Charge Controller Setting for battery

[monogram]

Hello,

I just bought a new MPPT charge controller made by Epever to charge 24V battery bank at 215A (4x6V GC2 from Sam Club) using two 315W panel in parallel.
By the default, Epever CC has Flood battery configuration set as:

• Over voltage disconnect: 32V
• Charging limit voltage: 30V
• Over voltage reconnect: 30V
• Equalize charging: 29.6V
• Boost charging: 29.2V
• Float charging: 27.6V
• Boost reconnect charging: 26.4V
• Low voltage reconnect: 25.2V
• Low voltage disconnect: 22.2V
• Discharge limit: 21.2V
• Equalize duration: 120 min
• Boost duration: 120 min

Please let me know what is the best setting to keep the battery life as long as it can be.

Regards,
Key

[monogram]

any thought?

[Matrix]

Are those sealed AGM batteries or Typical Capped Flood Acid batteries? Your not going to charge them at 215A ... unless you want to fry them. So I assume they are 215 Ah batteries. The max charging current would be 26 amps.

Your Charge controller has a Charge volt limit of 30v? That seems low to me. Can that be increased or is that the fixed limit set by the CC or panels?

You should be able to go to the Battery Manufacture Web Page and get the charging specs for the batteries. You did not list which batteries you have.

But generally speaking for Trojan Flood Acid Batteries:
- Float is 27v
- Bulk should roll to Absorb at 29.6v. That is probably your Boost Charging setting. This would be a starting point and then you need to check the specific gravity of each cell to confirm the SG has risen to the manufacture level for 100% charged. Do not rely on volts as your guide to fully charged. And of course if these are AGM you can't check the SG
- Depending on DOD, 120 min (for what your charger is calling Boost Duration ?? ) Might be long enough.
- Absorb is generally done when the charge amps levels to about 1-3% of the battery AH
- And if you have not reached fully charged you would need to increase the Boost charge volts (which I am guessing is the absorb voltage)
- Then recheck SG after the next "full" charge
- you can then either increase Boost Charge Voltage or Boost Duration. But if you are running out of Sun .... Duration is not going to help you. So you increase charge volts to cram as much charge as you possibly can in the limited time of solar you have.

- EQ might be as hi as 32.4v (Trojan)... but you need to check with your manufacturer charging guide
- But if your Charge Limit voltage cannot be increased above 30v, you will probably not ever be able to effectively EQ the batteries. And if they are AGM, your not supposed to EQ them anyway.

[monogram]

Hi Matrix,

Thank you for your response.

• The batteries are Duracell GC2 Flood Acid type (from Sam Club) and yes, it's 215Ah batteries.
• Yes, my 30A Epever charge controller can change the voltage to any setting that I want.

I have a questions:

• How do I know when the battery is fully charged?
• How often do I have to check the SG for each cells on each batteries?
• How often do I have to add water to the batteries?

Would you please fill in your recommendation setting for the batteries:

SETTING	Default setting	User setting
Over Voltage Disconnect Voltage	32.0V
Charging Limit Voltage	30.0V
Over Voltage Reconnect Voltage	30.0V
Equalize Charging Voltage	29.6V
Boost Charging Voltage (Bluk)	29.2V
Float Charging Voltage	27.6V
Boost Reconnect Charging Voltage	26.4V
Low Voltage Reconnect Voltage	25.2V
Under Voltage Warning Reconnect Voltage	24.4V
Under Volt. Warning Volt.	24.0V
Low Volt. Disconnect Volt.	22.2V
Discharging Limit Voltage	21.2V
Equalize Duration (min.)	120
Boost Duration (min.)	120

The panel that I had is 315W Jinko

Thanks again for all your advise.

Regards,
Key

[Sunking]

Those batteries are made by Deka with a Duracell sticker. I will save you the boring details, but start with these voltages then use your hydrometer to fine tune the voltages.

Boost = 29.7 volts
Float = 27.2
EQ = 32.4

Reset

HVD to 33 volts
Charge Limit to 32.5
Rest does not matter

Monitor with Hydrometer. If reading are low, raise Boost. If high lower Boost.

[monogram]

Hi Matrix, Sunking,

I just posted a response to Matrix 10 mins ago with hyper link to battery and the panel but it's currently waiting for approval, do you know why?

[monogram]

Thank you Matrix, Sunking for your response.

My 30A Epever Charge Controller are customize able for battery setting.

I have a few questions:

• How do I know when the batteries are fully charged?
• How often do I have to measure SG? on each cells? each battery?
• How often do I have to add water to the batteries?

Does bellow user setting are correct to pro-long a batteries life: (any user setting that not fill will carry default setting)

SETTING	Default setting	User setting
Over Voltage Disconnect Voltage	32.0V	33
Charging Limit Voltage	30.0V	32.5
Over Voltage Reconnect Voltage	30.0V
Equalize Charging Voltage	29.6V	32.4
Boost Charging Voltage	29.2V	29.7
Float Charging Voltage	27.6V	27.2
Boost Reconnect Charging Voltage	26.4V
Low Voltage Reconnect Voltage	25.2V
Under Voltage Warning Reconnect Voltage	24.4V
Under Volt. Warning Volt.	24.0V
Low Volt. Disconnect Volt.	22.2V
Discharging Limit Voltage	21.2V
Equalize Duration (min.)	120
Boost Duration (min.)	120

The 2 panel that I had in parallel are 315W Jinko

Thanks again for all your response.

Regards,
Key

MOD NOTE. Adding links to your post will cause it to go through the approval process and delay it being seen.

[monogram]

Does above user setting OK for GC2 flood battery?

• How do I know when the batteries are fully charged?
• How often do I have to measure SG? on each cells? each battery?
• How often do I have to add water to the batteries?

[Matrix]

Does above user setting OK for GC2 flood battery?

• How do I know when the batteries are fully charged?
• How often do I have to measure SG? on each cells? each battery?
• How often do I have to add water to the batteries?

Looks ok. You will need to adjust your Time Durrations based on actual specific gravity readings. Which answers your first and second questions,

- How do I know when the batteries are fully charged?
- How often do I have to measure SG? on each cells? each battery?

You have to get a Temperature Compensated Glass Hydrometer and learn how to use it. You will baby sit these batteries until you get the numbers dialed in that lead to a full charge.

and your third question: A battery watering can is a cheap easy and effective method for delivering Distilled Water to the cells without over watering. Very simple to use. You simply open up the tops, look at where the water level is, (hopefully the plates are not exposed or your batteries are on the way to being dead), stick in the Jug nozzle and push down. It fills until the water level is where it needs to be and stops.

[Sunking]

Does above user setting OK for GC2 flood battery?

It is a starting point, but not where you will end up if done correctly

• How do I know when the batteries are fully charged?
• How often do I have to measure SG? on each cells? each battery?
• How often do I have to add water to the batteries?

A1. You will know when the batteries are fully charged when your temperature corrected hydrometer tells you they are fully charged.

A2. Initially every day near sunset until you find the right Boost Voltage that gets you to 100% without excessive gassing.

A3. As needed, about once a month.

What size generator and battery charger do you have? You will need one to monthly PM and EQ charges, plus to save your batteries from destruction. Please read this STICKY, then ask questions.

Break out a $10 spot and buy you a good hydrometer like this one.

[citabria]

• How often do I have to add water to the batteries?

Generally, I check my Trojan L16 water levels every 4 to 6 weeks and top them off. June (summer) is a really dry and hot month here, and the dry air literally sucks out the water, so I usually need more water and definitely don't go more than 4 weeks between water. I am over batteried and do not get vigorous gassing, but I do getting decent audible bubbling and generally attain float charge most days. I spot check the Specific Gravity prior to filling with distilled water. FYI, distilled water is generally sold in 2.5 gallon disposable plastic jugs. I Usually have 3 to 4 jugs on hand at all times. Remember....with batteries, you now have a new hobby.

[monogram]

Hi Matrix, Citabria
Thank you for your advises, hopefully my batteries will last longer by follow all your advise.
Does anyone know battery expectation life for it?

Hi Sunking,
I have read through your cheat sheet on " Are you killing your batteries", thanks for writing that, it's very helpful. The hydrometer and water jug are already ordered and on it ways.

I have some more questions:

• Q1: When reading the battery with Hydrometer, do I read it when the charge controller is at "Float" mode?
• Q2: With a default setting from above, at 6 PM yesterday, I noticed the CC is in Float charge mode at 27.6V. By the time the sun go down at around 6:30PM, the CC show battery voltage at 26.4 and by 10PM, it show 25.5V. This morning, it show 24.6V. (Note, the load is ALWAYS ON at 24 hours at about 90Watts). Does battery voltage drop look normal?

[Sunking]

Does anyone know battery expectation life for it?

Depends on many factors mainly depth of discharge. Limit daily discharge to 20 to 30%, take care of them and never allow them to discharge to 50% and they should last at least as long as the warranty period.

[*]Q1: When reading the battery with Hydrometer, do I read it when the charge controller is at "Float" mode?[*]Q2: With a default setting from above, at 6 PM yesterday, I noticed the CC is in Float charge mode at 27.6V. By the time the sun go down at around 6:30PM, the CC show battery voltage at 26.4 and by 10PM, it show 25.5V. This morning, it show 24.6V. (Note, the load is ALWAYS ON at 24 hours at about 90Watts). Does battery voltage drop look normal?[/LIST]

A1. Yes toward the end of the day before the sun goes down. Most likely you will never see the controller go into float unless you panel wattage is properly sized. In summer it should go to float, in winter likely never will go into float. When you see the controller go into Float, and your battery specific gravity is low is telling you the batteries are not charged up. The reason this is happening is because the Absorb phase is NOT A TIMED EVENT that solar charge controllers use. Absorb phase is a CURRENT TAPER EVENT meaning the current needs to Taper until charge current reaches rougly C/33 or 3% of C. Example a 100 AH battery is 3 amps. Absorb phase can take 6 to 12 hours. There are not enough Sun Hours in a day to do that. Only thing you can do is force the Charge Controller to stay in Bulk Mode until Sunset to harvest every possible AH out of the day. If not that is when you need to start the generator at least once a week to top off your batteries. Failure to do so is what destroys the batteries being chronically undercharged. Additionally you need the genny for EQ charge which can take up to 24 hours. Solar cannot do that.

A2. Yes that is normal.

[monogram]

Hello Sunking,
Another learning post for me, thanks again.

As I remember correctly, my battery go into float mode by noon time or around 1 PM, the panel also reduce the wattage into the battery; is that mean my panels provide more power than the batteries can absorb?

• Two 315W panel in parallel
• Four 215A 6V battery
• 90W load, always ON 24/7
• Panel faced South at 73 degree angle
• Nothing block the panel
• I'm in Southern California, Anaheim.

For example, last Saturday, at 11AM, the PV output 360W with 90W load. When I increase the load to 250W then the PW output jump to above 500W.

Is that mean the panels provide more power than the batteries can take in?


Side note, is it MSEE stand for: Master of Electrical Engineering? and PE for Professional Engineering?

[Sunking]

As I remember correctly, my battery go into float mode by noon time or around 1 PM, the panel also reduce the wattage into the battery; is that mean my panels provide more power than the batteries can absorb?

The panels do not do anything, they are dumb as a rock. It is the Controller and the way batteries work that reduce the power. In a perfect world you want to go into float around noon so the batteries no longer take any current. Power has to have someplace to go. Like a glass of water, when it is full, you cannot put more water in the glass. Ideally when the batteries reach float at mid day, any power demand comes from the panels, not the batteries assuming conditions are right for the panels to generate enough power. If not the batteries have to make up the shortage.

It is a bit complicated, read this sticky and all the sticky's in the Battery section

Is that MSEE stand for: Master of Electrical Engineering? and PE for Professional Engineering?

Yes, PE means Professional Engineer licensure like a doctor or lawyer licensure. Means we are fully liable and held accountable for our work. So in the event a bridge or building falls down, or an electrical fire, a peer review will be done, and if we mess up, we pay to clean up the mess and can do jail time.