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

+ 1

Efest had some spectacularly overrated cells that I tested and called them out on. They tried to rebut my conclusions with some technically pitiful statements and a laughable video and then tried to attack my integrity and discredit me. They had no idea how a battery rating was set.

And they totally miscalculated the massive backlash they received from it

I remember that now!

I think that's when I learned Mooch's name.

@BlueSwordM:

Sorry for bringing this back to attention once again but is my request from ► here ◄ reflected in the feature list? In terms of safety when charging LiFePO₄ I'd really appreciate a charger that not automatically (re)starts with a 4.20V default. So, requiring a "push button xyz to start charging" would be a nice and inexpensive add on. :-)

On a side note: Should you or the manufacturer need any help with native German language support for the manual, let me know.

Cheers,

Thomas

I doubt a charger would restart with a different chemistry/voltage setting unless power is cycled, which is wrong anyway. Charger restart sucks butt. As an example, according to HKJ reviews LiFePO4 restart is set so high in TP5000 DIY modules (old blue, newer red) that it keeps knocking on/over the battery.

I can say the same for (Castillian) Spanish. :-D

Presuming ≈85% efficiency for the internal buck converters let me say power consumption will indeed go well above 60W peak. 24V 3A power supplies are common (and relatively cheap).

We have to watch out for going too high in voltage though as it increases parts costs (due to their higher voltage ratings) and a higher input-to-output-voltage-ratio can be more expensive to design for. Voltage spiking from plugging an energized power supply into the charger will be more severe too and the supply’s switching duty cycle range can be limited with a high in/out voltage ratio. This limits the possible output voltage range of the supply.

Planned input voltage range for this charger goes up to 30V, to make it compatible with industrial vehicles.

I must admit that “high current” via a standard 5.5 × 2.5mm DC plug creeps me out a bit, already seen many shoddy plugs of that class. HP's 7.4 × 5.08mm DC power connector is a lot better, imho.

@Barkuti, 30V compatibility was not made for vehicles.

It’s been made from a suggestion from a prohiminent member from SecondLifeStorage.

This below?

Who cares anyway. Lets make it good.

Not only TheOnlyDocc, but someone else I will not yet name until I post a similar thread to SecondLifeStorage.

And yeah, who cares?! It’s a great feature anyway for not only automobile users, but also 7S li-ion battery pack owners.

Mmm, how about centrifugal fan cooling? Sucking from above and shooting to a side, above or below. 4 small, inexpensive centrifugal fans on the floor could also work very nicely (with throttling, of course), shooting to the sides or above and below and providing redundancy. The high presure of blowers ensures airflow even if by design the chassis is a bit restrictive.

After reading some of the resent comments this is probably going to be something much more complicated than most people need. I think I’d be much better off with something like the DLYFULL UT4 someone posted about earlier in the thread.

Oooohhh…good point!

May someone explain me WTF with 7S li-ion battery pack owners? Pretty much sounds like a joke for me.

Yeah… I was thinking about that as well…
A charger doesn’t have a lot of volume available to make a large (92mm+) axial fan work.
But a single centrifugal fan would do just fine for what something like this needs. No need to complicate things with multiple fans…


I’m not sure what kind of form factor has been discussed but if it’s what 95% of chargers are out there then…
…with a centrifugal fan you could design a charger to be a teeny weeny bit taller such that a blower fits below the cells and it’s exhaust points towards the “top” where you have rest of the circuitry. That way the cells also get a bit of airflow because of the intake being below them.
And you don’t need to worry about ground clearance below the charger like you would do with an axial fan.

Looking at some blowers, 75mm x 15mm size is a thing. At that size the inlet is already about ~50mm wide so with a bit of clever design you can get that airflow to go past four bays.
Gdstime for example can do (almost) whatever you want. At 75x15 size they list 2500rpm all the way to 5000rpm, with starting voltage of 4V. A 2500rpm model is specified to move 10m3/h or push 9.1mmH2O.
They can make them with PWM as well, with that I guess it should be able to spin as slow as we realistically need.
Not sure if they can do hydraulic bearing blowers but at least ball bearing is an option. Not sure if I’d consider a sleeve. (Whether axial or centrifugal)

But regardless, a blower fan should be considered/should not be ruled out.
Let the designers choose what they think is the best option to achieve an efficient design.

@Barkuti, 7S battery packs are often used with 24V inverters since they do support a larger range of voltages vs 12V inverters, so, they are much more used than 12V inverters.

@Lag, just using an 120mm axial fan at 20% fan speed would do the trick, as we don’t need a lot of static pressure to push out the air.

Definitely not a joke for the DIY Powerwall community. :slight_smile:

+1, no autostart would be very nice.