge Calculator that I use.

 

[Hungfish]

#6 - Ferrule usage

When to use ferrules and when not to use them. This is sometimes hotly debated depending on the type of terminal block

Use them when -
The screw terminal just has the screw directly contacting the wire and the wire is fine stranded.
When the mfg calls for them

When not to use them -
On stranded THHN when the screw pushes on the wires directly unless the mfg calls for it
when the mfg says NO - like the victron MPPT
In any sort of spring push connection like wego unless they are called for
on any sort of solid wire.

Optional -
When the screw pushes down a plate that is cupped so that it gathers the stranded wire together - like the victron MPPT
When the screw pushes down a plate that is flat and the wires are not fine stranded (like thhn)
When the hole is a hex shape and cups the wires top and bottom

Ferrules are like everything these days - mfg in china - all of them for the most part.

Good ones are:
thin enough to deform with the crimper but NOT become crooked like a snake.
When they are crimped they are straight.
Long enough to bottom out on your socket

Bad ones are:
thin and when you crimp them they tear at any point
Not long enough to bottom out in the connection you are using them in - touching plastic is not bottoming out.
So thick they are super hard to crimp and they don't make a nice shape


Correct crimping technique -
strip the wire long enough to go all the way to the end of the ferrule and have the wire sheath inside the ferrule plastic
Push it all the way through and trim if needed.
Use the correct crimper - 4, 5 ,6 and 8 sided ones exist. For electrical stuff it will be the 4 or 6 sided typically. This depends on if the socket is a flat plate/screw or if it is the hex shapped socket.
If you need to trim after the crimp you probably didn't do something right - like it didn't fill the ferrule.

do NOT twist the wire before inserting - you want a cold weld type bond and twisting will cut strands.
it is permissable to double the wire back on itself, but discouraged.
And there are non-insulating ferrules that don't have the plastic bit. These are typically larger awg

It shouldn't deform the wire into a snake.
It shouldn't tear the metal of the ferrule
it should fill the ferrule completly before you crimp if it doesn't you will get a snake

Ferrules come in sizes like AWG and they are also in mm in metric. Just like crimpers they can be mismarked.

A good reliable source of ferrules is - you get what you pay for.

Ferrules Direct​

Insulated Ferrules, Non-Insulated Ferrules, Terminals, Wire Ducts, Crimping Tools, Cable Accessories, Terminal Blocks, Push Buttons, Heat Shrink, Compression Lugs, Automotive Products, Wire Cutters, Wire Strippers

www.ferrulesdirect.com

Ferrules come in different length: 9mm, 10mm, 12mm, 18mm... which one is commonly used for solar connectors? i need those used for #12, #10, #6 and #4 wires. Please advise

 

[HRTKD]

The ferrule length increases as the size of the wire increases. This is usually good enough for most terminals. Before crimping the ferrule I check to see if it hits the back of the terminal. My ferrule kit contains the normal length ferrules and they have worked for all terminals except for the small terminals on the Victron Cerbo GX where I needed the 15mm length ferrules for 16 awg wire.

Take a look at the kits at FerrulesDirect.com. They have the standard length ferrules. To get the longer ferrules you have to order the specific length you want. None of their kits have the longer lengths. The different series (W, D, T, etc) are just different colors as I recall.

 

[robbob2112]

Ferrules come in different length: 9mm, 10mm, 12mm, 18mm... which one is commonly used for solar connectors? i need those used for #12, #10, #6 and #4 wires. Please advise

It really depends on the devices you are using to plug the fine wires into that need the ferrules.

For Victron MPPT - no ferrule per mfg

For everything else the standard length of real ferrule per size wire is usually what you want. as @HRTKD mentioned the length increases with size. Make sure to account for the plastic collar if you are using those verse just bare ferrules.

With some things the simplest is to use a caliper to measure the depth of the hole you are inserting into and aim to either hit botton or close to it.

To use the caliper you just use the bottom end and dial down inserting it until you bottom out. On holes to small for that you can just insert the wire until it bottoms out then mark, and measure the length with the caliper when it comes out.

 

[robbob2112]

My new toy for when I want to do general troubleshooting and don't want to haul out the scope and find a plug to power it...
$80usd off Aliexpress.

3 digits accuracy on the DMM readings and matches the accuracy of the Fluke or Hoiki meter exactly.

If it had a clamp or current loop for it then it would be ideal.

 

[robbob2112]

OK, ordered both of these - should let me see spikes and other issues plus measure current as if it were a clamp meter - I ordered both and will send back one if they don't live up to the specs quoted.... there are a couple of other lower cost models like this one... the ones from labs tend to cost over $1000 so this will be more than enough for me.

OWON CP024 AC/DC Current Probe for Oscilloscope
Hantek Oscilloscope CC650 AC/DC Current Clamp Meter Multimeter Probe

​

 

[robbob2112]

And my 8 cells from 18650batterystore.com have shipped.

 

[robbob2112]

This is almost perfect for those that don't have a meter and want to do solar...only 20MHz... but that is more than sufficient for solar stuff.

https://www.aliexpress.us/item/3256808311783214.html

Or better this

https://www.aliexpress.us/item/3256808296116940.html

or from amazon - a bit more expensive for the same meter

Amazon.com

 

[BoonieBasher]

#6 - Ferrule usage

When to use ferrules and when not to use them. This is sometimes hotly debated depending on the type of terminal block

Use them when -
The screw terminal just has the screw directly contacting the wire and the wire is fine stranded.
When the mfg calls for them

When not to use them -
On stranded THHN when the screw pushes on the wires directly unless the mfg calls for it
when the mfg says NO - like the victron MPPT

PPT

Victron says no to ferrules?
So bare wire into the IP22?
Ordered a ferrule crimper for just that - go figure.

In any sort of spring push connection like wego unless they are called for
on any sort of solid wire.

Optional -
When the screw pushes down a plate that is cupped so that it gathers the stranded wire together - like the victron MPP

When the screw pushes down a plate that is flat and the wires are not fine stranded (like thhn)
When the hole is a hex shape and cups the wires top and bottom

Ferrules are like everything these days - mfg in china - all of them for the most part.

Good ones are:
thin enough to deform with the crimper but NOT become crooked like a snake.
When they are crimped they are straight.
Long enough to bottom out on your socket

Bad ones are:
thin and when you crimp them they tear at any point
Not long enough to bottom out in the connection you are using them in - touching plastic is not bottoming out.
So thick they are super hard to crimp and they don't make a nice shape


Correct crimping technique -
strip the wire long enough to go all the way to the end of the ferrule and have the wire sheath inside the ferrule plastic
Push it all the way through and trim if needed.
Use the correct crimper - 4, 5 ,6 and 8 sided ones exist. For electrical stuff it will be the 4 or 6 sided typically. This depends on if the socket is a flat plate/screw or if it is the hex shapped socket.
If you need to trim after the crimp you probably didn't do something right - like it didn't fill the ferrule.

do NOT twist the wire before inserting - you want a cold weld type bond and twisting will cut strands.
it is permissable to double the wire back on itself, but discouraged.
And there are non-insulating ferrules that don't have the plastic bit. These are typically larger awg

It shouldn't deform the wire into a snake.
It shouldn't tear the metal of the ferrule
it should fill the ferrule completly before you crimp if it doesn't you will get a snake

Ferrules come in sizes like AWG and they are also in mm in metric. Just like crimpers they can be mismarked.

A good reliable source of ferrules is - you get what you pay for.

Ferrules Direct​

Insulated Ferrules, Non-Insulated Ferrules, Terminals, Wire Ducts, Crimping Tools, Cable Accessories, Terminal Blocks, Push Buttons, Heat Shrink, Compression Lugs, Automotive Products, Wire Cutters, Wire Strippers

www.ferrulesdirect.com