Skybox with backup questions, bms and battery & settings questions, + pic of my new bank!

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
I have a bank of 100ah ready to go, other than the BMS. have just a few questions. Not much experience using these batteries so I'm asking here first.

I got my bank from a local guy. He resells from his Chinese supplier. Tests and balances them before sending me the complete pack ready to use (minus bms)

1. is it safe to use without a bms until i get one? someone told me it was ok with lifepo4 with the skybox, but I kind of have some doubts. They won't get heavy use, mainly just in case backup is needed until I get my BMS installed. Then I may use to offset evening grid use.
2. what specific settings do I use on the skybox? it is not straight forward to me yet.. I guess I know I will choose "custom lithium" since they only have a few commercial versions in the menu.. I've pasted some of the other settings below in case anybody has experience with these.
3. is it ok to have a bank of 100ah and add another bank of 280's later on? If I parallel the two 48v banks will skybox just need to know it is a 380ah single bank?
4. I'm planning to use 2awg cables about 5' long or less. I think this is ok for either the 100ah or 280ah pack.
5. i plan to order an 80 amp and a 200 amp bms for the 100ah and 280ah. are these about right? (assuming I can mix the banks)

Charge Efficiency Factor Default: 98 %
Battery Installation Cost Default: 0
Absorb end amps per string Default: 10 A
Charge amps per string Default: 30 A
Discharge amps per string Default: 30 A
Number of strings Default: 1
Minimum SOC Default: 20 %
Maximum SOC Default: 100 %
Absorb Charge Default: Timed
Absorb Voltage Default: 55 V
Rebulk Voltage Default: 48 V
Max Absorb Time Default: 00:30 HRS:MIN
Low Battery Cut-Out Voltage LBCO Default: 50 V
High Battery Cut-Out Voltage HBCO Default: 58 V
LBCO Time Delay Default: 00:10 MIN:SEC
HBCO Time Delay Default: 00:10 MIN:SEC
Low Battery Restart Default: 51 V
High Battery Restart Default: 56 V


100ah_bank.jpg
 
Last edited:

newbostonconst

Solar Addict
Joined
Sep 24, 2019
Messages
661
The Skybox will start and stop charging depending on how it is set but will not stop one cell from getting to high of voltage and expanding….I wouldn't run without a BMS to shut the power off if one cell gets to high.

@Ampster has a skybox and might be able to answer questions. I have a Outback GS4048.
 

Ampster

Renewable Energy Hobbyist
Joined
May 3, 2020
Messages
4,645
Location
Kenwood, California
is it safe to use without a bms until i get one? someone told me it was ok with lifepo4 with the skybox, but I kind of have some doubts. They won't get heavy use, mainly just in case backup is needed until I get my BMS installed. Then I may use to offset evening grid use.
You are correct to have doubts unless you want to be the BMS 24/7 while using them. I use an Orion Jr BMS on my Skybox but I have 28kWh of batteries and am going to upgrade to 42kWh. A good BMS with a 100Ahr pack would be the Overkill Solar BMS. They now sell one for 48 volt packs. I have used their 12 volt version on some smaller packs for backup systems for relatives.

Once you get your BMS installed I can give you the correct settings for the Skybox. Those settings are too agressive. Have you top balanced the cells and wired the Skybox to your critical loads panel yet or installed solar yet?
 
Last edited:

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
You are correct to have doubts unless you want to be the BMS 24/7 while using them. I use an Orion Jr BMS on my Skybox but I have 28kWh of batteries and am going to upgrade to 42kWh. A good BMS with a 100Ahr pack would be the Overkill Solar BMS. They now sell one for 48 volt packs. I have used their 12 volt version on some smaller packs for backup systems for relatives.

Once you get your BMS installed I can give you the correct settings for the Skybox. Those settings are too agressive. Have you top balanced the cells and wired the Skybox to your critical loads panel yet or installed solar yet?
Ok. I'm sure thankful for you guys on these forums!

I had gone ahead and ordered a daly 80 amp for this pack. Of course after reading a bit more and a reply over on the other forum it seems I shouldn't mix the 100ah and the 280ah planned bank. So I'll likely be selling this whole 100ah bank bms and all after a couple months.

I still need a bms for the 280ah bank. I plan to have two of those at least and was going to order the 200 amp Daly version. but with the Skybox only able to pull like 115 amps do I even need the 200 amp BMS? I'm not that far along yet in my understanding.

Yes I have everything up and running great. Have even been net metering for a week now. But that may be short lived if my insurance agent doesn't step up and figure out how to add my PoCo onto my homeowners policy.

Everything is working great. Am pulling up to 5.4kw from my panels, producing 15-30 kwh/day.

Have not top balanced the cells. But the guy I bought them from said he did. He capacity tests and top balances all his cells before shipping. He even had this one packed nicely in the case and ready to connect up.
 

Ampster

Renewable Energy Hobbyist
Joined
May 3, 2020
Messages
4,645
Location
Kenwood, California
Okay. Sorry to be cryptic in my earlier post. I just realized we have been in a dialogue for a couple of months.
Here is my suggestion for conservative settings for your use as backup. Absorb voltage of 54 would keep the cells below 3.4 volts until you get a BMS. Then you can go back to 55 volts or more if your cells stay close. 55 volts for the pack is 3.43 volts per cell. That was the voltage when the deltas started increasing.
 

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
Okay. Sorry to be cryptic in my earlier post. I just realized we have been in a dialogue for a couple of months.
Here is my suggestion for conservative settings for your use as backup. Absorb voltage of 54 would keep the cells below 3.4 volts until you get a BMS. Then you can go back to 55 volts or more if your cells stay close. 55 volts for the pack is 3.43 volts per cell. That was the voltage when the deltas started increasing.
No worries.

I actually got the bms yesterday and started connecting it. The instructions are probably from google translate so they are a bit hard to follow if you've never done it. But I think I got the idea. I think after connecting all the sensors in the right order, connect B- to the 48v battery negative (total negative in my instruction sheet), and the P- connects to the skybox battery negative in the BOS box. I will look on YT and on here to try to figure all this out as well but I know you have done all this and could do it in your sleep ;)

And just to be sure, the second wire (first red) goes to the last cell where the "total" positive terminal is? and the first (black) wire goes to the "total" negative. Then you start from the 3rd wire (red) and connect it to the + terminal on the very first cell (the one with the total negative) and go from there until all + terminals have a sensor. And they say its very important not to get the wires in the wrong order.

I did a quick test as they mention in the instructions, checking each battery voltage and they were all still 3.32, total voltage was still 53.2 I think. so no shorts on any connections or wires. I plugged in the sensor harness to the bms and had 53.2 volts from + battery to B- on the BMS before it was even connected to battery neg. I guess that's normal. I didn't connect the B- to the battery yet, I wanted to read up and watch a couple YT vids to make sure I did everything right before turning anything on.

So I'll start with the 55 volts setting. I think the cells are all sitting at 3.32 or 3.33v right now. My meter is old and cheap so who knows if it is even accurate to .01 volts. And then once I figure out the BMS BT I'll be able to see the individual battery voltages I think.

As far as the other Skybox settings, are they ok as default?

Thanks!IMG_E1915.JPG
 

Ampster

Renewable Energy Hobbyist
Joined
May 3, 2020
Messages
4,645
Location
Kenwood, California
I don't know your BMS but usually the small black BMS wire goes to cell #1negative and first red to cell #1 positive. Cell #1 is the only one with two wires.The so on positive of each sucessive cell until last wire on #16 positive. Note the bus bars will be between negative and positive and it doesn't matter which terminal the BMS wire is attached to but I like to use the positive for simplicity to check wiring. Your voltage sounds correct.

I would change the following:
Rebulk Voltage Default: 48 V Change this to 50 volts. This is the voltage where the inverter will recharge the pack.

High Battery Cut-Out Voltage HBCO Default: 58 V. I would lower this to to 57 volts. 58 volts is 3.625 v per cell. You want the inverter to stop charging first not the BMS. The lower setting is 3.56 per cell and probably 99% full. Things happen fast at that voltage and this gives you cushion.
 
Last edited:

ereams65

Solar Addict
Joined
Feb 10, 2021
Messages
293
Yes, on the Daly BMS, the First red wire goes on the Positive of the cell where you put the only Black wire (main pack Negative), and it's in succession until the last red wire will be on the Main Positive.
 

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
Maybe that is how I did it, I can't remember and my pic has the plug covered up. I will have to read the instructions again. I thought I read that the first red wire goes to the "total" positive terminal, which I took to mean the 48v (54v) output terminal.
 

ereams65

Solar Addict
Joined
Feb 10, 2021
Messages
293
Nope. First red wire goes to the positive side of the main negative cell. LIke mentioned above, it's the only cell that actually gets two wires; positive and negative
 

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
Nope. First red wire goes to the positive side of the main negative cell. LIke mentioned above, it's the only cell that actually gets two wires; positive and negative
Ok, so I found another instruction sheet online. It is written different that the little scrap of paper they sent with my BMS. It is more clear that the first red thin wire goes onto the B1+ terminal. My instructions were not written that way if I am remembering correctly. It said to connect the first red wire to the total + of the pack. I will verify that tonight, I could have read it wrong.

But are we 100% sure all the Daly BMS are the same wiring order? Mine is the smart 48v 16s 80 amp..

And what is the light board they are talking about in the instructions?

Does anybody know of a good YT video of installing and setting up one of these? I can't really find a good one yet.

Thanks!
 

Ampster

Renewable Energy Hobbyist
Joined
May 3, 2020
Messages
4,645
Location
Kenwood, California
I looked at the picture and can see that the BMS black sensor wire is on cell #1 negative. Since the B- wire is not connected yet it is an important precaution to pull the connector from the BMS before connecting it to terminal. I don't know about the Daly but many BMSs suggest unplugging sense connector before disconnecting or rearranging any sense wires. This is to prevent abnormal voltages on sense wires. To connect the B- lead you would have to lift off the small black wire, even for just a moment.
 

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
I looked at the picture and can see that the BMS black sensor wire is on cell #1 negative. Since the B- wire is not connected yet it is an important precaution to pull the connector from the BMS before connecting it to terminal. I don't know about the Daly but many BMSs suggest unplugging sense connector before disconnecting or rearranging any sense wires. This is to prevent abnormal voltages on sense wires. To connect the B- lead you would have to lift off the small black wire, even for just a moment.
Yeah, I didn't connect my plug to the BMS yet. I've only so far wired the individual sensor wires to the terminals. I think the instructions did say to not connect the plug while connecting sensor wires. But that's a good point to make sure I keep it unplugged while putting the B- on because that sensor wire will come loose.

Thanks!
 

Dforster67

Solar Enthusiast
Joined
Feb 2, 2021
Messages
57
. I just realized there is a separate place for bms discussion. I may start one there since this is more of a bms question at this point.

I did get mine connected. The only thing that concerns me is the voltage out of the p- is only showing 49.1 and the voltage of the pack is 53.something. Is that normal? Seems like it should be the same.

Also, how do I connect to Bluetooth to see the batteries?
 
Top