Daly BMS Amazon store

[G8trwood]

The bms function search makes my head hurt. Trying to decide OKS vs Chargery vs
16s
Golf cart for farm, 500a controller, max I have seen logged is a few 300+ amp spikes
Charging only 25a tops
Running contactors to separate charge and discharge circuit
2C current from most likely 150ah cells

Ideally I would prefer an external shunt, so that leaves Chargery? Or just run a separate monitor and shunt for capacity separate from the bms? Is there a best practices.

It looks like some of the apps allow warning notices to be triggered to your phone but it would nice to have an external trigger for a low battery warning at a set level (for the others who use cart) weather resistant is nice.

I welcome any other suggestions, I have downloaded a few apps to look for functionality that is not listed in the manuals,

 

[Frank in Thailand]

The bms function search makes my head hurt. Trying to decide OKS vs Chargery vs
16s
Golf cart for farm, 500a controller, max I have seen logged is a few 300+ amp spikes
Charging only 25a tops
Running contactors to separate charge and discharge circuit
2C current from most likely 150ah cells

Ideally I would prefer an external shunt, so that leaves Chargery? Or just run a separate monitor and shunt for capacity separate from the bms? Is there a best practices.

It looks like some of the apps allow warning notices to be triggered to your phone but it would nice to have an external trigger for a low battery warning at a set level (for the others who use cart) weather resistant is nice.

I welcome any other suggestions, I have downloaded a few apps to look for functionality that is not listed in the manuals,

Welcome to the forum!

Best practices?
Yes, absolutely there are.
And you probably don't like the price tag. (Batrium is one of the better)

When you look at all the higher end BMS (+$500,- starter pack) they all use contactor.

I have to disagree with @BabylonFive . He clearly didn't read enough in the forum yet.

Many times contactors have been shown as superior choice for high amperage contact.

The QUCC guys are funny.
You have to be Chinese budget minded to use a car starter motor contactor for continuous contact..
Lol.
And then wonder why it fails

Luckily they have upgraded their design now with a slightly better contactor.


A higher quality contractor like this is +/- $125,- (for 50A)

Lower quality I use:

About $25,- for 50A

I have the 50A to disconnect the solar (= charge) and a 400A unit to protect discharge.

The 50A uses about 5 watts to keep contact, the 400A about 7 watts.
If that's a lot? Up to you.
My continuous used solar system with +50 kWh LiFePO4 doesn't care.
20Ah systems... That's different.
You also would not use +100A

And yes, compared to mosfet, that's a lot more!

Their sister, solid state relay uses just a little energy also, but have tremendous voltage drop so it requires a massive heatsink.
In standby, its very energy efficient.
Pump 100A... And it's suddenly a heater

Back to best practices:
Looking at the price of one quality contactor (50A uses 3 watt) you can understand that anything below $500,- including Contactors is not really quality.

Quality contactors for charge and discharge already set you down like $300,-

Chargery is good,
Electrodacus is good, but need to use 2x 24v.
The Contactors can be wired in parallel, if one controller tells it to disconnect,it will.

I like DIYBMS, especially the new version (4.40) and new controller.
It have WiFi and Bluetooth, canbus and all toys one would like.

But it's DIY so include soldering and flashing firmware.
Good thing is that it is almost as good as Batrium, for a fraction of the price and open source.
Each cell (or parallel cells) have own cell module and temperature controller. With small heatsink 1.2A balance dumpload (standard 0.8A)

Talking about that.
Daly is sweet, and at low capacity, really good quality. "Set and forget" as @Will Prowse would say.
Up to 100A, those units (Mosfet based) are good.

Higher amperage the voltage drop becomes an issue, and the heat + lower quality mosfets, make many high capacity Daly fail in the first year.

Their Balance dumpload is 0.08A.
That's all.

I hope you understand the charging cycle, how it goes from constant current, the maximal amperage that you can push into the battery with your charger, to constant voltage.

That phase you see the amperage slowly drop, at the end 0.001 or so.

Balancing is the process to hold back the cells that charge a little faster. That can be due slightly different internal resistance.

At a slow charge/discharge rate like solar (+/- 10 hours charge, 14 discharge) the difference is small, and when the first battery comes close to 3.65v, the charge capacity has dropped to or under 0.08A
(For 51.2v (S16) about 5 watt)

Fast charge and discharge in automotive requires different approach.
(Or when you top balance every 3-6 months)

Their imbalance will be significant.
You probably still are charging at 10A or more when the first cell hits the balance threshold.
Automatic result, you need the same capacity balancers.

Lucky they are cheap and separate available.
More expensive models have Bluetooth.

Best practice for 300A golfcart?
With C2 loads?
(Compared to C0.2 on most solar installations)

Yes, contactors.
BMS can be anything.
Even 20A spilt port Daly.
You don't need to feed all the current via the BMS.
And the cheap Chargery can control the Contactors
Better: Chargery, electrodacus, (and probably a few more contactor based I don't know their name)
Best: Batrium or DIYBMS.

For the capacity monitoring, there are many AMmeters available that do a great job.
Higher quality is Victron.
Lower is aliX like this
They all do the job.
If you plan to draw 300A, use the China margin, +25% so a 400A shunt.
For Victron, 250-300A.
Don't buy 1000A as it will give less correct reading.

 

[Frank in Thailand]

Apparently the contact in the QUCC, I don't know what it's called, tends to fail open though. Too much current and the contact will weld it in place. So that's a drawback. You'd think the BMS could monitor that and send an alert if it fails but I don't think it does. Anyway I got the QUCC BMS but the battery cells are about 2 months out still. The BMS doesn't look at all like the one the youtuber has.

@Off-Grid-Garage used to have the one with car starter contactor.
And that one obviously failed.

Their new model have slightly better contactor.
It can be good enough, I truly hope so.
If not, replacement on aliX is about $50 for 400A
Or $ 175,- for quality via Mouser or Digikey.
Knowing that a higher quality is $175...
You can not expect the world from the QUCC.

I hope yours have a contactor that looks like the higher quality one, and not the black car starter contractor
(If you want to search, change the wording to "starter relay" and you find cheap alternatives that are NOT adviced to use, as they are made for short time contact)

 

[G8trwood]

Welcome to the forum!

Best practices?
Yes, absolutely there are.
And you probably don't like the price tag. (Batrium is one of the better)

When you look at all the higher end BMS (+$500,- starter pack) they all use contactor.

I have to disagree with @BabylonFive . He clearly didn't read enough in the forum yet.

Many times contactors have been shown as superior choice for high amperage contact.

The QUCC guys are funny.
You have to be Chinese budget minded to use a car starter motor contactor for continuous contact..
Lol.
And then wonder why it fails

Luckily they have upgraded their design now with a slightly better contactor.

View attachment 45189
A higher quality contractor like this is +/- $125,- (for 50A)

Lower quality I use:
View attachment 45190
About $25,- for 50A

I have the 50A to disconnect the solar (= charge) and a 400A unit to protect discharge.

The 50A uses about 5 watts to keep contact, the 400A about 7 watts.
If that's a lot? Up to you.
My continuous used solar system with +50 kWh LiFePO4 doesn't care.
20Ah systems... That's different.
You also would not use +100A

And yes, compared to mosfet, that's a lot more!

Their sister, solid state relay uses just a little energy also, but have tremendous voltage drop so it requires a massive heatsink.
In standby, its very energy efficient.
Pump 100A... And it's suddenly a heater

Back to best practices:
Looking at the price of one quality contactor (50A uses 3 watt) you can understand that anything below $500,- including Contactors is not really quality.

Quality contactors for charge and discharge already set you down like $300,-

Chargery is good,
Electrodacus is good, but need to use 2x 24v.
The Contactors can be wired in parallel, if one controller tells it to disconnect,it will.

I like DIYBMS, especially the new version (4.40) and new controller.
It have WiFi and Bluetooth, canbus and all toys one would like.

But it's DIY so include soldering and flashing firmware.
Good thing is that it is almost as good as Batrium, for a fraction of the price and open source.
Each cell (or parallel cells) have own cell module and temperature controller. With small heatsink 1.2A balance dumpload (standard 0.8A)

Talking about that.
Daly is sweet, and at low capacity, really good quality. "Set and forget" as @Will Prowse would say.
Up to 100A, those units (Mosfet based) are good.

Higher amperage the voltage drop becomes an issue, and the heat + lower quality mosfets, make many high capacity Daly fail in the first year.

Their Balance dumpload is 0.08A.
That's all.

I hope you understand the charging cycle, how it goes from constant current, the maximal amperage that you can push into the battery with your charger, to constant voltage.

That phase you see the amperage slowly drop, at the end 0.001 or so.

Balancing is the process to hold back the cells that charge a little faster. That can be due slightly different internal resistance.

At a slow charge/discharge rate like solar (+/- 10 hours charge, 14 discharge) the difference is small, and when the first battery comes close to 3.65v, the charge capacity has dropped to or under 0.08A
(For 51.2v (S16) about 5 watt)

Fast charge and discharge in automotive requires different approach.
(Or when you top balance every 3-6 months)

Their imbalance will be significant.
You probably still are charging at 10A or more when the first cell hits the balance threshold.
Automatic result, you need the same capacity balancers.

Lucky they are cheap and separate available.
More expensive models have Bluetooth.

Best practice for 300A golfcart?
With C2 loads?
(Compared to C0.2 on most solar installations)

Yes, contactors.
BMS can be anything.
Even 20A spilt port Daly.
You don't need to feed all the current via the BMS.
And the cheap Chargery can control the Contactors
Better: Chargery, electrodacus, (and probably a few more contactor based I don't know their name)
Best: Batrium or DIYBMS.

For the capacity monitoring, there are many AMmeters available that do a great job.
Higher quality is Victron.
Lower is aliX like this
They all do the job.
If you plan to draw 300A, use the China margin, +25% so a 400A shunt.
For Victron, 250-300A.
Don't buy 1000A as it will give less correct reading.

Thank you for the detailed response. That is the direction I was going but most of the info was directed towards low c rate discharges. I play a bit in the marine environment and have been looking at the design and separation of the high amp draw devices there.
I already have contactors (3) in use from a rewire and I think they were around 125 each for the mid priced 400a modules. I tried a cheaper version, what a joke it was, It is quite easy for me to see how price escalates, especially with quality.

 

[Frank in Thailand]

It's not crazy to pay + $100,- for a contactor, and you need 2.

BMS doesn't do much more then monitor cell voltage and act of one goes too high or too low.

In low amperage set-up it makes sense to use solid state relay build-in the BMS.

Strangely it seems to be really difficult to let go of Mosfet at higher Amperage.

The 20A Daly BMS will work just fine with 400A C2 setup.
As long as you don't flow the current Via the BMS but the relays, that can easily be controlled by the 20A split BMS.

Just the balancing.
Just as crazy as Chinese manufacturers seem to hold on to mosfet, they hold on to low capacity balancers.

Seriously. When you charge 300A, you live in a totally different world then the 20A kind.
Your imbalance will increase, and your "end" charge capacity is more likely to be in the 10A range.
Not 0.08A like Daly.

In light used setup, or smaller, it probably is enough.

With the lower pricing, 50 kWh LiFePO4 (+1000Ah) powerwall isn't anymore extreme.

1000Ah will need noon solar spike of +250A to charge.
Still just C0.25.
It does make a difference, 100Ah on C0.25 or 1000Ah.
Cells don't behave the same, higher Ah doesn't directly match with higher charge, and you can't expect the same behaviour.
This also goes for S4-S16, where more cells does increase the complexity.

When people buy 400A Daly, I smile.
And know they are in for a wake-up call sooner or later.

If they use 400A, the Daly will get hot (Mosfet voltage drop)
The charge/discharge efficiency suddenly is a lot worse.
But you have a free heater.
And if they do on regular basis..
It will fail.
After a few weeks intensive use, they will notice that the BMS stops charge (or discharge) frequently.
0.08A Balance isn't really helpful with their 200A charge.

Luckily for most owners, they use 50-100A and charge with the same.
On rare occasions they have a 3-400A spike.
In that setup, it will work fine.

 

[G8trwood]

Looks like batrium now offers more modularity and increased series connections at associated price increases.

 

[Frank in Thailand]

Looks like batrium now offers more modularity and increased series connections at associated price increases.

I like them, but outside my budget.
With DYIBMS as result.

Good thing I like tinkering

 

[G8trwood]

I like them, but outside my budget.
With DYIBMS as result.

Good thing I like tinkering

Have to say the DIYBMS looks very well thought out. Unfortunately at this point in life I am no longer soldering anything small

 

[Frank in Thailand]

I'm at the same point, with some magnefing glasses, it's really doable.

They are about $10,-

Usually, you only solder the attiny841 and the headers for the wires.
Stuart made tutorials on YouTube.
Adam Welch has several videos about DYIBMS also

The headers are really easy to do.
In my first order, the video on how to order wasn't released, so I made a few errors..
I forgot the SMD 0602 thermistor.
Now that was a crime to solder, even with digital microscope.

Naked eye (eyesight not so perfect anymore) it looked like a small grain of sand.
I can not advice anyone to do that.

During the first Covid wave in April/may/June, restrictions where strong here, and all parcels went 3 weeks quarantine + desinfection with alcohol.
What wasn't nice for the address labels. Many parcels got lost.

With result that I couldn't reorder the PCB's (+ over confident ... How hard can it be? )
Really hard.
Don't try 0602 SMD components by hand.
0804 are already good to do.
Attiny841, really doable.
Headers easy.


The thermistor R19

End result:

(Heatsink isn't mandatory, but increase the balancing dumpload from 0.8A to 1.2A)

Check out the video's and see if it's something for you.

Programming now is also a lot more easy. No longer need for visual studio and platform IO, just a firmware flashing tool.

 

[G8trwood]

I'm at the same point, with some magnefing glasses, it's really doable.
View attachment 45454View attachment 45455
They are about $10,-

Usually, you only solder the attiny841 and the headers for the wires.
Stuart made tutorials on YouTube.
Adam Welch has several videos about DYIBMS also

The headers are really easy to do.
In my first order, the video on how to order wasn't released, so I made a few errors..
I forgot the SMD 0602 thermistor.
Now that was a crime to solder, even with digital microscope.

Naked eye (eyesight not so perfect anymore) it looked like a small grain of sand.
I can not advice anyone to do that.

During the first Covid wave in April/may/June, restrictions where strong here, and all parcels went 3 weeks quarantine + desinfection with alcohol.
What wasn't nice for the address labels. Many parcels got lost.

With result that I couldn't reorder the PCB's (+ over confident ... How hard can it be? )
Really hard.
Don't try 0602 SMD components by hand.
0804 are already good to do.
Attiny841, really doable.
Headers easy.

View attachment 45460
The thermistor R19

End result:
View attachment 45459
(Heatsink isn't mandatory, but increase the balancing dumpload from 0.8A to 1.2A)

Check out the video's and see if it's something for you.

Programming now is also a lot more easy. No longer need for visual studio and platform IO, just a firmware flashing tool.

I will check it out. I do have a couple magnifiers and one with the side doubler. I need to add the fancy led lights to mine!

 

[BabylonFive]

I think you mean to avoid 0603 not 0602, but they are just possible with a pair of small irons. 0402 and smaller are wildly impossible for anyone but a pro..

 

[opticalcarrier]

Wow - the Daly BMS on Amazon is WAY more expensive than going through Ali!

 

[Frank in Thailand]

I think you mean to avoid 0603 not 0602, but they are just possible with a pair of small irons. 0402 and smaller are wildly impossible for anyone but a pro..

I mean 0402.

With a microscope and patience, with the pointy tip (like Ice picker),
And patience...

It took about 30 - 90 minutes per thermistor to solder by hand.

Biggest problem was that it sticks to the soldering iron.
And as it's so damn tiny, tweezers aren't much help.
Holding down with an Injection needle (28) worked, but sometimes got stuck to the needle.....

Once.
Never again.

 

[Frank in Thailand]

Wow - the Daly BMS on Amazon is WAY more expensive than going through Ali!

Yes.
You get Amazon warranty!!!
They need to provide real warranty, not the crappy fake.
Result, they need to calculate this in the sales price.

What also gives a good indication of the quality that is sold via AliExpress.

 

[opticalcarrier]

Yes.
You get Amazon warranty!!!
They need to provide real warranty, not the crappy fake.
Result, they need to calculate this in the sales price.

What also gives a good indication of the quality that is sold via AliExpress.

so if buying one from amazon, do we need to de-rate 0.5x on the specs? where If I wanted to charge @ 100amps, if I buy from Amazon, would I still need to get the 200amp version? because they are around 2x the price from amazon.

 

[Frank in Thailand]

China safety margin is usually 25-50%

If you are going to use 100A some times for a short period of time, 100-150A will be sufficient.

If you are using 100A as "standard load"... Absolutely buy the 200A.

Personally I can not advise any Mosfet based BMS above 100A.

They fail a lot.
Besides this, the voltage drop with higher amperages is significant.
That's why they have the huge heatsink.

Own power consumption at 100A can easily be 30 - 50 watt.

Besides this, Daly have low balancing capacity, 0.08A.

Chargery use Contactors, so does electrodacus, Batrium, 123smartbms etc.
The last 2 are in the $500 range for 4S 12v, $900-1000 for $16, 51.2v

Chargery, I didn't look for pricing recently.

If you use on regular basis 100A, your imbalance will increase.
I can't really advice the Daly for that work.

If it's your theoretical maximal power draw, and you usually stop at 75A or so, Daly could make you happy for a long time.

(My first 250A Daly failed after 2.5 month, the 150A smart never really worked, it usually gets stuck in a startup-reset loop, even with minimal power draw or pre-charged capacitors of the inverter.
Sometimes I got lucky, but that isn't a workable setup.

If I did buy via Amazon, warranty no problem.
Ali.... Knowing the hassles from last time and the $75 it costs to send a defective (unrepairable, full epoxied) unit back.... I didn't even start the fight.)

 

[Stepandwolf]

Thank you for sharing!
Yeah, that's crazy.
He can hear the contactor click but it doesn't affect the connection.
(Apparently always on)

That's strange!
The click one hears is the iron core sliding with high speed in the electro magnet, and "ramming" onto the contact area.

No way a normal designed contactor could make that "click" if the electro magnet is defective.

And for a "short" it should be welded inside due the arc.
Meaning no movement, = no click.

Really bad designed...
Anything can happen.

Really a shame to hear this.
The design idea is good.

Off Grid Garage got a replacement for the Qucc BMS that was always on. In a recent episode, he sawed the contactor in two and discovered that the relay was not in fact stuck closed. He hadn't done further research yet to determine why the BMS was charging when he thought it shouldn't be charging.

I am dismayed to hear that my 250A Daly might not be a reliable model. Of course Daly never tells you they don't make it as implied earlier. Despite saying it would come with a manual it didn't and they included a wiring diagram that was for 16550 batteries in a totally different cell configuration. Still hoping someone has found or can come up with instructions specific to using the Daly in an 8S configuration. Thanks

 

[Aten]

China safety margin is usually 25-50%

If you are going to use 100A some times for a short period of time, 100-150A will be sufficient.

If you are using 100A as "standard load"... Absolutely buy the 200A.

Personally I can not advise any Mosfet based BMS above 100A.

They fail a lot.
Besides this, the voltage drop with higher amperages is significant.
That's why they have the huge heatsink.

Own power consumption at 100A can easily be 30 - 50 watt.

Besides this, Daly have low balancing capacity, 0.08A.

Chargery use Contactors, so does electrodacus, Batrium, 123smartbms etc.
The last 2 are in the $500 range for 4S 12v, $900-1000 for $16, 51.2v

Chargery, I didn't look for pricing recently.

If you use on regular basis 100A, your imbalance will increase.
I can't really advice the Daly for that work.

If it's your theoretical maximal power draw, and you usually stop at 75A or so, Daly could make you happy for a long time.

(My first 250A Daly failed after 2.5 month, the 150A smart never really worked, it usually gets stuck in a startup-reset loop, even with minimal power draw or pre-charged capacitors of the inverter.
Sometimes I got lucky, but that isn't a workable setup.

If I did buy via Amazon, warranty no problem.
Ali.... Knowing the hassles from last time and the $75 it costs to send a defective (unrepairable, full epoxied) unit back.... I didn't even start the fight.)

I bought a 100A 7s Daly from Amazon back in December but put it in my Li-Ion battery system only in June (long story). Sure enough, after a little more than a month later it overheated (~1V reduction at P-/B-). I've been watching my cells since and don't see anything out of the ordinary. I have no idea why it died. I'm discharging at 80A max and charging at max 50A. Is 50A charging current, on and off during the day, too much for a 100A BMS? Any idea why it might have died. I don't want to buy another (Daly) BMS before I understand why it overheats (fried FETs?). My voltage difference is <100mV (at high currents), mostly <10mV. I never go above 4V.

I'm surprised about your statement on 'Amazon warranty'. This is what it says:
"Please contact the seller directly for warranty information for this product. You may also be able to find warranty information on the manufacturer’s website." Does Daly warrant their product? I guess not. And even if so, it makes no sense to send the BMS to China for $40 or more. Could you clarify what you meant by saying "If I did buy via Amazon, warranty no problem"?

 

[Frank in Thailand]

Your purchase time and using time made the problem for Amazon.

It died in a month of usage.
Would that have been end of January begin februari, Amazon would refund without issues.

Yes you overloaded the BMS.
100A Daly is maximal 50A charge, 100A discharge.
It even should self protect above the 50A as it's limited.

Imagine your car, and look at the speed meter.
It probably tells you 200km/h
You might be able to reach that, long steep hill down, but your car won't like it.
If on a flat road you can do 180, it still won't like it.
And most likely will brake down in a few months.
Driving it on a "normal" 120-140km/h will last many, many years.

Just because it's absolute peak is 200km/h it doesn't mean you should do it.

Same for all electronic.
Your stereo have volume 1-10.
Putting it standard on 10 will not just get you in a fight with the neighborhood, your speakers will die soon.

That's normal "western" made electronics.
Besides the China margine....

I don't like Daly for the sole reason that they request return of a failed device that is fully epoxied and can't be repaired.
Test of failure is done quickly, and won't change if it's done in USA, Australia or China.
Like a lightbulb won't repair itself during transport.

Requesting it back is discouraged customer service, not standing behind your product and test for failure.

If you want a Mosfet based BMS, buy any brand, it won't be better or worse then Daly.

Their "smart" isn't build by them, OEM, just Daly sticker

50A charge, 80A discharge.
That is getting close to Contactor BMS, but yet still can get away with Mosfet based.

You already noticed the downside of Mosfet... The voltage drop can/will make it hot! (Burned of energy is lost energy)

Chargery, the BMS "off-grid garage" uses (I forgot the name, seach on YouTube and you quickly find his videos)
That's a funny one as that Chinese company started with using a starter contactor (cheap) what obviously failed after some usage..
Lol
They now use little better quality.

Good quality contactor (aviation grade) 100A is about $125,-
Only the contactor.

That does help realise what quality you buy if you pay 80 bucks for contactor BMS....

I can't decide for you, I have 2 Daly BMS dead, one dead on arrival.
Didn't even bother to start the fight for warranty.

Corsair... Power supply 1000 watt.
4 years old, gave probelms starting (soft start, a flip-flop electronic part)
I tried to fix, as its usually a small component.
I contacted support, to ask them where it is on the mainboard, so I could replace.

Yes, I broke all seals, and had the unit disabled.

Not a problem.
They collected the PSU, shipped to South Korea.
And a week later new PSU all costs paid on my doorstep.
Purchased in Europe, support request from Thailand.

Why? Simple.
PSU should start, it should not be defective at all.

Kudos for Corsair!!!

If they would make BMS, I would advise them for excellent aftersales.

Morale of the story?
Probably you get what you pay for.
Corsair isn't cheap.
But it does pay back in terms of stability, and aftersales support service.

There are a few more expensive options out there.
Price range $350-1000 for S16 setup.

They really might end up being the cheapest option.

Failed BMS can/ will damage the cells.
Many Micro damage can/will result in fire.
(As I have experienced, see my other thread)

 

[Aten]

I bought a 100A 7s Daly from Amazon back in December but put it in my Li-Ion battery system only in June (long story). Sure enough, after a little more than a month later it overheated (~1V reduction at P-/B-). I've been watching my cells since and don't see anything out of the ordinary. I have no idea why it died. I'm discharging at 80A max and charging at max 50A. Is 50A charging current, on and off during the day, too much for a 100A BMS? Any idea why it might have died. I don't want to buy another (Daly) BMS before I understand why it overheats (fried FETs?). My voltage difference is <100mV (at high currents), mostly <10mV. I never go above 4V.

I'm surprised about your statement on 'Amazon warranty'. This is what it says:
"Please contact the seller directly for warranty information for this product. You may also be able to find warranty information on the manufacturer’s website." Does Daly warrant their product? I guess not. And even if so, it makes no sense to send the BMS to China for $40 or more. Could you clarify what you meant by saying "If I did buy via Amazon, warranty no problem"

I understand your point (although a combustion engine is only remotely comparable to electronic devices ;-) )
Unfortunately what you are describing is not what is advertised. Quoting from Amazon:
What is the maximum burst current?100A? Or is 100A the continuous current rating
Answer: 100A is the continuous current rating
By DalyElec Seller on May 26, 2020

BMS protect battery charge current: 66A.
BMS protect battery discharge current: 300A.
BMS protect battery charge voltage: 4.25V.
BMS protect battery discharge voltage: 2.7V.
Continuous charging current: 50A.
Continuous discharging current: 100A.

I did not exceed these values.

It seems several people state your "view" that the BMS should be run at up to 50% safety margin.
If that's the case the above is false advertising and should be brought to the attention of Amazon. Maybe I'll do that.

Many people seem to indicate that there is a good chance that DALY BMS's break early. That's a joke when you consider that the high Amp versions cost $100-$200. And if I understood correctly, the 'dumb ones' don't even balance when the max voltage is limited to values less than 4.2V for Li-Ion batteries.

Overall, I have to say, given the quality of the product and the fact that they intentionally want the broken BMS sent to China, is a red flag. It's surprising though how many BMSs they sell. Perhaps the reason is there is no serious competition in that price range.

The whole BMS discussion is confusing. You have stated in this forum that DALY BMSs are just fine (I guess if oversized by 2x), I think Will indicated this view somewhere as well. But then there are so many complaints of broken DALYs...
So what are the options? There are also different opinions about Chargery that you mentioned above. Then there are the expensive options. But to spend hundreds of $ on a BMS to protect a $1000 battery makes little sense to me. Maybe I'll just trust my inverter on the upper and lower voltage settings (which I do since that DALY crap died) and use an active balancer instead of a BMS. I'll open a new discussion on this topic to get people's view.

 

[Just John]

One of the vendors who participates here recently found some Daly BMS that were not calibrated correctly. This caused them to heat up and will definitely shorten the lifespan. You may wish to contact current connected and purchase a Daly BMS from him, he correctly calibrates and tests them. Daly has a big problem with quality control, however they do seem to be reasonably accurately rated and reliable if you get a good one. Especially for a FET based BMS, a bigger current rating is always better for longevity. Another alternative is JBD, they seem to do much better testing and calibration.

 

[Frank in Thailand]

The seller provided you on Amazon with false information, where "common sense" might also come into play.
Your stereo have volume 1-10, continuous 10 will kill your speakers quickly in most pre-build sets.
You asked, and the seller told you that it can do, that is a reason for warranty.
An appeal to your warranty claim rejection might work for this reason.

Daly is "good" in their low range capacity BMS that do balance !! (dumb doesn't mean no balance, just no app to connect, or settings to mess up)
Depending on for what battery type you buy, lithium phosphate or lifepo4, BMS will act with correct pre-set voltages.

Best cheapest high quality BMS:
Daly split port 10-30A (doesn't matter)
Contactors in the ampere range you like.
something like this:


You'll be needing 2.
what you do is simple, no load via the BMS.
BMS monitors the cells, balance them, and acts at low or high state of charge.
it does not disconnect the main power line, but only the power to the contactor.
who in its turn will disconnect the main power line.

If you have solar charge controller and inverter in 1,
one contactor can be placed in the solar line, before entering the hybrid, the other between hybrid and battery.
Price per quality contactor $ 125,-
Price 10-30A Daly $35 (?) Total $285,-

lower quality contactor : (still $35-$40 per contactor)
total $115,-


You might find it as lot of money for just $1000,- of battery
Would you think the same if you needed to pay $3500?? (24 months ago) or $ 5000? (36 mnd ago)
That the lifepo4 cells are in "free fall" for price, doesn't automatically make all components drop the same in price.
You're just lucky you paid little money for the batteries!
Good. Now you have more left over for the safety.


Using your system without BMS like I did for several months, overall opinion is negative.
Where I'm absolutely sure a (Daly) BMS would not have stopped my accident, many disagree.

Its perhaps like a motor cycle.
All experienced drivers will tell you to first buy a good suit and helmet, and with the money that you have left buy a motor cycle.
they know this, as many of them did it the other way around.
buy motorcycle... ow yeah... need helmet..
Suit? maybe next month..
That becomes the next and next, till you do slip, and lose half of the skin on your leg.
Those people are the ones who now warn you to absolutely first buy that suit and helmet!

Some people (like me) need to fall first

 

[Aten]

One of the vendors who participates here recently found some Daly BMS that were not calibrated correctly. This caused them to heat up and will definitely shorten the lifespan. You may wish to contact current connected and purchase a Daly BMS from him, he correctly calibrates and tests them. Daly has a big problem with quality control, however they do seem to be reasonably accurately rated and reliable if you get a good one. Especially for a FET based BMS, a bigger current rating is always better for longevity. Another alternative is JBD, they seem to do much better testing and calibration.

That's interesting - it's a lottery lol
QC is key.
Seems JBD does have a better reputation. They are even cheaper than DALY (which worries me a bit). On AliExpress they sell for $107 for a 200A version. Since I am limiting my inverter to 80A discharge, that thing should not ever burn out.
Combined with an active balancer from Heltec for $27, this could be an affordable option worth trying.
Thanks for the hint!

 

[Aten]

The seller provided you on Amazon with false information, where "common sense" might also come into play.
Your stereo have volume 1-10, continuous 10 will kill your speakers quickly in most pre-build sets.
You asked, and the seller told you that it can do, that is a reason for warranty.
An appeal to your warranty claim rejection might work for this reason.

Daly is "good" in their low range capacity BMS that do balance !! (dumb doesn't mean no balance, just no app to connect, or settings to mess up)
Depending on for what battery type you buy, lithium phosphate or lifepo4, BMS will act with correct pre-set voltages.

Best cheapest high quality BMS:
Daly split port 10-30A (doesn't matter)
Contactors in the ampere range you like.
something like this:
View attachment 60459

You'll be needing 2.
what you do is simple, no load via the BMS.
BMS monitors the cells, balance them, and acts at low or high state of charge.
it does not disconnect the main power line, but only the power to the contactor.
who in its turn will disconnect the main power line.

If you have solar charge controller and inverter in 1,
one contactor can be placed in the solar line, before entering the hybrid, the other between hybrid and battery.
Price per quality contactor $ 125,-
Price 10-30A Daly $35 (?) Total $285,-

lower quality contactor : (still $35-$40 per contactor)
total $115,-
View attachment 60461

You might find it as lot of money for just $1000,- of battery
Would you think the same if you needed to pay $3500?? (24 months ago) or $ 5000? (36 mnd ago)
That the lifepo4 cells are in "free fall" for price, doesn't automatically make all components drop the same in price.
You're just lucky you paid little money for the batteries!
Good. Now you have more left over for the safety.


Using your system without BMS like I did for several months, overall opinion is negative.
Where I'm absolutely sure a (Daly) BMS would not have stopped my accident, many disagree.

Its perhaps like a motor cycle.
All experienced drivers will tell you to first buy a good suit and helmet, and with the money that you have left buy a motor cycle.
they know this, as many of them did it the other way around.
buy motorcycle... ow yeah... need helmet..
Suit? maybe next month..
That becomes the next and next, till you do slip, and lose half of the skin on your leg.
Those people are the ones who now warn you to absolutely first buy that suit and helmet!

Some people (like me) need to fall first

I read the story about your accident. That's quite a nightmare. Glad your family and house are ok.
I did not make my own battery. I got (barely) used BWW i3 Li Ion batteries that are built like a tank, high quality Samsung batteries in a thick aluminium enclosure. I guess they have to be like that for EVs. So I hope from that perspective I made a good choice.
Right now, after the DALY died I am running without a BMS. My Phocos hybrid inverter is doing a great job keeping the voltage limits. However, I do want to add a BMS soon as a safety net (that's all a BMS is for). The idea of using contactor+BMS is intriguing but I have not read much about how to do this. There is a Coursera class suggesting that you actually need three contactors. This may be a rock solid solution but is getting very complicated and expensive, and perhaps requires experience to avoid mistakes (that could ruin the inverter and/or battery?!).