Will My New System Work? You Tell Me!

[Nova22]

Complete Noob here who did some homework but looking for an expert to confirm my system will work before dropping the cash.

-4 x 275w Solar Panels

-Solar Inverter 24V DC to 230Vac, 24 V MPPT 3.2KW 24V Hybrid 80A.

-8 LifePo4 batteries 3.2 105A (series or parallel?)

-Not sure on the BMS needed, any suggestions?

I'm looking to add batteries in the future as well if this system will allow ( all I can afford for now) but simply just want to run a small cabin off grid.

Thanks for any feedback

 

[Dzl]

-4 x 275w Solar Panels

If you look on your solar panels spec sheet, you should see two figures "Open Circuit Voltage (Voc)" and "Short Circuit Current (Isc)" Post those numbers here and we can make sure everything is well matched, but based on the size of your controller, it almost certainly is.

-8 LifePo4 batteries 3.2 105A (series or parallel?)

Series is your only option for 24v with 8 cells

-Not sure on the BMS needed, any suggestions?

Spend some time browsing the BMS subforum, lots of info there, and many people who have asked similar questions there and in the beginners forum. If your needs are simple and you don't need low temp disconnect the Daly BMS is a good basic BMS, this is a good option for beginners, as close to plug and play as you can get. But there is no one perfect BMS, you will find differing opinions and that a lot comes down to what your needs are.[/QUOTE][/QUOTE]

 

[Nova22]

If you look on your solar panels spec sheet, you should see two figures "Open Circuit Voltage (Voc)" and "Short Circuit Current (Isc)" Post those numbers here and we can make sure everything is well matched, but based on the size of your controller, it almost certainly is.

First off you rock Dzl for helping out. It says Voc is 38.5 and lsc is 9.20A

Series is your only option for 24v with 8 cells

That what I figured, when I upgrade the batteries would that mean I build another set of 8 cells in series and then run the 2 sets in parallel to the controller?

Spend some time browsing the BMS subforum, lots of info there, and many people who have asked similar questions there and in the beginners forum. If your needs are simple and you don't need low temp disconnect the Daly BMS is a good basic BMS, this is a good option for beginners, as close to plug and play as you can get. But there is no one perfect BMS, you will find differing opinions and that a lot comes down to what your needs are.

[/QUOTE]
[/QUOTE]

So I browsed around on the forum with some good info but one of my concerns is heat not cold as I'm in the Philippines. That being said harder to find things, I could not find a Daly BMS I could order but found this no name. Would the one in the image work I sent you, my concern is the 100A does not match the 80A controller. Does that make a difference?

 

[Nova22]

[/QUOTE]

So I browsed around on the forum with some good info but one of my concerns is heat not cold as I'm in the Philippines. That being said harder to find things, I could not find a Daly BMS I could order but found this no name. Would the one in the image work I sent you, my concern is the 100A does not match the 80A controller. Does that make a difference?
[/QUOTE]

 

[JoseAgustinV]

Hi @Nova22 for bms check this page these are the ones they recommend, the one you listed come with very thin cables wich is not recommended, i suggest you to go for the ones they recommend as bms seems to fail a lot if they are bad quality.

Also, i wish to know if low temp cut off is mandatory for a non cold climate, there is no winter where i live and i want to know if i really need low temp cut off

 

[Forbisher]

Also, i wish to know if low temp cut off is mandatory for a non cold climate, there is no winter where i live and i want to know if i really need low temp cut off

Nah, if your LFP battery will never be in cold temps you do not need a low temp cut off.

 

[John Frum]

Nah, if your LFP battery will never be in cold temps you do not need a low temp cut off.

LFP is fine unless you try to charge them below zero Celsius.

 

[Dzl]

Also, i wish to know if low temp cut off is mandatory for a non cold climate, there is no winter where i live and i want to know if i really need low temp cut off

If you will never see 0*C / 32*F you don't need to worry about it.

So I browsed around on the forum with some good info but one of my concerns is heat not cold as I'm in the Philippines.

As far as I know there is really nothing a BMS can do about high ambient temperatures. But you are right to be concerned with keeping your batteries cool. The batteries are happy at about the same temperatures that you are comfortable, maybe a bit cooler. Do what you can to keep them under 30*C / 86*F, but this isn't really a 'hard limit'

That being said harder to find things, I could not find a Daly BMS I could order but found this no name.

The Daly is made in china and sold through Aliexpress, etc, I would think there is a decent chance it could be shipped to the Phillipines but idk. As for the BMS you found, I really don't have enough experience/expertise to give any useful input, other than that personally I would try to find a BMS that others have some experience with.

my concern is the 100A does not match the 80A controller. Does that make a difference?

That's fine. Actually that's good. Your BMS should be sized for the highest current (amps) that will flow through it, plus some safety margin. So the mismatch is no problem so long as the BMS is the one with the greater current rating. With a no-name, or cheap BMS like the Daly, you want to 'de-rate' it a little bit, not push it to its limit.

 

[Nova22]

If you will never see 0*C / 32*F you don't need to worry about it.



As far as I know there is really nothing a BMS can do about high ambient temperatures. But you are right to be concerned with keeping your batteries cool. The batteries are happy at about the same temperatures that you are comfortable, maybe a bit cooler. Do what you can to keep them under 30*C / 86*F, but this isn't really a 'hard limit'



The Daly is made in china and sold through Aliexpress, etc, I would think there is a decent chance it could be shipped to the Phillipines but idk. As for the BMS you found, I really don't have enough experience/expertise to give any useful input, other than that personally I would try to find a BMS that others have some experience with.



That's fine. Actually that's good. Your BMS should be sized for the highest current (amps) that will flow through it, plus some safety margin. So the mismatch is no problem so long as the BMS is the one with the greater current rating. With a no-name, or cheap BMS like the Daly, you want to 'de-rate' it a little bit, not push it to its limit.

Cheers again, I'm getting close to picking my BMS thanks for everyones help. I never used a forum before and amazed how helpful people are.

I'm split between 90ah lifepo4 8s3p. or 105ah 8s2p. I'm not sure how to calculate the max storage for my controller, can it handle more or is this about right?

I did find a DALY on AliExpress. Just confused by 2 things still. https://bit.ly/3bjobCi
1. Do I only need ONE BMS (24v 8s 100A DALY) for 8s2p, 8s3p or do I need one BMS for each parallel?
2. Maybe a stupid question but whats the difference between common and separate port?

 

[Dzl]

1. Do I only need ONE BMS (24v 8s 100A DALY) for 8s2p, 8s3p or do I need one BMS for each parallel?

You will need one BMS per 8S 'pack'. So if you have 8S3P you would need 3 BMS', but if you configured them in 3P8S you would need only one BMS for all 24 cells. There are pros and cons to each approach.
More info here

2. Maybe a stupid question but whats the difference between common and separate port?

Separate port allows cutting off only charging, or only discharging. Common port means both charging and discharging will be cutoff together. Because you have an All-in-one inverter/charger, common port would make the most sense for your situation.
More info in this thread

 

[JoseAgustinV]

I did find a DALY on AliExpress. Just confused by 2 things still. https://bit.ly/3bjobCi
1. Do I only need ONE BMS (24v 8s 100A DALY) for 8s2p, 8s3p or do I need one BMS for each parallel?
2. Maybe a stupid question but whats the difference between common and separate port?

1) a 24V battery is made from 8 cells in series, you need one 24V 8s 100A for it, if you have multiple 24V batteries to connect them in parallel i think you will need one bms for each one, im not 100% sure though.

2) This is answered on this thread.

 

[Nova22]

You will need one BMS per 8S 'pack'. So if you have 8S3P you would need 3 BMS', but if you configured them in 3P8S you would need only one BMS for all 24 cells. There are pros and cons to each approach.
More info here



Separate port allows cutting off only charging, or only discharging. Common port means both charging and discharging will be cutoff together. Because you have an All-in-one inverter/charger, common port would make the most sense for your situation.
More info in this thread

Cool, do you have a link for beginners to figure out the max amount of batteries for a controller?

 

[Dzl]

Cool, do you have a link for beginners to figure out the max amount of batteries for a controller?

Can you explain specifically what you mean by 'max amount of batteries' for a controller?

Start here maybe:

 

[Nova22]

Can you explain specifically what you mean by 'max amount of batteries' for a controller?

Start here maybe:

Thanks for the link, I really enjoy Will. The little knowledge I do have is thanks to him. It's slowly sinking in.
Sorry for the confusion, I guess what I'm curious about is can I continue adding 8s batteries to my parallels, example 8s10p? Is there max storage for a specific controller or I can grow my 24v battery arrays as long as it's running on a 24v controller.

 

[Dzl]

Thanks for the link, I really enjoy Will. The little knowledge I do have is thanks to him. It's slowly sinking in.
Sorry for the confusion, I guess what I'm curious about is can I continue adding 8s batteries to my parallels, example 8s10p? Is there max storage for a specific controller or I can grow my 24v battery arrays as long as it's running on a 24v controller.

Hmm, I suppose there are a couple ways you could look at it.

On a theoretical level, I'm not sure.

On a practical level, it makes sense in most cases for your battery and your charge controller + PV array to be sized somewhat proportionally. A 1000Ah battery bank, isn't really that useful in most cases if your PV array can only replenish 10% of its capacity. So as a practical matter, I suppose there is a soft limit to how much you would want to expand your battery bank. I'm not sure if there are other technical limits you would reach.

But back to your actual question, you could have multiple 8S packs being charged by a single charge controller (or vice versa for that matter).

Am I understanding your line of thinking correctly?

 

[Nova22]

You will need one BMS per 8S 'pack'. So if you have 8S3P you would need 3 BMS', but if you configured them in 3P8S you would need only one BMS for all 24 cells. There are pros and cons to each approach.
More info here



Separate port allows cutting off only charging, or only discharging. Common port means both charging and discharging will be cutoff together. Because you have an All-in-one inverter/charger, common port would make the most sense for your situation.
More info in this thread

Hi Again,

Thanks to everyone's help here on the forum I'm going to be placing my order this week. I'll be sure to post some pics when I have it all set up, I'm very excited and nervous. It's a lot of money for me and super scared I F$*& it up. I decided to go with a different controller from Sako,it looks better, has a better price point and meets all my parameters.

As for the batteries because I'm paying the same price for the shipping I'm going to include an additional 8 batteries. I looked at the info you guys shared on the BMS and still one thing I would like to clarify. Now that I have a total of 32 batteries at 3.2 105ah, I know I can run them either 4p8s with one BMS or 8s4p with four BMS. My question then is is it possible to run 2p8s with one BMS and parallel that with 2p8s with one BMS? Or does this not make any sense at all.
My reasoning is not wanting to buy 4 BMS but also not only have one running all 4 parallel.

Here's the controller I chose, I will be sure to let you guys know about it's performance.
3000W Solar Inverter - Max PV Input 4000W Has WIFI Function 80A= $367 with delivery