Classic 150 Settings

[inyour4head]

Here's what I've got:

(9) 285W SolarWorld PV's (three strings of three each wired into midnite combiner box)
Midnite Classic 150 Charge Controller with Whizbang Jr & 500a/50mv Shunt
MagnaSine MS4024 Inverter (4000W/24V)
(8 ) Trojan T105 Batteries wired in series/parallel (24V/450AH)

Here are the battery settings from Trojan:

EQ= 32.4
ABSORB= 29.6
FLOAT= 27.0

I'm currently getting anywhere from 8-10 kwh a day of sun and have estimated my daily usage to be about 4.5 kwh. The problem I'm having is that my batteries don't seem to be receiving a full charge, and even after the absorb stage is completed and it goes into float my battery AH or SOC continues to decrease when there is plenty of power still coming in to run everything directly off the pv's. Shouldn't my batteries remain at 100% SOC (if they are truly charged at 100%) until my pv's stop producing enough power to carry the loads? Or do I have to somehow hardwire the charge controller directly to my Inverter to run the loads directly off the pv's?

Here's what I've tried so far:

1. Calibrating the battery volts in the TWEAKS settings after letting them set for an hour or so without loads
2. Setting the CHARGETIME to 4 hours instead of 2 hours
3. Setting the ENDAMPS to 6.0v after watching yesterdays charge cycle

I have also noticed that sometimes it goes into FLOAT after the absorb charge and other times it goes into FLOAT MPPT. Whats the difference? There is no information in the manual about FLOAT MPPT. I also don't have a hygrometer just yet (apparently its a pretty handy tool for checking batteries) but I would think the Whizbang Jr and Shunt (yes they are properly installed) are supposed to accurately track the SOC/AH- at least that what I purchased them for. Am I wrong? We lost power the other night and the SOC was at least above 50% but the battery voltage was somewhere around 20v prompting me to start making the changes above the next day. I believe the Inverter shut the power off because of low voltage as it had to be reset. My batteries were at 76% when I got up this morning (I think the battery voltage was around 23.5v if I'm not mistaken) but after setting the ENDAMPS to 6.0v yesterday the absorb stage was so short that I completely missed it today, or it just went straight to FLOAT after the BULK MPPT stage completed. The pv's are bringing around 2000w right now and my battery bank is already down to 94% and counting.    Batteries are currently at 26.5v and the Classic continues to remain in FLOAT mode.

Any help would be greatly appreciated as we are new to off-grid living- and loving it despite the difficulties!

[dgd]

With flooded lead acid batteries such as the t105 you should plan for a maximum 20 to 25% depth of discharge in the daily charge/discharge cycle. See the manufacturers specs on DoD,cycles and life expectancy.
It would appear your battery capacity is too small for your overnight loads

The floatmppt state means there is insufficient input power for the classic to maintain the batteries at the float voltage setting.

You are seeing the 8 to 10kwhr daily energy from the Classic display?
How is the 4.5kwhr load estimTed? What are the loads?

And just to be sure, the only connection to your battery -Ve is one side of the deltec shunt?
All other -Ve connections inc the inverter go to the other side of the shunt?

Dgd

[inyour4head]

Thanks for the quick response!

From everything I've read its best to keep the batteries above 50% for longer life (less discharge is of course better) and with a 24v x 450ah battery bank that gives me a total of 10.8kwh at 100% discharge. Half of that would be 5.4kwh or 50% depth of discharge. The 4.5 kwh should leave me somewhere around 6.3kwh or 262ah remaining. Am I calculating this right? However, that 4.5kwh figure is for a full day of use so if my batteries were at 100% SOC in the evening when the pv's stop producing enough wattage to carry the loads then we should have plenty of headroom. Case in point after making the changes yesterday my batteries were fully charged at around 6pm and 12 hours later they were at 76% SOC- which is completely acceptable. Also, the well pump doesn't kick on at night and the laptop and modem are unplugged to reduce the load. Today my batteries were fully charged at around 12:30pm but the SOC/AH has been decreasing even though there is more than enough current coming in from the pv's to carry the loads. It has been in FLOAT ever since and holding the batteries at 26.5v so I don't understand why the SOC/AH continues to decrease. My batteries are currently at 86% or 388ah and my obvious concern is that they won't make it until the next charge. I'm not sure if I should REBULK and top them off while there's still enough current coming in from the pv's or not because by doing so I decrease the life of the battery. Am I wrong to think my batteries should hold a full charge in FLOAT while the excess current from the pv's supply the load as it is available?

Yes, the 8-10kwh is calculated on the Classic. The 4.5 is an estimate based on my figures using a kill-a-watt meter; refrigerator, small freezer, jet well pump, laptop, modem, led lights, etc.

The Shunt is on the negative side of my inverter with the battery on one side and the loads on the other. Also, the wbj is pointed towards the battery side as its supposed to be.

[dgd]

For FLA batteries That should be above 80% for longer life NOT 50%
Taking your batteries on a daily cycle anywhere near 50% DoD will kill them fairly quickly.
The 76% SOC looks good but not that good as it's showing you don't really have any reserve for the bad weather days where power input is low.
The solution is either more fla batteries or change to more efficient types such as LiFePO4 where 80% DoD is possible

reset the classic to the 2 or 3 hours absorb timing you originally had so that you get the 100% SOC after the absorb cycle completes

When you see SOC reducing and the classic is in Float is that actually floatmppt?

Dgd

[inyour4head]

Interesting. I don't have the link handy but I read somewhere that 50% dod would give me 4-6 years out of the T105's. People who keep them at 80% or more have reported 8+ years out of them. I'll definitely have to do some more research on the matter and consider adding another string. I've only been using them for less than a month so it shouldn't be a problem.

So do you recommend that I change the charge time, reset the ENDAMPS to 0, and REBULK the batteries today? We only have a couple hours left to store the power...

The Classic is in FLOAT (not FLOAT MPPT) maintaining the 26.5v but my SOC/AH continues to reduce. That doesn't sound right, does it?

**EDIT**

We just had some overcast come in and the Classic dropped into FLOAT MPPT so we'll just have to make it on the 80% SOC that's displayed. 

[inyour4head]

Can someone please tell me if the Classic is in FLOAT the batteries are to be kept at 26.5v and 100% SOC? Or is it normal for the SOC to decrease while the batteries are maintained at 26.5v?

[Vic]

Hi iy4h,  Welcome to the  Froum.

Just a few quick thoughts;

OK,  End Amps is a current setting  -- Amps.   When you "set EA to 6 V",  assume that you mean 6 Amps.   Rebulk is in volts,  and in the Advanced menu,  it is right next to the EA set value,  assume that you are really changing EA,  and not ReBulk,  which defaults to 8v,  and might possibly be settable to 6 V.  Know that you are not daft,  but just checking.

And know that you have the WBjr and Shunt installed correctly,  but,  just make sure that you have set things to USE that Shunt current and not the Classic's output current.

That Hydrometer is much more than a handy gadget,  it is THE ESSENTIAL TOOL for working with Flooded batteries.   Get two or three of them,  and test them all to see how well they agree.  Use one,  and set the others aside, in a safe place,  waiting for the time that the one you are using breaks.

Make certain that you are using the Battery Temperature Sensor (BTS).  Apply it to the side of the case on one of the batteries in the center of the pack.  IMO,  it is good to place a block of  Styrofoam(R)  over the BTS (1" - 2" thickness),  and tape it down to the clean battery surface.

You will probably want to get a DC Clamp Ammeter.   Sears has one for about $50-ish.   Very handy for measuring how well the two strings of batteries are sharing charge and discharge currents.

The WBjr is a great device,  and it counts Ah well.  But,  like any other battery monitoring device,  it is only as good as the setup data entered into it,  and,  at best,  it is a reasonable rough approximation of SOC of a battery.  There are many factors which can impact actual remaining Ah,  so constructing a good model for a battery is difficult.  And even if the data entry exactly described the nature of your battery on any given day,   the nature of a battery changes over a period of time,  and depends upon exactly how it is charged and discharged,  and so on.

Also,  batteries need a reasonable number of cycles to build full Capacity,   and perhaps your batteries are still settling in,  although,  after about one month of daily cycling,  they probably have developed their full capacity.

It might be time for you to do an EQ,  although,  it would probably be best if you fully charge your batteries,  measure the SG of EACH CELL,  and log this data in your battery Log Book.  Number each battery and each cell,  like #1 A,  B,  C;  2 A,  B,  C,   etc.

What is the battery Efficiency value that you have used,  when setting up the Classic for the WBjr?

Thanks,   Vic

[inyour4head]

Thanks for the reply Vic!

Yes, the ENDAMPS is set at 6 amps, not volts. It was a typo. That's the figure I came up with after carefully watching the batteries charge yesterday. I checked it every 10 minutes during the ABSORB time and it seemed to settle on 5.9A-6.0A. From what I've read its supposed to be 1-3% of the 450AH capacity so it certainly falls within that range.  However, I've read conflicting reports about even setting the ENDAMPS so I don't know if its best to use it or not. Whats your opinion on the matter?

So, how do I know if the Classic is using the Shunt current as opposed to the Classics output current?

I'll be going into town tomorrow and won't come home without the Hydrometers.

The battery temperature sensor is set and working. Thanks for the tip about the styrofoam.

I don't have an Ammeter but will add that to my list. I was careful to make the battery cables the same length so hopefully that pays off.

I haven't attempted to do an EQ just yet but that may be in order once I can get the batteries fully charged. Also, a battery log book is an excellent idea! How often would you recommend checking them?

I set the battery efficiency for the T105 at 85% per the Trojan tech I spoke with the other day.

[dgd]

Can someone please tell me if the Classic is in FLOAT the batteries are to be kept at 26.5v and 100% SOC? Or is it normal for the SOC to decrease while the batteries are maintained at 26.5v?

I have not seen this occur on any of my RE systems. If a load comes online during float then the Classic will increase it current  output to cover the load and maintain float voltage (assuming there is sufficient PV input power) otherwise it will drop back to FLOATMPPT and put all PV power into the battery/loads.

It would be good to see your wiring circuit info, do you have a diagram of this? and maybe some photos of your setup - battery wiring, DC distribution box wiring etc..
dgd

[inyour4head]

That's what leads me to believe the batteries aren't fully charging. I have seen the Classic increase its current to cover the load in FLOAT before but at the same time the SOC/AH still decreases. Perhaps the wbj is reading the Classics output current as opposed to the shunt output current as Vic mentioned??

I don't have any diagrams or pictures on hand but I'll try to explain.

The pv's run into the combiner box and then to the corresponding Classic terminals. I also have a midnite surge protector in the combiner box wired per the instructions that came with it. The Classic runs into the battery bank from the other set of terminals. Battery positive and negative run from the battery box to the bottom lugs on the inverter. Positive and negative run from the inverter terminals to the house breaker box. The wbj cable is connected to the AUX2 terminal then proceeds to the Shunt on the inverter cable lugs as previously described- battery on one side load on the other. I also plan to add some breakers in the future so I don't have to run to the combiner box or battery box every time I need to disconnect power. Hindsight is always 20/20.

[dgd]

The pv's run into the combiner box and then to the corresponding Classic terminals. I also have a midnite surge protector in the combiner box wired per the instructions that came with it. The Classic runs into the battery bank from the other set of terminals. Battery positive and negative run from the battery box to the bottom lugs on the inverter. Positive and negative run from the inverter terminals to the house breaker box. The wbj cable is connected to the AUX2 terminal then proceeds to the Shunt on the inverter cable lugs as previously described- battery on one side load on the other. I also plan to add some breakers in the future so I don't have to run to the combiner box or battery box every time I need to disconnect power. Hindsight is always 20/20.

Sorry, but the battery wiring needs explained more exactly
The +ve cable from the battery bank box goes to inverter +ve lug
The -ve cable from battery box ONLY goes to the one side of the shunt AND NOT TO THE INVERTER -ve lug
(You say above that it does!)
Then the other side of the shunt goes to the inverter -ve lug where all the other -ve connect to, such as the Classic -ve etc...
Is that what you have.
Please take a couple of photos as they will clarify

dgd

[dgd]

I would also strongly recommend you get a Midite Epanel or an MNDC box with 250A breaker for the inverter and 80A or 100A breaker for the Classic.
Both these boxes have space for the Deltec shunt/Wbjr and come with detailed wiring diagrams

dgd

[Vic]

That's what leads me to believe the batteries aren't fully charging. I have seen the Classic increase its current to cover the load in FLOAT before but at the same time the SOC/AH still decreases. Perhaps the wbj is reading the Classics output current as opposed to the shunt output current as Vic mentioned??

I don't have any diagrams or pictures on hand but I'll try to explain.

The pv's run into the combiner box and then to the corresponding Classic terminals. I also have a midnite surge protector in the combiner box wired per the instructions that came with it. The Classic runs into the battery bank from the other set of terminals. Battery positive and negative run from the battery box to the bottom lugs on the inverter. Positive and negative run from the inverter terminals to the house breaker box. The wbj cable is connected to the AUX2 terminal then proceeds to the Shunt on the inverter cable lugs as previously described- battery on one side load on the other. I also plan to add some breakers in the future so I don't have to run to the combiner box or battery box every time I need to disconnect power. Hindsight is always 20/20.

Quickly,

There are two places where you will see "Shunt"  on the Classic's MNGP display.
First one is in the Advanced menu,  and is under the set value for EA,  IIRC.
AND,  there is another on the WBjr Status display ...  about the fourth button-push on the Status pages.  This is the display of the WBjr battery charge Amps,  somewhere on that page,  it should say Shunt.

If the WBjr has not been setup to use the Shunt,  then those displays might say,  " Classic ".

IIRC,   Vic

[inyour4head]

Thanks for the info. I will definitely look into getting those breaker boxes.

As for my wiring perhaps I didn't explain very well. My +ve from the battery bank goes onto +ve inverter lug. The -ve from the battery bank goes onto one side of the shunt, and then the other side of the shunt goes onto the -ve lug on the inverter. My Classic does not connect to the inverter at all. The +pv and -pv from the combiner box goes onto the +pv and -pv terminals on the Classic. Then the second set of +ve and -ve terminals on the Classic go onto the +ve and -ve terminals on the battery bank. Does this sound correct?

I'll try to post a couple pictures when I have time.

[Vic]

Thanks for the reply Vic!

Yes, the ENDAMPS is set at 6 amps, not volts. It was a typo. That's the figure I came up with after carefully watching the batteries charge yesterday. I checked it every 10 minutes during the ABSORB time and it seemed to settle on 5.9A-6.0A. From what I've read its supposed to be 1-3% of the 450AH capacity so it certainly falls within that range.  However, I've read conflicting reports about even setting the ENDAMPS so I don't know if its best to use it or not. Whats your opinion on the matter?

So, how do I know if the Classic is using the Shunt current as opposed to the Classics output current?

I'll be going into town tomorrow and won't come home without the Hydrometers.

The battery temperature sensor is set and working. Thanks for the tip about the styrofoam.

I don't have an Ammeter but will add that to my list. I was careful to make the battery cables the same length so hopefully that pays off.

I haven't attempted to do an EQ just yet but that may be in order once I can get the batteries fully charged. Also, a battery log book is an excellent idea! How often would you recommend checking them?

I set the battery efficiency for the T105 at 85% per the Trojan tech I spoke with the other day.

Hi iy4h,

Yes,  looks like you have set up the EA correctly for a start.   Measuring SGs when the Classic goes to Float should confirm this EA value.   Or allow you to change EA a bit to get a full-charge.   I have ONLY used EA for over a decade on all systems that I deal with.   In earlier days,  used CC EA,  without a Shunt,  which can also work OK.

Very good that you are using the  BTS.

IMO,  a glass float/glass outer tube Hydrometer should be fine.  Try to find ones that have real numbers on the float,  and go from about 1.110,   to 1.3XX.   Colors on the float are OK,  just as long as there are actual numbers for measured SG.   Believe that the Trojans are typically 1.277-ish when fully-charged.

NAPA,  or other good Auto Supply store should have perfectly adequate Hydros.

85% Efficiency is a fine place to start for Flooded (FLA) batteries.

Often  one chooses one or two Pilot Cells.  These are often cells that have the lowest SG in the bank.  You can check this one or two cells as a quick survey of the approximate SG of the battery bank.

Initially,  you will probably want to check SGs fairly often,  every week  or so,  until your battery becomes fully-charged,  and you feel it has become predictable.

Here is a Link to Surrette Battery's article on measuring SGs:
http://support.rollsbattery.com/support/solutions/articles/4347-measuring-specific-gravity

More Later,   Vic