I have yet to build a DIY lithium battery, but have read enough that I feel confident to try it. But as for those 87 parameters, I don't know anything about. I'm sure if you post a new thread under the DIY battery subforum, you'd get some specific help on those.
Not sure how your BMS is setup, but why do you think the BMS should have shut down or sounded an alarm? 97% is not fully charged and most BMS's will not turn off the Charging MOSFET until at least one of the cells reaches 3.65V. Now even if you have set your target voltage of say 3.5V (14.0V for a 12v system, 56.0V for a 48V system ), the BMS will not shut down (aka "turn off Charging MOSFET" aka "charging protection") once it reaches that voltage. This is a good thing and what many of us aim for!! The charging protection feature of the BMS is ideally only triggered as a final fail-safe measure to protect the individual cells inside your lithium battery. Ideally, you don't want charging protection to be getting triggered every single day, because the MOSFET has a limited number of uses before it no longer works (how many? I have no idea, but probably hundreds at least.)
Yep, you got it, that's the goal here.
Thanks for that graph, that helps. I can see that the charging amps are about 8A around 7:45 and 15:45. This appears to be due to the nature of the sun rising and falling. Is this when you saw the 8A? If not, what other time(s) on this day did you see 8A and for long did you see that?
Also, what is the target voltage you have programmed in your charge controller? I see you have a 60A Renogy controller...this setting is labeled as "boost voltage" on the Renogys.
The DIY pack was easy to build. A friend and I built it in one night. The hardest part was trusting enough to send the money to China. I am very happy with the batteries and the case. Now to figure out all those parameters!
Not sure how your BMS is setup, but why do you think the BMS should have shut down or sounded an alarm? 97% is not fully charged and most BMS's will not turn off the Charging MOSFET until at least one of the cells reaches 3.65V.
I thought that the BMS came from the factory set to either 15 to 95% or 10 to 90%. That is why I am surprised it didn't trip at 97%. I turned off the solar breakers to protect the batteries.
Thanks for that graph, that helps. I can see that the charging amps are about 8A around 7:45 and 15:45. This appears to be due to the nature of the sun rising and falling. Is this when you saw the 8A? If not, what other time(s) on this day did you see 8A and for long did you see that?
This isn't the graph from the 8 amp day, but it shows the same thing. The graph from that day had a glitch in it. I wrote the software that makes that graph. It runs on an Arduino and the bugs are not all worked out yet. The low amperage I was talking about was when the renogy went into float mode, not when the sun went down. The lost power happened between 12:00 to 2:30 PM. In the graph, the float amps is 18, but it is much less than the possible charging current. Notice when I tweaked the settings, the current came back up. I changed the boost voltage to 14.4 instead of 14 at around 2;30.
Maybe I just need to be patient with this.
"Are Boost and Float both constant voltage settings, with the setting for the boost higher than the float? Is that the only difference between them?"
Yes Boost (often called Absorb) and Float are both Constant Volt charge setting with Boost occurring first and after the Boost Charge Time is complete Float begins.
The Sequence is:
MPPT (also called Bulk) Constant Current Charging. In MPPT charge mode until Boost voltage reached.
Boost (also called Absorb) Constant Voltage Charging. In Boost charge mode until Boost Charge Time has elapsed.
Float Constant Voltage (Not really charging Battery, but holding battery at near full charge voltage while supplying loads power)
"Thank you for all the posts about how to set this up. They helped a lot. I took my settings from them. I thought I had them exactly, but when I double checked, I had a couple of them wrong. Your controller seems to have a couple of settings that mine doesn't have. These are the settings I am trying today."
A few questions to help me help you:
Is your Solar Charge Controller (SCC) the Renogy Rover 60 amp?
How is the Renogy SCC programmed? Using front panel or Blue Tooth (BT) module and App on phone?
Is the Battery 48 volt made from 16 304AH cells?
What BMS is connected to the Battery?
In general the settings look like a good place to start.
The charge controller is the Renogy 60 amp PG (Positive Ground). It is programmed from the front panel. I don't have the Bluetooth adapter. The battery is 16 304 amp cells in the Apexium box with the Apex 48200 BMS. It is connected to a computer through RS485. There are breakers between the battery and the charge controller and the battery and the inverter. The inverter is a Schneider 4048.
I designed a relay system that switches between utility power and solar power. It is controlled by an Arduino that reads the battery voltage and opens and closes the relay. Now it is set that if the battery voltage falls below 49 it switches to utility power and if the voltage rises above 50 volts it switches back to solar power.
The inverter is programmed to shut off if the voltage drops below 48. It will then draw about 1.5 amps from the batteries.
It was too overcast to do any testing today.
"Are Boost and Float both constant voltage settings, with the setting for the boost higher than the float? Is that the only difference between them?"
Yes Boost (often called Absorb) and Float are both Constant Volt charge setting with Boost occurring first and after the Boost Charge Time is complete Float begins.
The Sequence is:
MPPT (also called Bulk) Constant Current Charging. In MPPT charge mode until Boost voltage reached.
Boost (also called Absorb) Constant Voltage Charging. In Boost charge mode until Boost Charge Time has elapsed.
Float Constant Voltage (Not really charging Battery, but holding battery at near full charge voltage while supplying loads power)
"Thank you for all the posts about how to set this up. They helped a lot. I took my settings from them. I thought I had them exactly, but when I double checked, I had a couple of them wrong. Your controller seems to have a couple of settings that mine doesn't have. These are the settings I am trying today."
A few questions to help me help you:
Is your Solar Charge Controller (SCC) the Renogy Rover 60 amp?
How is the Renogy SCC programmed? Using front panel or Blue Tooth (BT) module and App on phone?
Is the Battery 48 volt made from 16 304AH cells?
What BMS is connected to the Battery?
In general the settings look like a good place to start.
"Are Boost and Float both constant voltage settings, with the setting for the boost higher than the float? Is that the only difference between them?"
Yes Boost (often called Absorb) and Float are both Constant Volt charge setting with Boost occurring first and after the Boost Charge Time is complete Float begins.
The Sequence is:
MPPT (also called Bulk) Constant Current Charging. In MPPT charge mode until Boost voltage reached.
Boost (also called Absorb) Constant Voltage Charging. In Boost charge mode until Boost Charge Time has elapsed.
Float Constant Voltage (Not really charging Battery, but holding battery at near full charge voltage while supplying loads power)
"Thank you for all the posts about how to set this up. They helped a lot. I took my settings from them. I thought I had them exactly, but when I double checked, I had a couple of them wrong. Your controller seems to have a couple of settings that mine doesn't have. These are the settings I am trying today."
A few questions to help me help you:
Is your Solar Charge Controller (SCC) the Renogy Rover 60 amp?
How is the Renogy SCC programmed? Using front panel or Blue Tooth (BT) module and App on phone?
Is the Battery 48 volt made from 16 304AH cells?
What BMS is connected to the Battery?
In general the settings look like a good place to start.
The charge controller is the Renogy 60 amp PG (Positive Ground). It is programmed from the front panel. I don't have the Bluetooth adapter. The battery is 16 304 amp cells in the Apexium box with the Apex 48200 BMS. It is connected to a computer through RS485. There are breakers between the battery and the charge controller and the battery and the inverter. The inverter is a Schneider 4048.
I designed a relay system that switches between utility power and solar power. It is controlled by an Arduino that reads the battery voltage and opens and closes the relay. Now it is set that if the battery voltage falls below 49 it switches to utility power and if the voltage rises above 50 volts it switches back to solar power.
The inverter is programmed to shut off if the voltage drops below 48. It will then draw about 1.5 amps from the batteries.
It was too overcast to do any testing today.
