Liitokala Lii-600 : Some improvements on thermal dissipation problems

[Filippo52]

I tried to search before opening this new topic but I couldn't find anything about this model:
My intention is to dismantle the object, discuss its strengths and weaknesses (especially the defects), show photos of the interior and propose some improvements to the defects where possible; and also talk about some functions but without becoming an exhaustive test from this point of view.


First of all, I propose (attaching 2 PDF files) an electronic version in English and Italian of the user manual, obtained by digitizing the one attached to the product

to disassemble the Lii-600 at the back you must remove the 4 rubber feet and under each of them there is a small self-tapping screw; furthermore in the central part there are three other screws
In the following photo I have circled the screw positions in red.



The screws are tiny and the seats are plastic so be careful otherwise opening them several times will damage them. Use the well-known tricks. Those who know them, forgive me if I mention them for beginners.
Rub the screws with a thin layer of silicone oil and before tightening, rotate the screw anti-clockwise: when you hear a slight click it means that you are aligned with the thread and you can screw it on without risk of ruining it.

Let's continue; Once the back part is removed, what you see will appear



It's the main board. Circled in red you see the back of the "rail" where the batteries to be recharged are inserted, you have to free the spring at the top from the sliding part. Here I have already done it and, saving the last track to show you, I removed the other sliding parts. At that point you can lift the card but with caution because it is connected to the display with a flat cable. By unhooking the flat cable the card will come off and you will have the Liitokale divided into the following three parts




as you can see there are three pieces starting from the left: the back part, the front part where you can see the display board and the main board. At the top left you can see one of the two semiconductor heatsinks with the TO220 case disassembled. Immediately afterwards I'll tell you why.
As I told you, the photo is missing:
- the flat cable
- the moving parts of the tracks that serve to hold the back of the batteries

The first flaw of this apparatus immediately appears quite evident. Compared to the previous ones and the competition, this device has increased the choice of charging and discharging currents and their maximum values; reaching 3 A when charging and 750 mA when discharging. For this purpose, the power supply supplied together (if you buy the one with the power supply) is 5 A.
Unfortunately, as you can see, there is very little for heat dissipation. Even of the 4 MOSFETs that each drive a charge/discharge channel, two are equipped with heat sinks, even if very small, and two are without anything, which is almost incredible in a device that gets so much publicity.
There are videos on the internet that show how these components undergo substantial overheating with the highest charging and discharging values. Furthermore, as is obvious, tracks 1 and 4 will cause minor overheating while it is strongly discouraged to use the higher charge and discharge currents on tracks 2 and 3 because without anything you risk. In one video a reviewer shows the solder terminals of this mosfet darkened the color of the board in their immediate vicinity.
It is clear that the main problem is the space before the cost of the heatsinks and the designer's desire not to use active cooling with fans.
However, dissipation is certainly the biggest problem of this device used at higher currents and there are many difficulties in remedying it due to missing space as already written.

I found a way to upgrade the heat sinks that are already there, like the one already disassembled, but I'm still trying to figure out how to do it for the ones below.

in the following photo you can see that I created a larger "custom" radiator like a puzzle with a lot of effort. I left the original on the left so you can see the difference. In this other photo



I placed the two heat sinks: the original and my adaptation, next to each other to better understand. The size of my heatsink takes up practically all the space available when reassembling the device. In the puzzle I made, all the parts are tightened well with screws and some conductive paste helps the thermal conductivity between the various pieces.

Let's go back to the photo of the whole board and look at the Mosfets on the lower part.




They cannot be put upright because they would hit the "opposite" board: the display one. I only managed to add two mini heat sinks held with a clamp; but it is a completely insufficient solution. On this point the contribution of some "willing" people would be appreciated by all; However, I will continue to think about it and if I find some barely acceptable solution I will propose it to you.
I'll end this first post here, leaving you to further discussions

Thank you

[DaneLaw]

It's an English-speaking forum, why on earth are you pushing a foreign language again and again.??
You can clearly write & comment in English just fine, in regards to your previous thread-starts & numerous posts..# https://www.eevblog.com/forum/testgear/usb-meter-kws-v30/msg5166534/#msg5166534
# https://www.eevblog.com/forum/repair/lcr-meter-bside-esr02-pro-problem/msg4559869/#msg4559869

Translate it, - it ain't something each user should do on their own, as otherwise, this forum would be down the drain if each user started to write posts in their native tongue.
https://translate.google.com

[coppercone2]

bele bele arengele

[axantas]

Filippo. ComeDane Law a scritto, non c‘è tanta gente che parla italiano. Come Dan scrive, sarebbe gentile di far tradurre tutto in inglese - sia Google o meglio deepl.com.

[coppercone2]

[Filippo52]

sorry it was a distraction, it was late when I finished and I completely forgot to pass what I had written to google translator before publishing it.
If you look at all my other posts on this forum they have always been in English
If I can I'll correct the initial post immediately

[DaneLaw]

sorry it was a distraction, it was late when I finished and I completely forgot to pass what I had written to google translator before publishing it.
If you look at all my other posts on this forum they have always been in English
If I can I'll correct the initial post immediately

Not quite, out of your last 6 posts - 5/6 have been in a foreign language. https://www.eevblog.com/forum/profile/?area=showposts;u=912403

But in general, its helpful for all parties to translate it to English which are the foundation of this forum, so we can interact with each other, you can always modify a post after the fact, as well as a given headline on a thread-post.

Got a few Liitokala chargers but all pretty old models..
Got one of Lii-500 with 4 compartments (though under the Colaier rebrand) and two of the Liitokala Lii100 single chargers.
Mostly use the Lii500 and it still works fine here like a decade later, it could do most of the chemistry types 4 out of 5.. plug and play and it will mostly sort it out.
https://lygte-info.dk/review/Review%20Charger%20LiitoKala%20Lii-500%20UK.html

I was unsure if I should go with the Lii500 or the Opus C2000 but after a minor due diligence, I was left with the feeling that the Lii500 charge cycle was a tad preferred, whereas the Opus seemed to rely on some aspect of pulse charging, but In hindsight not sure about the pro & cons between the different charge approaches.. Its many years ago..and the Lii500 was dirt-cheap at around 15 to 20 US delivered with 12v PSU, though nowadays I mostly use it with a 12V TypeC PD to DC adapter.

This site I found quite helpfull, as the owner has been through a shutload of these chargers, and highlighted how well they performed alongside a tear down, - the site holds a lot if good info (reviews). the owner is also a user here on EEVblog
It also gives you the ablelity to compare your cirquitboard against previous revisions.  https://lygte-info.dk/info/indexBatteriesAndChargers%20UK.html

[Filippo52]

Yes, you're right, but out of almost 60 of my posts, about 10% are in Italian and concentrated in one place "Cheezeball DC Load: DL24P: Pump, or Dump " where due to the difficulty of the topic discussed when writing with the translator I didn't understand each other with the person with whom I was carrying on the discussion.
Thank you for the address provided "lygte-info.dk/info/indexBatteriesAndChargers%20UK"
really excellent full of many reviews done very well with many measures. The only thing I would have liked is at least some wiring diagrams but you can't have everything.

[Filippo52]

Let's stay in the area of thermal dissipation. After highlighting that two of the 4 mosfets do not have any heat sinks on the websites, I noticed that some users have put very small heat sinks on SMD resistors. The resistors are these circled in yellow on part of the photo shown in the first post and enlarged here



As you can see on each charge and discharge slot there are two 150 mohm SMD resistors in parallel, i.e. 0.075 ohm.
This value suggests shunt resistance for measuring current. If so, the maximum value of current that can pass is that of the maximum charge at 3 A.
the power dissipated according to ohm's law will be
W = R * I * I = 0.075 * 3 * 3 = 0.675 W
for that type of resistor (I think 2 W) there shouldn't be any problems, i.e. in my opinion the additional heatsink is not necessary and since it must be glued carefully to avoid unwanted electrical contacts I would avoid installing them. What do you think?

this is the photo of additional heatsink



See you again in the next post

[Filippo52]

We remain in the field of thermal dissipation which is perhaps one of the most critical aspects. I will make some reflections and don't take them at face value, they are just my opinion.
The 4 mosfets present in the Liitokala are of the "30N60" type; The tecnical  data is 60V 30A and 80W; so we are there as limits but we see things in terms of dissipation.
The most critical process is certainly the "discharge"; all the battery power is burned into heat inside the Liitokala; the contribution of the 0.150 ohm shunt resistors is negligible.
The maximum discharge current is 750 mA with the nominal voltage of a lithium battery we are talking about 3.7X0.750= 2.775W.
From the mosfet datasheet it can be seen that the "junction-to-ambient" thermal resistance of the component without any air heat sink is well
62.5 °C/W
as unfortunately could be expected
so if we talk about the mosfets of tracks 2 and 3 we go above the maximum 150°C and if all goes well the mosfets will go into thermal protection otherwise we risk losing them.
For the two MOSFETs with heat sink (tracks 1 e 4) things are decidedly better and taking data from a heat sink similar to the one used we will get a total of around 30°C/W. the case will then be hot, impossible to touch with your hands, but the MOSFET will work within its specifications.
With the changes I have made and shown you, I believe that the heat sink I placed on tracks 1 and 4 will still be very hot but everything will operate in even greater safety.
I fear instead that the two tiny heatsinks that I added on the MOSFETs connected to tracks 2 and 3 will not be enough to solve the problem and it will be necessary to remain with max discharge current values of 0.5 A and even then the MOSFET junction will be beyond the 100°C.
Discharging more batteries together with higher currents can only make the situation worse as there is little space and very little natural ventilation.

In the charging process things could be even worse since 2 batteries can be charged at 3 A; but in the charging process I believe the voltage value is corrected with the switching technique. This is suggested by the inductors and capacitors present on each rail. Even considering a modest efficiency coefficient of 80%, the same values of 2W dissipation return more or less and therefore the situation is similar.

With these considerations, if they are valid, my advice comes back to increase the size of the heat sinks present on mosfets 1 and 4 as I showed in the initial message of this thread and not to use tracks 2 and 3 for heavy tasks.

If we then find someone who has solutions to propose for tracks 2 and 3 and more generally for everything, we are here to listen

Greetings

[Filippo52]

Here I am again talking about the Liitokala Lii-600. Unfortunately, even if someone has read these posts of mine, there have been no contributions on the main topic of heat dissipation. However, as promised, I also looked for solutions on my own for the mosfets used in tracks 2 and 3 of this device. As you remember from the figures in my first post, these mosfets are without any type of heat sink and are therefore subject to the dissipation possible with only the to-220 container with which they are equipped. and 2-3W of dissipation is enough to reach and exceed 100°C.
I found the solution you see in this photo



As you can now see, the two MOSFETs of tracks 2 and 3 are also equipped with heat sinks. They are semiconductor heatsinks with to-220 package with these dimensions
width 30mm
length 25mm
height 12mm

Unfortunately I have to tell you right away that the adaptation is quite tiring and if anyone has easier ideas to follow they are always welcome:
To install them I had to remove the two mosfets by desoldering them. It is then necessary to install three vertical feet where you can then reinstall the mosfets after having bent the terminals at 90°.
The feet must be of adequate section for good reasons:
- they must carry currents of 3 A without problems and overheating
- they must allow robust unslading
- they must carry the weight of the heatsink which will remain raised compared to the motherboard
I placed a square of silicone plastic under the heat sink as an insulator to avoid contact with the underlying components of the motherboard which would be disastrous:
Furthermore, for the left heatsink you will have to do various things. A small part of it will overlap the "flatcable" connection socket with the display and this will make it more difficult to reinsert it and above all to operate the blocks; but with a little patience it can be done. Furthermore, as you can see from the photo it will be necessary to remove an upper left corner to leave space for one of the pins on which the Liitokala container closes.
For the right heatsink, however, it is necessary to move the 16V 100uF capacitor which otherwise would end up partly under the heatsink or in any case too close to the cooling fins.
Moving this capacitor is an operation that in my case proved difficult and must be done with great care. The holes where the capacitor is soldered are "through" and when installing the insulated extensions (which are red and black in the photo) you must make sure that they are soldered well on both sides of the printed circuit board. In my case, in fact, after having reassembled this capacitor, one contact was missing (perhaps the hole in the printed circuit was not tinned well or it had been damaged during the operations) but the LiitoKala no longer turned on again.

I had to redo everything and in my case I moved the capacitor to the other side of the printed circuit, placing it in a horizontal position; I can assure you that there is space to close the box.
By doing this in the holes where the capacitor was soldered you can pass two pieces of the "lead" of a resistor easily soldering on both sides and then overlap the capacitor.
I think the solution is easier to implement, you can see it in the following photo



We can now redo the calculations.
The mosfet alone in air had a thermal resistance of 62.5 °C/W and with just 2 W it exceeded 100°C
Now we have a heat sink that alone has around 15°C/W, the contribution of the mosfet if well fixed with thermal paste is around 4-5°C/W; we are at a total of 19-20°C/W and we can dissipate 5W before approaching 100°C.
Furthermore, things are more similar to heat sinks, practically self-built, placed on tracks 1 and 4.
Now all the Liitocala tracks can be used without fear of having dangerous mosfet temperatures.
As always, if you have any doubts, I'm here as far as I can.
A greeting