This protection PCB uses a TL431 and 2 transistors to protect/balance the 2.5V 700F supercapacitor
By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
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I have 6 of these in series (12volt arrangement) and I noticed when the supercaps have discharged one of them was reading a negative voltage! I assume it was weak and discharged first but since the others are still discharging the weak one starts charging negative. It made me think the protection circuit should have reverse protection too.
Can we use that 2.5volts protection board to a 2.7 500f super Capacitor?
whare is led and its resistor in schematic?
I agree with Superdau, simple linear reg. If you want an Led in there put a 2.5V Led where the TL431 is. Cant guarantee it would work but the led should draw enough current to pull the pnp on and force the npn to start draining power. Hope this helps. You might be able to just parallel it across the TL431 but it will draw much more power than the tl431. As minimum turn on is about 1ma.
The TL431 does have a little heat sink. Nine vias to the large copper region on the back. Not great, but better than nothing.
Hey, i'am in dispair. I got 10x 2,7V 500F Caps, welded in series. With a quite similar Board as yours, but the transistor gets hot at 1,6V, and stop discharge at 1,2V. i tried to weld different resistors because of 2,7V instead the stock 2,5V (Voltage divider: R1: 1,25k R2: 18k on stock => 2,667V on the formula in the Datasheet 431)
nothing changes.
i have no clue why, EVERY board has the same behavior :/
greets from Bavaria 🙂 The raccoon 🐾🦝
With capacitors having relatively wide tolerances with regard to capacitance, I wonder what the tolerance for working voltage is? And I wonder what the tolerance is for that TL431 chip? You wouldn't use a 16V electrolytic capacitor in a circuit with a 15V power supply, you'd use one with a considerably higher voltage rating, say 25V. The numbers for this circuit are all way too close together!
If you want to know if your base-connected LED would work, divide the collector current you want to see by the typical (or minimum) beta of the transistor. That will give you the base current at that point.
Can I put a ziner diod 2.6v between 431 legs ?
What you need is an indicator light that shows the super capacitor is charging and that turns off when the required charge is met.
super
Sir u make pcb plese 2.5v
Why do you use blue led's and not other colours?
Great channel. So with all this talk about never exceed the rated voltage, just as with any warning, I'm curious. Yes I know when you whack an electrolytic up over the rating it explodes, BUT I'm dying to know what one of these baby's does. Someone should set up a proper bunker, notify the authorities, scan the surrounding quarter mile for any living object, don protective gear and remotely detonate one of these (for educational purposes of course) AHEM and to provide a visual reminder that won't easily be forgotten. I'll keep watching this and others for an answer but after a period of time I can no longer tolerate waiting I will do it myself. What kind of voltage/current do you think would provide the best result?
Good job on the reverse engineering !
Thanks a lot for this video. I'm using similar 2.5V balancers in a hybrid system with a 4S li-ion pack in parallel and I have been vary of pushing these boards too hard and not going over 2.58V per capacitor being afraid I would roast them. Apparently I can safely go to 16V or 15.9V (2.67V per capacitor balancer board), which I need for my battery being charged without having the transistor desolder, and have much faster balancing, minutes instead of hours.
Julian, Do you think you can do a video in the "SUPERCAP ACTIVE BALANCING" or SAB, using an SAB IC which does not waste capacitor energy with heat-emitting resistors–it distributes the energy among the series cap bank?