How to verify BMS (Daly) is working?
- Thread starter jzpchen
- Start date
I heard this smart one in a YouTube: https://www.aliexpress.com/item/32945565819.html?spm=a2g0o.cart.0.0.29953c00QDH9GK&mp=1. I am thinking about trying. Now sure if there are discussion there and see how well it works.
Will did a video on it title is 72 dollars
https://www.aliexpress.com/item/32975679107.html?spm=a2g0s.9042311.0.0.1d7a4c4deeQUEp
https://endless-sphere.com/forums/ has a lot of people on it in regards to software, taking it apart etc I looking for a more recent version of the software
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Do not buy BMS with balancing. It does not work or the balancing current is too low and has no effect. And mostly it is resistive balancing wasting energy.
Good matching cells do not need constant balancing but they may need when aging. You can always buy a separate energy transfer balancer later when it becomes necessary.
Do not buy common port BMS. Common port BMS is a crazy concept:
It disconnects the battery when cells get low, which is perfect.
But it also disconnect battery (B-) when cells get higher than 3.65V. Means your inverter or load is switched off when your battery is full !
You can't switch on your inverter again until the BMS turns on again. That may take long time because the cell voltage drops slowly since there is no load connected. And as soon the BMS turns on again, your PV starts charging also. Makes the cells rise quickly because your battery is full so you end in a deadly loop of BMS turns on/ off with short intervals.
Every time high inrush currents to your inverter/BMS and damage to your electrical appliances may occur.
Buy only BMS with separate charge port
With separate port BMS, the charge port disables the PV, generator, etc when the battery is full but the load/inverter stays on. When cell voltage drops the charge ports enables again and PV can charge. When full, port turns off again. Has no effect on your load.
But..
Be sure the charge port can handle at least the max available power you are using (PV, generator etc)
Many BMS (like Daly) has charge ports with limited current and should not be used.
If you don't find specs about the charge port current, don't buy it.
Whatever BMS you buy, it should have at least some cell diagnoses by leds, preferably with display, bluetooth or wifi.
You should see the cell voltages as this will be an indicator later which cells are weakest or failing.
And you should be able to set parameters for the lowest or highest cell voltage you prefer to use. Monitoring total voltage, current or set maximum current is useful.
For now, I don't think chinese BMS has all these necessary features and is worth to buy.
Good matching cells do not need constant balancing but they may need when aging. You can always buy a separate energy transfer balancer later when it becomes necessary.
Do not buy common port BMS. Common port BMS is a crazy concept:
It disconnects the battery when cells get low, which is perfect.
But it also disconnect battery (B-) when cells get higher than 3.65V. Means your inverter or load is switched off when your battery is full !
You can't switch on your inverter again until the BMS turns on again. That may take long time because the cell voltage drops slowly since there is no load connected. And as soon the BMS turns on again, your PV starts charging also. Makes the cells rise quickly because your battery is full so you end in a deadly loop of BMS turns on/ off with short intervals.
Every time high inrush currents to your inverter/BMS and damage to your electrical appliances may occur.
Buy only BMS with separate charge port
With separate port BMS, the charge port disables the PV, generator, etc when the battery is full but the load/inverter stays on. When cell voltage drops the charge ports enables again and PV can charge. When full, port turns off again. Has no effect on your load.
But..
Be sure the charge port can handle at least the max available power you are using (PV, generator etc)
Many BMS (like Daly) has charge ports with limited current and should not be used.
If you don't find specs about the charge port current, don't buy it.
Whatever BMS you buy, it should have at least some cell diagnoses by leds, preferably with display, bluetooth or wifi.
You should see the cell voltages as this will be an indicator later which cells are weakest or failing.
And you should be able to set parameters for the lowest or highest cell voltage you prefer to use. Monitoring total voltage, current or set maximum current is useful.
For now, I don't think chinese BMS has all these necessary features and is worth to buy.
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simple2010
New Member
- Joined
- Nov 9, 2019
- Messages
- 7
Operating blind concerns me a lot with the Daly products. I have a 100A common that I'm starting to suspect isn't doing its job. Subjecting my cells to abuse in an attempt to see if Daly will step in isn't fun but there doesn't seem to be a reliable way to ensure it's operating correctly.
I ordered a bluetooth based BMS to try out since the "not knowing" is killing me.
I ordered a bluetooth based BMS to try out since the "not knowing" is killing me.
same with me, I want to know the bms is working, and when you can program all the details yourself. if you screw up your fault if Daly screw up ..the are not going to take it back.. blame you meanwhile you have fried batteries,
I delt with Daly (Kevin) Though Alibaba.. no thank you.
I delt with Daly (Kevin) Though Alibaba.. no thank you.
I understand how it feels.
There is a simple way to test the Daly if you have an adjustable voltage source ( can be a 6V battery with a linear voltage regulator) and an accurate multimeter (at least one where the voltage is correct or verified.)
Connect the BMS ground (B-) with the ground - of your voltage source. Make sure the ground is always connected firmly during the test.
Connect the multimeter permanently to the voltage source and set your voltage source to the same voltage of the first cell. Voltage should never exceed 4V.
Use a light bulb or whatever as load on the BMS output to see if the BMS is on or off. Disconnect inverters or other loads.
Leave all BMS wires connected to your cells, except the red one to the first cell. Never disconnect the black wire!
Disconnect only the wire to the first cell and connect it to the positive side of your voltage source. Your BMS should stay on or turn on when it was off.
Slowly decrease the voltage to 2.4V. The BMS should turn off.
Increase voltage slowly back to the cell voltage. BMS should turn on.
Increase further to 3.8V. BMS should turn off again.
Do this several times to find the voltages where the BMS turns on and off.
The low and high cut off voltages should be +- 2.5V / 3.65V.
There may be a small delay (1-20 sec) before a BMS turns off at the cut off voltages. Don't change the source too fast.
If it does not turn off at the high and low points, disconnect it and put it in your trash before it destroys your cells.
Don't mess with cables during the test, it may kill your BMS...
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I think knocking the BMS because yours doesn't work is a little chidish . You make some strong statements there but offer no circuits or values to prove what you say or back it up in any way .
For instance why would the inrush current to the inverter damage the BMS ? They are usually good for 10 times the rated current for a half a second or so just like your fuses. Sustained current at that rate would but its charged in a quarter second or less.
The 30 mA is there for small cells and pretty useless for larger cells you might think but when your pack is getting close to full is when it comes into play. Your charge current gradually reduces as the voltage comes up .If it started at 30 amps then its probably at 3 amps round then and 30mA gets passed through a resistor to ground so the other cells still get 3 amps and the high cell gets 2.97 amps giving the others a chance to catch up .Thats the theory .
I've not had a problem getting my BMS connected and I would like to see some circuit logic to back that suggestion up. Why would a ground reference be needed while plugging in a loom which is tied to high impedance inputs?
Usually its off at 2.5V +- .5v
I find Ali-express to be totally unreliable for refunds or returns . Ali baba would be proud of them . Its a punt every time you deal with them and ebay are streets ahead on problems.
For instance why would the inrush current to the inverter damage the BMS ? They are usually good for 10 times the rated current for a half a second or so just like your fuses. Sustained current at that rate would but its charged in a quarter second or less.
The 30 mA is there for small cells and pretty useless for larger cells you might think but when your pack is getting close to full is when it comes into play. Your charge current gradually reduces as the voltage comes up .If it started at 30 amps then its probably at 3 amps round then and 30mA gets passed through a resistor to ground so the other cells still get 3 amps and the high cell gets 2.97 amps giving the others a chance to catch up .Thats the theory .
I've not had a problem getting my BMS connected and I would like to see some circuit logic to back that suggestion up. Why would a ground reference be needed while plugging in a loom which is tied to high impedance inputs?
Usually its off at 2.5V +- .5v
I find Ali-express to be totally unreliable for refunds or returns . Ali baba would be proud of them . Its a punt every time you deal with them and ebay are streets ahead on problems.
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Your charger should be set to stop charging at 3.5V. You are not getting the basics yet and should not be spouting this without that practical knowledge.. people might actually be mislead .
sajjen
New Member
You're off by a factor of ten. If you are charging with three amps, a cell balanced with 30mA would get 2.97A charge.
We are talking about battery banks. In my case 16S 200Ah 48V.
How should a PV charger stops when a cell is at 3.6V? It just deliver 58V output. There is no link to the cell voltages.
Only the BMS is measuring cell voltages and decides to switch off the complete load/charge when a cell reach the limits.
I think I have more than enough experience with my 36 trouble cells because anything that can go wrong with such configuration, I have had it.
The fact about the common ports is something from my real situation. I hated being switched on/ off during summertime because my battery was full and the charge was higher than the load. Then I changed to a separate port and this switched off as well when the charge was higher than 35A.
Yes both DALY.
And if you think I have lack of knowledge: because all of this mess I made my own BMS hardware and software from scratch. With datalogging, 24h graphs, cell voltage monitoring, Cell temperature, PV shadow detection, current monitoring, KWh in /out, Switches and safety controls.
Over wifi, Warning me on telephone and emailing me the dataset every day.
Does your system gives you the same information and control?
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It should not damage the BMS if it's well constructed and the parallel mosfets are good enough. Can you say the Daly uses sufficient mosfets with low RDSon and high voltage? Noone can look inside. It may survive a few hundreds inrush currents until one mosfet burns and the rest follows.
Do you have an idea of the inrush current from a 200Ah 48V system to a capacitor bank of 10000µF or more? Put a 0.2 ohm powerresistor in series and use your occilloscope. You will be surprised.
Like you said: that's the theory.
Good matching cells do not need balancing. Balancing is made to compensate small cell differences.
Daly had totally no effect on my cells, not even after a week without charge/load. The Broodio 16S brings the cell voltages equal to +- 50mV after a few hours with a current of about 1A.
It s Chinese as well but at least it works and has diagnostic leds.
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I do not agree with this too.
There are many unreliable Ali sellers who try to escape when they have to refund but Aliexpress does a real good job.
As you can see I have quite a lot of orders there. And many disputes over the years.
But I only dispute with good reasons and with decent evidence.
I always win the case and they return the money without much questions.
How do they balance 30mA with high impedance inputs? It's more than an input.
Also high impedance inputs can be easily damaged. ADC inputs from an MCU are also high impedance and can be quickly damaged with small overvoltages and a few milliamperes.
That's what can happen to the BMS if the ground wire is not connected first.
If you don't believe me again then I suggest your are playing with the black ground wire of your BMS and see how long it takes before it's dead.
I have had a few disputes on Aliexpress, if it is damaged you can prove it with a photo, instant refund. if they advertise false claims, that's okay, as long as it works. no refund.
That's right. It must be very difficult for those Aliexpress people to judge about so many different products. Buyers are not always honest as well...
So we need to provide clear evidence to make that decision more easy. Sometimes that's difficult.
But it's more than that. Buyers and sellers have profiles. The ratio buying/dispute is important. If the seller has too many disputes, bad for him too.
My last dispute is about 10 fake mosfets (15$). Chinese go far to make money. BLS sells bad batteries but even simple mosfets can be faked. How more they cost how more chance they are faked.
That's what they do: they take a cheap chinese mosfet with the same dimensions; they grind the surface flat and laser the specs of an expensive US/ EU brand. They sell it to 70% of the western price. At first sight nothing wrong with the product, it acts as every mosfet but of course the specs are not the same and under power they heat up or blow up faster.
When you discover that something is wrong with the product and not with your schematics, you give 5 stars already and the dispute period is over.
Aliexpress stars are not very reliable. I only read the 1-3 stars comments, more chance they are true.
Pictures: flat grinded mosfet, nicely remarked.
But: original parts are marked with a strong and fast laser because they have to name millions of parts. So the characters are written in one pass.
Chinese counterfeiters use a cheap laser and have to write the characters in 2 times to get enough depth and width. It is slow and not precise enough and burns holes when it stops in a character. So, no doubt it is fake.
Such parts may be used in BMS, etc , hard to say.
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Sometimes those 2 or three stars comments never get entered, Also for the supplier to get paid, you must click received, Then if you fill out the review 5 stars, Then to find out the product is crap. too late.
Did you get your refund or the normal I pay you 20% credit.. I ordered a set of ER32 collets for my mill they sent er11 collets told me they ran out of 32, would credit me part of the cost. wtf, I got full credit and have er11 that i do not need.. Bangwood site.. much lower on the standards
We should all buy more local quality but it's so cheap in China...Bangwood site.. much lower on the standards
It's best to test as much as possible and wait until the last day before clicking Received. We have still 14 days for a dispute if the case is finished automatically.
If you got crap and you are too late for a dispute, open the "Manage feedback" and add your experience. It can not help you anymore but prevent others from being cheated. Don't make it easy for such sellers.
On the other hand, sometimes I have very good experiences as well. Once I bought 5 boosters (90$) and it was held by customs. I had to pay +-56$. I did nothing and customs had to send it back. The seller contacted me spontaneously when he received it and offered to send it again for 4$.
I paid, he send and this time it passed. (but it took 6 months all together..)
I guess we are going off topic
