Charge Controller Setting for battery

[Matrix]

Hi Matrix, Citabria
Hi Sunking,
I have read through your cheat sheet on " Are you killing your batteries", thanks for writing that, it's very helpful.

Please note: Not only is there a Part 1, but also there is a Part 2 to the "Are you killing your batteries" that is equally informative. But I do not think Sunking linked to Part 2 from Part 1.

[monogram]

I have learned a lot today after reading all of those writing, hopefully I understand it.

When you are talking about "C" number, is that AH when batteries are fully charged or at 50% SOC?

How to calculate the time require to charge the battery?

The batteries are rate at 215AH, the loads are 3.5A or 86W for 14 hours, by 8AM, the battery show 14.2V. Does it mean I the panel & charge controller need to inject 1200W into the batteries to get it full charged again?

Let assume a 630W panel and charge controller provide 500W to the battery then I need 2.5 hours for the battery to fully charged then it will enter the Float, right?

I just made adjustment on my charge controller, would you please review and let me know if all the setting are right?

SETTING	User setting
Over Voltage Disconnect Voltage	33
Charging Limit Voltage	32.5
Over Voltage Reconnect Voltage	32.5
Equalize Charging Voltage	32.4
Boost Charging Voltage	29.7
Float Charging Voltage	27.4
Boost Reconnect Charging Voltage	26.4
Low Voltage Reconnect Voltage	25.2
Under Voltage Warning Reconnect Voltage	24.4
Under Volt. Warning Volt.	24.1
Low Volt. Disconnect Volt.	24
Discharging Limit Voltage	23.8
Equalize Duration (min.)	120
Boost Duration (min.)	120

Since my charge controller use different term for BULK and ABSORB, which one is reference to those?

Thanks again for all you response.

Key

[Mike90250]

At the end of the solar day, what is the hydrometer reading ?

[Sunking]

When you are talking about "C" number, is that AH when batteries are fully charged or at 50% SOC?

The rated Capacity of the battery in Amp Hours.

How to calculate the time require to charge the battery?

Simple algebra. As stated C = the rated AH capacity of a battery. So if you see something like C/8 C is the capacity and the integer 8 hours. Time for the math.

Amp Hours = Amps x Hours
Hours = Amp Hours / Amps
Amps = Amp Hours / Hours.

So if we have say an 80 AH battery and charge at C/8; how many amps will be required? 80 Amp Hours / Hours = 10 Amps
How long would it take an 80 AH battery charge with 10 amps? 80 AH / 10 Amps = 8 Hours?

Easy Peazy right? Not quite, while everything above is 100% accurate is just an academic exercise and not how the real world works. To start with a FLA battery is only 80% efficient which means you have to pump in 1.2 AH to get 1 AH of charge. Second is as batteries charges you reach about 80 to 90% capacity and your charger switches from contant current to constant voltage and charging slows way down and keeps slowing down until no current flows when the battery saturates and is fully charged. That Absorb Phase can take 6 to 12 hours. So if you assume a C/8 charge rate is completely long as it takes an additional 6 to 12 hours.

The batteries are rate at 215AH, the loads are 3.5A or 86W for 14 hours, by 8AM, the battery show 14.2V. Does it mean I the panel & charge controller need to inject 1200W into the batteries to get it full charged again?

You are talking oranges (AH), working with apples (watts), and made fruit salad jibberish. To start if your load is 3.5 amps on a 12 volt battery is 42 watts. I have no idea where you came up with 86 watts . If your load is 3.5 Amps for 14 hours, you used 3.5 Amps x 14 hours = 49 AH from your 215 AH battery. You can also solve using Watt Hours and Watts. You have to work with the same units, not fruit salad.

Watt Hours = Watts x Hours
Watt = Watt Hours / Hours
Hours = Watt Hours / Watts.

To find the watt hour capacity of battery = Battery Voltage x Amp Hours = Watt Hours. So your 215 AH x 12 volts = 2580 Watt Hours. So if you use 42 watts for 14 hours you used 42 watts x 14 hours = 588 Watt Hours. Both ways work and can be proven because 588 Watt Hours on a 12 volt battery is 588wh / 12 volts = 49 AH.

So if you use 49 AH or 588 watt hours your panels must replace it + another 20% and will take longer than you thin.

Let assume a 630W panel and charge controller provide 500W to the battery then I need 2.5 hours for the battery to fully charged then it will enter the Float, right?

500 Watts x 2.5 Hours = 1250 watt hours or 104 Amp Hours is all I can tell you on the incomplete data you gave me. . Beats me if that would charge your battery or not, you did not specify the capacity and the Depth of Discharged.

[monogram]

Hello Sunking,

I'm sorry to confuse you about the apple and orange (AH & watts) as I forgot to mention it's 24V system, let me explain it again with more detail:

• I have four 6V batteries that rated at 215AH and in series to make it 24V bank. The loads are 3.5AH run on 24.5V (at 6PM), for 14 hours it used 1200W or 49A. By 8AM, the battery show 14.2V. Does it mean the panel & charge controller need to inject 1200W into the batteries to get it fully charged again?
• Let assume a 630W panel with MPPT charge controller output 500W to 24V batteries bank with 215AH at 50% SOC. Does it mean I need 5 hours (500W x 5hrs = 2500W) for the battery to fully charged before it enter the Float, right?
• How can I tell batteries % when I have the voltage from batteries? Example: battery voltage reading at 24.6V

Thank you in advance for all your contributed.

Regards,
Key

[Matrix]

How can I tell batteries % when I have the voltage from batteries? Example: battery voltage reading at 24.6V

Simple, You can't really.

Battery voltage is not a good indicator of State of Charge (SOC) AND the batteries must be at NO LOAD. If you want to know the SOC of your batteries, you take a specific gravity (SG) reading and compare those numbers to the manufacture gravity numbers. If your voltage is at 24.6v no load, you might be at about 65% ... but how do you know? Take an SG reading. If it's 1.217, you are at 70%. Now you Know, you are not Guessing with Volts.

When charging using your charger settings, and your charger finishes charging, take the SG and compare that to the manufactures 100% SOC SG. If you did not reach that SG or higher, Increase your boost charge voltage OR increase your boost charge duration. If you ran out of sun at the present settings, then duration is not an option. You would have to increase your voltage, by 0.1-0.2 a volt and wait for the next sunny day and test again to see if you got a full charge. Repeat until you get an SG that matches the Manufacture Fully Charged SG or higher.

Here is a basic SG chart, which also has voltages, but voltages are a best guess. The more you learn your batteries, the more voltage might be useful occasionally. But also remember, there has to be NO LOAD on the battery for voltage readings. battery-state-of-charge.jpg

[littleharbor]

Not hijacking this thread. Just want to know, Your 24 volt battery bank is down to 14,2 volts by 8 am? Are these numbers correct?

[monogram]

Hi Matrix,
Thank you for the chart, I will measure SG when I receive my Hydrometer (it's on the way)
Will the voltage or SG to be the same for all battery made by different manufacture? (I bought mine from Sam Club, GC2). Where can I find the spec for it?
You mentioned to increase voltage by 0.1-0.2 volt, is that mean increase the Float Charging Voltage?


Hi Littleharbor,
When sunset, the charge controller show battery voltage at 25.6V (around 6PM). With the load of 100W ON (this load is running 24/7), the battery show 24.2V-24.4V by 8AM the next day, Is that normal for 215A batteries bank at 24V?

[littleharbor]

Hi Matrix,

Hi Littleharbor,
When sunset, the charge controller show battery voltage at 25.6V (around 6PM). With the load of 100W ON (this load is running 24/7), the battery show 24.2V-24.4V by 8AM the next day, Is that normal for 215A batteries bank at 24V?

That's likely all good. Your voltage would even rise a little if you were to remove all loads for a few hours. The reason I asked is your post said the 24 volt battery was down to 14.2 volts, Now we see it was a typo but if not a typo your 24 volt batteries are so severely discharged that they could have been ruined.. If you want accurate answers you need to give accurate information.. May I suggest you proofread your questions and look for typos and incorrect terminology before you post. You can even go back and edit previous posts.

[Matrix]

Hi Matrix,
Thank you for the chart, I will measure SG when I receive my Hydrometer (it's on the way)
Will the voltage or SG to be the same for all battery made by different manufacture? (I bought mine from Sam Club, GC2). Where can I find the spec for it?
You mentioned to increase voltage by 0.1-0.2 volt, is that mean increase the Float Charging Voltage?

Do NOT rely on the voltage chart.

The Spec for the Battery? SunKing already told you in post #5. Google is your friend for that.

Those batteries are made by Deka with a Duracell sticker

You need to go to the manufacture site and look at their battery maintenance guide, or specific Data sheet for your batteries. There you will find the SG numbers for your specific battery. The chart I posted is an example. It MIGHT be your batteries SG readings, or it might not be. Only the maker of the battery can tell you how much electrolyte mixture they specify and what the SG should be, especially for fully charged.

If you cannot find a Manufacture Spec Sheet, Your best bet might be to fully charge the batteries, check the SG then begin an Equalization Charge at 32v checking the temperature and SG every hour until the SG stops rising in the cells. Don't let the batteries get hot.

[Sunking]

[LIST][*]I have four 6V batteries that rated at 215AH and in series to make it 24V bank. The loads are 3.5AH run on 24.5V (at 6PM), for 14 hours it used 1200W or 49A. By 8AM, the battery show 14.2V. Does it mean the panel & charge controller need to inject 1200W into the batteries to get it fully charged again?

Time to spank you. This is complete rubbish. 3.5 Amps x 14 Hours = 49 Amp Hours. Not 49 amps. You got to get this striaght.

3.5 amps x 24 volts = 84 Watts. 84 Watts x 14 Hours = 1176 Watt Hours. Use the battery nominal voltage Again you got to understand the difference and why you are confused.

Amps and Watts are the RATE in which power is being used. Amp Hours and Watt Hours are the energy consumed. Power and Energy are two different things. Powers is Watts, Energy is Watt Hours. Amp and Amp Hours are meaningless without a voltage specified.

AMP x HOURS = AMP HOURS, not AMP
WATT x HOURS = WATT HOURS, not WATTS

So you have a 24 volt battery @ 215 AH.
The battery capacity is 24 volts x 215 AH = 5160 Watt Hours.

For now forget Amp Hours as that is not energy. Use Watt Hours. So if you have a 84 watt load and run it for 14 Hours is 84 watts x 14 hours = 1176 Watt Hours or roughly 23% of your battery capacity.

Where the hell are you getting 14.2 volts?

[monogram]

Hi Sunking,
I'm sorry to confuse you again. Yes, I understood what you mentioned. The reading is 24.2V not 14.2V as typo error, my fault, sorry.

So if you have a 84 watt load and run it for 14 Hours is 84 watts x 14 hours = 1176 Watt Hours or roughly 23% of your battery capacity

Which mean it take about 2.5 hrs to to fully charge the battery again ? (assume I get 500W output from Charge Controller)

[monogram]

Hi Matrix,

Yes, I did see the post from Sunking, found the spec but I could not find SG for the battery, did I missed it? If yes then I need a new glass.

http://www.eastpennmanufacturing.com/wp-content/uploads/Golf-Car_EV-Battery-Care-Maintenance-1932.pdf

[Matrix]

Hi Matrix,

Yes, I did see the post from Sunking, found the spec but I could not find SG for the battery, did I missed it? If yes then I need a new glass.

http://www.eastpennmanufacturing.com...nance-1932.pdf

You are Correct Sir, not a lot to go on there, but there are many clues to testing and SG beginning in section 3.2 til the end of the document.

They seem to indicate what I was telling you. EQ a fully charged battery (or at least a battery that is at 1.250 SG) until the SG stops rising. I would think that this point where your battery stops rising is the full SG reading. It will probably be somewhere in excess of 1.277 SG. While doing the EQ, monitor the SG, Cell water level and Battery Temp Regularly. The document gives you charging temps.

I think your main concern with solar charging will rarely be over charging ... you will more have to be concerned with chronic and repeated under charging. Unless you are way over paneled.

[Sunking]

I'm sorry to confuse you again. Yes, I understood what you mentioned. The reading is 24.2V not 14.2V as typo error, my fault, sorry.

No apology needed.

Which mean it take about 2.5 hrs to to fully charge the battery again ? (assume I get 500W output from Charge Controller)

On paper yes roughly, but not in practice. On a solar system with a MPPT Controller to put 1 usable watt hour into a battery requires the panel to generate 1.5 watt hours to overcome the inefficiencies. Understand?

Second issue is 2.5 clock hours do not equal 2.5 Sun Hours. A solar panel does not generate it specified power when sun light strikes the panel. At solar noon gets close for a few brief minutes. If you were to look at a graph of Power vs Time from sunrise to sunset would be a Bell Curve? Understand?

So depending on where you live, even though it may be light 14 hours will only yield you 4 to 6 sun hours in summer, and half that in winter. So in a design you need to know Sun Hours so you can determine panel wattage required. So if you need say 1000 watt hours, the panels must generate 1.5 times that much power of 1500 Watt Hours. You then look up your worse case Sun Hours in winter and lets say it is 3 Sun Hours. Now it is time to find Panel Wattage by factoring out hours so Panel Wattage = Watt Hours / Sun Hours, or 1500 Watt Hours / 3 Sun Hours = 500 watts. So it would take all day to equal 3 Sun Hours in Winter despite it being light 10 clock hours.