Lishen 272ah Cells Aluminum Case Positive?

[michael d]

a report of 10 mA is how much on a 280 Ah battery? check my math, please?

280 Ah battery cell times 1000 mA per 1 amp = 280,000 mA
correct?
so 10 mA divided by 280,000 mA = what percent of the battery capacity?
10/280,000= 3.5.... to the neg 5th power x 100 = 3.5 to the neg 3rd power.
it will take 10 seconds to lose 1 milliamp.

60x60x24= second in 24 hours = 86400 second per day
86400 divided by 10 seconds equals 8640 milliamps per day
8640 milliamps divided by 1000 milliamps per amp = 8.64 amp loss per day(if you have that amount of leakage).
that would be significant if it was being drained off to something.
I think my 6 250 watt solar panels pushing 45 amps at over 28 volts will overcome that loss (if it is actually there).
my 2p8s 24-volt tops out most days but I will be increasing the battery bank size and the solar array significantly.

I think it best to insulate the aluminum cased prismatic cells between and under them with a non-conducting material.
then, you will keep the electrical inspectors happy, satisfy the NEC, and your battery build will be safer than with only the blue shrink wrap they arrive in.

One milliampere is equal to 1/1,000 of an ampere, which is the electrical current equal to the flow of one coulomb per second. The milliampere is a multiple of the ampere, which is the SI base unit for electric current. In the metric system, "milli" is the prefix for 10-3.

 

[Gazoo]

yes someone is reading something into Lishen specification sec 6.9 that is not there.

That someone is me and I am not ashamed to admit it. Feel free to contact Lishen and ask if you need all the details.

But yes...it is there the way I interpret it.

6.9 Don’t contact cans directly or with other conductive materails during the using process.

Notice the word conductive? It is listed under the Warning section of the spec. sheet. The warning to not contact the cans directly is there for a reason, and I can't think of any other reason than the cans having leakage current. Can you?

8640 milliamps divided by 1000 milliamps per amp = 8.64 amp loss per day(if you have that amount of leakage).
that would be significant if it was being drained off to something.

This was a basic test on one cell. Some could be less, some could be worse. I am not going to check your math. The fact there is any leakage is concerning. Can it get worse over time? I don't know.

I think it best to insulate the aluminum cased prismatic cells between and under them with a non-conducting material.

That was my whole point of starting this thread and I don't believe leakage current should be dismissed as nothing to be concerned about.

Can you explain what would happen if two cans are connected to each other in a circuit running at high amps?

 

[michael d]

That someone is me and I am not ashamed to admit it. Feel free to contact Lishen and ask if you need all the details.

But yes...it is there the way I interpret it.

6.9 Don’t contact cans directly or with other conductive materails during the using process.

Notice the word conductive? It is listed under the Warning section of the spec. sheet. The warning to not contact the cans directly is there for a reason, and I can't think of any other reason than the cans having leakage current. Can you?


This was a basic test on one cell. Some could be less, some could be worse. I am not going to check your math. The fact there is any leakage is concerning. Can it get worse over time? I don't know.


That was my whole point of starting this thread and I don't believe leakage current should be dismissed as nothing to be concerned about.

Can you explain what would happen if two cans are connected to each other in a circuit running at high amps?

the NEC says to insulate it also. so insulate it!

at what point is it a defective battery cell?
should you check yours and ask for a refund?

maybe you should only buy plastic-cased cells so the work is already done for you.
most products have warnings about things not to do. and that may occur if you accidentally do something wrong to limit their liability.
again I repeat --- the Lishhen spec sheet does not say what you claim -- you can contact Lishen and ask them or Eve or Trojan or any battery manufacturer you like.
10 milliamps is nothing essentially. a minuscule issue! if it is even there!

Battery Capacity

Battery Type	Capacity (mAh)	Typical Drain (mA)
AA	2400	50
AAA	1000	10

if it is more or you receive a damaged cell or the cell is leaking; take it out of service; don't put it in service, ask for a warranty if you can get it from the vendor/manufacturer. I doubt you will get much warranty unless you ship it back to them and can prove there is an issue.

what happens when you attach 2 cells at 280 amps directly -- nothing until you incorrectly connect the positive to negative on all 4 terminals. the current can not flow. no amps flow until all 4 terminals are incorrectly connected.

cause a direct short to negative to positive and negative to positive- all on 2 cells(don't do it) and you will cause arc-ing between the cells and like an arc welder things will start to melt as it heats up.
again (don't do It) insulate between cells - don't trust the blue shrink wrap or buy plastic-cased cells instead!

I put non-conductive plastic cutting mats between the aluminum cased cells and they are mounted in a stationary position in a clamping compression fixture on top of a non-conductive melamine coated particleboard. or non-conductive hardwood plywood (((before I read any concerns about a possible 10mA leakage observed by 1 person.))) all are inside a superinsulated solar power shed. heated by a single light bulb to 65-70 degrees Fahrenheit.
5800 dollars in batteries >>>> 64 new Lishen 272Ah connected together safely.

I will watch to see if there are any significant reports in the future and hope they will be promptly reported so the product quality can be improved for the end consumer in the future.

thanks for your efforts ?

 

[Gazoo]

at what point is it a defective battery cell?
should you check yours and ask for a refund?

I don't understand what you are trying to say here. I never claimed a cell with leakage current is defective so I don't get your point.

maybe you should only buy plastic-cased cells so the work is already done for you.
most products have warnings about things not to do. and that may occur if you accidentally do something wrong to limit their liability.
again I repeat --- the Lishhen spec sheet does not say what you claim -- you can contact Lishen and ask them or Eve or Trojan or any battery manufacturer you like.
10 milliamps is nothing essentially. a minuscule issue! if it is even there!

Dude, I am not going to argue with you about the Lishen specs. and I am not going to call them. I don't have a problem understanding what Lishen is conveying. Apparently you do but yet you agree it's best to place an insulator between the cells... ?

if it is more or you receive a damaged cell or the cell is leaking; take it out of service; don't put it in service, ask for a warranty if you can get it from the vendor/manufacturer. I doubt you will get much warranty unless you ship it back to them and can prove there is an issue.

I don't know of any supplier that has asked for a damaged/defective cell to be returned to them. They don't want them. And in the majority of cases the supplier has resolved the issue, whatever it may be, to the buyers satisfaction.

what happens when you attach 2 cells at 280 amps directly -- nothing until you incorrectly connect the positive to negative on all 4 terminals. the current can not flow. no amps flow until all 4 terminals are incorrectly connected.

I am not stupid and that's not what I asked...lol. I will try to clarify. What I was asking is what happens if the cans (the aluminum shell) with leakage current are connected together in a 12 volt system for example.

I put non-conductive plastic cutting mats between the aluminum cased cells and they are mounted in a stationary position in a clamping compression fixture on top of a non-conductive melamine coated particleboard. or non-conductive hardwood plywood (((before I read any concerns about a possible 10mA leakage observed by 1 person.))) all are inside a superinsulated solar power shed. heated by a single light bulb to 65-70 degrees Fahrenheit.
5800 dollars in batteries >>>> 64 new Lishen 272Ah connected together safely.

Good, you should be proud of yourself.

I will watch to see if there are any significant reports in the future and hope they will be promptly reported so the product quality can be improved for the end consumer in the future.

You won't be the only one.

thanks for your efforts ?

You are welcome..?

 

[michael d]

Gazoo Dumb Dumb asks >>>"I am not stupid and that's not what I asked...lol. I will try to clarify. What I was asking is what happens if the cans (the aluminum shell) with leakage current are connected together in a 12 volt system for example."

you will have to find that answer. but again the NEC says to insulate with non-conductive materials between them the metal case.
I would say ask your local electrical inspector that question.
I can't give you that answer.
I am not doing the off-grid batteries the way you are asking.
I build 24-volt and 48-volt systems.

perhaps there is an electrical engineer who can address that question correctly for you.
maybe Will Prowse can give you the correct answer!
hopefully, you will find the answer! ?

 

[Gazoo]

Gazoo Dumb Dumb asks >>>"I am not stupid and that's not what I asked...lol. I will try to clarify. What I was asking is what happens if the cans (the aluminum shell) with leakage current are connected together in a 12 volt system for example."

Gazoo Dumb Dumb must have a asked a reasonable question.

you will have to find that answer. but again the NEC says to insulate with non-conductive materials between them the metal case.
I would say ask your local electrical inspector that question.
I can't give you that answer.
I am not doing the off-grid batteries the way you are asking.
I build 24-volt and 48-volt systems.

The question would apply to 12, 24, 48, 96, or whatever volt systems. I used 12 volts for an example and said so.

perhaps there is an electrical engineer who can address that question correctly for you.
maybe Will Prowse can give you the correct answer!
hopefully, you will find the answer! ?

Gazoo Dumb Dumb asked a reasonable question and it's unfortunate you can't answer it. I would very much like to get an answer to this. You saw the thread concerning the fire in the van. While I don't think the subject we are discussing had anything to do with the fire, in my view it's better to be safe than sorry and do all we can to prevent a disaster from happening.

And BTW, why does the NEC maintain an insulator needs to be placed between the cells? If you don't know the answer that's fine. Hopefully someone with more knowledge than us will address these questions. I am contemplating shooting off an e-mail to Lishen for an explanation, even though I said I wouldn't.

 

[michael d]

Gazoo Dumb Dumb must have a asked a reasonable question.

The question would apply to 12, 24, 48, 96, or whatever volt systems. I used 12 volts for an example and said so.

Gazoo Dumb Dumb asked a reasonable question and it's unfortunate you can't answer it. I would very much like to get an answer to this. You saw the thread concerning the fire in the van. While I don't think the subject we are discussing had anything to do with the fire, in my view it's better to be safe than sorry and do all we can to prevent a disaster from happening.

And BTW, why does the NEC maintain an insulator needs to be placed between the cells? If you don't know the answer that's fine. Hopefully someone with more knowledge than us will address these questions. I am contemplating shooting off an e-mail to Lishen for an explanation, even though I said I wouldn't.

yes, you need to pose the question to an electrical engineer. there are electrical engineers on this forum but probably won't answer you on a public forum without the data to back them up.
Ask Eve or Lishen both are chinese manufacturers of LiFePO4 aluminum cased prismatic cells.
as to the NEC --- my understanding is there is a board of electrical experts who set the NEC rules to make electrical systems safer. if you read up on them you could probably find someone with who you could address your question.
the local electrical inspector is who passes and approves the system.
they also say the local electrical inspector has jurisdiction and may set standards slightly different than the NEC according to their interpretation.
ask a reputable licensed electrician. they can guide you.
I am a DIY home remodeler with 40 plus years of experience.
after all, this is a DIY solar forum.
I have used solar panels for 30 years but with the LiFePO4 battery banks I have only 1.5 years of experience with this technology.
Personally, I do not care for 12-volt systems myself except to charge the truck battery and lawnmower battery, etc.
my present solar PV build is a DIY solar off-grid system stationary 24-volt and 48-volt designed to fully power the farm.
even the motorhome is 24-volt.
again thanks for your efforts! ?

 

[InMyImage]

The reason I started this thread was because when leakage current was first reported with the EVE cells I didn't think it was a big deal. When I read what Bud Martin posted I changed my mind and I felt it appropriate to start this thread since I had also been posting leakage current wasn't a big deal. It was the only way I knew to admit my lack of concern was wrong, and to warn others out of an abundance of caution.

And I thank you for doing so. I was musing about actually putting aluminum sheets between the cells in a 24v pack and connect them to aluminum sheet on the outside to act as a heatsink for the pack given that they will be put into the belly of my 5th wheel.

Lloks like I should source some thin rubber sheet instead.

Thanks!

 

[Dzl]

The heatsink idea is has been pondered and discussed before, my perspectice (and I think the general consensus) was that for normal energy storage applications (1) a heatsink is not necessary (2) a heatsink would not be very effective.

My thinking is based on the idea that for low C-rate applications (less than maybe <0.5C and definitely <0.25C continuous), the cells will only rise a few degrees above ambient. So if heat becomes a problem, it is almost certainly mostly due to external factors (whether that is just hot weather or other heat producers in your electrical bay), A heatsink probably could not help this situation since it works by transferring heat from the device to something cooler (cool air for instance, or maybe something cool and massive like the vehicles frame or a water tank).

 

[mhdgraphics]

Regarding Lishen cells, it has been pointed out here that what is seen between the aluminum case and the negative terminal is considerable leakage current.. With EVE cells it was confirmed here when measuring between the cells negative and the aluminum case there was very little leakage current.

It would be helpful if anyone else can test one of their Lishen cells by applying some type of load between the negative terminal and the aluminum case. Please do it safely. The Lishen spec sheet does note to not connect the raw aluminum cases together but I am surprised they don't mention the aluminum case is positive, and they don't note it in their drawings. So if anyone can confirm that the case is tied to positive, and/or the amount of leakage current it would be appreciated.

It's very possible other manufacturers are designing their cells with the case positive. So this is a general warning that could apply to any manufacturer regardless if it's noted in the spec sheet or not.

For anyone planning to clamp their cells tight, especially in a mobile application, it is suggested to put an insulator between the cells and do not rely only on the PVC wrap for insulation.

I have a similar issue with Navitas Prismatics from BatteryHookup:

Topband Navitas Prismatic Cells - Voltage (and uAmp current) between case and terminals???

I posted this on the Facebook group for BatteryHookup but I am not getting the info I need. Just got my case of Navitas batteries and took one out to look it over. The terminals look good though I dont see how they are insulated from the case. So I took voltage readings relative to the case...

diysolarforum.com

 

[koobs]

Hmm what are you guys using to insulate between batteries then? I am building a 24s 85v pack for an ATV, with aluminium case cells. So assume some movement over time and possibly the shrink wrap wearing down.
Was planning to use natural rubber sheets, but realised that is actually quite flammable.
Any suggestions on thin insulating non flammable materials to place between cells?

 

[gmoylan]

I hear you. I was actually surprised by the reports of EVE cells having positive voltage on the cells case. It was determined to be leakage current and nothing to be concerned about. But after reading and hearing about the Lishen cells, I am suggesting placing some kind of insulator between the cells, no matter who the manufacturer is. Especially if being used in a mobile environment. Better safe than sorry.

I would like to hear @willprowse comments on this issue. I have seen everyone of his videos but a fair amount and don't recall this issue being discussed.

 

[gmoylan]

I would like to hear @willprowse comments on this issue. I have seen everyone of his videos but a fair amount and don't recall this issue being discussed.

@Will Prowse

 

[Gazoo]

I measured the voltage on the case of one of my EVE cells. The voltage was the same as the voltage measured at the terminals. I didn't measure the current yet. Another forum member member commented in this thread with regards to the topic. I too would like to hear what Will has to say about this. However, better to be safe than sorry is my policy no matter how much one tries to minimalize my paranoia.

 

[koobs]

I measured the voltage on the case of one of my EVE cells. The voltage was the same as the voltage measured at the terminals. I didn't measure the current yet. Another forum member member commented in this thread with regards to the topic. I too would like to hear what Will has to say about this. However, better to be safe than sorry is my policy no matter how much one tries to minimalize my paranoia.

Yep I think I'll be rebuilding my home solar battery with some 1mm neoprene rubber insulation between cells, and I'll do that with the ATV battery too. Better to be safe than sorry.

 

[Will Prowse]

@Will Prowse

Oh right, this problem is well known. I never mention it because the cells I test are sleeved. I did some testing on this a few months ago and pretty much all cells have this leakage current on the case.

If your cells are sleeved, you do not need to worry about it.

Are people buying cells without sleeves? Is someone selling them this way?

I never saw it as an issue because nearly every cell on the market is sleeved. Manufacturers sleeve the cells for this very reason.

 

[Will Prowse]

I just read the entire discussion, and I don't think you guys need to use plastic/rubber sheets etc. The sleeves work fine and are designed to isolate each cell. The engineers know of this problem, and that is why the cells have sleeves. That shrink wrap they use is durable stuff. There are UL listed packs with cells hugging each other, with nothing more than the heat shrink. I wouldn't worry about it, even with high vibration.

A high moisture environment could be problematic and defeat the purpose of the sleeves. So keep the cells dry as most manufacturers recommend. Even if your pack had water inside and leaked current, it is pretty small. I did a dead short test on a 4S pack to the case and the current that flowed was very tiny. I wouldn't worry about it.

 

[Gazoo]

I just read the entire discussion, and I don't think you guys need to use plastic/rubber sheets etc. The sleeves work fine and are designed to isolate each cell. The engineers know of this problem, and that is why the cells have sleeves. That shrink wrap they use is durable stuff. There are UL listed packs with cells hugging each other, with nothing more than the heat shrink. I wouldn't worry about it, even with high vibration.

A high moisture environment could be problematic and defeat the purpose of the sleeves. So keep the cells dry as most manufacturers recommend. Even if your pack had water inside and leaked current, it is pretty small. I did a dead short test on a 4S pack to the case and the current that flowed was very tiny. I wouldn't worry about it.

Thanks Will. I like the idea of an insulator for peace of mind and many of us are clamping their cells to extend cycle life. The other concern is the expansion and contraction of cells when charging and discharging which may or may not cause the sleeves to wear over time.

I am curious what would be the worst case scenario if two bare cells are shorted together in a pack, or the case makes contact with the negative terminal and remains that way over a period of time. I know the current is very tiny when measured on one cell. Would either of these scenarios cause the cells to develop more current through the electrolyte? And would the BMS voltage readings be thrown off?

Remember we are talking of a very possible minimum 10 year life from the cells. That's a long time of cells being clamped and expanding and contracting and a lot of vibration if used in a mobile environment.

The comment posted in this thread is one of the points I am referring to. Thanks.

 

[JimJr]

Hmm what are you guys using to insulate between batteries then? I am building a 24s 85v pack for an ATV, with aluminium case cells. So assume some movement over time and possibly the shrink wrap wearing down.
Was planning to use natural rubber sheets, but realised that is actually quite flammable.
Any suggestions on thin insulating non flammable materials to place between cells?

Natural rubber is a good vibration absorber and is not that abrasive. If you have enough heat to ignite it , you have more other problems it itself .
There are better materials for fire resistance but are more abrasive and less vibration absorption properties. With rubber I would not use solid
buss bars , they will stress the bolt connections, use braided wire or welding wire for your ATV

 

[gmoylan]

I have

I just read the entire discussion, and I don't think you guys need to use plastic/rubber sheets etc. The sleeves work fine and are designed to isolate each cell. The engineers know of this problem, and that is why the cells have sleeves. That shrink wrap they use is durable stuff. There are UL listed packs with cells hugging each other, with nothing more than the heat shrink. I wouldn't worry about it, even with high vibration.

A high moisture environment could be problematic and defeat the purpose of the sleeves. So keep the cells dry as most manufacturers recommend. Even if your pack had water inside and leaked current, it is pretty small. I did a dead short test on a 4S pack to the case and the current that flowed was very tiny. I wouldn't worry about it.

Thanks for responding Will.
I was mainly interested in your view from a mobile perspective with the vibration and motion. And how that would affect these cells years down the road. I was wondering just how durable the wrapper is. However, when you mention the OE's are producing homolgated products and other company like BB have UL accreditations. Then I'd think all the durability testing was carried by those guys to pass the tests anyhow. ?
Its a non Issue as you say.