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[Note: If someone out there has the same CATL 271Ah batteries and has either the actual manufacturer spec sheet or has their own real-world voltage tables for this model of cells, please let me know and I can make updates to anything in this post] I recently purchased some 280Ah cells from the...

Oh gawd please don't use water. Lithium + water = chemical reaction + hydrogen gas. You don't really want to mix the two...

I've seen a few posts about cell Ah ratings from various vendors, and whether they were true or if the vendors were stretching the truth. I wanted to share what I've found over the last couple months, in the hopes it might be useful to someone. The specs below are specific to CATL but I assume...

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...

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...

Any reason not to use threadlocker for this? just one drop spread over the thread and it's not ever coming off, I think it requires something like 300 ft lbs of torque to break loose... https://www.amazon.com/Loctite-Threadlocker-Red-0-20-209741/dp/B000FP8EUS

YOU need something to lock. Anywhere you have a nut you need to use loctite or at least nylock nuts, IMO, at least in your frame. As things expand and (more importantly) contract, your nuts will loosen and move slightly. For your battery connections you should use lock washers with your...

Thanks, that's good info. My big concern with helicoils is they are stainless steel being mounted into aluminum, which risks galvanic corrosion over time. I would not use anything in aluminum other than zinc. YMMV of course.

Batteries arrived today. AliExpress had estimated 5/24, and today is 6/2. From the prior 17track.net info it looks like the majority of that delay was actually getting from China to Hong Kong. The batteries appear to have arrived in good condition. There's a small dent on one cell (second...

It's a hack. I think it depends a bit on how much you need to recharge the battery each day. If you need a lot of amps to get back to near full then you want more absorption time, but if you don't drain your battery much and you have decent sun then you might be OK with a lower voltage. I...

No problem, man, I was just worried for you for a minute there ;-) Post pics when you're all done, and let us know what you end up doing with the compression setup along the way. This was my first LFP build so I'm sure I could do it better next time... always looking for ideas how others build...

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'...

We live in Chicago, so winter temps can get down to about -10F for a week or two at times, and often hover around 0-10F with overnight lows. We heat about 3000 sq ft with about 200k BTU boiler through baseboard and free-standing radiators. Our walls have no insulation at all, windows and doors...

Any auto mechanic will have a tap and die set on hand. Electronics repair shops probably have them handy too (and might be more willing to do it to a battery) Honestly I'd say spend $40-50 and buy one off Amazon and do it yourself. It's pretty easy to do, particularly a soft material like...

What's your required heating load? Rule of thumb is 30-60 BTU per square foot, so 30k BTU implies you're trying to heat a 500-1000 square foot space. That rule of thumb is misleading though as the location (North Dakota vs Louisiana), construction materials (canvas yurt vs R19-insulated walls...

A 2 stage furnace will heat at 60% and run the fan at a lower speed unless it can’t keep up when it’s really cold. I’m not sure if you can find a 2 stage but if so it’ll list run at 18k btu normally and only at 30k if you’re trying to heat the room quickly

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...

Thanks, that makes sense. I'll give the zero-absorption config a shot. Might go over this evening and turn on some higher load fans just to bleed off some capacity and see how it does. I'm not sure I can disable floating but I am sure I can at least turn it down to a point where it's...

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

The QR code, yes. I also provided test data showing a lower Ah value and then calculated the value of the refund based on that delta x total cost I will update with more details once I actually see the refund in my account

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

I'm curious why two controllers?

The BMS will draw so little power I'd leave it. Otherwise what happens if the repair shop turns the 12V power on to push out a slide or test a circuit? Ideally you should store LFP at 30-50% charge. Assuming yours are at 90%+ I suspect they'll still be fine just sitting until you're ready...

Yeah I really don't use the BMS SoC (mine is the knockoff Overkill version) as I've noticed it seems slightly off sometimes vs what I'm seeing in my Simarine panel in my trailer. It's generally close, but I think the overkill BMS is sampling current draw every second or so and calculating based...

I did and AliExpress ruled in my favor. We'll see how long it takes to actually receive the refund

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...

They changed their page, but last week it had a "Ships From" option of either China or United States. I chose US. https://www.aliexpress.com/item/1005001651207341.html?spm=a2g0s.9042311.0.0.6a8a4c4do27QD1 My *assumption* (which is probably wrong) was that they ship a pallet of these to the...

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...

Yep that's what I'd expect. I guess I'm confused by this statement "That means you need to charge at a high enough rate that the battery doesn't get to full before it pops into the high knee." What I was saying is that even at a low C rate I've still seen the switch-over happen as it...

Generally no, the base is flat and thick and the stud is welded on top. I suspect if you insert something non-metallic in there (toothpick, zip tie, etc) it will stop as it hits the base that the stud was welded to.