diy solar

diy solar

Large amperage gap between 2 identical batteries in parallel

kolek said:
I really think this thread has outlived its usefulness, and like most all of my threads, it was probably never useful to begin with. :rolleyes:
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A couple of takeaways I would think are that with multiple packs in parallel, short of a buying a xxxx.xx dollar high end BMS that can control all cells in the packs simultaneously that it is just something that happens.

If you have checked all connections, and they are all as good as can be, then its just something to live with. like I said I have the same problem went through many of the same thoughts and in the end chalked it up to being something I cannot control.

that being said, you have gotten lots of good advice/input on what to look at in regards to wiring, connections, balancing and a whole other host of things, so I would not call it fruitless.
 
Daddy Tanuki said:
that being said, you have gotten lots of good advice/input on what to look at in regards to wiring, connections, balancing and a whole other host of things, so I would not call it fruitless.
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Actually I was joking when I wrote that. lol. There was lots of good input and advice.

Mainly at this point I'm just hoping we can all convince @Hedges to part with his secret design which enables us to DIY something similar to the Midnite Solar SPD for pennies on the dollar. ;)
 
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Bananaman321 said:
I'm not saying you can't Polish washers I'm saying the likelihood of maintaining truness when polishing is very unlikely
Polishing tends to round over corners reducing true-ness and contact surface area

I feel time is better spent checking and true in bus bars and terminal logs

Crimping can sometimes disfigure a terminal lug reducing contact surface area

And with the small terminals on these lithium batteries the light torque is not enough to draw down a disfigured connector or busbar
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See, I was thinking just a polishing cloth to remove any surface tarnish or oxides... not a time for mechanical means
 
kolek said:
Actually I was joking when I wrote that. lol. There was lots of good input and advice.

Mainly at this point I'm just hoping we can all convince @Hedges to part with his secret design which enables us to DIY something similar to the Midnite Solar SPD for pennies on the dollar. ;)
Click to expand...

I already did. Just get MOV with thermal protection, either 2-lead or 3-lead if you want to be able to check with DMM if it has failed. (if you connect lights like Midnight and others, realize they may be at high voltage. Made me nervous about sticking LED through hole in bezel as I considered.)

Voltage rating sufficiently above peak line or PV voltage that it never conducts any current. Amperage and Joule rating as big as you want, or multiple in parallel. I soldered on wires and connected to circuit. For a breaker panel I would wire to 20A or 30A breaker. In combiner box I would would wire to fused or breaker input (other PV strings feed, MOV is backfed.)

SpongeBob said each line to ground. I would also consider line to line (sometimes that is a different max voltage.)
 
ThaiTaffy said:
Found oneView attachment 228171
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If the copper washer I read about, no effect so just air-core coil.
If steel, you'll get eddy currents at higher frequencies, more loss. Maybe that's what you want.
Material performance varies. Iron used at low frequencies. Ferrite particles at high frequencies.
Yes, this is stuff I've dug into and tried to measure/model.
Wound wire around a 1/2" thick toroid of special magnetic lens material trying to measure it, applied 240V with Variac and ended up with a 150W induction heater at 60 Hz but no "S" shaped BH curve (this is why laminations are used.) I did model the heater successfully, though (resistive model of eddy current path in core.)
 
Hedges said:
If the copper washer I read about, no effect so just air-core coil.
If steel, you'll get eddy currents at higher frequencies, more loss. Maybe that's what you want.
Material performance varies. Iron used at low frequencies. Ferrite particles at high frequencies.
Yes, this is stuff I've dug into and tried to measure/model.
Wound wire around a 1/2" thick toroid of special magnetic lens material trying to measure it, applied 240V with Variac and ended up with a 150W induction heater at 60 Hz but no "S" shaped BH curve (this is why laminations are used.) I did model the heater successfully, though (resistive model of eddy current path in core.)
Click to expand...
Cheers for the science lesson hedges I was just taking the p*** tbh, when I went to market earlier I was reading posts in the car and thought of being a troll and how to make a washer have impedance. I knew i had some transformer wire and a washer handy in my workshop, so after the ball and chain was finished I sped home to make this before going out to eat.
 
I was focused on washer under lug and missed the toroid winding idea.
Ironic, I just unwound a couple 3-phase chokes at work to get the toroid for use on some cables.

If you've got a scope and signal generator you could even test that. Well, maybe into a capacitor, need another impedance for it to react with. Impedance analyzers measure magnitude and phase to determine R + jX. Making something analogous to RC circuit lets us see it easily with scope.

I was fixated on LC filters and a colleague came up with RC notch filter, which we will used to block the excitation signal of a sensor. (good for signal not power circuits.)
 
Hedges said:
I was focused on washer under lug and missed the toroid winding idea.
Ironic, I just unwound a couple 3-phase chokes at work to get the toroid for use on some cables.

If you've got a scope and signal generator you could even test that. Well, maybe into a capacitor, need another impedance for it to react with. Impedance analyzers measure magnitude and phase to determine R + jX. Making something analogous to RC circuit lets us see it easily with scope.

I was fixated on LC filters and a colleague came up with RC notch filter, which we will used to block the excitation signal of a sensor. (good for signal not power circuits.)
Click to expand...
No scope here, bigger items just took too much space/weight in my luggage I've been slowly buying things as time has gone on but haven't had need for a scope here yet. I bought a hardigg case a few years back to put my server, scopes and some other more sensitive items in, but by the time it was full, it weighed 80kg/180lbs so never ended up bringing it. I just buying servers here and slowly been buying odds and ends as I need them like insulation testers, welders etc but still no microscopes or oscilloscopes as of yet.

I made a toroid a few years back for bench PSU but got carried away with the PCB and never ended up finishing it it's still on one of my workbenches waiting to be finished.

Concrete mixer is next I don't trust anyone making it here in Thailand and I need a shed built for my mowers and storing timber and another shed as a power plant as well as footings for my solar mount.
 
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hwy17 said:
They are fine imo, they have to balance out at the top and the bottom on the voltage curve legs. In the middle, they can wander around on each other but it's ok because from top to bottom you will always get full capacity out of both.

I pick one battery to be preferred and I use its SOC for my SOC based triggers, and the other battery I ignore and it's just along for the ride. If it wants to take more or less of the load / charge at any point in time that's fine.
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If my BMS are out of whack - say, the batteries have been drifting between 20 and 60% SOC, so the "system" thinks it's 40% SOC, which may-or-may-not be accurate - would it be wise to use shore power to "top it off" to 100% to reset the SOC sometimes?

My solar isn't keeping up with usage as the temps have been climbing. The SOC on all my batteries can get wildly out of sync, so that some batteries are reporting 1%, and others reporting 40%. It's a Bluetti AC300, so I can't change the way it operates, unfortunately.
 
plympton said:
If my BMS are out of whack - say, the batteries have been drifting between 20 and 60% SOC, so the "system" thinks it's 40% SOC, which may-or-may-not be accurate - would it be wise to use shore power to "top it off" to 100% to reset the SOC sometimes?

My solar isn't keeping up with usage as the temps have been climbing. The SOC on all my batteries can get wildly out of sync, so that some batteries are reporting 1%, and others reporting 40%. It's a Bluetti AC300, so I can't change the way it operates, unfortunately.
Click to expand...
Yeah definitely. My battery is middling around all the time so I fully charge it from the grid about once every 15-30 days or so. Mainly for the purpose of resetting the SOCs.
 
Hedges said:
I was focused on washer under lug and missed the toroid winding idea.
Ironic, I just unwound a couple 3-phase chokes at work to get the toroid for use on some cables.

If you've got a scope and signal generator you could even test that. Well, maybe into a capacitor, need another impedance for it to react with. Impedance analyzers measure magnitude and phase to determine R + jX. Making something analogous to RC circuit lets us see it easily with scope.

I was fixated on LC filters and a colleague came up with RC notch filter, which we will used to block the excitation signal of a sensor. (good for signal not power circuits.)
Click to expand...
I just jizzed... can I have your baby?
 
robbob2112 said:
See, I was thinking just a polishing cloth to remove any surface tarnish or oxides... not a time for mechanical means
Click to expand...
I know this is not very scientific but I conducted a little experiment with a couple of household cleaning products VS an aluminum acid.
20240712_174427.jpg
20240712_174822.jpg20240712_174851.jpg20240712_174919.jpg20240712_174748.jpg I figured the aluminum acid would win this competition but I expected better results out of the wheel cleaner.
I started by applying with the q-tip and then this decided to throw the washers in the solution dwell time was 3 to 5 minutes like I said not very scientific. The last one I used as the control i only use the wire brush all parts were cleaned with 91% Iso. alcohol to remove solutions.
Parts of copper and brass with approx 40 years of garage storage oxidation.
I was impressed with the CLR did not work nearly as fast as the aluminum acid but nonetheless.
The aluminum brightener is hydrofluoric acid and sulfuric acid I assume it's around 8-10% acidity judging by reactivity.
20240712_204336.jpgLeft to Right: wheel cleaner, CLR, Aluminum Acid, Wire Brush Control.
20240712_224058.jpg Barrels of bottom row cleaned with q-tip and aluminum brightner.
20240712_175728.jpg These are some basic tools I like using for preparing electrical connections
20240712_171944.jpg These are some corrosion inhibitors that I never leave home without
20240712_171923.jpg I don't expect anyone to do as I do. But if they were to follow the simple instructions on the backs of either one of these inhibitors plus proper torque I don't believe they would have a problem.

I like acid oxidation removal for aluminum battery terminals and the inside of ?able lugs were it is difficult to mechanically clean these areas or if you're just lazy in general.

If using wire brushes or steel wool only use stainless steel as to not further contaminate your connections.

Anyways that's my $0.02
I hope no one takes any of this throw away I value all of your shared knowledge
 

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Bananaman321 said:
I know this is not very scientific but I conducted a little experiment with a couple of household cleaning products VS an aluminum acid.
View attachment 228332
View attachment 228329View attachment 228328View attachment 228327View attachment 228330 I figured the aluminum acid would win this competition but I expected better results out of the wheel cleaner.
I started by applying with the q-tip and then this decided to throw the washers in the solution dwell time was 3 to 5 minutes like I said not very scientific. The last one I used as the control i only use the wire brush all parts were cleaned with 91% Iso. alcohol to remove solutions.
Parts of copper and brass with approx 40 years of garage storage oxidation.
I was impressed with the CLR did not work nearly as fast as the aluminum acid but nonetheless.
View attachment 228336 These are some basic tools I like using for preparing electrical connections
View attachment 228333 These are some corrosion inhibitors that I never leave home without
View attachment 228334 I don't expect anyone to do as I do. But if they were to follow the simple instructions on the backs of either one of these inhibitors plus proper torque I don't believe they would have a problem.

I like acid oxidation removal for aluminum battery terminals and the inside of ?able lugs were it is difficult to mechanically clean these areas or if you're just lazy in general.

Anyways that's my $0.02
I hope no one takes any of this throw away I value all of your shared knowledge
Click to expand...
Thank you for your experiment! And for sharing knowledge
 
ScropusGobbleBottom said:
Thank you for your experiment! And for sharing knowledge
Click to expand...
My knowledge is a smorgasbord of places I've worked people I've worked with books and internet research honing in on skills and techniques of others mistakes I've made and my father who was a lineman, cablesplicer, troubleman for Florida Power utility for over 40 years certified in lead and submarine splices. He was an inspiration to me and my interest in electrical work.

I feel that reading these posts learning from others and NOT sharing is just plain SELFISH and thats NOT where I want to be in my life.😄
 
Bananaman321 said:
I know this is not very scientific but I conducted a little experiment with a couple of household cleaning products VS an aluminum acid.
View attachment 228332
View attachment 228329View attachment 228328View attachment 228327View attachment 228330 I figured the aluminum acid would win this competition but I expected better results out of the wheel cleaner.
I started by applying with the q-tip and then this decided to throw the washers in the solution dwell time was 3 to 5 minutes like I said not very scientific. The last one I used as the control i only use the wire brush all parts were cleaned with 91% Iso. alcohol to remove solutions.
Parts of copper and brass with approx 40 years of garage storage oxidation.
I was impressed with the CLR did not work nearly as fast as the aluminum acid but nonetheless.
View attachment 228382Left to Right: wheel cleaner, CLR, Aluminum Acid, Wire Brush Control.
View attachment 228336 These are some basic tools I like using for preparing electrical connections
View attachment 228333 These are some corrosion inhibitors that I never leave home without
View attachment 228334 I don't expect anyone to do as I do. But if they were to follow the simple instructions on the backs of either one of these inhibitors plus proper torque I don't believe they would have a problem.

I like acid oxidation removal for aluminum battery terminals and the inside of ?able lugs were it is difficult to mechanically clean these areas or if you're just lazy in general.

If using wire brushes or steel wool only use stainless steel as to not further contaminate your connections.

Anyways that's my $0.02
I hope no one takes any of this throw away I value all of your shared knowledge
Click to expand...


That is very useful. I think you should put this information into a resource.

I don't suppose you have a YR1035+ meter? So you could maybe test the resistance in the milliohm range?
 
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robbob2112 said:
That is very useful. I think you should put this information into a resource.
Click to expand...
Thank you I will look into that still trying to figure out all the Bells and whistles this is the only social outlet I'm a part of.
BTW You put out some very informative content and I value your input and look forward to reading your post.
 
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