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

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.
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now try it at a 3 amp discharge.
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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.
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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.

@mrheosuper, that would be a good idea, as the inclusion of a USB-PD power supply would’ve obviously risen the cost a lot.

A 20V 3A USB-C input would be nice.

It offset all these features that will add cost, I propose saving money by making this project just a module. Basically just the heart of the charger, no case. At least until version 1 units are sold to BLF fans. Iterating a full product would be much more expensive than just a module. And functionality is the same.

we can detect the protocol of the AC adapter we are using, if it’s low power( 5V2A or 12V1.5A) we can limit the maximum charging current, it’s easy to implement in software, no need to include 20V3A PD psu( 60w adapter is quite overkill IMO)

We’re not going to include a 60W adapter.

It’s going to be 60W capable.

It needs to be to support 12A of charging current.

As a flashlight (not powerwall) user, I think this is important. 2C seems to be a pretty typical discharge rate for this purpose, and for today’s higher capacity batteries, even 3A is minimal. The ideal would be four cells at 3A, but the bare minimum should be at least one cell at 3A. As a side note, the MC3000 can discharge four cells at 2A, with a 60W (12-18V) power supply. The power supply is an in-line brick that seems fine to me, in terms of size.

I know there are compromises to be made here between use cases (flashlights, power walls), size, cost, etc., and I will support this project however those turn out.

@CLB, the MC3000 can only discharge 2A*4 NiMH cells.

With lithium ion, it’s limited to 1A*4 lithium-ion cells.

You don’t need a large power supply to discharge cells at all.

You just need enough heat dissipation.

I did not know about the 15 watt limit, so thanks for the correction, BlueSwordM. At least it can discharge one LiIon cell at 2A. (3A would be better. But, yes, 3A * 4 would generate a lot of heat.)

My comment about the power supply was not meant to relate to the discharge function, but I realize that wasn’t clear, sorry. Earlier today @Moderator007 posted that “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 was just pointing out that I’m aware of 60 to 90 watt power supplies (including USB-PD) that that seem pretty compact (and cheap) to me, and wondering if the power requirement is a particular challenge for this charger. But I admit I’m over my head in the engineering design discussions, and should stick to commenting on operational features that at least I have a dim grasp of. Carry on!

Nowadays, a small 100W switched mode power supply can be bought on eBay for well under $20, even under $10 for some. A 60W USB-PD adapter is $25 on eBay. If that’s the case, how much would it cost the manufacturer to include a 60W power supply with this charger? I’d think it could be done pretty reasonably, since it would be selling along with the cell charger, not stand-alone. Whatever this charger needs for power, it should come with it. Other “features” can be cut to save cost, but how do you justify selling a “charger” that requires you to buy another “charger” to power it? :person_facepalming:

:person_facepalming:

A 60W USB PD power supply would be nice.

I’m going to be trying to include it.

Guys, I’ll also try working with XTAR if possible.

Talked to SkyRC in the past. Hope you have better luck as they seem just so not interested in doing any improvements to their MC3000 let alone a new charger that undercuts their price structure.