310w panel Vmp issue

Aguarancher

if you do a search of the board, there are some very efficient ceiling fans. forget the name and they're not cheap, but quality seldom is..

Photowhit

"...4s2p the reading was 159V..."

How was this measured? If it was the voltage that shut down the charge controller, the same problem still exists, they weren't producing (no or little load on the power) so the numbers represent closer to the VOC...


If measured with a meter from the ends... it is the VOC in the current situation...

BB.

Remember that a charge controller as the battery fills up, more or less, reverts to PWM mode... On/Off... So, as the battery nears 100% full, the controller is drawing very little current, and the peak (average array) voltage is getting closer and closer to Voc (maximum array voltage, no current flow).

-Bill

dapago

THe reading at 159v was on the CC with the 4s2p wiring. This is why the installer had to disconnect 2 panels and left me with 3s2p, setting i am having right now until a solution be find to connect my 8 panels.

bill. Let me get the info you just gave me strait. When batts get near 100%, voltage rise closer and closer to VOC, meaning >37v Vmp and < 45.9v..Does that mean when the batts are in Float (100%) voltaje get even closer to VOC? If that the case then because equalization performs only when the batts are in float mode, voltaje should be enough to equalize at 62v. Am I right? If so then I will not have problem to equalize batts on a hot day (mostly all year).

BB.

Yes, in principle, that is what is happening.

In practice, you want somewhere around 2.5-5.0% of your banks rated capacity for "proper" equalization at around 60-61 volts.

Bank voltage is less critical than bank current (you are setting voltage high enough to get equalization current).

I.e., if you get 5% current at 59 volts (because your battery back is warn), then all is well.

Watch your battery bank temperature. It is very easy to overheat even at 2.5% rate of charge with hours of equalization current.

I hope I am answering your questions... Sometimes it is easy to answer the "wrong questions".

-Bill

dapago

BB. said:

Watch your battery bank temperature. It is very easy to overheat even at 2.5% rate of charge with hours of equalization current.

Yes you are. About the bank temp, if a remote thermometer is connected from the batt directly to the CC, doesn't the CC automatically take the temp data into account and terminate equalization when batts reach a certain temp to avoid damages to the bank? And if not what the max temp value for the batts to monitor during equalization?
tks..

Vic

Hi dapago,

The Classic has the option of Temperature Compensating the EQ voltage,  in the Charge Temp Comp menu.  IMO,  you should set this to 'YES'.  You should use the value of Temperature Compensation recommended by Trojan.

Also follow the Trojan recommendations for EQ voltage range,  time,  and when to EQ the battery bank,  as well as how to know when the EQ has done its job.

A battery that is in need of an EQ,  can require a lot of current to reach EQ voltage,  OR,  if the EQ current is limited,  it may take a considerable amount of time to reach the target EQ voltage.

Before the Classic has reached the temperature compensated EQ voltage,  the MNGP display will say that it is in 'EQ MPPT' mode,  meaning,  that the target EQ voltage has not been reached,  and that the EQ count-down timer will not yet being counting down the EQ minutes that have been set.

Opinions,   Vic

BB.

Monitor current and temperature--I do not know about the Midnite details (Vic certainly does)--But many charge controllers do not actively manage current/voltage/temperature during equalization--So keep an eye on the system until you are sure that all is working well.

-Bill

dapago

Guys.New data about the batts. It seems that the T105RE is the Smart Carbon model. Trojan says on its data sheet that this model (not the old T105RE) needs to perform equalization at 64.8V.
Million dollar question:
will the 2s4p wiring delivers that voltaje?

BB.

And, you will keep having these questions every time there is another something that pushes the voltage envelope... Longer term (all things being equal, which they rarely are), you need to get your 3s array + controller (or 4s+higher voltage controller going) and you have one less thing to worry about.

I cannot answer the question--It is on the edge. Normally, "hot batteries" need lower charging voltages. And you only need to equalize once a month (more or less--some folks equalize 1 times per month, others will equalize when high to low cell is ~0.015 to 0.030--One of Trojan's recommendations). So, perhaps you can pick your conditions and make it work.

http://www.trojanbattery.com/tech-support/battery-maintenance/

Correct the charging voltage to compensate for temperatures above and below 80° F (26.6°C). (Add .028 volt per cell for every 10° below 80° F (26.6°C) and subtract 0.028 volt per cell for every 10° F (12.2°C) above 80° F (26.6° C))

Lets say that your bank is running 15F over 80F...:

• 24 cell bank * 0.028 volts per cell per 10F * 15F rise = 1.008 volt drop at ~98F battery bank...

So, that does not make for the (pretty high) equalize voltage--But it helps a little bit. Hopefully, somebody here has the Trojan batteries can type about their equalization voltage/current profile in a warm climate.

But, this raises another issue... You have to look at the specifications for your AC inverter (and other DC loads)--Historically, high voltage cutoff for many AC inverters was 60-62 VDC--So during equalization, the inverter would shut down (high voltage alarm). Some newer/higher end AC inverters will run at higher DC input voltage--Just another "gotcha" in the off grid power world.

High charging voltage of battery banks is generally not an issue in hot climates--But our friends in the great white north with lots of sub freezing weather have high battery bank/inverter shutdown issues quite often.

Here is an AC inverter with 68 volt max input voltage:

https://www.solar-electric.com/lib/wind-sun/FXR_A_specsheet.pdf
https://www.solar-electric.com/lib/wind-sun/Magnum-MS-PAE-datasheet.pdf

And a 63 VDC max input:

https://www.solar-electric.com/lib/wind-sun/Sunny-Island-specs.pdf

I am really sorry I don't have better answers--Sometimes it seems that there is way too much "try and see if it works" out there in off grid power. Having an installer/supplier that can answer these questions (accurately) can be a God send.

-Bill

Photowhit

Trojan has be in conflict with it's self for several years, I guess they have a new separators out, but they have had the same info about equalizing in their literature for years, including the link Bill provided;

• "...Trojan only recommends equalizing when low or wide ranging specific gravity (>0.030) are detected after fully charging a battery."

But they also provided this video in 2012;

https://youtu.be/jCl5klSF4tE

Please note, they also don't differentiate between a maintenance and corrective equalizing, just stating that some chargers do equalizing automatically...

dapago

Bill, Photowhit and others here, I want to thanks you for your help. I just had a serious talk with the seller and he recognized his mistake, specially after I told him that the new Trojan Smart Carbon needs 64.80V to equalize. Apparently as Photowith said, he was doing maths with the "old" T105RE (61.92v to equalize).
As said Bill, with 62v I was just on the edge with a 2s4p wiring but 64.8v I passed the edge and equalizing would have been a problem for almost 9 months a year and certainly void the batts warranty.
So we decided to install a Midnight Classic 200 and keep with the 4s2p wiring at no extra cost for me.

Now my next step will be to understand the various settings the midnight 200 has and try "on the go", and with this forum help, to optimize my system in relation with my location and needs.

Thanks again and sorry for the (too) many questions I have been asking. I have been on other forums and this one is definitively the most effective for newbys like me and others. I haven't understood all of your answers but have tried my best to get my head on it.

Best regards.

Vic

dapago said:

Bill, Photowhit and others here, I want to thanks you for your help. I just had a serious talk with the seller and he recognized his mistake, specially after I told him that the new Trojan Smart Carbon needs 64.80V to equalize. Apparently as Photowith said, he was doing maths with the "old" T105RE (61.92v to equalize).
As said Bill, with 62v I was just on the edge with a 2s4p wiring but 64.8v I passed the edge and equalizing would have been a problem for almost 9 months a year and certainly void the batts warranty.
So we decided to install a Midnight Classic 200 and keep with the 4s2p wiring at no extra cost for me.

Now my next step will be to understand the various settings the midnight 200 has and try "on the go", and with this forum help, to optimize my system in relation with my location and needs.

Thanks again and sorry for the (too) many questions I have been asking. I have been on other forums and this one is definitively the most effective for newbys like me and others. I haven't understood all of your answers but have tried my best to get my head on it.

Best regards.

Sounds like a good choice,   it is good that the seller will accommodate you,  due to his error.

Let us know how your system is doing.   Good Luck,   Vic

dapago

Certainly will....