Does the housing of Lifepo4 battery has a potential

HKZBob

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Nov 7, 2020
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52
Hello FOLKS,

Short question, does the housing of a Lifepo4 battery cell has a potential.
The means und the blue plastic is the AL case. Is that isolated or does it has a potential. Who knows about this?

Greeting Bob
 

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curiouscarbon

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Hello @HKZBob and welcome to forum

From what I have read, yes the Aluminum case shell has voltage potential. Valuable to ensure blue vinyl wrap is fully intact, maybe consider adding 1mm of electrically insulating material between cells if this concerns you.

Cheers, nice looking build
 

Gazoo

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Short question, does the housing of a Lifepo4 battery cell has a potential.
Short answer, yes. I posted a thread about it. The QR code is stamped on the aluminum. If you take your DMM and place one probe on the QR code and the other on the negative terminal you should get a voltage reading on your DMM.

 

HKZBob

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Nov 7, 2020
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Is this current on housing a leak current driven by the electrolyte filling in the milliampere value or can that be high risk if one housing touches another.

Maybe Will can do test to check out if this is a high risk potential.

Thanks
PS
I hope the moderator can pass this concern to him.
Here my specs on my batteries.
 

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Gazoo

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Is this current on housing a leak current driven by the electrolyte filling in the milliampere value or can that be high risk if one housing touches another.

Maybe Will can do test to check out if this is a high risk potential.

Thanks
PS
I hope the moderator can pass this concern to him.
Here my specs on my batteries.
Will commented in my thread. Also another member who is much more intelligent than I am said it could be a problem if the cells are making contact over time. If you read through my thread carefully you will find it as well as many other tid bits of information.
 

HKZBob

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Nov 7, 2020
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If you pack the cells in series as the photo is showing and you have not used isolation paper 1mm, would you dissasembly the RV Battery Pack and add the paper? Man I thought I was done with that project. I am very upset of my Lishen Lifepo4 battery developer. What make them think to put positive on the cans.

This is very bad and a safety issue. FDA should ban this design.
For example your RV having an accident. You won't die on the impact but on the stupid fire from the battery, since the housing isolation gets damaged and gets short to ground.

Man that so stupid.
Cannot sleep with this design.
Greetings Bob
 

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curiouscarbon

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@HKZBob It depends. Before installing, was there check for 1) deformations inward or outward (i.e. dent) on any cell and 2) the blue vinyl wrap appeared to be intact on all of the horizontal sides and 3) cells are constrained and don’t shift if the assembly is shaken (e.g. by hand, no feel of jostling cells)? If you feel confident 123 that the cells are pretty much dent-free and the wrap seemed good on install and the assembly is a firmly secured unit, then probably not urgent to disassemble to add a padding of your choice.

Given all that I’ve read about this topic on the forum, I advise you to consider the pros and cons of using 5mm neoprene padding between your cells given your expressed concern about mobile application.

There’s a user on the forum, I can’t remember their name right now… they said that with 5mm or so neoprene sheet between each mutual cell face, and then compress it such that the final dimension is 25% less the cumulative thickness of the neoprene sheets. e.g. four cells. three mutually abutting faces. three sheets of neoprene 5mm. cumulative thickness 15mm. compress the four cell assembly by (5mm*3)*0.25 =3.75mm hope this helps. i really think neoprene 5mm is good for mobile applications. the cells expand and contract a little bit (i’ve heard it’s a few mm) so having 2.5mm on each side so to speak (2.5*2=5mm) seems like a great compromise. anyways i’ve rambled long enough. please take with big grain of salt. i haven’t actually used this solution in practice before.

hope you can feel good about your DIY battery pack more and more soon!

Please feel free to share more photos of the pack if you have areas that you are specifically concerned about. Cheers
 

HKZBob

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52
Thanks I have checked the battery isolation and it was mint. Then I have added two layers of 3M automotive double sided foam tape and stick the cells together with some light 2mm space in between. As you know that the case center is slightly bow.
The outside ist wrapped us with blue PVC package tape.
So the to stick together and I don't see how they can have a movement.

See pictures to review.
Regards Bob
 

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Zwy

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@HKZBob It depends. Before installing, was there check for 1) deformations inward or outward (i.e. dent) on any cell and 2) the blue vinyl wrap appeared to be intact on all of the horizontal sides and 3) cells are constrained and don’t shift if the assembly is shaken (e.g. by hand, no feel of jostling cells)? If you feel confident 123 that the cells are pretty much dent-free and the wrap seemed good on install and the assembly is a firmly secured unit, then probably not urgent to disassemble to add a padding of your choice.

Given all that I’ve read about this topic on the forum, I advise you to consider the pros and cons of using 5mm neoprene padding between your cells given your expressed concern about mobile application.

There’s a user on the forum, I can’t remember their name right now… they said that with 5mm or so neoprene sheet between each mutual cell face, and then compress it such that the final dimension is 25% less the cumulative thickness of the neoprene sheets. e.g. four cells. three mutually abutting faces. three sheets of neoprene 5mm. cumulative thickness 15mm. compress the four cell assembly by (5mm*3)*0.25 =3.75mm hope this helps. i really think neoprene 5mm is good for mobile applications. the cells expand and contract a little bit (i’ve heard it’s a few mm) so having 2.5mm on each side so to speak (2.5*2=5mm) seems like a great compromise. anyways i’ve rambled long enough. please take with big grain of salt. i haven’t actually used this solution in practice before.

hope you can feel good about your DIY battery pack more and more soon!

Please feel free to share more photos of the pack if you have areas that you are specifically concerned about. Cheers


 

ArthurEld

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If you pack the cells in series as the photo is showing and you have not used isolation paper 1mm, would you dissasembly the RV Battery Pack and add the paper? Man I thought I was done with that project. I am very upset of my Lishen Lifepo4 battery developer. What make them think to put positive on the cans.

This is very bad and a safety issue. FDA should ban this design.
For example your RV having an accident. You won't die on the impact but on the stupid fire from the battery, since the housing isolation gets damaged and gets short to ground.

Man that so stupid.
Cannot sleep with this design.
Greetings Bob
This issue has been bugging me for a long time. I would rather be safe than sorry.
But I haven't heard a sure solution either. People talk about putting all kinds of crazy materials between their cells.
I would prefer something that won't fuel a fire. I haven't found a solution yet.
I think something like asbestos paper would be good but of course it is banned.
Other options aren't cheap.
 

curiouscarbon

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1/4 inch neoprene about 6.3mm should be ok


~11 usd for enough to cover many cells

this is the cheapest neoprene i know of from a brand i’ve used before. it’s really decent stuff but not the super top shelf. fwiw i’ve used it to pad large speakers, interfaces between stuff, insulating bottle holder, padding for everyday hard spots like hard wood corner near shins.

again i haven’t tested this neoprene+280Ah cells personally but i do have a fair bit of experience with that type of neoprene in quite a few engineering arts and crafts projects… 😊

☀️
 

curiouscarbon

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Messages
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Thanks I have checked the battery isolation and it was mint. Then I have added two layers of 3M automotive double sided foam tape and stick the cells together with some light 2mm space in between. As you know that the case center is slightly bow.
The outside ist wrapped us with blue PVC package tape.
So the to stick together and I don't see how they can have a movement.

See pictures to review.
Regards Bob
looks pretty ace to me.

my feeling is low urgency to rebuild given your description and additional photos. low risk of cell wall short i think…

pro: very secure, already a 2mm gap from tape

cons: lack of cell flex pushback

if i were you i’d probably keep it as is for now and maybe rebuild it with neoprene or some other ~5mm material if and when you expand or upgrade or otherwise do a big maintenance event

cheers
 

HKZBob

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Nov 7, 2020
Messages
52
Is a resistance measurements from Cell1 plus to Cell2/3/4 plus terminal a way to identify the isolation quality that I have?

Should be infinity high resistance?
 
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