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

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.

Good, thank you. Someday, I suppose everyone will already have a drawerful of USB-C PD adapters for their other devices, but we are not there yet.

Also good. The Dragon has shown that Xtar has some ambitions for an analyzing charger, and their quality seems (perhaps prejudicially on my part) higher than most of the other Chinese brands.

the $20 100w psu you are mentioning is unsafe and bulky, a $25 PD charger is usually safer and “friendlier”, you can also use it to charge your phone or laptop if yours supports.

but as i said, 60W PD charger is over kill, a 45W is more reasonable, you still can charger more than 10W per slot( or nearly 3A per slot), and it doesn’t cost much, i guess less than $10 if we buy many.

The 100w power supply I was thinking of is simply cheap. No comment from me on whether it is good or not. I’m sure the 60w PD charger I found is higher quality. But my point was that for a manufacturer, it should be even cheaper to include a PD charger with the battery charger, which you seem to agree with. Also, I don’t want a power source included that doesn’t power up every feature of the device it is supposed to be supplying power to. If the battery charger BlueSwordM creates is a 60w device, it should include at least a 60w power supply.

Yes, we understand you want the pimped version to be no additional cost. But it should also appeal to the kind of beginner that only needs to charge 1 battery at a time. If we force a 60w power supply into the price you may drive them away.

It cannot be everything to everyone. If someone just has one battery to charge, is this really the charger for them?? Just asking a serious question, not arguing. :+1: