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Dyness B4850 charge settings


Tsa
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Anyone know the correct\best settings for the Dyness B4850 2.4kwh batteries for Bulk and Float voltages?

I see a lot of data on the Pylons, but havent seen a spec sheet detailing these 2 settings yet. OR just not looking where I should.  TIA

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Agreed, interesting though is that when you set the Batt Type to Lithium on Growatt inverter and select L01 profile it then sets Bulk & Float to 54V. I was informed by Growatt that L01 is the profile for Dyness and L02 we know is for Pylontech from what others have posted on the forum.  

However when you do this method you are actually making use of that expensive BMS one paid for with the battery and would hope that it is the better option. 

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6 hours ago, Tsa said:

Agreed, interesting though is that when you set the Batt Type to Lithium on Growatt inverter and select L01 profile it then sets Bulk & Float to 54V. I was informed by Growatt that L01 is the profile for Dyness and L02 we know is for Pylontech from what others have posted on the forum.  

However when you do this method you are actually making use of that expensive BMS one paid for with the battery and would hope that it is the better option. 

Never tried it.

We just set it as USE = 52V

Perhaps I must run it with L01 for a bit and see the effect.

Make sure the BMS is actually working.

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  • 4 weeks later...

Quick one for the technical guys. Based on the below specs...

image.png.fa9782b4c540e6167e6e70fffc8273d8.png

 

Ignoring losses and other technicalities for this example.

One would be able to discharge this battery at 2,4kw for one hour. 1,2kw for 2 hours, etc etc.

1) Is it more damaging to the battery to discharge at 2.4kw vs 1.2kw vs 0.6kw? Sure BMS will have some sort of protection in place if discharge current is too much, but thinking more in terms of prolonging battery life\health. 

2) Is there any benefit in only discharging Lithiums to 20% vs discharging to 10% (what about 5%?) ?

How does the above change when you have say 3 of these in parallel? 

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On 2020/03/23 at 5:16 PM, Tsa said:

1) Is it more damaging to the battery to discharge at 2.4kw vs 1.2kw vs 0.6kw? Sure BMS will have some sort of protection in place if discharge current is too much, but thinking more in terms of prolonging battery life\health. 

It's hard to say. It says you can discharge at 2.4 kW, but what factor of safety have they included in this figure? It's always better for battery life to discharge a battery more slowly (lower power). The practical question is, at what point does the battery life benefit outweigh the hassle of lower discharge power?

These cells are presumably designed for energy, not power. Generally, these seem to get around the 1C rating, as these do. So I'd say 2.4 kW is a practical figure.

Quote

2) Is there any benefit in only discharging Lithiums to 20% vs discharging to 10% (what about 5%?) ?

I believe so. 80% DOD seems to be the accepted figure. Occasional excursions to 10% SOC or even more rarely to 5% SOC should be relatively safe.

Quote

How does the above change when you have say 3 of these in parallel? 

All the power figures treble, i.e. 7.2 kW should be safe. The SOC figures stay the same: stick to 80% DOD or less most of the time.

Edited by Coulomb
Added "SOC" twice to clarify
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Thanks @Coulomb, appreciate the replies.

3 hours ago, Coulomb said:

I believe so. 80% DOD seems to be the accepted figure. Occasional excursions to 10% or even more rarely to 5% should be relatively safe.

I have set my back to grid at 15% and low power cut off @ 10%.  I have not seen the 15% yet, so far worst has been 19%.

3 hours ago, Coulomb said:

All the power figures treble, i.e. 7.2 kW should be safe. The SOC figures stay the same: stick to 80% DOD or less most of the time.

Understood, was more referring to it now being able to technically handle 7.2kw for 1 hour, but now the 2.4kw doesn't draw doesn't sound that bad vs just having 1 battery at 2.4kwh.

I also found the following data regarding these batteries which gives some more detailed info and basically confirms what you have also said. 

 

image.png.8b6d27b778285b2b00ce694e92189d7a.png

My only reason for asking all of these questions was to be able to answer the question you also asked, getting the balance between battery life and discharge power. 

If it will extend my battery life considerably I would rather set my back to grid @ 20% instead of 15% for instance. 

Also to try and make a plan to be sure the load isn't more than 2.4kw at any point when on batteries. This is a bit difficult as I have seen that the batteries get charged to 99/100% and then PV is disconnected automatically and load is covered by the batteries only, until it gets to 95% again where PV kicks in again and starts the charging up to 99/100%.

Edited by Tsa
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  • 4 weeks later...

Further to the above. Some clarity please.

If nominal discharge is 25A (0.5C), and you have 3 batteries in parallel, is nominal discharge then 75A total?  50A if it was 2 batteries in parallel? OR will nominal remain 25A no matter how many batteries you have in the pack as that is the characteristics of the cells?  

Basically I'm just worried about driving my battery bank too hard. 3x of the above batteries in parallel but sometimes do see a load on batteries of around 2kw which is above 25A (nominal discharge) for 1 battery. 

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19 hours ago, Coulomb said:

Yes. Battery modules in parallel means the current limits add.

Thanks for the confirmation. So then even 2.4kw draw (max power for 1 battery as per spec) would not be an issue on a 3 battery stack.

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  • 2 weeks later...

When running from batteries, would it be normal for the lights to flick for a millisecond when a microwave starts(1kw) or the fridge motor kicks in(1A)?

Don't see it happening when on grid power, only on batteries. Overall load at that stage is 200W - 400W max prior to appliance coming on. 

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4 hours ago, Tsa said:

When running from batteries, would it be normal for the lights to flick for a millisecond when a microwave starts(1kw) or the fridge motor kicks in(1A)?

Don't see it happening when on grid power, only on batteries.

Yes, it's normal. Some lights are more susceptible to flicker than others, and some humans are more annoyed about it than others. A bigger, newer battery will probably cause less flicker.

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  • 8 months later...
  • 8 months later...
22 hours ago, master chan said:

dyness lithium  battery  and what it doing when i set it at pylon , give me 61 flashing

According to this post, Dyness use the same CAN bus protocol as the Pylontechs. But Pylontechs also have RS-485 protocol, and RCT/Mecer/Kodak/Axpert inverters use RS-485 protocol when talking to the Pylontech BMS.

It's possible that Dyness didn't also copy the RS-485 protocol, or perhaps you are using a cable designed to talk to a BMS via CAN bus. Where did your cable come from? Do you know its pinout?

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