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

Interested in 1

Does it have a fan for cooling? Then I hope it is easily replaceable, unfasten a few screws and unplug, as this is the most likely troublemaker. Also possible a flashing port.

Put me in for 1.

I would like to get in on this as well. Thank you!

Have you tried pushing the slider terminal with the cell you’re inserting? That’s how I always do it. I haven’t touched a terminal in ages.

interested

Interested!!!

Perhaps something similar to a shooter rod on a pinball machine. Or something as simple as making the negative tab tall enough to provide a leverage point to grab, pull back the slider, insert the cell, and then gently release. Even simply choosing springs with less force; they only need to be secure, not act as a vice.

Relying on the cell at act as the lever, or shoehorn, of sorts, is less than optimal, and I hate the crude execution used by most, if not all chargers in general.

There are many more elegant ways to approach it, but the status quo is cheap.

Interested!

Interested in 2, thanks.

I like the constant current modes. Interested. Thanks.

Could updates in post 1 be dated going forward?

slmjim

I had a feeling that this would happen. While i admire how inclusive you guys have been regarding the design of this charger, it apparently has fallen victim to the old adage… “Too many cooks in the kitchen”. There comes a time when the people in charge need to take the initiative and stop trying to be all to all people and get things done.

Feature creep kills products, especially those that actually make it to market. Keep the essential features missing from most other chargers, dump the rest. To me, that means keep polarity protection, the multi-chemistry compatibility (but for NiZn, a boutique feature few will use, plenty of NiZn chargers out there), keep the resistance testing, the constant current charging modes, but bail on some of the adjustable charging, 0.03A – 0.05A – 0.08A?? Why. I also don’t believe active cooling is necessary, nor a Li-ion storage charging feature, which is redundant if it supports LiFePO4, just charge Li-ion to that 3.7V and store.

But what do I know?

Sign me up for 2 please.

Count me in for 1 please

Actually, BlueSwordM seems to have a good idea of what he’s doing. The only thing it’s “fallen victim” to is delays, which are understandable given that he’s largely doing the project alone (and also had a recent injury).

Never did this. I push the negative terminal back with the battery (Lii-500).

I’d be interested too - but it has to be better than the Opus BT-C3100. which does most of what people want for a good price as it is. I don’t mind spending a little bit more for some ‘Pro’ features and a very high quality build.

I know it says feature list is locked - but:

- Sometimes when cells are very depleted, they are not recognised. If there were a way to force a charge to start at a particular voltage to get the charging started (apologies if this is already on the list and I didn’t understand)

- Nice color OLED screen with info

- USB connected to download data - but also crucially, to update firmware with new features and bug fixes

- Ability to run custom sequence of programs. I.E. run an internal resistance test, charge/discharge battery 3 times while taking resistance test and record battery capacity between each charge. Output data. If it could store extra data during the whole charge/discharge process - all the better - this can be exported and graphed externally.

- Easy serviceability - particularly the fan. Dont solder onto board, and don’t use some weird-ass sized fan you can’t find anywhere (looking at your Opus!). If it were a ‘silent’ fan - that would be a bonus!

- For internal resistance, give a warning if the battery voltage is too low to give an accurate measurement. Take several measurements, and give an average, or mean value.

As a power user I tend to dislike mommy chargers. Just do what I command and STFU. But of course I take care.

In case of need setting an over-discharged cell in parallel with a healthy one using some (thin) wires (a few touches here and there) is a solution.

Concerning the internal resistance measurements, depending on how that is implemented a too high voltage warning may also be wise. Certain chargers like the popular Lii-500 measure internal resistance by injecting a given current into the rail and substracting the no-load rail voltage to the measured rail voltage while the current is flowing, then dividing the difference by the current (dV/I). However, since rail voltage cannot go above maximum charge voltage, if a cell is close enough to maximum charge voltage the resistance measurement is invalid because rail voltage maxes out. Chargers which operate in such a way should warn whenever rail voltage reaches maximum charge voltage upon cell IR measurement.

In any case, I hope this charger implements cell voltage monitoring right at the cell terminals.