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I had a similar experience with Docan. But I don't complain as I got pretty good LiFePo4 cells. I directly ordered and paid (both cells and shipping) 4 x CATL 100Ah old-style prismatic cells with a plastic enclosure. These happened to be out of stock. I was offered a replacement - EVE LF105...

If you go for a system that works on the worst day there will be plenty of excess energy that you can use for other purposes. In such a case, I would go with a grid-tie inverter, not with direct water heating.

I would try to pay attention to avoid tripping the BMS circuit. 100Ah + inverter + AC gadgets is already a pretty decent weight for going "deep into the woods" If you still decide to go with the additional battery weight - get a battery with BMS.

Find out why they got to that voltage before going ahead. Either your BMS is not working as expected or the cells have very high self-discharge.

Use the stock PV parameters. You can't measure the exact parameters outside a laboratory and you can't get the exact aging impact. Old panels IIRC have a drop in both the voltage and the current. So if you go theoretically you can estimate some values. But don't measure them in field conditions.

Even a volt or two won't be a ripple that would reduce much the power. If you have 300Vmp then 3V would be 0.5% less power (this is ripple and the half is 1.5V) than the maximum one. If you add the voltage drop on the transistor you would still be close (or even above) the efficiency of most...

MPPT charger has a DC output. The direct water heater has a square wave output. The MPPT tracking here is to have such a duty cycle on the transistor, that the capacitor voltage * duty cycle has the highest value. Or something like that. I haven't thought much about the math behind it, but the...

Exactly. That is why if you parallel 3 wires you don't go for 3 times the max current a single wire can handle. IIRC the number was 80% of the max current when wires are in parallel. But still - the job must be done correctly to avoid overloading a single wire. I've seen flexible busbars for...

I will go for the Bluetti if this is what I needed. If you decide to build it by yourself you won't be able to match the price tag unless you go with bare components (cells and BMS instead of a battery, inverter module instead off the shelf inverter). And you won't even get closer to the...

I don't trust Chinese specs. A recent one was a LiFePo4 BMS that got fully tested on 4 old 3.7V 18650 cells. Just to make sure cutout voltages are as expected and the balance voltages are right. This one worked pretty well. And for something that is a bit more high-tech than regular junk always...

I'm repeating the questions but did you top balance your cells? How does your BMS balance the cells? What are the cell voltages when your SCC goes in float mode? Something is terribly off with your setup. If cells are similar they should drain equally. With properly top balanced cells the...

The boost voltage was increased to 13.9V. The SCC reads the cell voltage with 0.1V lower than it is. There is a minor voltage drop across wires, fuse, switch, and connectors (0.05-0.06V at 8A) also. With the current settings, the SCC gets the cells at ~3.45V, keeps them there for around 10...

And it's done! I might disassemble it once again to get one more transparent coat on top of the wood box, but that's all. A bit disappointed with the SCC. There is a 0.2V drop on it with a 6A load. But I'll live with it. In and out wires are 4mm2 and I don't think it is a wiring issue.

Wiring completed. And it works :) !

Some more progress. The enclosure is almost ready and the front panel is in progress. The grey "caps" around the terminals are used to secure the cells from vertical movement in the enclosure. The terminals are used only to center them. They are putting pressure on the cells around the...

The car battery should be charging at ~14V with a running engine. I believe you can start the engine and connect the LiFePo4 directly to it to "reset" the BMS. That's valid of course if you have a car with you when camping :) . The other option should be SCC. The BMS should be able to accept...

Measure the cell voltage and you'll get your answers. The battery bank being connected, but the load disconnected sounds like the broken charge controller was still connected. If so - it may have overcharged the cells. And it is normal to see swollen cells if they were overcharged.

I see several issues in the way that these were mounted. You have plywood on top, but cell bottoms are visible. These should be secured to the floor and the only option to fix them with that enclosure will result in pressure over the cell terminals. The busbars are non-flexible and the cells...

LitoKala, let me guess :) . If I'm right they are known for selling low-grade cells. But I have some doubts that this is caused by the cell itself. How were these mounted? With terminals on top or on one side? What was the enclosure? How were these secured in place? Any chance that something...

Put a lug on the terminal and connect it to the ground. The cells and the terminals are rated at a log higher current than the welding process needs.

Yep, TIG spot welding will be sufficient. And if there is enough time between spots there will be no cell overheating. If this is performed by somebody with experience it will be better than the laser welding they do in the factory. If this goes OK I would go through all cells to make sure this...

Compress it and it will flatten the dent a bit. All the force will first push at that point. I would not worry about such cosmetic issue. There are videos of folks tearing down prismatic cells in youtube. Based on what's inside, a dent like that will have zero impact on the cell.

I know, but they do. There are like 3-4 more millimeters left.

I doubt that you'll be able to mix components from multiple manufacturer and get the working with the priorities that you've listed without custom components. Check the options to get all the equipment from single manufacturer that can guarantee the functionality that you want. If it was me - I...

Busbars and wires are in the final arrangement. The items on the stud (stainless steel) are as follows: 1) silicone grease 2) tin-plated copper busbar (or lug) 3) stainless steel washer (to spread the pressure on the whole busbar area) 4) spring washer (zinc plated, without a cut, to guarantee...

They have not used a CNC for retapping based on the pictures. And CNC or drill press would be a lot more precise for removing the stud leftover, but for retapping it would be a challenge to get it right. Regarding the stainless steel vs steel - the main goal I think is to protect the cell...

Out of curiosity - why the nut should be stainless steel? There is no contact between the nut and the aluminum terminal. So there should be no impact on the cell terminal related to the nut. Regarding the seizing - do oxidized stainless steel nuts seize too? Regarding the retapped cell...

This is AC to DC charger if I'm reading the specs correctly. You'll have quite a loss in converting DC from input battery to AC and then back to DC. Victron has a 48V Orion-Tr DC-DC Converter that is designed for that purpose. But the highest power model can only drive 8A of current. ISDT has...

And the distance is still 115.98mm with all 4 cells charged. I guess that this is either the compression fully preventing the cell expansion or charging at a low rate resulting in no expansion. I'll use the solid busbars.

I'm planning to do the same - use excessive energy to heat water. But since I'll do this through a heat pump it is not going to use all the energy. One option that crossed my mind is to store the excess energy as hydrogen. But this was just a spike and I haven't researched many details. Some...

Here are the 16mm M4 stainless steel studs with a red thread lock. I suppose this can be considered a permanent mount now. The first cell took a bit over 50Ah. At around the 45th amp hour, the voltage was still 3.35V. The last few Ah took it up to 3.65V. Seems like with a low charging current...

Finally, got the battery running. The internals of the device is ready. The BMS and the fuse were mounted on the first layer, the SCC was mounted on the second layer. Next is the external enclosure. Likely 8mm or 12mm MDF, as this is what I have. The first start of the battery was a bit tricky...

Agree with the fact, that voltage is not a guarantee for keeping the cells below 100% SOC. But it is at least a step in that direction. I suppose I'll still be getting to ~100% SOC due to the low charging current. The SCC and the panels produce at most 8A from what I've seen with the lead-acid...

So far so good. The cells arrived a week ago and today I managed to assemble the compression part. The plates are 5mm thick aluminum (some hard version, not sure about the exact type). Springs are putting a bit over 200kgf and have around 5mm more travel. The studs are 6mm and are covered with...

On the 1206AN you can do that from the controller itself. It is a lot of clicking and is not user-friendly, but you can change quite a few parameters. Last I recall was that I switched something there to get it working properly with my gel battery. I suppose the need for MP50 is to be able to...