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I would say that the data from the BMS rules out an internal short. We know the cell voltage was at 3.34 and then one second later was at 0. Its reasonable to believe that the cell was at least 1/2 charged if the voltage was above 3.3. So 140ah would have had to discharge in one second. That...

I just posted some information I learned about using Loctite on aluminum and stainless steel in another thread here. Essentially, you need to use a primer or it won't properly cure. This is causing issues for some people when it doesn't harden and then oozes out on top of the terminal when the...

From NEC 2020 article 690 - PV system, the ESS doesn't include the inverter From NEC 2020 article 706 - ESS might or might not include the charge controller and inverter I think there are too many design variations to make an all encompassing statement.

Since I've been looking at battery system code in the NEC book for other reasons today, I thought I would chime in with the relevant code section. It says that all it takes to trigger the requirement for insulating battery supports is for a battery case to have a voltage on it. This could...

I don't understand how that chart can be accurate without taking into account the system DC voltage. I didn't see any indication if it was for a 12, 24, or 48 volt system. I think the Blue Sea Circuit wizard calculator is a better tool. The real pain in this sort of system is that the voltage...

Internal resistance of a battery becomes easier to comprehend when you look at the processes in the battery in mechanical terms. This is a valid way to look at it because in the charging and discharging process, you are physically relocating ions from one location in the battery to another...

Me in second grade - "Can I stay up late cause I heard Tommy say school is going to be cancelled tomorrow." Mom - "You can't believe everything you hear." I go to bed and think about that I just HEARD that I can't believe everything I HEAR. A life long struggle begins.... or perhaps more...

Sympathy on the damage to your system. Glad it didn't cause damage to your barn. Thanks for sharing the pictures and the description of what happened. It appears to be a good lesson in being cautious about keeping electrical connections properly insulated from other parts of the system. Am I...

No need to take ourselves too seriously here. I think everyone understands your meaning. It's a fun topic.

@FilterGuy , I agree. Engineers expect that you know what they were thinking when they write a statement. Lawyers expect that you will use their definitions when you read their words Academics are insulted if anyone is able to decipher what they wrote. To help people reading the code book...

I looked up the Edecoa inverter on Amazon to read some reviews. The 2000w pure sine wave version says it has 4000w surge capability, however, the reviews have a split between people who are perfectly happy with it and others who say it let the smoke out. It appears to be a generic chinese...

I believe you stated this backwards. When combining panels, it is best to create strings of panels in series first, In this case it would be two panels in series. Then combine those strings in parallel. The reason for doing it this way is it makes the required fusing of the panels simpler...

@Sillyputty Sorry if it seemed I was poking fun at you or anyone else in the thread. I've just found the communication issues a little entertaining as a casual observer. I think it is a wise policy to never buy batteries from a vendor until they provide a datasheet for what they are selling...

Hi Xhumeka. I also used the iCharger X8 to do a bunch of cell testing. It has a connector on the side to allow for voltage sense wires which can connect directly to the cell terminals and give the voltage at the terminals. This eliminates the voltage drop through the wires carrying the...

It was entirely configuration of the drains and layout of the room, and where I was willing to run a hose. So esthetics, not physics.

Considering all of the circumstances you outlined yesterday, I really don't have a strong opinion on whether 12v or 24v would be better for your situation. I did happen to see a three year old video by Will Prowse today on this very subject. When it comes to inverter efficiency, I don't...

Economic advantage will nearly always take priority over political or ethical motivations in the world that we live in. For that reason, trade with China will remain available. I think you may be worried about sanctions against China causing trade to be interrupted they way it has been with...

Since you converted the temperature to °C, I think you have to also convert the coefficient. The coefficient is -0.29% per °F, and a °C is 9/5 larger than a °F, the coefficient become -0.522% per °C. The end result, using the calculator you suggested is 56.06 volts open circuit. So it...

The other thing to watch out for, especially on electrical components, is resellers who buy cast-off equipment (essentially equipment that failed to pass inspection) from manufacturers and then repackage it and sell it as good. They will have extremely low prices, but the stuff they sell can be...

Based on the visible portion of the encoding, that may be a Data Matrix, and not a QR Code. A QR Code has the concentric square pattern in three of the four corners. In your image, two corners of the code are visible and neither corner has that pattern. I believe it was stated earlier in the...

I didn't see that Steve S. addressed the "parallel shunt" part of your post. Shunts can only measure the current that goes through the shunt, so if you put them in parallel, only part of the current will go through each shunt and neither will provide an indication of the total current.. So if...

@Will Prowse Thanks for following up with the same test on a lithium iron phosphate cell of similar dimensions. I also appreciate the extra notes you put in the video with the temperature response curves and the run-away temperature for each chemistry. And it is also relavant to the question...

Tonight, I got to looking at this paper from NREL that has a lot of math I don't understand. In the paper they are using experimental data to try to create a formula that will predict LiFePO4 cell degradation. They modeled calendar degradation, separate from cycling, and came up with the...

The above is bad advice. @BTR500, you ALWAYS need to contact your utility provider before connecting any power generation equipment to the grid. If you supply voltage to the grid without their permission, you can endanger their workers. Depending upon the country, you may be liable for civil...

This gave me pause for thought also, especially when I saw that in response to the water supply system disaster that followed the power debacle, the authorities issued a 'boil' mandate for tap water. How are people supposed to boil water without electricity or gas unless they have an emergency...

Certainly understood that the loss of capacity is temporary. Lead acid is more likely to sustain damage at high temperatures, not low temperatures. However, the statement about LiFePO4 is not correct. You can discharge it below freezing, but unless specially designed you cannot charge it...

I think my answer to this is that you can't use the torque on the nut compensate for any curvature in your bus bar material. If the bus bar is flat and clean and the terminal is likewise, it won't take much pressure to create a good electrical connection. If the bus bar is trying to spring...

One of the useful things from the chart above is that, while the increase in stress on the battery with temperature is a smooth rise, the increase in stress with state of charge has distinct transitions where the stress rises. They note it in the text as follows and provide an additional graph.

Ha Ha. That made me remember this piece by Al Hess. "If airlines sold paint..."

I've read this new specification sheet for the EVE LF280K battery cell several times, at varying levels of sleep deprivation and alcohol consumption, and I'm just not convinced we are understanding it entirely. (please note that there is a difference in important details on the spec sheets for...

I bought a bunch of 304ah cells from Docan months ago. I've been methodically testing them, one per day since the middle of August. So far so good. I've built one 12 volt battery to use in testing the other cells. I have 14 more cells to go and then I'll post some about the results. So...

@fhorst I noticed that you have wind turbines in your system. I'm not familiar with wind turbine systems, but I have read that they can build up static charges due to the air movement over non conductive surfaces. The shocks you describe sound like static charges more than emf induced...

I've been pondering the best practice for this situation. It seems most people think of the battery as the source of the current in the event of a fault. However, there are three other batteries pushing current into the bus bar, so it actually has a higher available fault current than any...

So you're saying that they mean to say that the maximum charging rate is 13% of the capacity listed for the C20 discharge rate? That yields a more reasonable charging limit, but if that is the case, Trojan has a really poorly worded data sheet. Thanks for letting me know how you calculate it.

Thanks

These lithium iron phosphate cells are usually shipped at about 30% state of charge. Their maximum rate of loss of charge is usually stated on the spec sheet as somewhere around 3% per month, so in shipping they may get down to 20% if they sit somewhere for a long while. If your cells started...

The amount of summer peak demand and winter peak demand issues we see from grid operators in certain parts of the U.S. does not inspire confidence. I think for the EV transition to work well with minimum infrastructure upgrades, electric utilities will have to embrace rate structures that...

Sorry @rmaddy, but Merriam Webster and I disagree with the subject line of this thread: https://www.merriam-webster.com/thesaurus/looses It's the usage that's generally incorrect. Proper use would be a sentence like:

The only exception I see for the ground fault protection requirement in the 2014 code is: So if your solar power is generated on top of a building or is used in a building, you need the ground fault protection.

On this page, https://www.aliexpress.com/item/1005002958135242.html?spm=a2g0s.9042311.0.0.378e4c4dWNGTXR, It specifically states that the JDB 200A BMS is not rated for multiple batteries connected in series.

Maybe he is trying to refer to this, from wikipedia So, I think this is what differentiates Peukert's Law from internal resistance. Internal resistance dissipates some of the battery energy as heat inside the battery and the result is that some of the battery's chemical energy is unavailable...

The dates that come out of the QR code reader are in the order of day/month/year. So all of your cells are from February. The portion of the alpha-numeric characters around the QR code that give the date are C29. C is the year, 2 is the month, and 9 is the day.

I think as far as energy sources that are readily available to individuals, solar is good and getting better by comparison to other sources. And it has the advantage of being able to integrate into our current method of building structures. On a community level, there is a good argument to add...

I spent some time looking through their website. It is important to realize that this is a reseller who is based in China, similar to the other resellers people mention on this forum. They mention having warehouses in various countries, but don't give any physical addresses, so chances are...

In regard to the MG Carbon Paste, it appears that it might be inferior to products like Ox-Gard when it comes to joining dissimilar metals. The Ox-Gard has significant zinc content which helps prevent galvanic corrosion. The MG product appears to rely only on the grease excluding air and the...

@Dzl , The Bay Marine Supply calculator is much more flexible, and intuitive to use (for me anyway). Thanks for pointing it out.

I wish the whole 'Grade A' thing would just go away. There is no standard for a 'Grade A' cell. If you are asking if those cells meet the standard for use in electric vehicles, the answer is probably no. Otherwise they would not be on the secondary market at the price you were quoted. That...

Hi iClick. It might be helpful to post which battery brand and model you have. From your description I am thinking its one of the 12 volt lithium batteries in a plastic case with dimensions similar to a lead acid car battery. A brief short like that would not have damaged the cells. It may...

Until I see an official specification sheet from BYD on the cells in these batteries, I'm not going to get too excited about the temperature claims. There's just too much bad information out there. Various Alibaba merchants claim the charge temperature is from 0 to 45°C or from -10 to 50°C and...