The making of the BLF UC4 charger: the start of a new venture, INTEREST LIST, UPDATE 7 (Well, ramping stopped :/ )

@DavidEF, that’s a bit different

But you just gave me an idea on the software side that would be extremely nice.

Why not make an emergency mode in which it turns off charging if the voltage drops between 4,5-10V, trying to consume as little power as possible just to keep itself on and preventing settings from changing?

It should be relatively easy to implement.

Well, what I meant was that the hardware doesn’t have to crash or “reset” when a shadow looms overhead. It can be made to gracefully recover as if nothing happened. I don’t know if it needs software support for that or not. I assume not. But I’m not an EE. :wink:

Only french will understand : drapal !

If the discharge rate for a single cell was limited to 4.2v at 3 amps it shouldn’t take much more than a 30mm x 30mm space to have it inside the unit.
https://www.aliexpress.com/item/32528721413.html?storeId=923042&spm=a2g1y.12024536.productList_2808692.subject_9
In the model above, you would have to have a few more components added to turn the potentiometer into electronically digital controlled. Like this one.

https://www.aliexpress.com/item/32882318330.html?storeId=923042&spm=a2g1y.12024536.productList_2808692.subject_8
.
The icharger 208b is relatively small in size with alot of power handling but the power supply to reach the capabilities of the charger takes almost twice the size of the charger.
Charging 4 li-ions at 3 amps each would need around 70 watts from the power supply. The max charge rate would all depend on how small and efficient you could make the power supply for it’s size.

I think this was going to do 4 cells at once. 4cells*12.6w=50.4w

Yeah.

You’re going to need at least 50W to dissipate the heat generated by the fully-saturated MOSFETs at full load.

50W would be absolutely massive, especially for a CONSTANT CURRENT load inside of a charger

If your referring to ‘discharge’… I hope it is going to do four cells at one time.

If the heatsink setup mentioned above is added, can the discharge rate be raised above the 750 mAh that is planned now.

Would it be possible to get it up to 2000 mAh (2A) x 4 cells??

Is “mAh” the correct terminology for discharge rate?? :person_facepalming:

If your trying to find out the discharge capacity and have it graphed like HKJ does, I don’t see why you need to do more than one cell at a time. To me seeing what one cell can do at 3 amps is more important than what 4 cells can do at .5 amps.
Doing 4 cells at a time would require 4 data logging graphs going at once which I guess is possible but the first link I posted would handle one battery at 3 amps, so for 4, you’ll need 4 of those or one 4 times the size.

The DIY Powerwall community has hundreds of 18650s to load test. They often buy multiple 4-slot dischargers.

And how much power are they discharging and how big is the load discharger.
If its going to be all in one unit a middle ground has to be meet somewhere, if not then bulkier additional devices could be added I guess.

They only need to find matching cells, so I would guess the faster they can discharge a set and move on to the next set, the better.

And yes, this would be a use case for the CPU cooler add-on. Not a core requirement of course.

How about small cells like 10180?? Make it universal for evey battery out there. And make take protected and unprotected batteries with power bank functionality.

Opus and skyrc and maybe xtar is my choice for manufacturers

So I was went over to https://secondlifestorage.com before dropping a link in this thread, and it turns out BlueSwordM is an active member with a matching display pic. So I guess he’s more qualified to explain this use case. lol

Oh and it seems many of them check the capacity of Thousands of cells. :open_mouth:

Personally, I do not care about graphing. I’d just like to do a capacity test on 4 cells at a time. Hopefully at a discharge rate higher than 750 mAh.

Other people may have different wants/needs.

Graphing can help track the full behavior of the battery, seek for spikes, patterns, etc and understand the real life of the cell.

Or put simply: graphs is what makes "lygte-info.dk" so understandable and relevant, it helps bring objectivism to battery tests. A killer feature to me, and probably #1 reason why a MC3000 is sitting a cable away from my computer.

I hope HKJ don’t mind me borrowing some of his pics. Credit goes to him for the testing.
This is the reason discharging a cell at a higher rate (3 to 5 amps) can determine how good a cell is in the real world flashlight use. This is a bad example because I have chosen probably one of the worst again’t one of the best but it helps to understand the differences.
If you were to only discharge these two cells at .2 amps this would be what you get and the cells would seem very similar in use.
.

.
now try it at a 3 amp discharge.
.

.
In a flashlight 3 amps of current draw is becoming some what low now days, imagine the difference using those two batteries. If you couldn’t run a 3 amp discharge test on some fake 30Q’s with the Ultrafire cell wrapped inside you wouldn’t know the difference unless you had a authentic 30Q to compare it to.
Most all the 4 bay discharge chargers (unless on a professional level) I have seen are limited to 500 ma discharge that requires 4.2v x .5a x 4 = 8.4 watts of power to dissipate.
One cell at 4.2v x 3 amps = 12.6 watts of power to dissipate, 4 at that current would take 50.4 watts of power to dissipate. The 15 watt discharge tester I linked above used a 30mm x 30mm fan and heatsink. To keep the size down it could have a function to discharge only one bay at 3 amps and 750 ma with all 4 bays running.
.
All the hobby chargers I have owned used the case made out of finned aluminum and a small fan to dissipate the heat.

Logging is going to be harder than expected if it can do high discharge. The resistance of the wires will likely become significant.
Estimating the correction in software would be no fun, and having a separate set of wires for sensing would be no fun. I don’t have a fix, I just wanted to point out the hazard ahead.

i dont know how much will it add to the BOM, but there are a lot of interesting PD coding ICs from China

we can get rid of included AC adapter if we adapt to QC/PD usb C, so may save some cost

I really like the idea!
At the moment i am building 2 charger adapter to connect my opus to 2 external battery holder (26650) because my 26650 shocklis are popping out of the charger bay way to often.
But untill i find a charger that suits me better i will use the opus. This charger could be the one that sends my opus in retierment.