Real world efficiency of LiFePO4
- Thread starter Jeremiah
- Start date
They probably didnt just roll the dice.
No one is saying they did. I'm clearly trying to point out to you that a warranty is no guarantee of quality. Sheesh.
You really have an arrogant and obstinate way about your posts and because people stop arguing with you it doesn't mean you won or are right.
I'm with @Jeremiah. Peace out. Feel free to have the last word.
Summary: Battleborn tells you to charge to 100% only because they have a warranty and dont think their reputation matters, and that warranty is meaningless because they're insured, and the insurance company just charges a random over-priced rate that gets built into MSRP so battleborn can fool everyone into ruining their batteries.
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BarkingSpider
Carbon Lifeform
So whats the concensus for realistic LifePO4 longevity and cost effectiveness? i.e. 20% down to 90% up?
MisterSandals
Participation Medalist
I cannot speak of longevity or cost effectiveness, I've only been beating up a couple battery packs for 5 months. But in terms of managing the cells at the top and bottom SOC range, I like 12v bottom and 13.8 top. Individual cell cutoff at 3v bottom, 3.6v top. Looking at the voltage charts, 12v is 9% and anything over 13.6v is 100% charge.
From what I have seen, with my charge cutoff at 13.8v, everybody charges higher than i do. Yet almost everybody says they are 10%-90% or 10%-80%. So i cannot match the charging voltages people say they use, with their conservative use percentages.
I have plenty of battery, by design, and i have not had to squeeze the batteries to get thru the night or anything like that.
From what I have seen, with my charge cutoff at 13.8v, everybody charges higher than i do. Yet almost everybody says they are 10%-90% or 10%-80%. So i cannot match the charging voltages people say they use, with their conservative use percentages.
I have plenty of battery, by design, and i have not had to squeeze the batteries to get thru the night or anything like that.
Wow, no the conclusion I had publicly written up which you conveniently left out for whatever reason was ...
since the scientific literature proves it's bad for the life of the battery to hit 100% consistantly, and good to not go to 0, the guys at battleborn probably have a higher capacity in their batteries than advertised.
This is common sense, good engineering. You can do this yourself if you like. Just program your BMS to avoid the outer limits.
Watch the expression on the CEO when he answers Will's question regarding charging Lifepo4 to100%, he answers"we want people to charge OUR batteries to 100%." (doesn't cover the blanket question regarding Lifepo4 in general; I.e. the 100% that is available to the user b/c the BMS is probably masking the outer limits for you.
Super Easy to do if your product costs 3x what it could cost and it's good engineering.
Let's keep things intellectually honest. There's zero conflict between the Battleborn CEO's statements and the scientific literature we've been referencing. he's got his trade secret likely of only using x% of his bandwidth. Smart.
@BarkingSpider It's a trade off. If you want them to last 20 years and have 85% capacity leftor you are happy to burn through in 10 years with 75% left.
See the stats I posted, those are from Battery University as covered in a video by Will on how to make your lifepo4's last; results based on labs and are optimistic meaning real world should be worse.
All assumes optimal temp around 25 degrees C.
Doesn't seem to be conflicting data out there. Dont go to zero, don't go to 100% if you want them to maintain capacity (unless you have a nice brand like Battle born which probably designed this in already).
relax we are all on the same side; nobody is attacking Battleborn, they look awesome. if I had the loot I'd probably just buy battleborns and be done. BUt maybe not, I like tinkering and learning how to make stuff.
peace everyone
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boondox
Chief Engineer, RedNeckTech Industries
- Joined
- Mar 1, 2020
- Messages
- 789
Because there are some to whom asking any questions that might not put LFP in the perfect light is heresy. It seems almost cultish at times. I too am interested in learning the strong and weak points of all battery chemistries. Without the facts and data you can't design the system that works for you.
So I was chatting with @fhorst and he mentioned that the Tesla power walls only give the user a certain range of usage of the AH and they have a 10 year warranty as well. So seems our hypothesis regarding the Battle Born batteries totally makes sense as another great company is doing precisely what I posited Battle Born may be doing, hence the encouragement to "charge Battleborn's to 100%" makes sense.
Very interesting!
Very interesting!
OK so I just watched a video where Will tears down a BattleBorn and it turns out our theory was correct!
The battleborns absolutely have MORE capacity than they rate the battery for but the BMS keeps part of the bandwidth out of bounds.
That is why (as I postulated earlier in the thread), their CEO encourges people to cycle to 100% .. because the cells are NOT actually hitting 100%. The BMS is protecting that zone. It's a smaller margin than I thought but we also speculated that the warranty surely allows loss in capacity after 10 years.
At 6:38 Will concludes, "So with battleborn they overshoot the capacity so that they know that everybody will always have that capacity and they'll have an improved charge cycle life." That's exactly the point I was trying to get across (as a theoretical way to reconcile the Battleborn warranty with the scientific literature and sure enough; the 2 are not at odds!
Other markers to this effect in the video are 3:30 and 6:21.
It's a great watch for others who are designing their own batteries. One Cool thing is that the Battleborn's don't use Prismatic cells; there are like 40 small cells in parallel (per cell serial grouping) so that even if a cell dies, the battery will still work (again, I'm guessing the warranty doesn't claim 95% capacity after 10 years but that the battery will still work) and this will make it work. Those of us building our own batteries out of the XUBA or Dongguan threads; if just using those cells in serial and one dies, the whole battery will go kaput (but of course it's WAAAAY cheaper and also fun to DIY).
The battleborns absolutely have MORE capacity than they rate the battery for but the BMS keeps part of the bandwidth out of bounds.
That is why (as I postulated earlier in the thread), their CEO encourges people to cycle to 100% .. because the cells are NOT actually hitting 100%. The BMS is protecting that zone. It's a smaller margin than I thought but we also speculated that the warranty surely allows loss in capacity after 10 years.
At 6:38 Will concludes, "So with battleborn they overshoot the capacity so that they know that everybody will always have that capacity and they'll have an improved charge cycle life." That's exactly the point I was trying to get across (as a theoretical way to reconcile the Battleborn warranty with the scientific literature and sure enough; the 2 are not at odds!
Other markers to this effect in the video are 3:30 and 6:21.
It's a great watch for others who are designing their own batteries. One Cool thing is that the Battleborn's don't use Prismatic cells; there are like 40 small cells in parallel (per cell serial grouping) so that even if a cell dies, the battery will still work (again, I'm guessing the warranty doesn't claim 95% capacity after 10 years but that the battery will still work) and this will make it work. Those of us building our own batteries out of the XUBA or Dongguan threads; if just using those cells in serial and one dies, the whole battery will go kaput (but of course it's WAAAAY cheaper and also fun to DIY).
And pretty easy to troubleshoot and fix.
Battle Borns warranty is really an 8 year warranty with pro rating for the last 2 years.
You obviously have not read it. They say you can use up the lifetime cycles of their batteries within the warranty period and that would not be covered.
There are 30 cells in parallel in 4 groups making 120 total.
Your assumptions about Battle Born hiding useable capacity is wacky.
Will Prowse"s capacity test showed and used the full capacity over 100Ah.
I think a 120 cell type battery is superior to other configurations.
You obviously have not read it. They say you can use up the lifetime cycles of their batteries within the warranty period and that would not be covered.
There are 30 cells in parallel in 4 groups making 120 total.
Your assumptions about Battle Born hiding useable capacity is wacky.
Will Prowse"s capacity test showed and used the full capacity over 100Ah.
I think a 120 cell type battery is superior to other configurations.
Dragonfly Energy Corp. (“the Manufacturer”) warrants each Dragonfly Energy and Battle Born Batteries branded Li-ion battery (“the Product”) sold by Dragonfly Energy, Battle Born Batteries, or any of its authorized distributors or dealers, to be free of defects for a period of 10 years (“the Warranty Period”) from the date of sale as determined by either the customer’s sale receipt, the shipping invoice and/or the battery serial number, with proof of purchase.
Within the first 8 years of the Warranty Period, subject to the exclusions listed below, the Manufacturer will credit, replace or repair, if serviceable, the Product and/or parts of the Product, if the components in question are determined to be defective in material or workmanship.
After 8 years and up to 10 years, if the components in question are determined to be defective in material or workmanship, and the Manufacturer deems the components to be repairable, the Product will be repaired and returned.
If the Manufacturer deems the components to be not repairable, a new, similar Product will be offered at a discount of 30% off of the price listed at the time of the offer.
The offer will be valid for a period of 30 days after the date of notification.
And you have to pay the shipping to and from Battle Born.
This Limited Warranty does not cover a Product that has reached its normal end of life due to usage which may occur prior to the Warranty Period.
A battery can deliver only a fixed amount of Energy over its life which will occur over different periods of time depending on the application.
For example, cycling the battery more than 1 time daily, will cause the normal end of life to occur before the end of the Warranty Period.
The Manufacturer reserves the right to deny a warranty claim if the Product is determined, upon inspection, to be at its normal end of life even if within the Warranty Period.
There is a lot of info on Battle Borns website.
Hi Joshua,
A voltage of over 14.2 should give you a full state of charge and there is no need to set the charger to less than this. when 14 volts is reached then the passive balancing is activated and will keep the batteries in a balanced state over time.
The largest impact to decreased longevity is not from bringing the batteries to empty or from charging back up to 100%. It is from charging at a rate higher than .5c (50 amps for a 100ah battery), this will have the biggest effect on diminished lifespan.
Thank you,
Within the first 8 years of the Warranty Period, subject to the exclusions listed below, the Manufacturer will credit, replace or repair, if serviceable, the Product and/or parts of the Product, if the components in question are determined to be defective in material or workmanship.
After 8 years and up to 10 years, if the components in question are determined to be defective in material or workmanship, and the Manufacturer deems the components to be repairable, the Product will be repaired and returned.
If the Manufacturer deems the components to be not repairable, a new, similar Product will be offered at a discount of 30% off of the price listed at the time of the offer.
The offer will be valid for a period of 30 days after the date of notification.
And you have to pay the shipping to and from Battle Born.
This Limited Warranty does not cover a Product that has reached its normal end of life due to usage which may occur prior to the Warranty Period.
A battery can deliver only a fixed amount of Energy over its life which will occur over different periods of time depending on the application.
For example, cycling the battery more than 1 time daily, will cause the normal end of life to occur before the end of the Warranty Period.
The Manufacturer reserves the right to deny a warranty claim if the Product is determined, upon inspection, to be at its normal end of life even if within the Warranty Period.
There is a lot of info on Battle Borns website.
Hi Joshua,
A voltage of over 14.2 should give you a full state of charge and there is no need to set the charger to less than this. when 14 volts is reached then the passive balancing is activated and will keep the batteries in a balanced state over time.
The largest impact to decreased longevity is not from bringing the batteries to empty or from charging back up to 100%. It is from charging at a rate higher than .5c (50 amps for a 100ah battery), this will have the biggest effect on diminished lifespan.
Thank you,
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They rate 100ah so you can use 100ah keeping you from discharging below 10%. That doesnt mean youre not charging to full. Balancing requires the cells to reach 3.6v - 3.65v to balance.
Thats called "top balancing."
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The only way to hide capacity would be to have some bit of electronics inside the case that would somehow increase the battery resistance to increase voltage and stop charging. It would have side effects I'm sure.
That's not going on here.
Might be fun to make though!! Variable resistor that operates on cell voltage and C rate.
That's not going on here.
Might be fun to make though!! Variable resistor that operates on cell voltage and C rate.
Yeah I've seen that video, thanks
That's not what I'm talking about.They could certainly have the BMS cut off charging at some value bellow 3.6v leaving 100% capacity forever out of bounds.
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They could but they don't.
All Battle Born Batteries come with a built-in battery management system (BMS) that protects the cells for long-term cycling. The BMS protects against the following conditions:
High voltage: > 14.7V If an individual cell voltage exceeds a prescribed threshold during charging, the BMS will prevent a charge current from continuing. Discharge is always allowed under this condition
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