Four-string ternary iron-lithium active balancing circuit ETA3001

ETA3001 atypicality test

Originally, we wanted to verify that Yutai ETA3001+HYBB3A achieves active and passive dual balancing. In view of the proliferation of passive balancing, we omitted the test of the passive on the right side and directly tested the active.

Let’s talk about Yutai PDF first. The current given is UP TO 2A . When I actually saw this description, my heart dropped. What is Yutai doing? What does the card's 2A current mean?

Take a closer look at the schematic diagram. Since the MOS is plugged in, there must be something fishy about it. The key is to set the resistance value to 25mΩ .

This problem has been bothering me for several days, and I was thinking about it when I was scratching my throat. I made a special consultation through the technical contact information given by an awesome IC supplier. There was no clear answer as to whether the SW pin is current-limited. In the end, the unified caliber still can't surpass 2A. I asked back, it's 2A, so you plug in MOS just to look good? The other party hung up, so embarrassed

that I wanted to give it a try, so I decided to get out of the limitations of this form. Changing 25mΩ to 10mΩ may cause ETA3001 to explode.
JP's proofing is a little slower. When the board arrives, the pressure difference is tested after slag welding. The tools and supplies are all old actors.
Add 3.536V voltage to the first string

The second series connected 32650 two parallel iron lithium 3.431V, the voltage difference is 3.536V- 3.431V=0.105V

Test current 2.97A

The current is about 3A. I dare not increase the voltage for fear of exploding the capacitor. When I touch the board, the capacitor and MOS tube are very hot (2-3 cents a brand new one). ETA3001 is basically not hot, and the inductor is slightly warm. Heating from many sides indicates that the efficiency is not high. The measured current obtained from the battery side is about 2.5A (I forgot to take a photo). If there are components that generate heat, the efficiency will definitely be lower.
When I directly connected B-B1+ to a ternary 4.1V voltage battery (I didn’t dare to continue), the current was 4.2A, the 470uf electrolytic chip capacitor sizzled, and the MOS tube soldering oil was steaming. ETA3001 was still strong, and there was basically no temperature rise. .


Summary: No matter how bold a person is, how productive the land is , sometimes you can get surprises if you break through the shackles appropriately.
If the capacitor is changed to 4 1500uf solid capacitors, and the MOS tube uses a tube with a small junction capacitance and low internal resistance as required (if there is a corresponding low-voltage 247 tube, I will use the 247 tube), you may get an unexpectedly larger current.
ETA3001 has come to an end for the time being. I personally think that it is of little significance to conduct multiple string tests. What is certain is that the application of three to four strings is not a big problem.
As for the issue of current limit, after passing this crappy test, I believe that interested friends already have their own answers.
I coded late at night. If there are any omissions, please criticize and correct me. Thank you!

To be honest, hand-soldering these patches is really hard on the eyes. There is no way to change the IC after it comes out. It is best to replace all the ICs by hand with straight plug-ins, so as not to tire the eyes. Cost accounting: 3 ETA3001 together for 3 yuan, three 1-2uH inductors for 0.9 yuan, 6 mos tubes, the better ones cost 2 cents each for 1.2 yuan, and the capacitors cost 2 cents each for four large electrolytic capacitors. That's enough. I used two more, which cost 1.2 yuan. The other components together cost more than 5 cents. To find the board, please go to Jialichuang and Jiepu supports it.
3+0.9+1.2+1.2+0.5=6.8 yuan. This is the basic cost of manual DIY four-string 3A active balancing. If it is in batches, plus the PCB cost and patch cost, it should be similar to this. The key is to have a large quantity. .
At this price, the accuracy cannot be too high. The key is that the current can reach 3A under a large voltage difference of 0.1V. My other active equalizers such as transformers and capacitors should not be able to produce this at a cost of 7 yuan. Moreover, this price advantage is helpful for 12V battery manufacturers to reduce production costs. It can also be used in slightly inferior grades, and the effect is good. The price is cheaper, and it is more suitable for more mainstream users who do not care about accuracy.
    Low price is not the goal, good but not expensive is the best feedback to users.
    Maybe my personal understanding is limited, I hope some PDD merchants can do this, 10 yuan for wallet postage, should be able to get a wave of reviews with pictures.