Note that this function is part of the Cellwise control chip, which is by no means exclusive to DALY, and it's highly likely a function in other control chips in many other BMS designs.
DALY BMS Teardown & Failure Review (16S 40A)
- Thread starter methods
- Start date
A-DamW
100 W
methods said:
After mucking about in Circuitlab for way too many hours, I found this site:
http://www.falstad.com/circuit/circuitjs.html
Have not seen anything I don't like so far!
methods
1 GW
You guys are asking good questions and doing good work. I have to go to the coal mine, but I will check back in the evening(s) and respond.
I am not allowed to respond in the AM otherwise 1min turns into 1hr turns into 1 day.
The Good News?
Coal Mine Work is friends with ebike work.
-methods
I am not allowed to respond in the AM otherwise 1min turns into 1hr turns into 1 day.
The Good News?
Coal Mine Work is friends with ebike work.
-methods
methods
1 GW
I truly do not know what scares me more. The idea of someone hand tweezing those from a random pot...
* Or the idea that someone bought a reel of resistors that look like that?!!!
If those came off a reel, they would be as gray market and recycled as you could possibly imagine. If they were hand placed... It's the sloppiest process you ever saw.
DANGER WILL ROBINSON
For folks that don't understand what we are looking at, a robotic arm places all these parts from a reel (basically). All the parts in the reel are identical and aligned. What you see above is only possible in several scenarios.
* Heavily reworked
* Reflowed twice...
They just simply isn't an outcome that is good. Lead free makes it all worse because all the temperatures are higher.
This is why we have ISO 9001 certified process.
Ok
I guess in some insane reality they could have two reels going... Lol... Two reals populating the same part in random order (not).
TIME TO CRACK OPEN 4 MORE eh?
-methods
* Or the idea that someone bought a reel of resistors that look like that?!!!
If those came off a reel, they would be as gray market and recycled as you could possibly imagine. If they were hand placed... It's the sloppiest process you ever saw.
DANGER WILL ROBINSON
For folks that don't understand what we are looking at, a robotic arm places all these parts from a reel (basically). All the parts in the reel are identical and aligned. What you see above is only possible in several scenarios.
* Heavily reworked
* Reflowed twice...
They just simply isn't an outcome that is good. Lead free makes it all worse because all the temperatures are higher.
This is why we have ISO 9001 certified process.
Ok
I guess in some insane reality they could have two reels going... Lol... Two reals populating the same part in random order (not).
TIME TO CRACK OPEN 4 MORE eh?
-methods
methods
1 GW
Based on how much solder I see
* Hand applied solder paste
There's way too much solder on those SOT23-3 parts.
-methods
* Hand applied solder paste
There's way too much solder on those SOT23-3 parts.
-methods
Unfortunately these days even highly skilled people are cheaper than machines (plus maintenance) to do a job, not just in China.
methods
1 GW
I'm lagging on this.
Been working on a pilot production for weeks... But soon it will be the weekend.
-methods
Been working on a pilot production for weeks... But soon it will be the weekend.
-methods
That does look hand soldered. Yikes.
I wouldn’t want that as a job.
But all the joints look pretty decent.
I wouldn’t want that as a job.
But all the joints look pretty decent.
methods
1 GW
This is a BMS that has successfully passed Short Circuit testing. It turns off in less than 1mS against a 58V 12AWG short.
PCM-L16S60-562(A)
From a sample of over 200pcs I had 1 failure. It landed DOA and presented very obviously. Strong smell, excessive heat, failed to RUN. You can fail a BMS to STOP or GO. There are arguments either way. STOP is safer for battery but far less safe for vehicle etc. GO is dangerous news for battery, but more reliable.
So this one -
It has its issues, but it has features like
* External Temperature Probes
* Internal Temperature Probes
* Short Circuit Protection
* Obviously balance and power cut
* ...
You can see from the name it is 16S rated for 60A. I found a sample on the BahBah, but I have not bought anything off that place in 10 years
https://www.alibaba.com/product-detail/16S-60A-lifepo4-battery-bms-pcm_1673300508.html
That is it tho
* Bottom layer is all balancing
* Top layer is all power handling
* Two sets of 100mil jumpers tying them together
Has a bunch of fasteners all over that I am not pleased with. They have about 3 turns of thread and no locTite. Just asking for it.
-methods
PCM-L16S60-562(A)
From a sample of over 200pcs I had 1 failure. It landed DOA and presented very obviously. Strong smell, excessive heat, failed to RUN. You can fail a BMS to STOP or GO. There are arguments either way. STOP is safer for battery but far less safe for vehicle etc. GO is dangerous news for battery, but more reliable.
So this one -
It has its issues, but it has features like
* External Temperature Probes
* Internal Temperature Probes
* Short Circuit Protection
* Obviously balance and power cut
* ...
You can see from the name it is 16S rated for 60A. I found a sample on the BahBah, but I have not bought anything off that place in 10 years
https://www.alibaba.com/product-detail/16S-60A-lifepo4-battery-bms-pcm_1673300508.html
That is it tho
* Bottom layer is all balancing
* Top layer is all power handling
* Two sets of 100mil jumpers tying them together
Has a bunch of fasteners all over that I am not pleased with. They have about 3 turns of thread and no locTite. Just asking for it.
-methods
Attachments
methods
1 GW
Again
I have never purchased those, I have just tested them "along the way" as they were part of a different system. I have other BMS of this style. I guess the potting is just a bunch of bling that I dont need, because I could at least repair this one if I wanted to.
I have a blown one here and we could check the fets, but -> No point! They can change on every board run (and do!).
-methods
I have never purchased those, I have just tested them "along the way" as they were part of a different system. I have other BMS of this style. I guess the potting is just a bunch of bling that I dont need, because I could at least repair this one if I wanted to.
I have a blown one here and we could check the fets, but -> No point! They can change on every board run (and do!).
-methods
methods
1 GW
Similar Datasheet
https://www.batteryspace.com/prod-specs/6242-PCM-SM31-37V%20.pdf
https://www.batteryspace.com/prod-specs/6242-PCM-SM31-37V%20.pdf
methods
1 GW
Wow... 30mOhms is nothing to be proud of LOL
Be super easy to get that down to 3mOhms, then 1/3mOhm
Similar but programmed for 3.7V instead of 3.3V
That is definitely the same kit
https://www.aliexpress.us/item/2251832641076334.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US
I dont see the temp sensors external, but I see the internal one tucked in. The internal temp sensor is on a wire.**
$70 buckolaz
Those are like $250 if you buy it from a retailer.
-methods
Be super easy to get that down to 3mOhms, then 1/3mOhm
Similar but programmed for 3.7V instead of 3.3V
That is definitely the same kit
https://www.aliexpress.us/item/2251832641076334.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US
I dont see the temp sensors external, but I see the internal one tucked in. The internal temp sensor is on a wire.**
$70 buckolaz
Those are like $250 if you buy it from a retailer.
-methods
methods
1 GW
I can confirm good consumption current, not noticeable
Here is a nice link
https://quawin.en.made-in-china.com/product/zvInmEYjOphN/China-5s-16s-60A-High-Power-PCM-BMS-for-57-6V-59-2V-Li-ion-Lithium-Li-Polymer-48V-51-2V-LiFePO4-Battery-Pack-Size-L120-W80-T25mm-PCM-L16S60-562-.html
-methods
Here is a nice link
https://quawin.en.made-in-china.com/product/zvInmEYjOphN/China-5s-16s-60A-High-Power-PCM-BMS-for-57-6V-59-2V-Li-ion-Lithium-Li-Polymer-48V-51-2V-LiFePO4-Battery-Pack-Size-L120-W80-T25mm-PCM-L16S60-562-.html
-methods
methods
1 GW
methods
1 GW
Unfathomable $37 single piece sample price. I will buy 10 right now at that price.
-methods
-methods
methods
1 GW
Oh, I see
$25-35 but you have to buy 200pcs
Ohhhhh Kay
Not sure I am ready to dip my junk into that blender quite so fast. I IMAGINE I could ship them a few tubes of fets to build with, but would that not be a nightmare.
Humpf
Sample order does me no good. I need like 40pcs
-methods
$25-35 but you have to buy 200pcs
Ohhhhh Kay
Not sure I am ready to dip my junk into that blender quite so fast. I IMAGINE I could ship them a few tubes of fets to build with, but would that not be a nightmare.
Humpf
Sample order does me no good. I need like 40pcs
-methods
methods
1 GW
methods
1 GW
Forked. 
[youtube]D0qQH78EVCU[/youtube]
[youtube]D0qQH78EVCU[/youtube]
40mOhm @ 60A would be something like 144W of heat dissipation. You could heat up your lunch with that.
Hopefully it’s actually a lot less than that.
Even 14.4W is kind of lot but certainly manageable.
Hopefully it’s actually a lot less than that.
Even 14.4W is kind of lot but certainly manageable.
methods
1 GW
Super Good Deal
* I vouch for the 12 volt 100 amp hour
* I hammer them in my golf cart four strung in series
I paid like $420 each
Worth every penny
-methods
P.S. yep - the 20mOhms in the data sheet is probably garbage
* I vouch for the 12 volt 100 amp hour
* I hammer them in my golf cart four strung in series
I paid like $420 each
Worth every penny
-methods
P.S. yep - the 20mOhms in the data sheet is probably garbage
methods
1 GW
There is another video not posted but still available where I make the argument that you have to have short circuit protection.
I now judge bms's by whether or not their short circuit protection works**
Basically
If it doesn't work, then the first time you have a big snap, you might have shorted your fets
-methods
I now judge bms's by whether or not their short circuit protection works**
Basically
If it doesn't work, then the first time you have a big snap, you might have shorted your fets
-methods
methods
1 GW
Data point
For the last few years I've been seeing almost everything fail to Short Circuit as opposed to open circuit. Those who've been around for 15 years will chuckle.
-methods
For the last few years I've been seeing almost everything fail to Short Circuit as opposed to open circuit. Those who've been around for 15 years will chuckle.
-methods
methods
1 GW
Ok, memory held 1 week
We are on to what was QA002 or QC002 marked FA002
Red on red so it's easy to miss. It's been hooked to the battery all week and as it sits I read the following
With balance tap attached and valid battery voltage
* Diode check reads short in both directions
Perfect
With balance tap removed and unit powered down
* Read diode 500mV with anode toward the pack
That would indicate the other fet is shorted. As the capacitance in the circuit bleeds away (or fills up from the meter) the reading becomes harder to grab.
* Very clear and strong reading right after power down
* Mushy reading after a minute
Yeah something is charging up from the meter
-methods
We are on to what was QA002 or QC002 marked FA002
Red on red so it's easy to miss. It's been hooked to the battery all week and as it sits I read the following
With balance tap attached and valid battery voltage
* Diode check reads short in both directions
Perfect
With balance tap removed and unit powered down
* Read diode 500mV with anode toward the pack
That would indicate the other fet is shorted. As the capacitance in the circuit bleeds away (or fills up from the meter) the reading becomes harder to grab.
* Very clear and strong reading right after power down
* Mushy reading after a minute
Yeah something is charging up from the meter
-methods
methods
1 GW
I DID NOT "steal that cup"!
They stole my cup!!! It's exactly the same but it doesn't say guest. I put it through the dishwasher and then it disappeared. Some gaffler on site.
Anyway
That was the gnarliest job ever...
-methods
methods
1 GW
Okay I need to cut this one out of the pack. I think it's time to start connecterizing. I use wago 221 now
* Big one
* Little one
The big one will go all the way up to 10 AWG. The little one will go up to 12 AWG. I have them in every size and shape.
-methods
* Big one
* Little one
The big one will go all the way up to 10 AWG. The little one will go up to 12 AWG. I have them in every size and shape.
-methods
