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  1. T

    Which is worse, discharging to empty or charging to full?

    CATL recommends keeping my battery in the 10-90% SoC range. I think most of the LiFePO4 batteries are similar. However below is my actual battery voltage during a discharge with a <0.01C load applied (which is super low, I know). I started the discharge 24 hours after charging, so the battery...
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    Which is worse, discharging to empty or charging to full?

    It's a lot harder in my experience (practically speaking) to prevent charging to 100% than it is to prevent discharging to 0%. For the latter you can always just set your BMS cut-off higher. For the former though using voltage is a poor way to judge SoC, it's difficult to find a charging...
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    Containing a battery pack meltdown.

    Sort of. Water is your friend if you have a lot of it available to drown the pack and dilute the lithium-to-water ratio. To the OPs original question I wouldn't try to drown a lithium battery fire with a (melting plastic) gallon of water. Water will cool the pack but will react to lithium so...
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    Containing a battery pack meltdown.

    Oh gawd please don't use water. Lithium + water = chemical reaction + hydrogen gas. You don't really want to mix the two...
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    AliExpress LiitokalaVariCoreFlagship Store 280AH LiFePO4 Fraud

    yeah. for my purpose they're ok. I have a RV, and I was using a 100Ah lead battery. So ~250Ah of LiFePO4 is far better capacity at the same weight. And in fairness I bought 280Ah cells instead of 200Ah cells because I was afraid all cells wouldn't test out at the spec rate. I knew it was a...
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    AliExpress LiitokalaVariCoreFlagship Store 280AH LiFePO4 Fraud

    Meh, it depends on your definition of "luck". My "280 Ah" Liitokala cells had 271Ah CATL QR codes right on them. They tested to 262Ah at 0.01C (2 Amp load), which is 1/100th the rated load. I'm sure if I could test at 1C I'd find these were even less capacity... probably ~240Ah-ish. Given...
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    420Ah Cells on Aliexpress!?

    1. Definitely could be. $50 out of $675 is probably an easy chargeback to deal with. I do agree I'm surprised they put up with the amount of fraud that seems to happen, but then I just assume my surprise is because I'm a westerner and I get all righteous when someone tries to scam me whereas...
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    Clawing back money for miss-sold "420ah" cells

    If you modified the vehicle title to say "1948" then the buyer gets their $ back in full. If you want the Corvette back you need to pay to retrieve it. At least that's how the law generally works in the developed western world. It might be one thing if the seller mistyped 420 instead of 240...
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    420Ah Cells on Aliexpress!?

    I have a very US-centric view of the world, even having been to a few other countries in Europe and Asia. But I suspect AliExpress survives because there's a very large part of the world, especially developing countries, that doesn't expect honesty and very much follows a "buyer beware"...
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    liitokala Official Store

    I paid for express shipping on mine back in ~May, but even still they took close to the full time listed. Given mine had what looks like an official CATL QR code, and had an official Liitokala sticker for even high Ah, but tested lower than both, I highly suspect the stuff Liitokala is selling...
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    liitokala Official Store

    tl;dr - My Liitokala cells (from the official AliExpress store) came with only 90% of advertised capacity. Possibly less if I were to put a real load on them. I highly suspect these were used cells. I pulled my Liitokala battery from my trailer for the winter (probably unnecessary but we do...
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    XiaoXiang BMS Spontaneously resets Remaining Capacity display

    Other than replacing the BMS, has anyone found a fix for this? Is there a firmware update, or a different phone (or desktop) app which will allow tweaking of how the SOC calc works? I'm doing a multi-day, low draw capacity test on my ~271Ah pack and I got down to 30% last night. Voltage was...
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    DIY batteries a lot cheaper?

    I built a 12V, 270-280Ah battery for about $650 once all the parts were accounted for. If I'd tried to build ~200Ah it probably would've been $550, give or take. So about half the cost of the SOK (though IIRC the BattleBorn batteries I was originally comparing pricing to were around $900 for...
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    The secret to compression

    If you want a rigid plate instead of a flexible bladder, just put a plate between the cell and the bladder(s) to distribute the force. i.e. bladder -> plate -> 3.2V cells -> plate -> bladder I personally wouldn't want a flexible rubber/poly-something/etc bladder against a sharp corner of a...
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    The secret to compression

    Nice clean build there I prefer the German method of "gutentight"
  16. T

    Combining Fixed Solar Panel and Portable Briefcase

    Ah ok, I wasn't sure if there was a specific compatibility issue or if two differing panels might mess with the MPPT algorithm. His setup sounds fairly small and unlikely to grow significantly. I'd personally start with a single Victron 75/15 and if there was a desire to move to 24V in the...
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    The secret to compression

    Thanks. I feel it's decent enough for my purpose, though I don't feel like a great carpenter. FWIW I used some leftover 8020 extruded aluminum rails in order to join the box corners, and that really helped provide strength, and ensure everything is square. 0.5mm thickness seems small to me...
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    Combining Fixed Solar Panel and Portable Briefcase

    I'm curious why two controllers?
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    The secret to compression

    My battery doesn't have any springs or compressible "foam" pads. My compression setup is fixed... Just wood with some threaded rods and lock nuts, and a few very thin plastic sheets between the cells. If I was going to do it again though I'd use the foam sheets. Pic of the innards during assembly
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    The secret to compression

    AirLift WirelessOne does this for vehicles with air suspension. I can't recall if that model automatically inflates/deflates for you to maintain a specific PSI or if there's another model I'm thinking of, but the general principle exists, yes. Downsides I've heard: If it's pumping humid air...
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    Structure building w/ LFP is different than building w/ lead acid

    It's the Hotel California for the mice, but the rats around the 9:30 mark will have none of it. Rats in my experience are much smarter than mice. They also a profound climbers and jumpers - while a 5 gallon bucket will trap a mouse, doing the same with rats requires a 55 gallon drum... they...
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    The secret to compression

    Might work for a stationary setup, assuming it never leaks air and the temperature stays constant. Wouldn't work for mobile installations like an RV, particularly if you go from sea level into the mountains. I can tell you what happens to a sealed bag of popcorn at 10,000'...
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    Combining Fixed Solar Panel and Portable Briefcase

    Re: #1 - I've become a fan of the suitcase method, at least for some of your panels. Fixed is fine if you always have sun (like in a literal fixed setup where your panels are mounted on poles), but if you're camping in the woods your fixed location panels may not get sunlight. However a...
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    Victron recommended settings for LFP 10-90% SoC

    Right now my float is 13.2V, which is below the battery. During the day once the SCC goes into float mode that powers the parasitic loads for hours but it's below the ~13.3V the battery rests at so the battery doesn't receive a charge (and the BMS seems to confirm that). I actually feel pretty...
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    Victron recommended settings for LFP 10-90% SoC

    Thankfully the tail current doesn't take effect until the charger switches to absorption phase. So at least for LFP, the "penalty" is only at the top of the curve once the controller has switched from CC to CV. At least that's my understanding. So if your goal is to stop at around 90% SOC (as...
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    Victron recommended settings for LFP 10-90% SoC

    That is not true. Screenshot right from https://www.victronenergy.com/accessories/smart-battery-sense: I would expect the Victron to enter bulk, but then to exit bulk fairly quickly (within a few minutes) as if the battery is already >90% SOC then the SCC should switch from constant current...
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    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    Apparently the CALB cells are more tolerant of voltage variations than the CATL cells. Or less tolerant. I actually can't tell which since CATL specifies a voltage cut-off and then two separate over voltage protection limits. Confusing. 302Ah CATL cell info below. I have the 271Ah cells...
  28. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    I'm not a battery engineer, but if 3.45V is 99% SOC (according to the LiFePO4 SOC charts floating around on this forum) then I would think it would in fact harm the battery. At least to your point below, I'm convinced of this until a battery manufacturer or someone who is a chemical engineer...
  29. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    No I'm actually only consuming about 1A per day. It's just parasitic draw from the BMS, SCC, SOC meter, gas detector, and stereo when I'm not in the camper. Total draw is maybe 75mA, but the SCC handles that when it is in float mode so it's only roughly 0.075A x 12. When I use the camper (one...
  30. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    When you are staying well under 3.65V, I can't imagine a reason to NOT want that additional 10%. Battery life. CATL claims 4500 cycles if I cycle my battery within 10-90% SOC. The number is lower if I charge to 100% (the docs I've found say 2500 cycles). 2500 cycles is roughly 7 years...
  31. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    Victron MPPT SmartSolar can be configured to do both of those. The issue I've had is that at any voltage I've tried, even when already full the controller seems to want to go into bulk mode for a while before moving into the variable/configurable absorption phase. I can drain 1A off my 280Ah...
  32. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    Absorption (on LiFePO4) only adds about 10% capacity, at least at 3.65V. His charge graph is a good example, at some point with a higher voltage (3.65V) the current drops off precipitously when the charge switches from CC to CV. At that point he's at least close to 90% charge, if not over...
  33. T

    What is the best voltage to charge your cells to? 3.65, 3.55 or 3.45?

    So ideally: charge at 3.65V in order to charge quickly (since 3.45V takes almost twice as long) but stop charging when the cell hits 3.45V because you're at 99.4% capacity. (Or arguably stop at 3.35V or whatever is 90% SOC... something I'd like to do but haven't quite mastered the Victron...
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    Victron recommended settings for LFP 10-90% SoC

    Update: I set my absorption to 13.6V for now with 0 absorption time, and float to 13.2V. Result: The SCC will bulk charge at 1-2A for 6-8 hours each day before kicking over to float (which does not apply a charge). Once the bulk charge is done, the battery eventually drops down to ~13.3V...
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    Last fire.. :-(

    I'm not commenting on what caused your fire or whether your nuts came loose. I'm replying to your comment where you ask "who needs something to lock?" When you build your next battery, you should use lock nuts or loctite on nuts like threaded rods where the compression frame can move, and you...
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