Heltec 4S 5S 6S 5A Active Balancer Fried - Is there any issue with my connections?

[richardw]

I have one LiFePO4 battery which has one cell that hits the max charge sooner than the other 3. I never did top balance the cells due to time. I am not terribly concerned about it as I am getting plenty of capacity for my needs from the two 12v LiFePO4 batteries, which I built. Also, I just ordered 16 new cells from Dacon, which I will likely configure as a 24v system, but I am still doing my research about it.

In any case, I purchased a Heltec active balancer to see how it would work at balancing this 12v 4S battery. I connected the wires per my understanding from the manual. Two wires were not used since it could balance up to a 6S battery. Once the wires were connected to the battery cells the same as my BMS, I connected the wiring harness to the active balancer and set it on the wood panel on top of the battery. A few seconds later, I felt the active balancer wires to see if everything was okay. The orange light was on. The wires were starting to feel very warm. They kept getting hotter so I picked up the active balancer to get it off of the wood. At this point, I was getting very concerned. The board got so hot that I couldn't hold it to disconnect the wiring harness, and the board felt sticky as if it were melting. I finally got the negative lead disconnected from the battery and got a paper towel and was able to disconnect the wiring harness. I seriously thought this thing was possibly going to burst into flames.

I contacted Amazon, and they are sending a replacement. However, I have my concerns about how safe these things are and am not sure I want to connect another one.

In the meantime, I want to know if I have the wiring connected properly. Would you all please review the attached photos and let me know if there is any issue with my wiring?

 

[MisterSandals]

In the meantime, I want to know if I have the wiring connected properly. Would you all please review the attached photos and let me know if there is any issue with my wiring?

Have you tested the voltage of the pins on the balance lead connector?
Pin 1 is negative.
Pin 1 to pin 2 should be ~3.2V
Pin 1 to pin 3 should be ~6.4V
Pin 1 to pin 4 should be ~9.6V
Pin 1 to pin 5 should be ~12.8V (exactly your battery voltage)

 

[richardw]

I should have one wire connected to the negative terminal where the BMS main negative cable connects and one wire connected to the main positive cable outbound from the battery just like the BMS wires along with the intermediate cell wires, correct?

No, that will be interesting to try. The BMS gives me the voltage of each cell, though. I can check the wires with a meter later today.

 

[codfish]

Yes, it looks like there is an issue. The connections go sequentially up the connector from Negative, then to each positive terminal. It sure doesn't look like Green ( pin 5) goes anywhere, and for a 4S the top two pins (6 & 7) should be disconnected. It looks like pin 7, red is connected.

 

[MisterSandals]

And why is pin 7 used at all? For a 4S battery, only pins 1 - 5 should be connected.

I should have one wire connected to the negative terminal where the BMS main negative cable connects and one wire connected to the main positive cable outbound from the battery just like the BMS wires along with the intermediate cell wires, correct?

No!
Pin 1 black, goes to negative on cell 1 (negative end of battery)
Pin 2 goes to positive on cell 1
Pin 3 goes to positive on cell 2
Pin 4 goes to positive on cell 3
pin 5 goes to positive on cell 4 (positive end of battery)

pins 6 and 7 should not be used.

 

[richardw]

Here are my results.

Description	Voltage
Pin 1 (B -)
Pin 1 to 2	3.334
Pin 1 to 3	6.69
Pin 1 to 4	10.03
Pin 1 to 7 (B +)	13.36

 

[codfish]

Pin 7 should Not be connected, Pin 5 (Green) should go to that terminal

 

[richardw]

The reason I used Pin 7 was because all of the diagram examples I saw in the manual and other places seemed to have the first pin wire connected to the main battery negative and the last pin wire connected to the main battery positive. A 6S battery would have all wires connected because it would have two more cells than my 4S battery so I assumed that the B- and B+ wires would be connected, along with B1+ through B3+ for my battery.

 

[richardw]

Pin 7 should Not be connected, Pin 5 (Green) should go to that terminal

Do you think this could have caused the overheating issue?

 

[codfish]

Absolutely. I suppose there is some minuscule chance the board wasn't fried, but I'd never trust it.

 

[richardw]

Absolutely.

Okay. I will change the wiring before trying the replacement when it arrives.

 

[MisterSandals]

Here are my results.

Wired wrong.

Do yourself a favor and put wires 2-4 on the proper positive terminals too instead of the connected negative terminals. It will make more sense when you or anybody else looks at it.

 

[richardw]

Wired wrong.

Do yourself a favor and put wires 2-4 on the proper positive terminals too instead of the connected negative terminals. It will make more sense when you or anybody else looks at it.

Okay. Thank you!

 

[richardw]

Well, I got curious today and examined the Heltec device and the cabling. I saw no visible damage to the Heltec and the cabling seemed fine so I thought I would do a test while I am waiting for the replacement to arrive. I put a ring terminal on the wire coming off of pin 5 and connected it to the positive battery terminal in place of the wire from pin 7. I checked the voltages between the pins as I did per the recommendation yesterday. I connected the wiring harness to the Heltec and monitored it to see what would happen - mostly expecting a result similar to yesterday. However, the orange light came on and the device maybe got a little warmer over several minutes. It seems to be operating. The battery seems to be getting balanced. I thought the balancing would happen faster, though, since this device says it can go up to 5 amps. If it is balancing, it is almost as slow as when the battery voltage comes to rest on its own, though it does seem like the cells are coming closer together. At one point, I did turn the charger on to see how it would behave when the highest cell would reach the cutoff point, and all cells reached a higher voltage this time. That was about 1 to 2 hours ago. When these Heltec active balancer devices are functioning properly, what does the balancing activity look like?

If this works, I am going to be a user of these devices going forward, but probably not constantly - only as needed.

 

[MisterSandals]

It seems to be operating.

Good deal! Glad its working. That's a good letter of testimony to the Heltec's design and build quality.

 

[Samcat]

How some balancing leads should be connected depends on the design of balancer or BMS. You need to follow instruction diagram for specific unit you are using. Going after YouTube videos are no go because many are different in way how they are engineered. And installing fuses for all leads would be appreciated if this is going to be permanent always on setup.