Active Cell balancer and BMS equalizer

[tim0shel]

Let me simplify something for those getting muddled in the minutia.
These large bulk cells are not like small cells so treat them accordingly.
KISS Applied: Assume a 100AH cell, you can safely assume 100mv floatabilty. For 280AH then say 280mv is within tolerance... 1mv for 1 amp hour is within acceptable ranges.

Active Balancing the larger cells requires more amperage to deal with the capacity. Again a 50AH cell can be managed with a 1.5A balancer but 250AH will need 2.3 or better if you want anything done within a reasonable amount of time... The bigger the battery pack cell the more OOMPH you will need to shift the juice around efficiently.

The standard LFP Prismatics will float up & down when charging/discharging, they also settle once no + energy being applied to them, floating them below determined max voltage allows for resting too (not quite the same though).

Very well said like to say this helped me some. I have been seen large fluctuation with mine when charging i.e. one cell hit 3.6x while some of the others where 3.3x which hit somewhere around a 250-300mv difference. when it disconnected the charge input they settled back down and last night I seen them at around 3-7mv within each other. So I might look into something that can balance a bit more quicker or more amps than the Chargery. Then I would need to turn this function off of the Chargery.

 

[Steve_S]

Very well said like to say this helped me some. I have been seen large fluctuation with mine when charging i.e. one cell hit 3.6x while some of the others where 3.3x which hit somewhere around a 250-300mv difference. when it disconnected the charge input they settled back down and last night I seen them at around 3-7mv within each other. So I might look into something that can balance a bit more quicker or more amps than the Chargery. Then I would need to turn this function off of the Chargery.

What you see is quite typical actually, especially the bigger the cell capacities get. Imagine now for a sec, if we were using 500AH cells, lot's of room for differential. I dunno if EVE makes 500AH cells... just thinking out loud you might say.

If you check out some of the video's which have Chargery BMS & Active Balancer, the Chargery's Passive Balancer is turned off (the two can conflict unpleasantly as some found out). Now in this situation with a Chargery & Active Balancer, it seems the wiring harness can also be a bugaboo as the Chargery Wire Harness is only 22ga ? so that cannot carry a 5A+ potential. Now Chargery was designed for light EV & E-Bikes originally and they love the use of Balancers in those applications and so they have a wide assortment of Adapter Boards (although the connectors are a bit greek to me) http://chargery.com/doc/Chargery Accessories list v2.6.pdf

IF the cells we have been buying were properly Voltage & Internal Resistance Matched into sets, Active Balancing would be pretty much irrelevant (an expensive timeconsuming process). The cells like the EVE 280's are Grade-A New and fall within the Broad Spectrum specs for their cells BUT they are not properly matched & sorted into identical batches for Volts & IR. Because of that, we do see more variation between the cells in packs.

Used Batteries like the BYD Packs and even EV Batteries (Tesla, GM Volt etc) especially if they are used can benefit from Active Balancing, PROVIDED that the Active Balancer is sized for the task (enough Amps for the Cell sizes being dealt with). 1.5A on a 280AH cell i sslowwwwww versus say 6A... Timeliness is also a big consideration.

 

[tim0shel]

What you see is quite typical actually, especially the bigger the cell capacities get. Imagine now for a sec, if we were using 500AH cells, lot's of room for differential. I dunno if EVE makes 500AH cells... just thinking out loud you might say.

If you check out some of the video's which have Chargery BMS & Active Balancer, the Chargery's Passive Balancer is turned off (the two can conflict unpleasantly as some found out). Now in this situation with a Chargery & Active Balancer, it seems the wiring harness can also be a bugaboo as the Chargery Wire Harness is only 22ga ? so that cannot carry a 5A+ potential. Now Chargery was designed for light EV & E-Bikes originally and they love the use of Balancers in those applications and so they have a wide assortment of Adapter Boards (although the connectors are a bit greek to me) http://chargery.com/doc/Chargery Accessories list v2.6.pdf

IF the cells we have been buying were properly Voltage & Internal Resistance Matched into sets, Active Balancing would be pretty much irrelevant (an expensive timeconsuming process). The cells like the EVE 280's are Grade-A New and fall within the Broad Spectrum specs for their cells BUT they are not properly matched & sorted into identical batches for Volts & IR. Because of that, we do see more variation between the cells in packs.

Used Batteries like the BYD Packs and even EV Batteries (Tesla, GM Volt etc) especially if they are used can benefit from Active Balancing, PROVIDED that the Active Balancer is sized for the task (enough Amps for the Cell sizes being dealt with). 1.5A on a 280AH cell i sslowwwwww versus say 6A... Timeliness is also a big consideration.

That all makes sense I think my biggest concern is running something else directly to the cells that if something happened no protection and just introducing another potential problem when thinking im making something better by balancing the cells.

 

[keepsake]

I have the 2A Active Balancer -- Blance enroute as I write.

Amazon.com: 2A Blance Active Equalizer Battery Active Balancer Li-ion, Lipo, Lifepo4, LTO, 2S ~ 24S BMS APP Super Capacitors Continuous Active: Home Audio & Theater

Buy 2A Blance Active Equalizer Battery Active Balancer Li-ion, Lipo, Lifepo4, LTO, 2S ~ 24S BMS APP Super Capacitors Continuous Active: Electronics - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Anyone else here using this ?
Seems to be an issue finding the app to control the settings. Anyone done that ? Or have links ? Need to procure some open source for this.
Thanks in advance.

This is the product descip .

Size:2A

Support 2S to 24S battery packs;
◆ Single cell voltage collection range: 1V ~ 5V, accuracy: ± 3mV;
◆ Support all pool types such as : Li-ion, Lipo, Lifepo4, LTO, super capacitors and other batteries
◆ The balance current is set independently in the range of 0.1~2A, independent of the cell voltage difference;
◆ Support balanced cascading to apply to more than 24S of battery packs, in theory, can be cascaded indefinitely; for exsampel , can 28S , 32S , 36S , 40S ... and so on
◆ Support Bluetooth communication, equipped with mobile APP, real-time view of battery status;
◆ Equilibrium line resistance detection, abnormal contact failure is found in advance;
◆ Power supply range: 40V~ 100V;
◆ Low voltage shutdown function to prevent battery damage;
157*98.2*18.7 size
Package Included:
1 x Battery Equalizer

 

[Dzl]

I have the 2A Active Balancer -- Blance enroute as I write.

Amazon.com: 2A Blance Active Equalizer Battery Active Balancer Li-ion, Lipo, Lifepo4, LTO, 2S ~ 24S BMS APP Super Capacitors Continuous Active: Home Audio & Theater

Buy 2A Blance Active Equalizer Battery Active Balancer Li-ion, Lipo, Lifepo4, LTO, 2S ~ 24S BMS APP Super Capacitors Continuous Active: Electronics - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Anyone else here using this ?
Seems to be an issue finding the app to control the settings. Anyone done that ? Or have links ? Need to procure some open source for this.
Thanks in advance.

There is a link in the last picture of the amazon ad you linked to

 

[John Frum]

I plan to, so I hope it works.

Did you get an active balancer?
Does it coexist peacefully with your bms?
I'm thinking about this one https://heltec-bms.com/project/5a-capacitive-active-equalization-active-balancer/
Hopefully I can put a switch on either the most positive or most negative lead to turn it off.

 

[keepsake]

Do you mean the QR code that is said to be broken ?

Otherwise I cannot find what you talk about. Please post the actual link rather than be vague. Thanks.

 

[Dzl]

Do you mean the QR code that is said to be broken ?

Otherwise I cannot find what you talk about. Please post the actual link rather than be vague. Thanks.

Was not trying to be vague, was trying to be helpful.

And personally I thought this was pretty specific:

There is a link in the last picture of the amazon ad you linked to

 

[ArthurEld]

Check here too - https://www.jkbms.com/

Here's your balancer - https://www.jkbms.com/product/jk-b2a24s/

And they tell you to download the app here - https://www.jkbms.com/support/

 

[toms]

Although i haven’t used an active balancer in an installed system, keep in mind that with LiFePO4 the voltage differential between cells isn’t constant across the SOC range.

You may well be adding charge to a cell at lower voltages, then removing charge from the same cell at high voltages.

While this can extend your system capacity, it isn’t something that i would want to do in any system i have installed to date.

Also it is very common for my system to sit at less than 1amp charging at 3.4V while in use. Balancing at this current doesn’t overheat the passive bleed resistors, and i have had no problems keeping 200ah cells in balance with a 500mA passive balancer.

 

[snoobler]

Did you get an active balancer?
Does it coexist peacefully with your bms?
I'm thinking about this one https://heltec-bms.com/project/5a-capacitive-active-equalization-active-balancer/
Hopefully I can put a switch on either the most positive or most negative lead to turn it off.

Yes. Had them awhile.
(avoids eye contact).

I'm still in the process of building my LMO/NMC battery. I have the active balancers, and I've used them on different configurations without BMS. I have encountered a gentleman who has already done what I plan to do, but he already built his own BMS and uses the same active balancers.

Once I get the Batrium, I fully expect to have no issues with the active balancers since they're completely independent of the BMS and the BMS will only see the cell voltages change accordingly.

 

[John Frum]

Which active balancer did you get?

 

[snoobler]

https://www.electriccarpartscompany.com/3v-1s-lithium-battery-balancers-equalizers Had them quite awhile.

Ran on the 12P7S 24V test bank of the LMO/NMC battery WITHOUT a BMS. I checked cells manually like a neurotic terrier.

I'm currently using the 12V version to keep my 4S2P FLA batteries equalized:

Affordable Electric Vehicle Batteries & Components from Electric Car Parts Company

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www.electriccarpartscompany.com

 

[Topper]

I can vouch for the electriccarparts balancers. I've been running 10 of them for a few years on my 24v agm bank( 2s10p=24v@1360ahr) Even with a failing cell, they maintained voltage quite well. Led indicators are great at a glance, ie all green is good. Red light may need attention(cause i had an unexpected shorted cell).
My agms are coming to the end of thier useful lifespan so thinking it's time to take the Lifepo4 leap. I'm still doing my homework on the next logical step. Prebuilt or diy with raw cells.

 

[keepsake]

Vouching goes around !!

Got the jkbms 4 days ago. It works like a charm. My disappointment is it talks about low cell voltage cutoff by in reality it provides no control output of any kind to perform a battery cutoff. Seems to be saying that its internal function stops. This device offers no overall protection to a battery stack.
My next and last step in this project is to remotely access this bluetooth connection with github code. And in another monitoring device, read all 16 voltages and make an external assessment if one cell is at its upper or lower limit. Python 3.x seems to be the ticket to the BLE data.
If anyone here has done this, please share back with a link or more info.

 

[Steve_S]

FYI the ECPC Active Balancers ARE the QNBBM Active Balancers. I am using 4 QBMM-8S units, one in each pack.
Don't get too ticked off when you see the markup....

QNBBM Balancer, QNBBM Balancer direct from Changsha Deligreen Power Co., Ltd. in CN (alibaba.com)

 

[Bob Steel]

Been running an active balancer on my LFP's for 3 years . BMS as well.
No issues .
The passive balancers only cut in at about 3.5v and feed a small current to ground through a resistor creating heat.
Not much current and not much heat.
The active balancers work only if one cell differs by 100mv and moves some voltage to the lower cell. Electrodacus are 10mv diff.
If they say its a 3 amp active balancer that only means if you have 2 volts difference between one cell and another 3 amps might possibly flow . Usually at 100mv its milliamps only and not much of them.

 

[snoobler]

$5.50 mark up to be able to purchase from in-country? I'm good.

 

[Topper]

My experience with the ECPC QNBBM-12V has been very good. They continually balance through the entire voltage range, not just top end. IMHO , this opens up some extra capacity for those out of the ordinary circumstances to keep running, like our 40+hr outage after a 100mph wind storm.
Thought it may be worth mentioning

 

[snoobler]

Yep. Due to extreme cold (8°F), very heavy furnace use, and wife's electric blanket, we took our 4S2P T-1275 bank down to 30% SoC. Fortunately, the balancers kept the 12V within 0.1V of each other, which is an improvement over the prior deep excursion (0.5V on the outlier).