DIY Battery Handbook Initiative

JohnTHQ

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May i note that lots of what we do here is based around the laws and fundamentals of dc/ac electricity. amperage/voltage ratings and standards/limitations across the board. You can only teach so much before skill must out run curiosity. I have often found myself not wanting to even give certain folks any shred of "diy knowledge" just because they really are just the type of person who will end up blowing/burning something up or down. I feel its almost a personal insurance policy so i dont feel guilt later or worse avoid the so so "you told me how to do it, why didnt it work? its your fault" arguments. Maybe its just my experiences.
 

upnorthandpersonal

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May i note that lots of what we do here is based around the laws and fundamentals of dc/ac electricity. amperage/voltage ratings and standards/limitations across the board. You can only teach so much before skill must out run curiosity. I have often found myself not wanting to even give certain folks any shred of "diy knowledge" just because they really are just the type of person who will end up blowing/burning something up or down. I feel its almost a personal insurance policy so i dont feel guilt later or worse avoid the so so "you told me how to do it, why didnt it work? its your fault" arguments. Maybe its just my experiences.

Yes, I agree. But this is a DIY forum so personal responsibility from participants is implied. It's up to each person to decide if they are capable or not, and if they're not, to consult someone. The goal of this text is only to give a 'best practices' from a safety point of view. Too many people come here on the forum with basic issues such as bloated cells from a top balance gone wrong - which can easily be avoided. Best case, the document prevents someone from burning down their cabin, worst case: someone just needs to copy/paste a link to it every time a new guy comes in with the same questions after not taking 5 minutes to do a search...
 

upnorthandpersonal

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Main outline is done:


I need to flesh out the sections further over the coming days. Comments and suggestions welcome!
 

Sanwizard

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Main outline is done:


I need to flesh out the sections further over the coming days. Comments and suggestions welcome!
Who is your technical editor? It would be nice if it were peer reviewed to assure all the assumptions are correct via review by someone who is an EE. You may be one, but more eyes is always a good idea. I think we have a few on this forum who may want to help.
This is a great idea by the way, and very much needed. The hard part is taking a complex topic and making it easy for a novice to understand. Believe me I know. Perhaps Will would add a section?
 

upnorthandpersonal

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I'm open for anyone to have a look - that's why I explicitly asked comments and suggestions and why this thread exists. The idea was never that I would do this alone. I would start the general outline and some guidelines, but it should be an effort by multiple people.
 

curiouscarbon

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Love this initiative.

Sorry in advance if the formatting of this is annoying. Unstructured as read...

Feedback on current live version:
•good intro establishing motivation and "method" (knowledge accumulates, scattered across random threads, many threads have at least one "slightly off topic" gem in addition to an on topic one.

•maybe specify voltage requirement for lab power supply

•good overview of chemistry

•maybe emphasize the necessity or rationale of setting voltage before connecting cell(s) (some metaphor about cruise control popped into my head, idunno.)

•while not having over temperature disconnect, under temperature disconnect, can be relatively safe in my view with LiFePO4 but in my view those ought to be listed together with OVD and UVD. the longevity of the user's battery pack, which might have been bought on money with no replacement money available, OTD+UTD would prevent loss of service. in my opinion, long term dendrite failure mode can be considered a catastrophic failure that the BMS can protect against
(charging/discharging during certain cell material being at certain temperatures)

•love the recommendation for flexible bus bars. thinking about the 3D g-force time signal being applied to the terminals and the jelly roll makes me want to find a press to smash some copper onto some braided ground patch conductor or whatever.

•re:busbar maybe add distinguishing bit that flexible bus bar is called for in mobile application especially with motion, but stationary application, in some cases the cell is not flexing over SOC curve (mobile/stationary : flex/solid : breathingcell/nonbreathingcell)

•fixure: perhaps distinguish between "breathing cells" and "non breathing cells" e.g. those which geometrically deform due to the changing internal pressure inside the aluminum cell shell's volume. maybe emphasize the nature of electrical insulation (thermal insulation may be needed in an orthogonal manner to electrical insulation in some cases)

•disconnect: maybe list a few types of appropriate types of disconnects e.g. solenoid spring mechanical contact type, mosfet, maybe a tiny comment about derating and local temperature.

•cables: maybe clarify specific type of conductor desired. in my case the type of conductor desired is stranded bare copper or stranded tinned copper. maybe emphasize fineness of conductor as a factor in being able to "make the bend"

•maybe add small mention of a few different types of acceptable cable insulation. Silicone is one that I like a lot, but it's kind of easy to nick.

hope this is in some way helpful and if any part comes across as upset about the quality of the article, not to worry, it's great. this whole place is great.
 

Steve_S

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Thanks for the feedback! I'll work on incorporating your suggestions.
Lookin Good, I don't know if you saw this but I caught the Neoprene mentioned and figured I'd give you a link to this. https://diysolarforum.com/threads/lifepo4-cell-separator-material.28023/

I believe that it should be very clearly stated that non-conductive casing/boxes are preferable but if metal cases are used, that the cells should be properly isolated with a layer of non-conductive material. In particular a neutral material which will not degrade, is temperature & chemical neutral which will not breakdown over time.

Binding cells also helps prevent "friction" from occurring in mobile applications which over time can create assorted issues (that thin wrap doesn't take much), should also be mentioned, as it is generally "good practice" to "bind" the cells for many reasons.

I Believe a Highlighted "bolded" special note on Temperatures, in particular freezing should be prominent. While there is Cold Temp rated LFP which is Yttrium Doped (much more $) that is not what is generally being used or discussed in this forum and people should be aware of that.
 

toms

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Thanks! Feel free to give your opinions and criticism on the topics - much appreciated.

My long term experience is with plastic cased cells (GBS/Winston/Sinopoly etc). I have had some recent experience with cells similar to EVE’s, they are significantly different to deal with.
 

Smokin

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Best Pratice is
Don't mess with Lithium Ion Batteries.
Snuggle up with 3 Dogs at Night to stay warm.!!!!!
 

curiouscarbon

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Best Pratice is
Don't mess with Lithium Ion Batteries.
Snuggle up with 3 Dogs at Night to stay warm.!!!!!
Amazing advice! Be nice to lithium ion batteries, be nice to dogs, snuggle up with 3 dogs at night to stay warm!
 

curiouscarbon

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(that thin wrap doesn't take much)
thoughts on polyimide tape individual wrap? high labor maybe. i'm seriously thinking of it after having gouged the blue vinyl wrap so easily a number of times. i.e. leave blue wrap in place, add single/double layer of polyimide on top. (got 6 inch wide 1 Mil roll)

i am motivated primarily by distrust of the blue wrap, and would be doing it essentially as a "wrap i can trust" to "raise the wrap standard"
 
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