Recent content by brum

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    Beware of Docan Technologies (Issue Resolved)

    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...
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    Direct to water heating.

    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.
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    Jump Starter to Reset BMS?

    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.
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    My CALB cells have swollen

    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.
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    Used/aged solar panels calculation

    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.
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    Direct to water heating.

    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...
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    Direct to water heating.

    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...
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    Wire size

    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...
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    Help me decide: Bluetti vs DIY?

    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...
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    The down side from buying Chinese goods

    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...
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    Difference of Cell Voltage @300mv+ and I do not know how to stop it without from climbing!

    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...
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    Feedback on a battery pack approach

    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...
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    Feedback on a battery pack approach

    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.
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    Feedback on a battery pack approach

    Wiring completed. And it works :) !
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    Feedback on a battery pack approach

    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...
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