Is BIG BATTERY full of Crap??

[Dzl]

Good day; I almost hate to wade in here as this has been an interesting conversation.

But for me: My 280ah batteries for my RV have a 14w heater on each side for a total of 28 watt consumption. The testing I did last spring showed that the heaters could increase the temperature of the battery by about 10 degrees in an hour. To go from O deg F to 40 deg F (which is where my Victron mppt controllers are set at to allow charging) it would only take 28 watts (each battery). And only 56 watts over 2 hours in the morning to get to an even safer 50 deg F.

With this in mind why would a person risk charging at anything below 40 or 50 deg even at a low .1C rate when the energy cost is so low to heat them up to a much safer range ? A rough calculation in this instance would be about 3% of the battery capacity to heat them up and get them to that 50deg mark where they can take a much higher current.

You make a good point and I do like your solution, and think it needs more discussion here

I think there are a few good reasons its still worth considering low temp cutoff or charging though.
1. Most people will not go to the trouble of designing a custom battery heating solution. Even if it dos make a lot of sense.
2. Layered protection is still a good idea. And multiple approaches to solving a problem is a good thing.

The most interesting part of the conversation for me is not the practical 'how do i protect the battery' question, but understanding the theoretical/scientific aspects of when and to what degree charging is harmful and what factors effect it.

I am also curious whether your numbers are accurate. I don't know anything about calculating how much energy it takes to raise the temperature of a certain amount of mass, but its hard for me to imagine that 56 or 112Wh of energy could raise and hold the temperature of ~100lbs of mass 50 degrees in 2 hours. Is it possible 0*F an 50*F is the air temperature not the cell temperature, or that you mean 0*C not 0*F?
(or is it possible I should keep quiet since I don't know what I'm talking about here )

 

[Bob B]

I feel I usually err on the side of caution also (some would say overly so).

In this case, I suppose the point I was trying to make, is if someone controls low temp cutoff at the charge controller instead of the BMS, they have no more or no fewer lines of defense than someone that controls it only at the BMS. Since most people only control it at the BMS and do not have the capability to do so at the charge controller, @myrkr's approach has no fewer layers of protections than the default approach.

That said, I think you make a very good and valid point that there is value in the simplicity of a single device being able to cut all charging if temperature drops to freezing. More complexity equals more chances to misconfigure something or more chances for something to fail. A BMS based solution would be simpler in a multi-charger situation. This is especially valuable for someone that does not feel confident in there ability to design/configure there system and wants something that 'just works'.

That said, Victron makes very high quality equipment and its designed to integrate pretty well. IF low temperature cutoff can be managed centrally by the BMV or by a GX device, or be managed individually by each charge source I would tend to trust it. Sure its a bit of added complexity but on the other hand you are trusting a much more reputable company than whoever is making most of the BMSes we use.

You make very good points also.

I am falling back to the rules I followed in my work career. I worked with control systems that had control devices that had could be programmed individually, had peer to peer communication and commands could be sent from peer to peer.The system also had master and slave operator interfaces. Those operator interfaces also had global programming capabilities .... So there were a LOT of levels that things could be controlled from.
One of my basic rules I followed was that no critical function would be reliant on communications because that was somewhat of a weak link. I always programmed critical functions to still work if a device lost comm and operated stand alone. Local programming with hard wired control was always preferred for critical functions.
I have seen things go WAY wrong when communications failed and the possibility of a comm loss hadn't been considered.

 

[Dzl]

You make very good points also.

One of my basic rules I followed was that no critical function would be reliant on communications because that was somewhat of a weak link. I always programmed critical functions to still work if a device lost comm and operated stand alone. Local programming with hard wired control was always preferred for critical functions.
I have seen things go WAY wrong when communications failed and the possibility of a comm loss hadn't been considered.

I might borrow this logic, I like it.

 

[Will Prowse]

@ghostwriter66 was correct everyone. I repeatedly asked for a data sheet, and bigbattery did not provide one. I talked to the head engineer (there are 3 engineers designing these packs), and he specifically stated that the new cell can handle -20C charging, and no other cell to date could. So I figured we can test it ourselves in the next video, and I figured it would work as they claimed it would.

Till just now. I have the data sheet and it says that these cells cannot be charged below 0C. I then texted the CEO, Eric, and he said that they screwed up.

He is saying that he promises a 100% refund, and any that are shipped out will be reprogrammed with the correct parameters. They were on backorder since the video was posted, so any of those packs shipping out since my video will have a updated BMS pack (or so they say, I will test it).

And now I look like an idiot because I trusted their engineer.

Next time I will ensure that I have a data sheet, and I will not listen to any companies claims. They need to substantiate claims with evidence, or I won't state it. I did question this in my video though, and figured it would be fun for us to destroy a battery, but I do not want to mislead anyone. I will add an update to the video.

This pisses me off. NEVER trust any company.

Here is the data sheet. English is in second half of PDF:

 

[Deleted-User]

@ghostwriter66 was correct everyone. I repeatedly asked for a data sheet, and bigbattery did not provide one. I talked to the head engineer (there are 3 engineers designing these packs), and he specifically stated that the new cell can handle -20C charging, and no other cell to date could. So I figured we can test it ourselves in the next video, and I figured it would work as they claimed it would.

Till just now. I have the data sheet and it says that these cells cannot be charged below 0C. I then texted the CEO, Eric, and he said that they screwed up.

He is saying that he promises a 100% refund, and any that are shipped out will be reprogrammed with the correct parameters. They were on backorder since the video was posted, so any of those packs shipping out since my video will have a updated BMS pack (or so they say, I will test it).

And now I look like an idiot because I trusted their engineer.

Next time I will ensure that I have a data sheet, and I will not listen to any companies claims. They need to substantiate claims with evidence, or I won't state it. I did question this in my video though, and figured it would be fun for us to destroy a battery, but I do not want to mislead anyone. I will add an update to the video.

This pisses me off. NEVER trust any company.

Here is the data sheet. English is in second half of PDF:

Can I have your new freezer?

 

[Dzl]

And now I look like an idiot because I trusted their engineer.

Next time I will ensure that I have a data sheet, and I will not listen to any companies claims. They need to substantiate claims with evidence, or I won't state it. I did question this in my video though, and figured it would be fun for us to destroy a battery, but I do not want to mislead anyone. I will add an update to the video.

This pisses me off. NEVER trust any company.

Here is the data sheet. English is in second half of PDF:

Kinda scary that the folks 'engineering' these products can screw up or be ignorant of such simple/fundamental parameters. A parameter that even most newbies are well aware of, and did not catch their mistake even when questioned on it...

Did they explain how they screwed up? Misinterpreted/misread the specs? programmed the BMS wrong?

 

[Will Prowse]

We are still going to destroy batteries with the new freezer ?

Should we trust the A123/winston data sheets? We should test them and see if those are wrong as well.

 

[Will Prowse]

Kinda scary that the folks 'engineering' these products can screw up or be ignorant of such simple/fundamental parameters. A parameter that even most newbies are well aware of, and did not catch their mistake even when questioned on it...

Did they explain how they screwed up? Misinterpreted/misread the specs? programmed the BMS wrong?

They said they are going to post on this thread.

And I have seen multiple companies mess this up. It happens a ton. I do not understand how someone could screw this up. I simply do not understand. It is such a basic protection feature. And he specifically told me that they can charge to -20C, and that previous cells couldn't. With confidence. Where did he come up with this? It clearly states on the data sheet that 0C is the limit.

 

[Bob B]

We are still going to destroy batteries with the new freezer ?

Should we trust the A123/winston data sheets? We should test them and see if those are wrong as well.

I like it ..... Lets see just how bad cold temp charging really is.

 

[Hedges]

I am also curious whether your numbers are accurate. I don't know anything about calculating how much energy it takes to raise the temperature of a certain amount of mass, but its hard for me to imagine that 56 or 112Wh of energy could raise and hold the temperature of ~100lbs of mass 50 degrees in 2 hours. Is it possible 0*F an 50*F is the air temperature not the cell temperature, or that you mean 0*C not 0*F?
(or is it possible I should keep quiet since I don't know what I'm talking about here )

Looks like good intuition to me.

Look up specific heat of a material in Wikipedia. Water is a good place to start, with 4.2 J/g/K. Lithium is close at 3.58.
Joule is watt-second. Heating 100 pounds of water with 112 Wh I calculate gives 2 degree C rise. Need about 1 kWh for 20 degrees C, 80 Ah @ 12V or 20 Ah @ 48V.

 

[Hedges]

We are still going to destroy batteries with the new freezer ?

Should we trust the A123/winston data sheets? We should test them and see if those are wrong as well.

Do an AGM too. Just so you can admit an old dog already knew the trick! ?‍?

 

[Hedges]

Kinda scary that the folks 'engineering' these products can screw up or be ignorant of such simple/fundamental parameters. A parameter that even most newbies are well aware of, and did not catch their mistake even when questioned on it...

Trust me, this happens everywhere. ??

 

[ghostwriter66]

@ghostwriter66 was correct everyone. I repeatedly asked for a data sheet, and bigbattery did not provide one. I talked to the head engineer (there are 3 engineers designing these packs), and he specifically stated that the new cell can handle -20C charging, and no other cell to date could. So I figured we can test it ourselves in the next video, and I figured it would work as they claimed it would.

Till just now. I have the data sheet and it says that these cells cannot be charged below 0C. I then texted the CEO, Eric, and he said that they screwed up.

He is saying that he promises a 100% refund, and any that are shipped out will be reprogrammed with the correct parameters. They were on backorder since the video was posted, so any of those packs shipping out since my video will have a updated BMS pack (or so they say, I will test it).

And now I look like an idiot because I trusted their engineer.

Next time I will ensure that I have a data sheet, and I will not listen to any companies claims. They need to substantiate claims with evidence, or I won't state it. I did question this in my video though, and figured it would be fun for us to destroy a battery, but I do not want to mislead anyone. I will add an update to the video.

This pisses me off. NEVER trust any company.

Here is the data sheet. English is in second half of PDF:

Great job @Will Prowse following up with them ... I kinda figured that when one of my engineers called them after your video and asked how their LiFePO4 chemistry was different then all the other LiFePO4 chemistry in the world so that it could be charged below 0/32 and at what voltage/amperage were they charging it and we got back the "well.... uhhh .. hmmmm ... MAGIC BEANS !!!..." answer that something was up and why I wanted to warn everyone in the first place.

Personally YOU have literally taught an entire "big-ass" community about solar. When the company pulled me out of corporate in LAX and told me that I was going to South Texas to work the oil patches and that i needed to also get smart on solar - I thought - how hard can it be - I'm a goddess at designing AC circuits and this solar stuff is kids play -- BOY was I wrong ... AC vs DC is like Gasoline vs Diesel ... they sort of do the same thing but are totally different in capabilities and configurations .. I say all of this because it was YOUR videos that I ran across first in trying to learn the basics. Literally everything I learned to begin with was because of your videos ....(and a few small fires I started - but I digress) ... so i wouldn't change anything on the way that you are doing your videos... and there are probably a few thousand that would say the same thing ...

NOW from where I sit - BigBattery knew exactly what they were doing - we just fortunately/collectively called their bluff before allot of ppl ran out and purchased these Magic Beans ......

 

[Dzl]

We are still going to destroy batteries with the new freezer ?

Should we trust the A123/winston data sheets? We should test them and see if those are wrong as well.

Personally I wouldn't put too much faith in that old datasheet. but with WInston there is the wildcard of the Ytrium being added to the mix, IDK what effect that has, and its apparently proprietary so it seems there isn't much data available, but at least its a possible explanation as to why or how they could perform better in the cold.

That said, If I bought Winston cells I would NOT trust the supposed minimum charging temperature of -45*C! that is NEGATIVE 50 DEGREES FAHRENHEIT!!! Not the sorta claim to accept without seeing some 3rd party verification, especially when its based on a proprietary formula nobody else is using.

Also worth noting, Victron who appear to use Winston cells in at least some of their batteries state the operating range for charging is 5*C to 50*C which is consistent with normal slightly conservative LFP parameters. Datasheet

One thing I'm not clear on is whether Winston only manufactures the LYP cells now or if they also still manufacture vanilla LFP

 

[backwash]

You make a good point and I do like your solution, and think it needs more discussion here

I think there are a few good reasons its still worth considering low temp cutoff or charging though.
1. Most people will not go to the trouble of designing a custom battery heating solution. Even if it dos make a lot of sense.
2. Layered protection is still a good idea. And multiple approaches to solving a problem is a good thing.

The most interesting part of the conversation for me is not the practical 'how do i protect the battery' question, but understanding the theoretical/scientific aspects of when and to what degree charging is harmful and what factors effect it.

I am also curious whether your numbers are accurate. I don't know anything about calculating how much energy it takes to raise the temperature of a certain amount of mass, but its hard for me to imagine that 56 or 112Wh of energy could raise and hold the temperature of ~100lbs of mass 50 degrees in 2 hours. Is it possible 0*F an 50*F is the air temperature not the cell temperature, or that you mean 0*C not 0*F?
(or is it possible I should keep quiet since I don't know what I'm talking about here )

sorry; all my temps are in Fahrenheit. so zero was actually freezing (32 deg F)

 

[backwash]

Will; got another use for your new freezer. after you destroy a couple of batteries.
how about a couple of different tests on battery heaters ? A single heater on the bottom of a 4s pack of 280ah cells. how much power to go from 32degF to 50degF, then a pair of heaters on each side. temp rate and power consumed etc. then how much consumption to maintain them at 50degF over a night of 32degF ? just a thought.

 

[MrGreen]

So i am looking for actual documentation. @Will Prowse video yesterday he was saying that BigBattery told him (and its ON their website) that their LISCHEN LiFePO4 batteries can be charged at: -20°C – 55°C. One of my guys called today and BB was of no help -- lot of well my sister's boyfriend neighbor knew a guy that said this or that but no spec sheet. LiFePO4 is a CHEMISTRY. Chemistry does NOT change because you simply put it in a different case. SOOO either 2 things are wrong - either my corporate R&D guys are waaaay behind pushing this info out to the field -- or BigBattery is pulling the wool over @Will Prowse and causing him to misinform millions of folks ... personally i would just like to see the test sheet they used ... NOW don't get me wrong -- YES we charge our LiFePO4 batteries when its well below 0C BUT its such a minor trickle charge - like 0.01C (don't quote me) ... BUT thats NOT what BB is saying ... they are saying that you can charge them normally at -20C ...

If anyone has any real info please let me know ...

https://bigbattery.com/product/12v-lifepo4-power-block/?ref=8 clearly states its LiFePO4 and clearly says charges down to -20C

Hello Ghostwriter66:

This is Eric Lundgren : CEO of BigBattery.com. Thank you for bringing this to my attention. You are Correct.

Although it can take a very small charge at -20°C, it was inaccurate and has been revised on our website here: https://bigbattery.com/product/12v-lifepo4-power-block/

Luckily, these units have been on Back-Order prior to Mr. Prowse Review and very few units have been sold prior.
Per our tests, I have been informed that the BMS was programmed prior to shut-off at (-5°C).
The BMS on all future units will be programmed to shut off at (0°C).

Although our tests have proven that -5C was not a safety hazard, We will be proactively reaching out to any customers whom received these initial batteries in our customer database to provide new replacements at no cost. We will be covering all shipping and provide a credit on future orders for their inconvenience. If anyone reading this message has purchased our (Gen 1) 12V/4SLA Power Block - Feel free to eMail me directly at Eric@BigBattery.com for your free return shipping label & replacement pack.

I created BigBattery to provide new battery tech the guaranteed best prices in the USA. We stand behind our products and if problems occur - we are here to fix them. This was an honest mistake by our marketing department when publishing per the temperature specs and I will make sure that it is fully corrected. . I truly appreciate your feedback and look forward to fully correcting this issue.

I have attached the spec sheet on our Lishen Cells below for your review. If you see any other issues with any of our products listed, please do bring them to my attention and they will be resolved immediately. Thank you for bringing this to our attention.

Sincerely,
Eric Lundgren : CEO
Eric@BigBattery.com

 

[DKyleM18]

As one of the early buyers with two of these Gen 1 batteries, the way they're owning up to and correcting this mistake makes me feel really good about this company. Also, could someone with more technical knowledge than myself be able to read that spec sheet and tell me what the optimal float, absorption, and discharge voltages would be? Specifically to get a 30-90% charge/DoD cycle.

 

[Dzl]

Also, could someone with more technical knowledge than myself be able to read that spec sheet and tell me what the optimal float, absorption, and discharge voltages would be? Specifically to get a 30-90% charge/DoD cycle.

I have not read this particular spec sheet, but this isn't the type of data you would normally find explicitly stated or defined in a cell spec sheet.

It will give you minimum and maximum voltage (for defined test conditions), which define 0% and 100% SOC, and will sometimes recommend a 'SOC usage window' almost always stated as 10-90%.

On the current side, usually there will be a recommended and a maximum continuous current rate given for charge and discharge as well a 'pulse' (short) discharge/charge rate. Good spec sheets will also include data on how temperature affects recommended C-rate, but many do not.

Most people choose roughly 3.5vpc to 3.65vpc as the upper limit for charging, and float at or below 3.4vpc. Really, the 3-stage charging terminology is inherited from Lead Acid.

Hard to say what 30%-90% SOC would be specifically without testing, this is something you should determine with your own battery and a battery monitor that can measure current. To get a ballpark you can check out this thread or this thread.

Also I recommend this short article for a nice primer

 

[DKyleM18]

To get a ballpark you can check out this thread or this thread.

Also I recommend this short article for a nice primer

Those were very informative, especially the third one. Thank you!