Active balancer, make it smart!?

[Hans Kroeger]

Do you mean you payed for the 8s version but they will send you one single 4s version instead?

I guess so, but I really don't care. The price is so low and I want to test this very unit!

 

[Vi s]

I guess so, but I really don't care. The price is so low and I want to test this very unit!

That's very generous of you! ?

That shop was also very generous towards me. I did order a 20A BMS from them and on the day they shipped it they sent me a message "SENT YOU 30A". That was a pleasant surprise!

 

[BradCagle]

Alright, I'm writing software that communicates with a bms for logging time series database for graphing, but also to trigger relays for controlling things like active balancers, and to control loads based on excess solar, etc..

It communicates via BT to the BMS, and runs on a raspberry pi. So when I'm done hopefully it'll just be an image you can flash to the sd card, and get down to business.

 

[Vi s]

Alright, I'm writing software that communicates with a bms for logging time series database for graphing, but also to trigger relays for controlling things like active balancers, and to control loads based on excess solar, etc..

It communicates via BT to the BMS, and runs on a raspberry pi. So when I'm done hopefully it'll just be an image you can flash to the sd card, and get down to business.

Hi Brad

Suppose you are also versed with Arduino, have you already seen this thread? https://diysolarforum.com/threads/jbd-bms-wi-fi-module.17252/

What would be missing is only a script to open close a relay at user defined voltages.
Advantage, arduino is more cost-effective and energy saving (almost all in one (jst 2.0 cable to connect to BMS and buck converter? missing)

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), even if everything would work on and with a zero 2 w.
Of course these are not always the most important factors of consideration, everything depends on circumstances and i am sure there are also those who very welcome and appreciate software for raspberry pi.

 

[Hans Kroeger]

That's very generous of you! ?

That shop was also very generous towards me. I did order a 20A BMS from them and on the day they shipped it they sent me a message "SENT YOU 30A". That was a pleasant surprise!

HI Max,
today I received 2 of the concerned balancers. I tested both Balancers with my 12 V battery simulator. I could not find out how to operate theses modules in a useful manner. Only one thing is obvious, the touch pad allows to turn on or off the Balancer manually. However there is certain delay time of some seconds.
The status LED is reacting slow when turning off. But the power consumption shows immediately if the module is on or off.
I could not find out how to get the Balancer turn on by itself, if the cell voltage goes above a certain voltage (e. g. 3.25 V). I also could not find out how the Balancer turns itself off if the voltage drops to a value below 3.25 V.
May be there are very long delay times, but waiting for a couple of minutes didn't reveal anything useful.
Without a manual this Balancer seems to be useless.
By the way, the balancing function seems to work. However, I didn't make any detailed measurements, because I believe it is a waste of time.
Regards Hans

 

[Vi s]

HI Max,
today I received 2 of the concerned balancers. I tested both Balancers with my 12 V battery simulator. I could not find out how to operate theses modules in a useful manner. Only one thing is obvious, the touch pad allows to turn on or off the Balancer manually. However there is certain delay time of some seconds.
The status LED is reacting slow when turning off. But the power consumption shows immediately if the module is on or off.
I could not find out how to get the Balancer turn on by itself, if the cell voltage goes above a certain voltage (e. g. 3.25 V). I also could not find out how the Balancer turns itself off if the voltage drops to a value below 3.25 V.
May be there are very long delay times, but waiting for a couple of minutes didn't reveal anything useful.
Without a manual this Balancer seems to be useless.
By the way, the balancing function seems to work. However, I didn't make any detailed measurements, because I believe it is a waste of time.
Regards Hans

Hi Hans

Thank you for your testing and sharing of your findings!

Pretty quick delivery! Disappointing to hear that these balancers seem not to match their stated specs.
So neither overall voltage 13V nor single cell voltage 3.25v triggered anything. :/

Best Regards

 

[Dynoman]

Alright, I'm writing software that communicates with a bms for logging time series database for graphing, but also to trigger relays for controlling things like active balancers, and to control loads based on excess solar, etc..

It communicates via BT to the BMS, and runs on a raspberry pi. So when I'm done hopefully it'll just be an image you can flash to the sd card, and get down to business.

Sounds like a good project.

Will your software for the Raspberry Pi work for the Overkill Solar BMS? I run two or their 8s 24vdc 100amp BMS and looking to get BMS(s) logging database for graphing etc.

 

[BradCagle]

Sounds like a good project.

Will your software for the Raspberry Pi work for the Overkill Solar BMS? I run two or their 8s 24vdc 100amp BMS and looking to get BMS(s) logging database for graphing etc.

Yes

 

[Roman59]

Which is more effective?... Condenser type balancer or INDUCTIVE type active balancer

 

[curiouscarbon]

Which is more effective?... Condenser type balancer or INDUCTIVE type active balancer

Hello,

So far, I have seen more posts describing success with Capacitive type active balancer as opposed to Inductive type active balancer.

The heltec capacitive active balancer seems to be somewhat effective; there are ones supporting 4,8,16 cell setups.

Good luck with battery stuff!

 

[Warpspeed]

Which is more effective?... Condenser type balancer or INDUCTIVE type active balancer

Both work, but effectiveness also depends greatly upon the detailed design.
Inductive balancers can use either flyback energy (from a choke) or forward energy (from a transformer).

The basic problem is being able to shift significant current between two different cells, where the voltage difference involved can be quite small.
This current almost always pulses very violently, and can be quite difficult to measure and interpret.

For direct cell to cell balancing, all the impedances in the balancer must be kept extremely low, and that is where a lot of the commercial balancers turn out to be pretty weak, when tested properly.

Its easy to for the advertising department to claim that a balancer can shift five amps. And that may actually be true if one cell is half a volt or a volt higher than another cell. A pretty unrealistic situation. And the buggers never tell you at what voltage difference their product is rated at.

If the voltage difference is 5mV instead of 500mV The balancing current may be closer to 50mA than the advertised 5 amps.
If you have pretty large cells, its going to take a very long time to reduce any voltage differences right down to with only a few tens of milliamps to do the job.

If you need very effective balancing for really large cells, you may have to build your own balancer.
The commercial units are all made down to a price, and some of the marketing people make some pretty wildly optimistic claims.
A really big strong well designed balancer would be just too expensive, and it would never sell.

So the reality is, we get to choose between many different offered products, many of which are greatly over rated crap.

 

[Skypower]

I’ve retired all my Heltec balancers and keeping my Neey clones for standby incase of a cell getting a bit sick in the future. The banks are all going to JK bms’s that have an smart active balancer that deliver two full amps right up to the moment it’s balanced. The Heltec balancers were great (with controllers) but they only deliver 5 amps at voltage differentials I’ve never had and much less as the get close to balance. That’s fine if your battery has enough time above your balance start voltage. Enter the Neey and exact clones with the latest revision. These have great control,apps and balancing power (4amps) till it’s done, but pricey $136 on Amazon. They also need a buck boost to power the logic part for 8 cells or less and that could cause some parasitic drain for a standby system. Or you could just go with a JK bms that will do it all that starts at $100 on Amazon depending on your needs (amps, cell count, balance current & connectivity). The JK has the best app on the market IMHO for android or iPhone. PS that was my video that someone posted at #6 of this thread (that’s system is gone now but it seemed to work, just the Daly bms went wonky.

 

[Hans Kroeger]

I’ve retired all my Heltec balancers and keeping my Neey clones .....Or you could just go with a JK bms that will do it all that starts at $100 on Amazon depending on your needs (amps, cell count, balance current & connectivity). The JK has the best app on the market IMHO for android or iPhone. PS that was my video that someone posted at #6 of this thread (that’s system is gone now but it seemed to work, just the Daly bms went wonky.

Hi there, I am 100 % with you! Nevertheless I would like to add one comment. I have modified the active 5 A Heltec balancers (flying capacitor) such, that the balancer turns on at 13.5 V total voltage (4 cells), and turns off at 13.3 V.
due to the fact, that the balancer stays in the active voltage range for quite a while, when charging (and afterwards ideling) the Heltec balancer does a good job.
The ciecuit is simple, as you can see below.
In the meantime I use the JK-BMS wit the 2A active balancer. This balancer can be set to turn on/off at 3.37 V cell voltage. The balancer does an excellent job. In particular, it compensates the voltage drop on the sense lines, which is caused by the +/- 2 A balancer current. The only drawback is the high power being consumed by the JK-BMS, which is between 60 and 100 mA. It is very unfortunate, that the high power is also consumed AFTER an overdischcharge disconnect!!! The power consumption goes down to about 8 mA after the Low Voltage shut down, which is still a bit high.

 

[Skypower]

Is your JK bms a 4S version? If so I betcha they have a little buck boost incorporated into it to keep the control board alive. A buck boost idle current might be what you are seeing.

 

[Hans Kroeger]

Is your JK bms a 4S version? If so I betcha they have a little buck boost incorporated into it to keep the control board alive. A buck boost idle current might be what you are seeing.

Yes, 4 S version..... I guess you are right. But I am wondering why there is still 8 mA after the Low Voltage shut down. 8 mA can deep discharge a 100 Ah Battery after one week.

 

[Skypower]

Just buck boost connected doing nothing(standby)draws amps.

 

[Ampster]

Have you also experienced that your non-smart cheap active balancer (example picture attached) causes your painstakingly top-balanced battery to loose its top-balance over time!?

Not at all. It brought my cells to within 10 mv within days versus the many weeks it would have taken the passive balancing of my BMS to get there. I do not agree with the assumption in that example that the top balance is lost over time. That has not been my experience.

 

[Skypower]

Yes, 4 S version..... I guess you are right. But I am wondering why there is still 8 mA after the Low Voltage shut down. 8 mA can deep discharge a 100 Ah Battery after one week.

A lot has to do with the battery use patterns whether or not a balance always or only above 3.4vpc will cause a wild delta. That’s why there’s been so much controversy. I never wanted to tempt fate knowing my luck.

 

[Hans Kroeger]

Just buck boost connected doing nothing(standby)draws amps.

True after overdischarge disconnect (UVP) . I doupt that the converter is still on after the final "Power Off" shut down which sets the BMS in a deep sleep mode. Will check if the is ripple voltage on the power lines.....

 

[Goboatingnow]

Hi did anyone reverse engineer the schematic for these Chinese switched capacitor units like heltec etc