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Topic: Lithium house battery bank charge rate (Read 1505 times) previous topic - next topic

Lithium house battery bank charge rate

We accidentally did an experiment today on how fast lithiums can rebound from heavy discharge. We moved from 8 days of 50 A service to Boondocking today. I went out in kayak while my wife fixed dinner. She forgot we were Boondocking and I came back to every light on, attic fan on high, Fantastic fan roaring, computer charging and a meal prepared with extensive use of microwave. I looked at the battery monitor and we had consumed over 35 Ah and our watts out were flying along at -1600 just as the sun was fading to a lovely glow. She had more microwave cooking planned.

I turned on the generator and started watching battery monitor with our Freedom 458 Xantrex in charge mode. My two 300 Ah batteries were accepting 90 A in bulk mode, within 30 minutes it switched to Absorption with charge voltage jumping to 14.52 V and a dramatic drop in amperage.

We will be boondocking for next two weeks. It used to be that running microwave off inverter always sounded not so great. Now she can't hear the difference.

Re: Lithium house battery bank charge rate

Reply #1 –
90 amps into 600 amphr capacity is only 15% of capacity.  Your batteries should include recommendations on maximum charge rates and best charge rates for maximum cycle counts.

BattleBorn allows charge rates up to 50% capacity, maybe more for a short time and says that a charge rate of 20% will get you the maximum cycle count.

Check your battery manufacturer's recommendations.

Re: Lithium house battery bank charge rate

Reply #2 –
Quote from: Roger & Susan in Home2 –
BattleBorn allows charge rates up to 50% capacity, maybe more for a short time and says that a charge rate of 20% will get you the maximum cycle count.

The first part of that statement is correct—but the second part isn't. Battle Born states that the cycle count is the same whether one charges at 20% or 50%. Roger has mis-interpreted one of Battle Born's examples of charge rate. They simply gave the example that charging a 100 A-hr battery at a 20 A rate is charging at a 20% rate. I sent them a message for clarification of maximum cycle count and they assured me that 50% rate will give maximum cycle count.

Re: Lithium house battery bank charge rate

Reply #3 –
My charger only produces 90 amps, the highest output I had seen with my old lead acid batteries was 40 amps during bulk if my memory serves me correctly.

Re: Lithium house battery bank charge rate

Reply #4 –
Inquiring minds want to know, is the max  charging rate for 1 battery day 100 amp, or the total of battery bank say 4x100 400 amp.

Re: Lithium house battery bank charge rate

Reply #5 –
The charge rate is based on the total bank - the batteries would split the charge between them. So for example a 400 AH bank of 4 x 100 AH lithium batteries could be charged at 200 amps or 50% of the total AH capacity, each 100 AH battery getting 50 amps.

Re: Lithium house battery bank charge rate

Reply #6 –
All this back and forth debate over lithium "maximum cycle count" got me thinking...

Battle Born says a "cycle" is discharge to 0%. Discharge to 50% is a 1/2 "cycle".

How many 100% full "cycles" will a typical user have in a year, maybe 100, maybe 200 (50% discharge every day would be 182 full "cycles" in a year). With solar probably much less.

Battle Born claims 5000 cycles.

5000 / 200 = 25 years battery life

Use your batteries, charge your batteries at the 50% rate, relax...

Re: Lithium house battery bank charge rate

Reply #7 –
Quote from: prfleming –
Battle Born says a "cycle" is discharge to 0%. Discharge to 50% is a 1/2 "cycle".

How many 100% full "cycles" will a typical user have in a year, maybe 100, maybe 200 (50% discharge every day would be 182 full "cycles" in a year). With solar probably much less.

Battle Born claims 5000 cycles.

5000 / 200 = 25 years battery life

Use your batteries, charge your batteries at the 50% rate, relax...

Exactly!

Re: Lithium house battery bank charge rate

Reply #8 –
I don't think I am misinterpreting anything, just reading, listening, and aggregating facts.  Others may see things from a different perspective. Each of you with any kind of batteries you have can treat them any way you want.  I am doing what I think is going to get the maximum life both in cycles and capacity I can. It is quite likely to be longer than we own our coach and I will be able to pass on LiFePO4 batteries in the best condition possible to the next owner.

Yes, you can charge your BattleBorns at 50% of capacity if you want to and can do so.  If you have 600 amp hr capacity of BattleBorn batteries or any other brand it is not likely many of us have 300 amp charge capacity, I don't, so it is not an issue.  Even when the batteries need charging, all charging sources on my coach in a perfect world at the same time will just get to 30%. Lower charge rates means lower temperatures, always a good choice.

BattleBorn batteries can be charged at as much as 50% of capacity if you are in a norm at temp range (40-80°F internal battery temp, not ambient temps). At 50% charge rate especially at the upper end of this range or above the batteries start to get hot and can be damaged degrading life expectancy and capacity

At low temps (25° F is the stated lower limit for BattleBorn Batteries) high charge rates will permanently damage the battery.  Denis Phares, the CEO of BattleBorn, said in his interview with Will Prowse (2:40 time) that a 20% charge rate is OK at cold temps. He also talks about charge profiles, high-temperature degradation, and more. This is a video worth watching and hearing.  https://www.youtube.com/watch?v=ywn-vBjKblI

From BattleBorn's website (4/3/2022)
Our 100 Ah 12 V LiFePO4 Deep Cycle battery has a life expectancy of 3000-5000 cycles* with a 100 Amp Continuous current, 200 Amp Surge Current (30 seconds), and ½ second surge for higher loads.

*Approximately 75-80% of the battery capacity will remain after 3000 cycles in applications recharging at 0.5C or lower. We have seen life spans of well over 5000 cycles in our lab testing.*

BB has retreated a bit from the 3500 cycles they stated a few years ago to 3000 cycles now and in controlled lab testing they have achieved over 5000 cycles.  50% C charge rates are the maximum they recommend, not necessarily what they recommend in all cases all the time.

This longer lab test cycle life comes from managing charge profiles, charge rates, discharge rates, recharging to 100% often enough to let the BMS effectively balance cell voltages (critical to battery capacity life, and maintaining battery temperatures at the internal temperature sensing location.

I am not an expert on LIFePO4 batteries, just an active consumer of available information. I hope this helps with understanding how to use your LiFePO4 batteries to get the best performance and life expectancy from them.  Technology keeps changing, keep up to date with it if you are considering a change to Lithium batteries when the time is right for you. You get to decide what information is useful to you.


Re: Lithium house battery bank charge rate

Reply #9 –
Quote from: Roger & Susan in Home2 –
I don't think I am misinterpreting anything, just reading, listening, and aggregating facts.  Others may see things from a different perspective.

BattleBorn batteries can be charged at as much as 50% of capacity if you are in a norm at temp range (40-80°F internal battery temp, not ambient temps). At 50% charge rate especially at the upper end of this range or above the batteries start to get hot and can be damaged degrading life expectancy and capacity.

I would really like to see the written statement from Battle Born that states that their batteries can be damaged by charging at a 50% charge rate—but it has never been provided.

I wrote to Battle Born and specifically asked if charging at a 50% rate would result in a shorter total life and they responded in writing that it would not. That seems quite straightforward to me!

Re: Lithium house battery bank charge rate

Reply #10 –
I've used LiFePO4 batteries since I built a 1000 amphour system in 2013.  Back then not much was known about charging.  It was even thought that floating was bad.  Since then a lot of empirical knowledge has come out.  There is still a lot to be discovered about these.  A point of reference is my 1000 ah system is still being used and still has 100% capacity.  I never did a capacity test so maybe they were under rated? 
On charging especially with a large system is there a reason why you need to charge at over 0.5C?  Sure it's nice to not have the long absorb portion but especially with solar there may be no need to charge that fast.  The fact is that these work great in most cases.  So just enjoy them and don't argue the things that don't matter. 

Re: Lithium house battery bank charge rate

Reply #11 –
Quote from: folivier –
On charging especially with a large system is there a reason why you need to charge at over 0.5C? 

I don't know anything about charging at over 0.5C. What I do know is that if you have Battle Born batteries then you can confidently charge them at 0.5C since Battle Born has stated in writing on multiple occasions that they *recommend* charging at 0.5C.

Re: Lithium house battery bank charge rate

Reply #12 –
Quote from: D.J. Osborn –
Battle Born has stated in writing on multiple occasions that they *recommend* charging at 0.5C.

Admit, no first hand experience with Li batteries.

But, is their statement "recommend charging at .5C"

OR IS IT

"recommend charging UP TO .5C"

I can see a need for bot answers as you will want to know the max charge rate if on generator AND will want to know "best practices for long battery life" if recharging overnight on shore power.

Re: Lithium house battery bank charge rate

Reply #13 –
Quote from: wolfe10 –
Admit, no first hand experience with Li batteries.

But, is their statement "recommend charging at .5C"

OR IS IT

"recommend charging UP TO .5C"

Battle Born states, "Our recommended charge rate is 50 amps per 100 Ah battery in your system."

Re: Lithium house battery bank charge rate

Reply #14 –
This is what BattleBorn said today.  I copied the email exactly, typos are theirs.

Charge at up to 50% C if you can, a rare circumstance. Lower charge rates will extend battery cycle life.

I hope this helps our understanding about charging your LiFePO4 BattleBorn batteries.

Please understand and follow the manufacturer's recommendations if you have a different brand.

From BattleBorn ...

Update for Case SUP33080 - "Battleborn battery charge rates to maximize cycle count."

Hello Roger,

Thank you for the email and support.

Yes, your correct if if your use a lower amperage you will prolong the lifespan of your battery bank. You're also correct that there is really anything on the market that will exceed 120amps. I believe that we have a engineer working on this scenario. Let me follow up with that department and I will circle back to you.


 Click here to update the Case online, or reply to this email

Message History
-----Original Message-----
From: Roni Ventura
Sent: 4/5/2022
Subject: Battleborn battery charge rates to maximize cycle count.

Hello Roger,

Thank you for the email and support.

Yes, your correct if if you[r] use a lower amperage you will prolong the lifespan of your battery bank. You're also correct that there is really anything on the market that will exceed 120amps. I believe that we have a engineer working on this scenario. Let me follow up with that department and I will circle back to you.

-----Original Message-----
From: 23350 Anonymous Customer
Sent: 4/2/2022
Subject: Battleborn battery charge rates to maximize cycle count.

I have 600 amp hrs of Battleborn GC2 batteries that I installed about 4 yrs ago.

I understand that these could be charged at up to 0.5C or 300 amps for my battery bank, any more than that can cause over heating and decrease life expectancy measured in cycle counts.

The question is what charge rate maximizes cycle count? When I bought these batteries the expected cycle count was stated at 3500 and in your own testing cycle counts up to 5000 were recorded. My understanding was that charge rates closer to 0.2C helped make that happen.

For 600 ah a 0.2C rate is still 120 amps. Not many common RV situations that exceed that.

Thanks,

Roger
___________________
Roger Engdahl
651 438 5931


Dragonfly Energy Corp is powered by NetSuite — One System. No Limits.

Re: Lithium house battery bank charge rate

Reply #15 –
Ya, the "up to 50% C" makes sense to me-- for all battery types it is common for a slower charge rate (at proper voltage) to be easier on the batteries.

Re: Lithium house battery bank charge rate

Reply #16 –
It's interesting read various responses from Battle Born Batteries. Here is the response I just received from them, and note that they clearly state that, "Our suggested max charge rate is .5c for the battery or battery bank. This charge rate will not reduce the cycle life of the battery. Any higher charge rate and you run the risk of shortening the cycle life," and, "You can feel safe knowing the charge rate can be a .5c or anything lower, and it won't affect the cycle life of your system."

Here is the e-mail response from Eric at Battle Born batteries:

David,

Thanks for your email and questions.

Our suggested max charge rate is .5c for the battery or battery bank. This charge rate will not reduce the cycle life of the battery. Any higher charge rate and you run the risk of shortening the cycle life.

The example you mention gives a proposed 500-amp battery bank and 100-amp charger, which would calculate to a .2c rate. We aren't trying to contradict ourselves here, merely just providing an example of approximate charge time. It is rare you'd find a robust enough charger to provide a .5c rate to a 500 amp bank.

You can feel safe knowing the charge rate can be a .5c or anything lower, and it won't affect the cycle life of your system.

Best,
Eric

-----Original Message-----
From: 30752 David Osborn
Sent: 4/5/2022
Subject: Confused About Charging Rate
In several places on your Website you state that, "Our recommended charge rate is 50 amps per 100 Ah battery in your system." However, in another place in one of your blogs you state "Another example is if you had five 100Ah (amp-hour) batteries for a total of 500Ah and a 100-amp charger. It would take about 5 hours of charging from empty to 100 percent while factoring in enough time to balance the charging cycle. We don't recommend you exceed this charge rate as it can lead to a shortened battery life." These two statements appear to disagree with each other. One statement recommend a 0.5C charging rate while the other statement appears to say that anything above a 0.2C charging rate can lead to a shortened battery cycle life. Is the 0.5C charging rate correct or will anything above a 0.2C charging rate lead to shortened battery cycle life? Thanks!
David J Osborn; Beavercreek, Ohio

Re: Lithium house battery bank charge rate

Reply #17 –
Just as an added piece of information.  My IH45 has two outback inverter/chargers that are capable of charging at combined 200 amps. I don't think I have ever seen it charge at that rate but have seen it at 160 amps a time or two for a few minutes when I first connect to shore power.

Re: Lithium house battery bank charge rate

Reply #18 –
Quote from: turbojack –
Just as an added piece of information.  My IH45 has two outback inverter/chargers that are capable of charging at combined 200 amps. I don't think I have ever seen it charge at that rate but have seen it at 160 amps a time or two for a few minutes when I first connect to shore power.

Interesting! According to Battle Born if you have at least 400 AHr of their batteries then you can charge at that 200 A rate and (quoting Battle Born's Eric, "You can feel safe knowing the charge rate can be a .5c or anything lower, and it won't affect the cycle life of your system."

Re: Lithium house battery bank charge rate

Reply #19 –
OK, don't really see a reason to continue discussing:

Charge at 50% C is IDEAL

VS
Charge at up to 50% C

Sad that Battle Born can't address this succinctly.  Shouldn't be that difficult!

But, without further input on this exact question by Battle Born, let's call this one.

Thanks.

Brett/moderator