I am interested as well. I’m tired of buying multiple chargers. I’d love to have one “do all”……
The end of March is approaching, and so is the mockup UI that is very detailed.
I don’t want to spoiler it, but do you think there should be a dedicated DC internal resistance calculation mode in the UI or whatnot?
Hmm. I’d say if it isn’t a good-accurate IR measurement (like nearly every charger out there) then maybe just leave it in the charging mode rather than a dedicated separate choice. However, separate could be handy for old NiMH cells that the charger rejects due to high IR. That is, if this charger will have all of those capabilities (sorry…need to go and read the OP again, been awhile!). 
With how annoying most chargers are towards accurate DC internal resistance measurements, I want to make sure the BLF UC4 actually does it reasonably well and accurately(regardless of whatever cosmic thing happens haha).
Something that does what it says it will do?? That could really upset some universes. Maybe even knock the CCT-Tint Continuum out of alignment!
Basically, you’d need 4 extra wires in the build.
They’d just be thin gauge wire, since they don’t need to carry much current at all.
I’d say do it…separate or not…a good 4-wire measurement would be a wonderful bench feature in a charger. It’s not the most important thing to me personally but it would be very nice to have and I’d be happy to pay for it. Also, just glanced at the spreadsheet and don’t see my name on there…maybe I never did an “interested” post, but count me in.
Will this be something worth buying if I already have an MC3000?
Well, other that differentiating physical features(having an output port to charge very large cells like 26800s as an example) and some interesting software features I’m planning to implement, I’m going to be honest in saying that no, this charger likely won’t be worth buying if you have an MC3000.
A couple things to say around here. 
The 4-wire measurement for internal resistance basically requires a special slot construction, or can be addressed with a much less special and practical slot design where the voltage probe wires should connect as close as possible to the very battery terminals (right ;-) behind them). Not long ago I did an experiment with my old Lii-500, where I soldered wires from the circuit board negative terminal to the rail negative moving contact part. Of course there were improvements in the internal resistance measurements; however, both rail and cell contacts must be as clean as possible, and the device electronics must anyway make reliable measurements. There's also people who just doesn't knows how their chargers do DC IR, and extract wrong conclusions because of this, i.e. you cannot properly measure DC IR with a cell close to fully charged in a Lii-500, because the charger does DC IR by means of injecting a small current into the cell, and the charger output voltage cannot go above maximum output voltage (4.2V). For this reason if cell voltage is already rather high the charger won't be able to inject the full current and measure a correct voltage difference, and so incorrect low DC IR values will be shown.
In any case, even if it is like in the Lii-500 I prefer to have this feature than not to have (I often find it useful to know if cell and rail contacts are clean, for example).
Looks like the way you plan to implement the DC IR measurement matches my insights, doesn't it?
I measure the internal resistance of Li-ion batteries fully charged to 4.2 V using the "Quick Test Mode" on my Opus BT-C3400 V3.1 charger which does not seem to have the same limitation as the Lii-500 according to the BT-C3400's manual:
To obtain consistent results, I use the same slot (occasionally comparing it to the other slots) and press slightly on the sliding battery contact (with a flat thin strip of wood since my finger is too large to fit, trying to use approximately the same force each time) both before and while measuring (along with twisting the battery one revolution against the contacts before measuring).
I do not know the implementation details or how accurately the Opus BT-C3400 charger is able to measure internal resistances.
I tried measuring "DC internal resistance" but was not very successful at obtaining consistent results using the method described by forum member "HKJ":
https://lygte-info.dk/info/Internal%20impedance%20UK.html
So, I would be very interested in a battery charger that was able to easily measure internal resistance as consistently and accurately as the dedicated internal resistance meters since those are rather expensive.
i’ve been away for a long while… when this project gets resumed, please put me in for 2.
thanks.
Put me down for one. I may buy a second but only after seeing a finished product. Is the project still on Star Citizen time?
Yes, because I was dumb and decided to do something else.
That something else is an LED group buy 
Can you make this charger high CRI? When you get around to it…
I’d be happy if he just got around to it…
Is there any movement on this, would be interested in one. Depending on final design, price, etc
Is DLYfull still intrested?
Yes, I’ve talked to them a few weeks ago.
However, XTAR might also be involved because of a recent event 
If you ever get this going I’d get one. I have an S4+ v2 and really like it, but the iR measurement is consistently 50% to 60% high. My Zanflare C4 has the most consistent and accurate iR measurement so far.