Do I need an Active balancer for two 12.8v 100ah in series?

I just bought a "Power Queen 2PACK 12V 100Ah Group 24 LiFePO4 Lithium Battery 1280Wh for Trailers" on sale to upgrade replace my working DIY 24v, 8 cell LiFePO4 battery pack in my large power wheelchair. As each of these respectable 12.8v battery packs have premium cells and each has its own high end BMS, I think I should put them in series and expect them to work fine. Perhaps I might top balance each pack to each other first. Any advise on that?

Power Queen Customer Support suggests I use an active balancer. I am doubtful about that, especially after reading other threads that are also on the fence on the subject. Perhaps they are upselling me on thiers? If the jury votes that I need one, what should I buy, and where, and at what ballpark price?

Without an inter-battery balancer the batteries will get out of sync and shut down to protect what they think is the problem battery.
No recommendations from me, I’d use a battery configured for the voltage I need.

If it were me, i'd charge them both completely full with good long absorb. Then put them into service and see how they behave before buying something you might need.

If they get out of balance, you could always charge them individually. Maybe this is a yearly task you are ok with? If its every other month then thats going to be annoying and a balancer will help that.

Give 'em a go!

Depends on how hard the charging voltage will be pressed. If charging to max voltage the balancer becomes more important. If charging somewhat less than max it is easier to monitor any imbalance and manually adjust as needed.

For wheelchair use it is less important as any issue will be discovered during the charge process at home.

2Big2B said:

If the jury votes that I need one

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Over time the batteries may/will become out of balance with each other leading to charging or power delivery issues. Since you will be using a 24 volt charger it's possible the weaker battery will hit cell overvolts and prevent the series pair charging successfully.
Perhaps just try operating in series after fully charging each, and monitor the mid point occasionally. Install a battery balancer if its proved necessary.

Thank you, MisterSandals.

That was my thinking too. As you can see, I have been a member here for awhile and have had the experience of building a couple of DIY 28.2v packs.

I own a variable bench power supply I used for cell balancing them which I could use to get 12.8v for a balancing 12.8v charger.

My only other concern is whether my 8s 28.2v 10ah lifePo4 charger is still OK to use for this. That is my plan. Swap in the top balanced 12.8v batteries to each other in series. It should be plug 'n play.

I expect the charger won't see any difference as the current runs through the batteries. One might argue that each pack has probably a 4s 12v 100Ah BMS, running the 28.2 volt current, and charging at 10Ah, it should work. At least the mfg marketing indicates that these can be stacked in all kinds of serial and parallel configurations (up to 8 total as I recall), and it has a solid 5 / 10 year warranty backed by great support. So, if it blows up, I can send them back under warranty!

I think it is a no brainer ... unless there is something else I don't know (which is why I am here!).

This is what their Customer Service rep told me:

Hi Harold，
Thank you for your message .
We offer a 5% discount code for first time customers for your order: FIRST
The main difference between the Power Queen 12V 100Ah LiFePO4 Deep Cycle Lithium Battery with BMS for Solar RV and the Premium for Trailers is that the Premium version is designed specifically for use in trailers . May i know the model of load you are using . I can check for you .
Because of the tendency to unbalance voltages in series, we recommend that you install a battery balancer in the series circuit to equalize the voltages.
Enjoy your shopping !
Best regards,
Cathy from Power Queen.

At the risk of sounding arrogant, I suspect she doesn't have much hands on practical experience and is trained to give out canned answers from common customer service calls all day. But I may be totally wrong. She could vd a qualified tech support engineer, as I once was. It is hard to assess though and it would be rude to challenge her qualifications.

From their website https://ipowerqueen.com/products/power-queen-12v-100ah-lifepo4-battery


No mention or illustration of using a balancer in any of their marketing literature.

• [Grade-A Battery Cells & Upgraded 100A BMS] Consists of Four A Grade Lifepo4 Batteries for higher energy and power, built-in 100A BMS protects the batteries from over-charging, over-discharging, over-temperature, over-current, and short-circuit.
  
  
• [Upgrade Of Group 24 Size] Complying with BCI standard minimum size, suitable for narrow space, lead-acid batteries can be directly replaced by group 24, and can be flexibly placed in a 24/27/31 battery box.
  
  
• [Eco-friendly & Widely Used] 4000 cycles +1280wh energy, saving you one-half of the utility bill, widely used in outdoor activities, solar energy systems, marine activities, etc.
  
  
• [Free Expansion & 10-year Lifespan] Support flexible series and parallel connection(4p/4s/4p4s), maximum composition 51.2v 400ah(maximum energy output 20.48kwh), 60% DOD for 15000+cycle times to reach 10-year longer lifespan.
  
  
• [24-hour Service & 5-year Warranty] Provide 24-hour one-to-one technical service and a 5-year battery warranty.
  

See what I mean? They are not using any active balancers. They seem to be all stand alone plug n' play batteries in various configurations -without balancing between them. That is what I expect.


And no, I am not a Power Queen troll ! This is not deliberate free advertisement for them!

BTW, I hope I am not ruffling anyone's feathers by talking about this brand. It has happened to me before. I was on a laser hobbyist forum. I got booted for innocently comparing two different brand safety goggles, because my choice was less expensive and had better styling than the recommended brand. It turned out that its moderator was a sponsor for the brand I was comparing against. Oops. It must be some unwritten rule to not critique the sponsored product in any way. So petty though. It was probably their only funding sponsor no doubt he was probably also the moderator. I wouldn't want to be involved with a forum that I wasn't allowed to freely contribute to anyway.


I know Will has a video that shows a teardown of a larger Power Queen 12.8v 200Ah. He respected the brand with the only usual misgivings about the lack a low temp sensor.

He raves about the Li-Ti(me) brand alot. I am not sure if they are a sponsor of his, or if he needs to defend sponsors. I believe he has more class, integrity and dignity than to put a sponsor's interests above the interests of his followers.


The spirit of this forum is for exchange of ideas and knowlege, free of sponsor censorship, I believe, as it should be. Not all forums are that way.
I like things here!

But if I have accidently done some similar tresspass, forgive me.

Peace.

As if that is possible anywhere lately...

2Big2B said:

Because of the tendency to unbalance voltages in series, we recommend that you install a battery balancer in the series circuit to equalize the voltages.

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So the manufacturer has recommended a balancer for batteries in series, several folks here have recommended a balancer for batteries in series, what was the question again?

The issue with out of balance is that a battery can shut down for over/under volt protection. An unattended system may create other problems if it shuts power off unexpectedly. When that deep freezer is unknowingly off line for a week it will be a mess. This is the type of thinking that needs a balancer. Not the same worry with a wheelchair where it is manually attended.

wpns said:

Without an inter-battery balancer the batteries will get out of sync and shut down to protect what they think is the problem battery.
No recommendations from me, I’d use a battery configured for the voltage I need.

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Thank you.

But, not possible to find a suitable single battery because of size constraints. They are all too long in length (13" or more).

So those batteries fit, which is good, but you either need a balancer for charging or you need to put them in parallel to charge, or you need to charge them in parallel occasionally (no, no-one knows how often), your choice. How much of a crisis is your chair stopping unexpectedly?

2Big2B said:

Thank you.

But, not possible to find a suitable single battery because of size constraints. They are all too long in length (13" or more).View attachment 212695

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Sounds like you will be charging them fully pretty regularly, in which case I don't believe you'll need a balancer. Just based on my experience with Redodo 12V 100Ah minis in series for 24V, and ecoworthy and djlb 24V 100Ah in series for 48V.

wpns said:

So the manufacturer has recommended a balancer for batteries in series, several folks here have recommended a balancer for batteries in series, what was the question again?

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I think the Power Queen Costomer Service agent is confused about this subject and my application.

This is a common unresolved topic of contention here, depending who I'd asked. I looked before my initial post, as I was supposed to.


Hence, I came here for a second opinion.

wpns said:

So the manufacturer has recommended a balancer for batteries in series, several folks here have recommended a balancer for batteries in series, what was the question again?

Click to expand...

The main difference between the Power Queen 12V 100Ah LiFePO4 Deep Cycle Lithium Battery with BMS for Solar RV and the Premium for Trailers is that the Premium version is designed specifically for use in trailers . May i know the model of load you are using . I can check for you .
Because of the tendency to unbalance voltages in series, we recommend that you install a battery balancer in the series circuit to equalize the voltages.

I think she is parroting a canned response she has been told as appropriate for a travel trailer. "May i know the model of load you are using."

What? I am not trying to buy a trailer hitch!

I need a 24v 100Ah battery to fit in my battery box as shown in a photo of it in thread. I am currently using DIY 8s 24v 100Ah LifePo4 pack with an "Overkill" BMS. Works great. But upgrading to a pair of, sealed, warrantied batteries not subject to wet weather has an appeal now that prices went this far down.

On related threads, some say it is necessesary, other say not, and and some say using an active balancer will actually cause problems. So, nobody is on the same page. Go figure.

time2roll said:

The issue with out of balance is that a battery can shut down for over/under volt protection. An unattended system may create other problems if it shuts power off unexpectedly. When that deep freezer is unknowingly off line for a week it will be a mess. This is the type of thinking that needs a balancer. Not the same worry with a wheelchair where it is manually attended.

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Thank you.

I agree with you. It is a matter of relevant context that confuse everyone.

I used 2x HA01 balancers in a previous 24v setup.

you can find them on ebay/amazon, they look cheap and questionable but do work well

I have a friend who will ask 10 people the same question until he finds someone with the answer he wants. Just saying.

If this will be charged often and discharged to low SOC, I'd install a balancer. The key is the low SOC, I can watch all 64 cells on my Batrium in my house bank and low SOC will create an imbalance between cells and get larger if 100% SOC is not reached and balancing doesn't occur. If discharge is minimal and recharge is to 100% every time, then you might get by without a balancer.

As for Power Queen, I just bought a 12V one myself. It is heavier than the pair of Zooms I bought for my boat trolling motor.

Brucey said:

Sounds like you will be charging them fully pretty regularly, in which case I don't believe you'll need a balancer. Just based on my experience with Redodo 12V 100Ah minis in series for 24V, and ecoworthy and djlb 24V 100Ah in series for 48V.

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Thank you. And you are correct about how I use my present battery pack, which I run a shunt to an ammeter on my control pad as a sort of fuel meter to watch how much I have in reserve while out and about. Works well. I like to keep it automatically topped up at 28.2v with my charger plugged in while shut down.

Zwy said:

I have a friend who will ask 10 people the same question until he finds someone with the answer he wants. Just saying.

If this will be charged often and discharged to low SOC, I'd install a balancer. The key is the low SOC, I can watch all 64 cells on my Batrium in my house bank and low SOC will create an imbalance between cells and get larger if 100% SOC is not reached and balancing doesn't occur. If discharge is minimal and recharge is to 100% every time, then you might get by without a balancer.

As for Power Queen, I just bought a 12V one myself. It is heavier than the pair of Zooms I bought for my boat trolling motor.

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Thank you. I hear you and appreciate your point about selective listening. A lot of that goes on in Congress lately. Nobody gets anywhere like that.

I keep it topped up and have never run at low SOC. Never below 40% while out and about, keeping an eye on my ammeter constantly.

pollenface said:

I used 2x HA01 balancers in a previous 24v setup.

you can find them on ebay/amazon, they look cheap and questionable but do work well

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Thank you!

IMHO without some kind of interbattery balancing they are going to drift and you will get BMS shutdown (maybe while charging, maybe while discharging, eventually both).

Hey, this is the DIY forum, take a synthesis of all the info you glean here and please come back and let us know what you did and how it worked out.