Battery Max Voltage

[Darth_mofadal]

Hello, I have a Panasonic 200AH AGM battery connected to a 200 Watt Solar Panel. when the sun is up the max voltage the battery goes to is 13.2V while PV voltage is 13.4V, sometimes even when the battery is not being used the voltage decreases a little bit, is there a problem with my battery, what's the max and min voltage the battery can go to?

[inetdog]

Do you have a Charge Controller (CC) between your panel and your battery?
If not, there is a good chance that you will destroy your lovely AGM battery one day.
If you do have a CC, what brand and model is it?

[Darth_mofadal]

Do you have a Charge Controller (CC) between your panel and your battery?
If not, there is a good chance that you will destroy your lovely AGM battery one day.
If you do have a CC, what brand and model is it?

Yes I have a Raggie PWM 30A controller.

[inetdog]

The battery voltage will normally decrease from the forced higher voltage from charging (even Float charging) without any load at all.
The resting voltage (after at least 4 hours without either charging or load) will give you a pretty good idea of the State Of Charge (SOC) of the battery. But the exact voltage values can depend somewhat on the battery plate composition and the electrolyte SG used by the manufacturer.

In addition, a battery will have an internal "self-discharge" current that will lower the SOC noticeably over a period of weeks or months. But that is not what you are seeing.

[Darth_mofadal]

The battery voltage will normally decrease from the forced higher voltage from charging (even Float charging) without any load at all.
The resting voltage (after at least 4 hours without either charging or load) will give you a pretty good idea of the State Of Charge (SOC) of the battery. But the exact voltage values can depend somewhat on the battery plate composition and the electrolyte SG used by the manufacturer.

In addition, a battery will have an internal "self-discharge" current that will lower the SOC noticeably over a period of weeks or months. But that is not what you are seeing.

Aha thank you, but is the 13.2V normal or it should go higher? Also does the distance between panels and controller is important (it's around 18m)?

[inetdog]

Aha thank you, but is the 13.2V normal or it should go higher? Also does the distance between panels and controller is important (it's around 18m)?

The distance is not important if you have large enough wires. Otherwise the voltage drop at 10A might be enough to cost you some energy. But a PWM controller will probably not notice the difference.

What are the voltage settings of the CC? I do suspect that 13.2 is an indication that your panel has not had enough time to bring the battery up to full charge. That is not a good thing and you may want to use an external charger to top the battery off to prevent damage by sulfation.

What are your loads each day, and were are you located?

[Darth_mofadal]

The distance is not important if you have large enough wires. Otherwise the voltage drop at 10A might be enough to cost you some energy. But a PWM controller will probably not notice the difference.

What are the voltage settings of the CC? I do suspect that 13.2 is an indication that your panel has not had enough time to bring the battery up to full charge. That is not a good thing and you may want to use an external charger to top the battery off to prevent damage by sulfation.

What are your loads each day, and were are you located?

I'm not sure what do you mean by voltage settings, but the Float voltage of the controller is 13.8V, my load is almost 200 watts (TV, charging phones and laptop), I'm in Yemen.

[PNjunction]

Hello, I have a Panasonic 200AH AGM battery connected to a 200 Watt Solar Panel. when the sun is up the max voltage the battery goes to is 13.2V while PV voltage is 13.4V, sometimes even when the battery is not being used the voltage decreases a little bit, is there a problem with my battery, what's the max and min voltage the battery can go to?

Hi Darth - that is normal for the battery to self-discharge a little bit when not being used. There may be a bigger issue here though.

Normally, an AGM can be taken up to 14.4v in the absorb mode, where it is held at that voltage and the current to the battery drops naturally. After either a period of time, or a measurement of current, the controller will flip to "float".

BUT, I'm not sure your controller even has an absorb mode! I'm pretty sure it is the model CM3024Z. It appears to be a "float only" controller, which is really more suited for standby/backup purposes. I looked at the specs for the Raggie and see only float (along with load controls). The Raggie is also a badge that the manufacturer "JUKA" handles as well.

Also no adjustments for chemistry, like a specific one for AGM, which usually takes absorb up to 14.6v or so.

Unless you have some better specs, that controller is harming your panasonic in your cyclic environment.

Let's also review your power budget quickly:

200ah Panasonic: 200ah * 12v = 2400 wh. But only HALF of that is usable if you want any decent cycle life from the panasonic, so you only have 1200 wh to play with each day.

If you are drawing 200w with the tv and so forth, then you should only be able to power your gear for 6 hours. (1200wh / 200wh).

DEFICIT CHARGE scenario:

Uh oh. If you pull 50% DOD from your battery, ie 100ah from the Panasonic, you need to return that AND about 10% more to fully recharge. And that is with a controller that is NOT just a "float only" type.

Panel output: 200w panel / 18v = 11.1a max output under best conditions.

Unfortunately, that means you will need at least 10-15 hours to complete a charge, which of course will never happen in a single day. Yemen is bright, but solar-insolation hours, the "meat" of the sunlight if you will, is far different than just sunrise-to-sunset hours.

In reality, we're talking at least 2 or 3 perfect days for a full recharge of that battery if taken down to 50% DOD.

What I'd do is get another panel, and also a better charge controller that has more specifics about it's function, with a current handling upgrade too of course.

The Panasonic, if a typical conventional agm, will withstand up to about .3C, or .3*200ah = 60A of continuous charge current. Heh, you could easily put 4 or 5 additional panels on your system if you needed to.

At the end of the day, you either gotta' cut back on tv a lot, or put some more quality gear into your solar system....

[radareclipse]

Ideally your panel voltage should be 17 or 18 volts, not at almost the float voltage. And you could use one or two more panels easily to bump up the charge amperage to your battery. Your kind of trickle charging it to death.

[Darth_mofadal]

Hi Darth - that is normal for the battery to self-discharge a little bit when not being used. There may be a bigger issue here though.

Normally, an AGM can be taken up to 14.4v in the absorb mode, where it is held at that voltage and the current to the battery drops naturally. After either a period of time, or a measurement of current, the controller will flip to "float".

BUT, I'm not sure your controller even has an absorb mode! I'm pretty sure it is the model CM3024Z. It appears to be a "float only" controller, which is really more suited for standby/backup purposes. I looked at the specs for the Raggie and see only float (along with load controls). The Raggie is also a badge that the manufacturer "JUKA" handles as well.

Also no adjustments for chemistry, like a specific one for AGM, which usually takes absorb up to 14.6v or so.

Unless you have some better specs, that controller is harming your panasonic in your cyclic environment.

Let's also review your power budget quickly:

200ah Panasonic: 200ah * 12v = 2400 wh. But only HALF of that is usable if you want any decent cycle life from the panasonic, so you only have 1200 wh to play with each day.

If you are drawing 200w with the tv and so forth, then you should only be able to power your gear for 6 hours. (1200wh / 200wh).

DEFICIT CHARGE scenario:

Uh oh. If you pull 50% DOD from your battery, ie 100ah from the Panasonic, you need to return that AND about 10% more to fully recharge. And that is with a controller that is NOT just a "float only" type.

Panel output: 200w panel / 18v = 11.1a max output under best conditions.

Unfortunately, that means you will need at least 10-15 hours to complete a charge, which of course will never happen in a single day. Yemen is bright, but solar-insolation hours, the "meat" of the sunlight if you will, is far different than just sunrise-to-sunset hours.

In reality, we're talking at least 2 or 3 perfect days for a full recharge of that battery if taken down to 50% DOD.

What I'd do is get another panel, and also a better charge controller that has more specifics about it's function, with a current handling upgrade too of course.

The Panasonic, if a typical conventional agm, will withstand up to about .3C, or .3*200ah = 60A of continuous charge current. Heh, you could easily put 4 or 5 additional panels on your system if you needed to.

At the end of the day, you either gotta' cut back on tv a lot, or put some more quality gear into your solar system....

Thanks for the detailed information, I didn't use the system yesterday and today the values are the following:

PV: Jumps between 16-17V
Battery:13.3

I know the controller is far from decent but it's the best I found in the market, my concern is will the controller ever charge the battery even if it's full thus exploding it or with this type of controller, the battery will never achieve full charge? as for the panels, I also have 3 20W panels, is it fine to just join them with the 100W panels or is it better if they have a different wires and controller?

[Darth_mofadal]

Ideally your panel voltage should be 17 or 18 volts, not at almost the float voltage. And you could use one or two more panels easily to bump up the charge amperage to your battery. Your kind of trickle charging it to death.

It's now jumping from 16 to 17V

[PNjunction]

PV: Jumps between 16-17V
Battery:13.3

For the PV panel voltage that is normal. But that is certainly not what you want to see at the battery, which the controller seems to be doing it's job, but it seems to be a float-only model.

I know the controller is far from decent but it's the best I found in the market, my concern is will the controller ever charge the battery even if it's full thus exploding it or with this type of controller, the battery will never achieve full charge?

Yes, with that controller seemingly limited to only 13.8v - common for a float voltage - it will take DAYS or WEEKS to get those batteries charged without you drawing anything from them in the meantime. The batteries not only have to merely reach 13.8v, but be HELD THERE for a long long time. Thus, that controller is mostly suited for "standby - backup" and not usable for cycling where one draws upon it from day to day.

In the end, it comes down to an unsuitable charge controller, and low panel output which will contribute to the early demise of that nice Panasonic. It will just sulfate, getting smaller and smaller in capacity internally.

I hate to say it, but unless you can somehow get another controller, or find a way of tricking or verifying that it will actually do an "absorb" at 14.4v, this is merely a very short-lived expensive project. Adding 60 more watts of random panels may help, but that controller is just the wrong tool for the job of cyclic activity if it only does 13.8v.

[Darth_mofadal]

For the PV panel voltage that is normal. But that is certainly not what you want to see at the battery, which the controller seems to be doing it's job, but it seems to be a float-only model.



Yes, with that controller seemingly limited to only 13.8v - common for a float voltage - it will take DAYS or WEEKS to get those batteries charged without you drawing anything from them in the meantime. The batteries not only have to merely reach 13.8v, but be HELD THERE for a long long time. Thus, that controller is mostly suited for "standby - backup" and not usable for cycling where one draws upon it from day to day.

In the end, it comes down to an unsuitable charge controller, and low panel output which will contribute to the early demise of that nice Panasonic. It will just sulfate, getting smaller and smaller in capacity internally.

I hate to say it, but unless you can somehow get another controller, or find a way of tricking or verifying that it will actually do an "absorb" at 14.4v, this is merely a very short-lived expensive project. Adding 60 more watts of random panels may help, but that controller is just the wrong tool for the job of cyclic activity if it only does 13.8v.

Today the battery is 14.3V and PV is about 18-19V, regarding the other panels, I'm still not sure if I should the same cabling/controller or a different one (I have a 5A Steca controller)

[Sunking]

Darth you appear to not know how Charge Controller, Solar Panels, and batteries work together.

You have a PWM Controller and a PWM Controller INPUT CURRENT = OUTPUT CURRENT. So your typical 100 watt Battery has a Voc = 22 volts, Vmp = 18 volts, and Imp = 5.5 amps. 5.5 amps x 12 volts = 66 Watts from a 100 watt panel. When you use a PWM Controller, you must use a Low Voltage Battery Panel. You have what sounds like a higher voltage Grid Tied Panel of 200 watts. Battery ccannot go to that high of wattage. 160 watt sis about the maximum for a battery panel. a 200 watt GT panel has a Voc = 45 volts, Vmp = 36 volts, and Imp of the same 5.5 amps. That means 5.5 ams x 12 volts = 66 watts from a 200 watt panel. Are you OK with that? You had better be OK with it because you are stuck with it for now.

A MPPT controller is a Power Converter where Power In = Power Out. Or Output Current = Panel Wattagge / Battery Voltage. You can use a Battery panel with them if you are foolish enough to use a very expensive battery panel of 2 to 6 times more than a GT panel. So a 200 watt panel into a 12 volt battery delivers 200 watts / 12 volts = 16.6 amps or 200 watts. Kind of a stupid question but why would anyone want 200 watts from a 200 wat panel when you can only get 66 watts and robbed. Vegas is a fun place and the only place you can go, get robbed, over pay for everything, then go home, brag about it, and cannot wait to go back.

As for voltages with a PWM Controller the voltage range at the Input as low as battery voltage at 100% Full On and Charging, to Voc when Off. MPPT will always be as low as Vmp at full Charging Power to Voc when off.

[PNjunction]

What is your configuration now?

Is it a 200ah panel to the Raggie / Juka float-only controller, along with those 60w worth of 3 total smaller panels going to the Steca 5A, and now both controllers connected to the battery?

I suppose that helps, and it is obvious that a 200w panel will fry the 5A Steca. If you can find a larger amperage Steca to handle your 200w of panel, preferably more, that would be the best thing to do.

If you are relying on the short-term overload capability of the Steca 5A to handle your 200w of panel, that will eventually fry.