Active balancer or not?

[MullerEnergy-Australia]

I'm getting the following made by a Chinese manufacturer and I'm very much in two minds if I should get them to put a 5A active balancer in or not, what are your thoughts? Cost is a touch over US$1000.

50x custom 12V 200Ah (202Ah Lishen cells) 4WD/Camper battery with a whole bunch of connectors (2x 50A Anderson connectors, 45W USB C, 18W USB A, cigarette lighter) built-in. Plus it comes with a Daly 250A BMS with bluetooth and all in a stainless steel case.

Thanks!

 

[curiouscarbon]

Dear @spludgey, Congrats on your prospective build.

1. Are the cells new?
2. How many years of service do you want out of them?
3. C-rate charging and discharging planned?

If 1) yes, then need for active balancer is reduced at start of pack service life. If 2) is a decade or more, then I suggest getting active balance from beginning with the understanding the cells will be old one day. If 3) high C then I suggest getting active balance from beginning.

For context, I require at a minimum Passive Balancing on my own DIY battery packs. However, due to the intrinsic inefficiency of Joule Heating based Cell Balancing, I wish to integrate a capacitive or inductive based active cell balancer in all future builds instead.

I have heard good things about JK brand of BMS with active balancer. And also good things about heltec. Search forum for JK or Heltec to find more.

Good luck on your project.

 

[mikefitz]

I'm very much in two minds if I should get them to put a 5A active balancer in or not

I would say not.
If the cells are of reasonable quality and are top balanced, then there should be no need. Any balancing needed will be taken care of by the Daly BMS, and via Bluetooth you have access to cell condition, so any serious imbalance due to manufacturing faults and cell degrading will be obvious. Its possible that a active balance would hide inadequacies in the battery.

Mike

 

[pollenface]

I don't see the harm in having an active balancer.

If it helps you sleep at night it's worth it.

 

[mikefitz]

don't see the harm in having an active balancer.

If it goes wrong it may damage the battery. The cells themselves are quite reliable ( unless they are junk to start with) so the more electronic 'stuff' you hang on to them the higher the chance of battery failure.

Mike

 

[Steve_S]

I use a QNBBM-8S Actie Balancer on all 5 packs. 3x 280 (two bulk, one properly matched & batched) and two 175AH EV Grade LFP cells.
They work WONDERFULLY but these are more costly than most want (8S 1 pc = $144 USD)

I'm not going to argue the point Active BMS is GOOD and wise, most especially with Bulk cells.
Watch this video, if still not convinced, then whatever...

NOT ALL Active balancers are the same, there are essentially 3 different types and they all behave differently depending on the cell chemistry. Not all are suitable for LFP or Large Capacity cells like we use. There is a great deal of Useless FUD being echoed about Active Balancers... Most forwarded by those who have NEVER used them or who chose the wrong type for their builds (far too common).

FUD = Fear, Uncertainlty & Doubt.

Engage in critical thinking and decide for yourself.
Hope it helps, Good Luck
Steve

 

[curiouscarbon]

BTW, on Heltec Active Balancers:


See that spot where it says "RUN"?

That's actually two separate electrical connections. You can simply remove the blob of solder there and wire in a physical switch instead. This will allow you to control the active balancer manually.

Just thought I'd mention this, to soothe any worries that it might go haywire....

As always, ensure that any balancer used is properly configured for the battery chemistry you're using and for the specific safety range you desire.

 

[Steve_S]

Pending on who's version, some actually have pins with a jumper and others have a micro-switch. I would choose one with pins & jumper and add my own switch that could be located where I want it (not having to open a battery pack is best) to do so IMO.

 

[Diysolar123]

active balancers are great and well worth the few extra dollars...because...
they actually do keep your battery pack balanced and do not rely on the mystical belief that you have, and always will have, perfectly matched batteries. Then again, if you want to go the pure "faith" based route, why have a BMS?? The only reason to have a BMS is if something goes wrong and well, thats just crazy talk isn't it!!!

 

[chrisski]

In my looking into active balancers, I am seeing that you really need to look at specs before choosing. I have several weeks before my cells arrive, and I am now choosing to not active balance, but depending on what I know a few weeks from now, I may purchase one.

Here are today's issues that's causing me not to active balance:
===================================
Do active balancers only work with low cell voltage? Or is this dependent on the manufacturer.

I am looking at this off alibaba for a Heltec Capacitance Balancer 6S 7S 8S 5A :



Balanced starting voltage: 2.0V-2.8V

With my EVE 280 cells having a charge voltage of up to 3.65, and a discharge cutoff voltage of 2.5 volts, this tells me an active balancer only works when the state of charge is really low. Perhaps this is bottom balancing.

On a side note, I do not plan to set my charge voltage at 3.65 per cell, that is what is listed on a spec sheet as the max. I plan on setting the charge voltage around 3.5 volts per cell. I was hoping that this active battery balancer would help the cells stay balanced at the top end also, but this does not seem to be what this active balancer is designed to do. Unless I'm reading specs wrong, then its for low end balance only.

Other manufactures like Hankzor seem to have a sleep voltage of 2.7 VDC, but will continue to balance above the 3.65 volts my cells are rated for. I'm looking at Qnbbm, but lists three types of batteries: 2 volt, 6 volt, and 12 volt. The 3.2 volt cells (or 3.65 volt cells if that's the proper name) are in between.

 

[rhino]

I use a QNBBM-8S Actie Balancer

Can you explain (or link to where you did already) the advantages of using those QNBBM balancers as opposed to the Heltec ones?

 

[chrisski]

FWIW, I put my post in because @Steve_S has said in this post https://diysolarforum.com/threads/d...eed-to-balance-cells.13498/page-2#post-164890 that both QNBBM and Heltec are good active balancers, so I'm pretty sure I'm misreading specs I see on the ali websites somehow.

If I get Active balancing, I want something that will balance 280 ah cell with a top range of 3.65. I want to get something that can help with low end balancing and also something that will do something to prevent a runner at higher voltages when my Bulk charge will be set to 3.5 to 3.55 per cell, realizing that nothing will stop a FUBAR battery from doing what it wants. I have a feeling both the 8S Heltec and the 8S QNBBM work fine, I'm just not reading the specs correctly. Its probably something to do with getting into the settings for a bluetooth app that I am not seeing on the aliexpress page.

 

[Steve_S]

Can you explain (or link to where you did already) the advantages of using those QNBBM balancers as opposed to the Heltec ones?

They are just DIFFERENT I never said one has advantages or better compared to the Heltec or Hankzor
https://deligreen.en.made-in-china....S-for-LiFePO4-Lto-Ncm-Lmo-18650-DIY-Pack.html

HankZor Active Balancers: https://www.aliexpress.com/item/1005002617607510.html?

The QNBBM has no UI as neither does the Hankzor, but like Heltec they do have some with those capabilities which pumps the $ up.
Active, Inductance & Capacitance methods operate different, they are not all the same.

 

[Steve_S]

OH.. Something a bit different. I accidentally shorted out one QNBBM-8S so it has a dead channel in it. When it is replaced, I intend to take it apart and examine it "closely", I'll create a thread and post photo's, just gotta do some waiting now. BTW that lost channel - the cell it is attached to is now a Wild Child and cranky. One itty bitty slip & ZOT !

 

[sprint2freedom]

Balanced starting voltage: 2.0V-2.8V

With my EVE 280 cells having a charge voltage of up to 3.65, and a discharge cutoff voltage of 2.5 volts, this tells me an active balancer only works when the state of charge is really low. Perhaps this is bottom balancing.

I believe you are looking at the specs for LTO, not LFP.

The relevant table is here (from Heltec's web site):

 

[curiouscarbon]

LiFePO4 Cell Voltage vs State of Charge%

3.375 V is maybe lowest i would want balancing to be active. this can be facilitated by a microcontroller reading the cell voltages from the BMS and then engage/disengage the active balancer based on programmed logic.

 

[toms]

The last three packs i’ve commissioned i have incorporated active balancing for the initial “top balance” period. They are then disconnected, as i am of the opinion that the less things hanging off your cells - the better.

If i was using high quality matched cells i wouldn’t use active balancers.

 

[curiouscarbon]

QNBBM-8S Active Balancer (8S 1 pc = $144 USD)

NOT ALL Active balancers are the same, there are essentially 3 different types and they all behave differently depending on the cell chemistry. Not all are suitable for LFP or Large Capacity cells like we use. There is a great deal of Useless FUD being echoed about Active Balancers... Most forwarded by those who have NEVER used them or who chose the wrong type for their builds (far too common).

FUD = Fear, Uncertainlty & Doubt.

Engage in critical thinking and decide for yourself.
Hope it helps, Good Luck
Steve

Wow thank you for sharing that video of Off-Grid Garage's real world experience with the QNBBM-8S Active Balancer HankZor Active equalizer

from watching the video, 380 mV to 10mV for 66 USD pretty good. they even suggest it for new cells because it won't hurt and also even balance them at LVCO, potentially increasing total usable energy from pack...

 

[Steve_S]

Wow thank you for sharing that video of Off-Grid Garage's real world experience with the QNBBM-8S Active Balancer

In the Video, he s using a HankZor Active equalizer, NOT a QNBBM. There is also a significant $$ Difference as well.
HankZor Active Balancers: https://www.aliexpress.com/item/1005002617607510.html?

 

[curiouscarbon]

Do you think Heltec is ok too?

Was under impression Heltec is rebranded JK.

e.g. for balance 8S LFP 24V bank: https://www.amazon.com/Heltec-Equalizer-Balancer-Transfer-Capacitor/dp/B08D9D4NGW