Active energy transfer balancing

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Inwo   10 kW

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Joined: Dec 13 2016 12:01pm
Location: SE MN. USA

Active energy transfer balancing

Post by Inwo » Jun 11 2019 11:36am

There are many new active balance boards showing up from China. I have tested most of them, if anyone needs an opinion before ordering.

It was requested that I do a more thorough test of the potted 4s board by a boat owner using 4s 60ah LiFePo4 for starting battery.

Getting to the end of test. I won't bother to list all the data points. Most important is how it finishes.

Test started by discharging #2 till dead <2v and charging #3 till near full.
.15 shunts to measure average current in and out.

Less than 2ma drain with switch off. Does not appear to be zero when using shunts.
The most current measured is less that 1.5 amps. However 5 amps has been seen by a user with an overcharged cell. Not me!

This is where it's at after about 3 days:
Cells 1-4

3.278 -142ma
3.239 +124ma
3.323 -68ma
3.292 -1.3ma

Differences between + & – may be test errors or losses. Ie. discharging more than charging.
Also expect high cell #3 to be discharging more than #1.
Who knows. Going the right direction in any case!

I have the same ones in 16s and 20s if someone wants to test and not wait for China.
potted 4s.gif
potted 4s.gif (58.85 KiB) Viewed 261 times
MVC-011F.JPG
MVC-011F.JPG (96.33 KiB) Viewed 261 times
MVC-010F.JPG
MVC-010F.JPG (94.57 KiB) Viewed 261 times
Shows current and waveform on balance leads only.
4s waveform.png
4s waveform.png (235.51 KiB) Viewed 260 times

Grantmac   1 kW

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Location: Victoria, BC

Re: Active energy transfer balancing

Post by Grantmac » Jun 11 2019 12:22pm

Are they available for Li-ion? Programmable? Can the 20s run a lower cell count?

Thanks,
Grant

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Inwo   10 kW

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Joined: Dec 13 2016 12:01pm
Location: SE MN. USA

Re: Active energy transfer balancing

Post by Inwo » Jun 11 2019 10:57pm

Yes, as they are energy transfer only, they are not chemistry dependant.
Works with lto up to 4.2v cells or supercaps.
Many versions available, such as 8s and 12s.
All work with fewer cells and can be overlapped for more. I'm building a harness for 36s. 3 volt modules in series connected 4p.
Using 2 pcs 20s balancers.
First thought was that volt leads would not handle the high current. Test shows <2amps average current..

Grantmac   1 kW

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Posts: 361
Joined: Oct 22 2018 12:43pm
Location: Victoria, BC

Re: Active energy transfer balancing

Post by Grantmac » Jun 12 2019 10:11am

That's a very interesting and hooefully robust way to balance cells.
Could they be used during a charge cycle or only after? Link?

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