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  1. J

    Be cautious ordering generic blue wrap LFP cells

    I also would not consider using those, Winston/Thundersky, CALB, GBS, Sinopoly and A123 (now Lithium Werks / Valence / Super B) is about it. Would take many years of stellar reputation to get on that list. But reco's always welcome.
  2. J

    Be cautious ordering generic blue wrap LFP cells

    Note BTW that the underside of solar panels generate a lot of surplus heat that lowers cell efficiencies. I've seen systems that boost PV output by cooling the panels, and capture significant "passive solar" energy used for hydronic heating. With decent insulation may even work in arctic...
  3. J

    Be cautious ordering generic blue wrap LFP cells

    Yes, I don't believe in drop-ins at all, so my LFP-related statements likely do not pertain. If a cheap BMS is how you balance for example, with likely a very low balance rate, you may need to sit holding 3.55V or more for many hours or even days after your cells already passed your desired...
  4. J

    Should I give this a try?

    37.4 Ah / 72 h = 0.52 amps Ah used per hour FTFY nit-picky I know Still **incredibly** low, if this is right, that's one efficient fridge. Would really like to see full freezer mode out in Death Valley or something
  5. J

    Be cautious ordering generic blue wrap LFP cells

    He actually hit over 2000 some time ago. Purposefully cycling to 80% every cycle, even when he doesn't need to. See, most people think you should charge to the "maximum stress" rating 3.6Vpc, when in fact that's idiotic. And 99.99% of the time there is absolutely no reason for **any** Absorb...
  6. J

    Be cautious ordering generic blue wrap LFP cells

    I think your statements are only true for those treating vendor specs as care recommendations rather than stressful maximums to be avoided with comfortable margins. Many people claim to cycle between "20-80% SoC", which I consider crazy wasteful of capacity. 3000 cycles with a 2-4% capacity...
  7. J

    Be cautious ordering generic blue wrap LFP cells

    LTO is really the way to go for such cold use cases, e.g. Toshiba Super Charged Ion Battery (SCiB) Much better at low temps, can go to zero volts with no damage, crazy high cycle life, 10,000+ is normal and can be fast charged up to 10C with little stress, so full charging in 6-15 mins and...
  8. J

    Be cautious ordering generic blue wrap LFP cells

    Another point, for a reasonably sized bank, say 600Ah, few owners will even have a charge source capable of going over 0.3-4C. Fitting an alternator or genset that actually delivers just 200A to the bank continuously, is a pretty challenging and expensive bit of infrastructure. So for most...
  9. J

    Be cautious ordering generic blue wrap LFP cells

    My goal is near zero capacity loss through over 5000 cycles. Each model battery will have its minimum "no charging anywhere near this temp or instant scrap" spec. Look at Thundersky/Winston's data sheet as opposed to CALB's. Again, getting exact numbers even with rigorous research which has...
  10. J

    Be cautious ordering generic blue wrap LFP cells

    Yes, an independently powered heat source is better than pulling the LFP bank power down to heat itself, but to my mind, the thermal mass and gentler, more precise temp regulation of a hydronic solution would be better than forced air. If left outside permanently, whether you maintain...
  11. J

    What size inverter to charge cordless tool batteries.

    I disagree. Inverter powered loads are rarely energy efficient, and if you are mostly-solar off-grid, that is the #1 criterion for selecting your devices. So hopefully only a few low-wattage devices require an inverter. Buying several high-quality PSW ones at the wattage just enough to handle...
  12. J

    Be cautious ordering generic blue wrap LFP cells

    Even within the LFP family, between say Winston cells and CALB cells, there are huge differences wrt specific number values. Extrapolating between LI research and what the IRL reality for LFP might be, can only be done in the most general terms. One sweeping statement seems clear - the...
  13. J

    Be cautious ordering generic blue wrap LFP cells

    Wow, talk about entitled attitude. You think I'm parsing the posts closely, as if this is a paid gig? I haven't been, to be honest since the cell commisioning, all these design & build ideas, I have no idea if workable or not, just quickly scanning here and there, trying to help out with an...
  14. J

    Be cautious ordering generic blue wrap LFP cells

    If I had those conditions, anywhere near freezing, I'd be bringing the bank inside my living space, certainly before charging. Be very careful about charge rates vs cold, even cool temperatures. Also if the cells start out cold, could easily take a couple of hours before can/air heating up...
  15. J

    Be cautious ordering generic blue wrap LFP cells

    To me, crazy expensive. should be well under $50 each, ordering under 20.
  16. J

    Be cautious ordering generic blue wrap LFP cells

    I bet just dropshipping from the chinese outfit on eBay.
  17. J

    Should I give this a try?

    That's apparently a duty cycle well under 20%, pretty amazing. What are the temps involved?
  18. J

    Question about charging batteries

    Not practical for most, but pre-warming to say 30°C will greatly reduce the longevity penalty of 1C or even higher, when fast charging is critically important.
  19. J

    Question about charging batteries

    Yes, lead chemistries are a completely different universe. There the issue is more reduced power output below freezing, and yes battery warmers on trucks are a thing in winter as you get farther from the equator.
  20. J

    Question about charging batteries

    Each model battery will have its minimum "no charging anywhere near this temp or instant scrap" spec. In truth you usually can charge at a **very** low C-rate around 0°C But in general, being conservative I'd start pre-warming below 10° if going over 0.1C 25° should be fine for 0.2-3C Faster...
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