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Victron SmartSolar Charge Controller MPPT 100/50 absorption time question

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Victron SmartSolar Charge Controller MPPT 100/50 absorption time question​

My post ask a question about absorb duration setting, asking why the device did not provide the absorb duration as set.

I never ask for help with BB Battery charging set points.

Your comments and direction are not within the scope of this thread. Post them somewhere elese please.

I have great respect for EE's. Unfortunately you may be the exception.
I am also an EE and what bruceb58 makes a lot of sense. For some reason you fail to see the obvious! Set the absorption time up to 30 minutes and see what happens.

I won't get into the 14.4V absorb comment you mentioned earlier since that seems to make you upset for some strange reason.
 
Set it for 30 minutes and see what you get! It's what you need to set it for anyway. There...does that answer your question? BTW..it's what I have said in at least 4 posts.
When I rebooted the SCC by momentarily isolating it from solar (simulating solar cycle) and battery, with no change to the 5 minute absorb time setting, the device initiated a CC boost/CV absorb/CV float cycle. The 5 minute absorb time happened as set, there was no need to change this setting. I posted this info with volt/current curves above. (post #4). I had no need to change the 5m absorb duration for this test.
 
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When I rebooted the SCC by momentarrily isolating from solar (simulating solar cycle) and battery, with no change to the 5 minute absorb time setting, the device initiated a CC boost/absorb/float cycle. The 5 minute absorb time happened as set, there was no need to change this setting. I posted this info with volt/current curves above. (post #4). I had no need to change the 5m absorb duration for this test.
So set it at 30 minutes and see what happens!

What other information are you looking for at this point?
 
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So set it at 30 minutes and see what happens!

What other information are you looking for at this point?
I have no need to set it at 30 minutes.
I am not looking for any other info from you or bruceb58 at this point.
Thank You.
 
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Went out and played with the SCC again today. Added an Auto Equalize charge that is schedued for once very 14 days. Voltage set at 14.2v, max duration set at 45 minutes, max current set at 5 amps. This will complete a good top balance on my three parrallel wired 100AH 12V cylindrical cell LifePO2 batteries bi-weekly. I am not using this feature to Equalize a LiFePO4 cell battery, but to top balance the four cell packs in each battery.

Equalization only happens after a Bulk and Absorb charge is complete. The SCC has to be in Bulk or Absorb when you start a Manual Equalize cycle.

It appears that there is only one Absorb charge allower (for the set absorb duration) per solar cycle (day). The SCC starts a new charge cycle when the sun comes up each day. This is how the victron 100/50 SmartSolar SCC I have seems to work. Anyone else have this experience or a different one ?


I initiated a Manual Equalize Start Now cycle and observed the Battery Input Voltage and Current. Manual Equalize has a duration of one hour, there is no changing that duration (but you can manually stop the manual equalize charge at any point). It all seemed to work as itemized in the Victron SmartSolar charge controller manual and Victron Connect - MPPT Solar Charge Controllers Guide.

I have just moved away from a Renogy DCC50S SCC with DC-DC charger, I am much happier with this Victron SCC. Using a Sterling DCtoDC charger now also.
 
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You are very confused. Setting a higher absorb voltage does not charge your battery faster. By the time you get to the absorb voltage, your batteries are basically charged. Basically, you are in bulk until you hit the absorb voltage and then you are in constant voltage mode. The absorb voltage just sets the voltage where the controller switches from bulk)constant current) to absorb(constant voltage).

14.1V is not high enough for top balancing to occur. All the videos you and I just posted said this!
Sorry, little off topic.

You say that by the time you are in absorb, the batteries should be charged, I agree. Can you tell me where you have set in the setting of the MPPT the "bulk" "charge" or however you like to call it, voltage?

In the settings there are only:

Absorb,float and eq. How does the SCC know at what voltage to charge, 14.4 let's say for most lithium's? I read on victron forum that absorb = bulk, but that just doesn't make sense!
 
Sorry, little off topic.

You say that by the time you are in absorb, the batteries should be charged, I agree. Can you tell me where you have set in the setting of the MPPT the "bulk" "charge" or however you like to call it, voltage?

In the settings there are only:

Absorb,float and eq. How does the SCC know at what voltage to charge, 14.4 let's say for most lithium's? I read on victron forum that absorb = bulk, but that just doesn't make sense!
There is no such thing as a bulk voltage. I have my absorb voltage set at 14.4V for my Battleborn.

Bulk is a constant current mode so basically you get the max current that the controller can put out until the absorb voltage is reached and then it switches to constant voltage at the absorb voltage.
 
Sorry, little off topic.

...........................

In the settings there are only:

Absorb,float and eq. How does the SCC know at what voltage to charge, 14.4 let's say for most lithium's? I read on victron forum that absorb = bulk, but that just doesn't make sense!
You are right, there are only three voltage settings for the MPPT SCC:
Absorb
Float
Equalize.

There are four charging modes:
Bulk
Absorb
Float
Equalize.

BULK charging is constant current charging.
In reality with a Solar Charge Controller, Bulk charging is the Max constant current charge available from the Solar Panels that is within the rated current of the SCC. SO if your SCC has a current output rating of 30A, that would be a 30A constant current charge (or max solar amps available less than or equal to 30A depending on solar panel sun conditions. Clouds, shadows can distract from max solar output, resulting in less than rated current output).
The SCC output voltage is monitored, and when the voltage is equal to the Absorb voltage, the charger goes into the Constant Voltage mode at the Absorb voltage set point.

ABSORB charging is constant voltage charging.
In reality with a Solar Charge Controller, the SCC maintains the set Absorb voltage. Absorb charging current is max current the battery/load will accept at the set Absorb voltage that is within the current rating of the SCC. Clouds, shadows can distract from max solar output, resulting in less than rated current output or loss of absorb voltage.
Absorb charging is terminated if the Solar Panels/SCC cannot maintain the absorb voltage set point, or in some cases if the battery attains a set SOC value, the charging current reduces to below a set current level or after a set absorb time.

FLOAT charging is constant voltage charging.
In reality the SCC targets a constant Float voltage, the battery drops from Absorb voltage set point to the Float voltage set point by supplying power to parasitic loads, small loads or battery cell voltage normalization.
Once the battery has reached the Float voltage, the Solar Panels/SCC maintain the float voltage until the load on the battery exceeds the power available from the Solar Panels/SCC causing the battery voltage to drop below a set point voltage variance below the Float voltage. Clouds, shadows can distract from max solar output, resulting in less than demanded power output and loss of Float charging.

At that point the SCC initiates a new Bulk charge. Once the Battery voltage has attained the Absorb voltage set point, the SCC goes back to the Float voltage set point.
The Victron SCC I have only allows the Absorb Voltage for any Solar cycle (solar day) to be in the absorb mode for a total time equal to the absorb time setpoint for any solar cycle (I do not use SOC or charging current set points to terminate the battery absorb charge).

Equalize charging is constant voltage charging.
Battery chemistry can demand equalize charging to extend the life of some batteries.
An Equalize charge for Lead Acid batteries is an occasional overcharging of the battery beyond 100% SOC to desulfate the lead plates and stur the electrolyte up a little. This produces Hydrogen that is vented from the battery. The electrolyte level drops, and the batteries have to be topped off with more water occasionally. Lead acid storage batteries have an equalize voltage and routine specified by their manufacturer.
 
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You are right, there are only three voltage settings for the MPPT SCC:
Absorb
Float
Equalize.

There are four charging modes:
Bulk
Absorb
Float
Equalize.

BULK charging is constant current charging.
In reality with a Solar Charge Controller, Bulk charging is the Max constant current charge available from the Solar Panels that is within the rated current of the SCC. SO if your SCC has a current output rating of 30A, that would be a 30A constant current charge (or max solar amps available less than or equal to 30A depending on solar panel sun conditions. Clouds, shadows can distract from max solar output, resulting in less than rated current output).
The SCC output voltage is monitored, and when the voltage is equal to the Absorb voltage, the charger goes into the Constant Voltage mode at the Absorb voltage set point.

ABSORB charging is constant voltage charging.
In reality with a Solar Charge Controller, the SCC maintains the set Absorb voltage. Absorb charging current is max current the battery/load will accept at the set Absorb voltage that is within the current rating of the SCC. Clouds, shadows can distract from max solar output, resulting in less than rated current output or loss of absorb voltage.
Absorb charging is terminated if the Solar Panels/SCC cannot maintain the absorb voltage set point, or in some cases if the battery attains a set SOC value, the charging current reduces to below a set current level or after a set absorb time.

FLOAT charging is constant voltage charging.
In reality the SCC targets a constant Float voltage, the battery drops from Absorb voltage set point to the Float voltage set point by supplying power to parasitic loads, small loads or battery cell voltage normalization.
Once the battery has reached the Float voltage, the Solar Panels/SCC maintain the float voltage until the load on the battery exceeds the power available from the Solar Panels/SCC causing the battery voltage to drop below a set point voltage variance below the Float voltage. Clouds, shadows can distract from max solar output, resulting in less than demanded power output and loss of Float charging.

At that point the SCC initiates a new Bulk charge. Once the Battery voltage has attained the Absorb voltage set point, the SCC goes back to the Float voltage set point.
The Victron SCC I have only allows the Absorb Voltage for any Solar cycle (solar day) to be in the absorb mode for a total time equal to the absorb time setpoint for any solar cycle (I do not use SOC or charging current set points to terminate the battery absorb charge).

Equalize charging is constant voltage charging.
Battery chemistry can demand equalize charging to extend the life of some batteries.
An Equalize charge for Lead Acid batteries is an occasional overcharging of the battery beyond 100% SOC to desulfate the lead plates and stur the electrolyte up a little. This produces Hydrogen that is vented from the battery. The electrolyte level drops, and the batteries have to be topped off with more water occasionally. Lead acid storage batteries have an equalize voltage and routine specified by their manufacturer.
Thank you Randy, for you detailed answer!

To my understanding, and from your write up, there is no actual "bulk" setting to set the SCC to, when it's charging the battery, the setting should be set to "lithium" type of battery, and the energy from the panels start pumping in energy into the batteries, at the respective amps the SCC is set to. The voltage here doesn't matter, it's the current that is being pushed to the batteries, but when the absorb is set to 14.4 let's say, then when the battery reaches this voltage, it stops charging, and that's what important, not to overcharge above the set absorb voltage.

I was just curious, when charging from the SCC let's say at 30-50amps, at what voltage are these amps being pushed inside the battery, or it's not relevant, as long as it's pushing current, and doesn't go above the set threshold for the absorb setting.
 
Thank you Randy, for you detailed answer!

To my understanding, and from your write up, there is no actual "bulk" setting to set the SCC to, when it's charging the battery, the setting should be set to "lithium" type of battery, and the energy from the panels start pumping in energy into the batteries, at the respective amps the SCC is set to. The voltage here doesn't matter, it's the current that is being pushed to the batteries, but when the absorb is set to 14.4 let's say, then when the battery reaches this voltage, it stops charging, and that's what important, not to overcharge above the set absorb voltage.

I was just curious, when charging from the SCC let's say at 30-50amps, at what voltage are these amps being pushed inside the battery, or it's not relevant, as long as it's pushing current, and doesn't go above the set threshold for the absorb setting.
In the Constant Current charging mode (BULK charging), the solar panels/mppt/scc are charging with the max current the combo can provide less than the current rating of the scc (or max charge current set point of the SCC). As the battery SOC (state of Charge) increases the battery voltage increases until it reaches the absorb voltage set point. At that voltage point the SCC charger enters the constant voltage Absorb mode.

When a battery is in a discharged state, its terminal voltage is less than its fully charged terminal voltage, lets say a 13.1v discharged point where 14.6v would be 100 % State of charge. The charging process methodically increases the battery voltage to the absorb set point, flowing amps into the battery to recharge it. At some point in the process, based on the charging algorithm setpoints you select, the SCC determines the battery is at 100% SOC and terminates the BULK and/or ABSORB charge process.

Instead of using the particular SCC manufacturers LITHIUM setting, you can select CUSTOM setting where you specify all the charging parameters. Personally I do not like to charge my LiFePO4 battery to 14.6 volts daily (100% SOC). I choose a different absorb voltage target point. Many people experiment with this setpoint to find out what works best for them. I prefer a 14.1v absorb point with a 5 minute absorb time. This gets my battery to about 99-97% SOC. There is no need to charge a LiFePO4 battery to 100% SOC daily.

Some battery sellers use a BMS (Battery Management System) that does passive cell voltage balancing in a range of 14.1-14.6 charging voltage. BattleBorn recommends this to force passive balancing every charge cycle. I prefer to limit the charge voltage to 14.1 v (within their recommended voltage charging range) and hold it there for 5 minutes (a duration that fully charges my battery and top balances it quite well). These are my in use SCC settings, when I am using the battery daily. My battery in storage SCC set points are much lower.
 
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....

I was just curious, when charging from the SCC let's say at 30-50amps, at what voltage are these amps being pushed inside the battery, or it's not relevant, as long as it's pushing current, and doesn't go above the set threshold for the absorb setting.
In a constant current charge mode, the SCC operates at the voltage required to push the constant current (amps) into the battery. As the battery is charged, its voltage increases, thereby requiring a higher voltage input to continue constant current charging. When the battery charging state voltage reaches the set Absorb voltage, the Bulk Charge mode stops, and if allowed, an absorbe charge begins.
 
You need to get them up between 14.2V and 14.4V occasionally to let them top balance.

This is nonsense. He says if you get a high voltage disconnect at say 14v due to cell imbalance you should charge to 14.2-14.4v to balance them. How do you get to 14.4v if you get a BMS disconnect at 14v?
 
This is nonsense. He says if you get a high voltage disconnect at say 14v due to cell imbalance you should charge to 14.2-14.4v to balance them. How do you get to 14.4v if you get a BMS disconnect at 14v?
You don't get a cell disconnect at 14.0V. You get a cell disconnect at a much higher voltage. You don't even get it at 14.6V!
 
You don't get a cell disconnect at 14.0V. You get a cell disconnect at a much higher voltage. You don't even get it at 14.6V!
If you get a BATTERY DISCONNECT at 14.0v with a BattleBorn 12v 100AH battery, there is a cell voltage imbalance. At least one of the 4 cells that make up the battery has gone into over voltage as seen by the BMS. 14.6 / 4 = 3.65v per cell. One of the four cells has exceeded 3.65 v, the max voltage level for a LiFePO4 cell. The other three cells may be at a lower voltage, for example cell voltages of 3.65v, 3.45v, 3.45v and 3.45v results in a battery voltage of 14.0v. If the battery is not kept in top balance condition (top balance means cells have equal voltage at the battery approaches 100% SOC) and one of the four cell voltages exceeds 3.65v, the BMS disconnects the battery from the charger . If any one cell is excessively out of balance with the others, it will cause the BMS to trip and the battery will be isolated from the charger. With this unbalance of cell voltages at the top end of the charge, the BMS stops the battery charge and the battery cannot attain its rated AMP-HOURS.

Yes, if the BMS trips open at a battery voltage of 14.0 v, its hard to charge it to 14.6 v. The trick is to charge at the highest voltage below the BMS cell trip point and hold the voltage there for the battery to fully charge and the battery cells to passively top balance at that charging voltage. So set the charger to 14.0v (or 13.95 v) and absorb charge at that voltage until the BMS passively balances the battery Cells (BB says 15 minutes per string of batteries). Then repeat at a higher voltage, as the cell voltages will be more balanced after the passive balancing allowing the battery voltage to increase before any one cell exceeds 3.65 v. If the BMS trips the charging current at less than 14.6 v, set the charger to absorb charge at a lesser voltage, lets say 14.2 v and go thru the process again. Work your way up to 14.6 v battery voltage in this way.

This is why Dennis directs BB 12v battery users to charge their battery to 14.2-14.4 volts every cycle and hold it at that absorb voltage for 15 minutes per string of batteries. Thus avoiding the battery top balance problem. This practice will also charge the battery to 100% SOC every charge cycle, eliminating complaints about the battery not delivering all 100 AH every charge cycle. You gotta push it to the max charge point to get max AH out of the battery when discharging. I personally do not choose to push my batteries to 100 % SOC every charge cycle. I can leave them at 95 %SOC and only loose about 15 AH of available power out of 300 AH rating at 95% SOC.
 
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If you had a battery disconnect at 14.0V because a cell had reached 3.65 before the others, That would mean the average voltage of the other cells are 3.45V. That would be a hard condition to reach even if you only let the batteries only top balance every few months.
 
If you had a battery disconnect at 14.0V because a cell had reached 3.65 before the others, That would mean the average voltage of the other cells are 3.45V. That would be a hard condition to reach even if you only let the batteries only top balance every few months.
No argument there. But if that happens, the battery is extremely out of top balance. The BB 100AH 12v batteries all have the same BMS. The BMS provides Passive top balancing at 14.1-14.6 v battery charging voltage.
 
No argument there. But if that happens, the battery is extremely out of top balance. The BB 100AH 12v batteries all have the same BMS. The BMS provides Passive top balancing at 14.1-14.6 v battery voltage.
It's too bad BB and other similar batteries don't have a diagnostic port to see what the cells are really at. Probably why I would buy the Lifeblue if I was buying that type of battery again. Looking forward to getting my DIY bank done so I have more control.

If a cell in the BB got to 3.65V and the others were a lot lower, I would think you might still get a passive balance from that one cell and then it would allow the others to charge higher. Depends on how the BMS initiates balance.
 
No argument there. But if that happens, the battery is extremely out of top balance. The BB 100AH 12v batteries all have the same BMS. The BMS provides Passive top balancing at 14.1-14.6 v battery charging voltage.
Personally I’d like to see top balancing start at the float voltage.
 
And how would that possibly work?
I’m off grid and my system is in use 24/7. My batteries normally reach absorb voltage by mid day, 30 minute later the SCC goes to float. If I set the balance threshold to say 3.50v per cell and the absorb voltage is 3.55v per cell the balance time is only about 45mins (30mins absorb and 15mins 3.50v to 3.55v charge time). Since the balance current is only about 200mA, not much balancing is achieved before the SCC drops back to float voltage of 3.4v per cell and the balancing stops. If however I set balance voltage to 3.4v then when the SCC goes to float and the charge current drops to virtually zero, the BMS will continue to discharge any high cells. As the high cell is pulled down, the pack voltage would drop but the SCC provides a small current to maintain the pack voltage. This way the lower cells are charged and the higher cell is discharged. This will continue for the rest of the day (4-6 hours) or until the cell difference is less that 3mV at which time the balancing stops. This strategy works well with my setup. It may not suit everyone.
 
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