vapenow Posted May 19, 2021 Report Share Posted May 19, 2021 Hi all. Looking for some advice from the technical experts for a safe(er) build. I want to build a box mod that utilizes batteries with the much safer Lifepo4 chemistry. I have combed through the every post on this technology, but have yet to find anyone who has successfully implemented it, makes me wonder WHY NOT? If it is as safe as the documentation says it is, I will just implement it myself Charger cost, cell cost, board cost etc.. is not much of a factor to me, anything in the range of $500-$1000 for the safety is well worth the cost and effort in my books. Not interested in turning this into a thread about how rare these thermal runaway events are and how it is user error etc... as when they happen they are often severe, violent and should be avoided if possible; rather, I want to use this thread as a reference point for myself and others who want to implement the technology. Need some advanced technical help to get this done right, please see questions below. 1. Best LifePo4 batteries for safety, please let me know if you have tested or know anything about them/good sources to get them or other LifePo4 batteries from? I found Lithium Werks that look like they fit the bill well, https://lithiumwerks.com/products/lithium-ion-26650-cells/ 2. Is there any current production mods that I can simply drop them into as is? I ask because the rest of this thread is really about building a mod from scratch... 3. Chip: I believe the only chip that supports LifePo4 is the 250/250C, correct me if I am wrong please. 3 a) Is Recharging possible in the device, through the chip, since 3.6 Volts required? Not a big issue if it is not as I usually charge externally anyways, will the chip placed in the mod turn on when powered by USB for Escribe access without batteries? 3 b) Discharge curve is very flat which presents some issues. How does the mod/chip know how much charge remains and when to cutoff? Seen many threads of people moaning about this, DNA 250C has 2.5V min that must be kept as is so a soft cut of 2.65 can be used I suppose. Depending on the current drawn, will it trip that cut before the battery needs to be charged? 3 c) Given the sharp drop off in the curve, what is the risk of accidentally jumping past the low threshold into dangerous territory? Does going below the low voltage threshold of a battery result in a BOOM or simple a dead battery ? 3 d) For the initial build I want to just use a single cell 26650. Can the chip manage 2 or more LifePo4 cells independently, just anticipating what could go wrong if try to use multiple cells. I think that is a good starting point. Please provide some feedback, guidance, and other potential issues I may have missed. Than you. Link to comment Share on other sites More sharing options...
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