Help with LifePo4 Build

[vapenow]

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.  

 

 

   

    

 

 

 

 

 

 

[BillW50]

The chipsets 200/250/250C can use LiFePO4 and you need to change the battery type with EScribe. These chipsets require 2 or 3 cells (250C up to 4) wired in series. So I don't follow trying one cell first. Nor do I foresee any problems with the battery level reading. If you do, just run the battery analyzer. And yes, if the chipset knows you are using LiFePO4, you can safely charge them in the mod. And you can turn on the board without cells through the USB connection. It won't fire of course.

Edited May 19, 2021 by BillW50
Additional info

[vapenow]

Thanks @BillW50 for the advice on chipset, if only the 200/250/250C support LifePo4, yup, it will require multiple cells in series. Noted. 

For the curve, have you looked at it, it is very Very flat. Unsure of 1) How the device knows how much battery is left and 2) Safety of dropping below threshold.

Does the chip have a profile for LifePo4 cells? 

[BillW50]

LiFePO4 cells does drop in voltage as they are discharging, although not as much as other cells and are almost flat. DNA boards also uses watt hours to figure out the battery level. So even if the discharge was perfectly flat, it would still accurately read the charge level. You can run the battery analyzer or enter the correct value yourself with EScribe. The default LiFePO4 profile probably works fine. Yes LiFePO4 is settable under the manufactures interface with any 200/250/250C.

[dwcraig1]

You can load various mods into EScribe without connecting the actual mod.

Just pick one from "Edit New Settings" 

 

[dwcraig1]

And make changes.

 

[vapenow]

Okay this is sounding like: Just put setting to Lifepo4 and you are done.

Please forgive me but there are a lot threads that allude to some issues: 

1) Must be multiple cells in series to run a 250C board, hence if cells voltage is not balanced perfectly Venting issue could happen

2) Min cutoff is 2.5 volts for board, cell is 3.3 V with sharp drop off and can run near board cutoff at high current draw poses many safety concerns, killed battery concerns, and malfunction/error 

Are these issues resolved, it cant be as easy as drop them into a mod and change the setting in escribe...I wish it were like that. In fact if it is I could just drop a pair of Lifep04 18650s from lithium werks or A123 directly into a Lost Vape Centaurus and risk-be-gone. 

Tell me if I am missing something, please. 

  

 

[BillW50]

Yes selecting LiFePO4 and save changes back to the mod and that should be it.

Cells should be the same type and capacity, age, etc. But perfectly balanced isn't really important since the DNA monitors the state of each cell anyway. And if one cell is lower more than the others the DNA will throw up an error and won't let it do something it shouldn't. The DNA does cell balancing after charging, but it is slow. So being closely balanced beforehand will be a lot faster.

The only problem I see is the default LiFePO4 Profile not reading the correct battery level. And running the battery analyzer will build a Profile tailored to those cells if it isn't right and your all set.

You can change the cell cutoffs if you like, but it shouldn't be necessary.

Edited May 19, 2021 by BillW50

[retird]

A quick google search and have not read thru them............

Legacy MOOCH review and test results if you are interested:

2015:

https://www.e-cigarette-forum.com/threads/a123-anr26650m1-b-2400mah-3-3v-26650-bench-test-results-an-extraordinary-battery-with-issues.770987/

2016:

https://www.facebook.com/batterymooch/posts/a123-anr26650m1-b-2400mah-33v-26650-bench-test-resultsan-extraordinary-battery-w/1793033857652859/