Need help - batteries not reaching full charge - adding more

[Westbranch]

Robbertwilliams,  Do your data sheets list a max charge rate in AMPS or  as % of Caoacity?  If not I would be inclined to set it to the 37A which is 10% of your battery capacity.

The rest looks OK to me.  pay it cautious.

Please add a description of you system in your signature line.

hth

[ClassicCrazy]

The temperature compensation is the adjusted charging voltage which is set by the Classic. So you put in -3mv and if the batteries are cold it will adjust the absorb voltage to charge higher than the setpoint.
For example
I have 28.8 set for Absorb Voltage .  with -3 mv in the temp compensation  the Temperature Compensated Voltage is now 29.9 volts because my batteries are -7 C .   So they charged to 29.9 v today for Absorb.  It also compensates float and equalize voltages ( optional on equalize voltage. ) So no you can't change that temperature compensated voltage unless you change the -3mv setting to something else.

What you describe with incoming watts going up when you turn on a load is how it is supposed to work if there is more available power than the batteries need.
Lets say you are charging 2 amps into the battery ( system amps ) but the panels have total 5 amps available. When you turn on a 3 amp load the incoming power will go up ,and 2 amps will still go to the battery but 3 amps is going to go to the load.  Of course amps in are not the same as amps out because they are different voltages. Watts is always the same though.

Again - the way the Classic charging works is Bulk you get all available power from panels into batteries. Once it gets to Absorb voltage ( which is temperature compensated )  the Classic will hold the voltage at the Absorb setpoint but decrease the amps to maintain that voltage.
At the end of absorb time or ending amps which ever comes first it goes to Float.

Not sure what to tell you about your other charger - don't have enough info on it to say.

Larry

[Westbranch]

Robbert, you said
I feel like something else is limiting my charge...what gives me this feeling is that incoming watts sit around 70w,

Yes you are correct, the internal resistance of the battery is most likely pushing back against the arrays output> CC's output current

[Vic]

Well, not sure if I have anything to report after today.  The "incoming" watts were at about 70w, and voltage at 34.5ish while in the absorb stage.  The battery peaked out at 29.8volts and the WBJr amps were at 1.6-2.0, kinda bouncing up and down but pretty much consistent.  So, I'm not sure if opening up the temp comp limits did much of anything. 

I feel like something else is limiting my charge...what gives me this feeling is that incoming watts sit around 70w, but when I turn the inverter on and start to draw on the system, the incoming watts go up to 175-200w (even more if I turn more stuff on). 

This is just becoming a bit overwhelming...the whole move in the middle of winter, not having this power thing figured out, our dog diagnosed with cancer, etc.

I did, however, fire up the generator and inverter/charger.  It seems to work well but am unsure of the settings.  The inputs are different than that of the Classic.  I've attached a couple pics that show what the Schneider electric Charger is looking for.  It's asking for amps instead of volts for the three charge stages.  Somewhere I believe I came across an article on C/5 for the bulk, C/10-15 for absorb, and C/20 for float...but I can't seem to find it. 

And what is Temperature Compensation Set Voltage?  And why is it 29.6?  Just curious, doesn't look like I can change it. 

Ok, my pictures are too big, even compressed, to add them as attachments. 

The SW is looking for the following:

Battery Type
Maximum Charge Rate - 100%
Max Bulk Charge Current - 48A
Max Absorb Charge Current - 37A
Max Float Charge Current - 2A
Charge Cycle - Set to 3 stage
Default Battery Temp - Not in Degrees but stated as "cold" or "hot" or "warm" (set to COLD)
Recharge Voltage - 25.0V
Absorption Time - 240min
Charger Override Enable/Disable - Disable

Do these settings look ok?

Hi robbertwilliams,

Several thingsl

When  you changed the Temp Comp Limits on the Classic,    did you press 'Enter' ?  Please check that you saved those changes  --  Enter does that.  Otherwise,  the Classic might revert to the previous Default values at Midnight.

Also,  you mentioned,   that in Absorb that the Input voltage was about 34.5   (assuming that this is on the Classic).   BUT,  in your initial Post in this Thread,  you said,  "4 Hyundai s250mg 250watt multicrystalline panels (series/parallel)"

If your input voltage is only 34.5 V,  and you have two PVs in series,  something is amiss.

If there are any clouds  PV production can be reduced significantly,   but normally one might expect that in this cases that the input voltage would be above about 60 - 70 V  on a cold day  but the power production would be low,  due to the clouds.

Are you certain that you have two PVs in series in each string?

If so,  you might want to try a different PV Mode for the Classic  --  Legacy P&O.   In cloudy conditions,  this different Mode can help.   The standard Mode of Solar,  does its MPPT Sweep very fast,  but at times in cloudy conditions,  it can sweep the PV input voltage down to about 4-5 volts above the battery voltage,  and this just kills PV power production.

What Firmware version is the Classic running ??   Press the Status button ( the small round one on the right),  about six or so times,  and note what the Classic FW version is.

You will get on top of this.   In the Winter,  in your part of the world,  things change a lot,  so there are quite a few factors that can be affecting your system.

Regarding the Schneider SW inverter,   unfortunately,  for the rest of us who do not use any of the Schneider stuff,   Schneider seems to choose to use completely different descriptors for almost every mode,  and setting for their solar hardware,  so,  folks like me,  do not know that they are thinking,   and what these unusual words mean for the operation of their gear,  there seems to be NO translator available.

Thanks for answers to the above questions.   You will get on top of the situation,  soon.  Vic

[Resthome]

Vic, hit the nail on the head. If your 4 panel are 2 series  2 parallel according to your panel specs you should be seeing around 60 volts on input of Classic not 34 volts. Something is wrong here.

Also what are all the checked setting for all items in the Tweats menu? Curious if LOWMAX is enabled?

[robbertwilliams]

That something wrong is my memory.  I just ran through it in my head; I have two parallel strings.

When I wired the panels I went with the setup to increase current, not volts.

Should I have done it differently?

I'm working on getting the signature description - hopefully later today.  I understand that trivia isn't fun for everyone.

Should lowmax be enabled?  I'll check it out this afternoon.  (Edit: LMAX is ON)  I'll also check to see which firmware.  Thanks again.  I really do appreciate this.

Edit:
The more I'm reading now...the better understanding.  I think my main reason for doing the panels in parallel was that then they'd be less susceptible to shade variances between the panels.  But it seems that I should've connected them in parallel, or at least series/parallel to adjust for the voltage drop from the panels to the controller (approx 50ft with 6 gauge).

[Vic]

Hi robbertwilliams,

If all of your PVs in parallel,   there can often be insufficient input voltage for an MPPT CC to find a good voltage for the PVs to produce very much power.

Have  not looked at the specs of your PVs,   but most Poly PVs are in the range of about 29 - 31 volt Vmp.   This is simply too low,   and is worse yet for Flooded batteries,  that need an EQ,   even worse than that,  would be cold batteries that need an EQ,  as EQ needs a relatively high voltage,  and so on.

EDIT:  BTW,  here is a footnote copied from the MidNite String Sizing Tool:

"   ...   Most all MPPT controllers will want to see a minimum of 130% of the actual high battery voltage. So if we have a 48v battery and it has an Equalize voltage if 62.3 volts than we would multiply that by 130% and we would need a minimum of 81 volts on the input on the hottest day of the year in order to have enough headroom for the MPPT to work   ..."

Here is the Link to the Classic Sizing Tool:
http://www.midnitesolar.com/sizingTool/displaySizing.php

Will look for the specs on your PVs.

More later,   Vic

[ClassicCrazy]

Robert ,
Could you get some photo's of how you have your panels wired up to the combiner box ?
Also some screen shots of Local Status App would help too - if you have that running.
Pictures worth a thousand words sometimes as the saying goes.
By the way - I run into that photo is too large to attach all the time too. I use Irfanview to half the size of the photo's.
Also you can lower the size image that your camera takes and then you won't have to resize them to attach.
Larry

[Resthome]

And to add to what Vic posted. If you are 50 ft from panels to controller you need to make it round trip for DC voltage drop. Here's a spread sheet that was posted here a long time ago for calculating Voltage drops. In this calculator you have to double the actual distant. So from Panel to Controller that would be 100 ft.

You can change the values in blue in the spreadsheet.

[robbertwilliams]

Still playing around.  I had adjusted the charge voltages on Monday morning.  I accidentally had plugged in the 24v voltages for the monobloc AGM, instead of monobloc FLA from the EastPenn chart.  So, it appears, based on the log, that it charged .6kw that day.  But then today, it sat in resting.  Must be just some dumb luck that Monday was a day of blazing clear sun, and today was a bit overcast...no idea.

So, based on what you all have said, I decided to switch my all parallel system over to, what I had originally quoted in the beginning of the thread, a series/parallel.  I'm assuming that the 130% MPPT rule has been keeping the controller at "resting".  In theory, with the new EQ set at 30.2v, my the controller would want to see 39.26v to start functioning (something that will never happen if I left the panels in full parallel). 

Tomorrow will be the first day with this new setup.  Hopefully, this will be when the ball starts rolling. 

Question 1, no one has gotten back to me on whether I should have "LMAX" on or off?

Question 2, in the original setup of the panels, I had (2) 20amp breakers in the combiner box.  I had (2) positive MC4  and (2) negative MC4 connections coming out of the combiner box.  Each connector then when into a 2way "Y".  So, each "Y" had either a set of (2) positives or (2) negatives.  With the new setup, I got rid of the "Y's", but I still have the (2) 20amp breakers.  SO, with that said, now that it is running in series parallel, do I need to resize these two breakers for each series string?

[Vic]

Hi robbertwilliams,   thanks for the Update.

IMO,  your system will perform much better with two PVs in series per string.

Just my opinion,  again,  but one would need to add to that EQ voltage of 30.2 volts,  any temperature compensation for the coldest temperature that you would ever expect the battery to endure.   SO,  YES,  the 2S X 2P PVs should help a lot.

Sorry about not commenting on LoMax.   You should be fine with this set to OFF,  it is not commonly used.

And,  good question about the size of the breakers in the Combiner.   You really do not need any breakers there,  with only two strings of PVs.   With three or more strings in parallel,  you would need a breaker for each string,   the maximum size of the breaker in that situation would be the Max Fuse size spec for your PVs  --  often this is 15A for recently manufactured PVs.   So,  you should be fine with those two 20 A breakers for now.

As stated previously,   you might want to plan for some additional PVs in the future,  just given the size of your battery bank's Capacity.

Good work on rewiring your PVs.  Good Luck,  please let us know how you are doing.
Vic

[Resthome]

Question 1, no one has gotten back to me on whether I should have "LMAX" on or off?

Question 2, in the original setup of the panels, I had (2) 20amp breakers in the combiner box.  I had (2) positive MC4  and (2) negative MC4 connections coming out of the combiner box.  Each connector then when into a 2way "Y".  So, each "Y" had either a set of (2) positives or (2) negatives.  With the new setup, I got rid of the "Y's", but I still have the (2) 20amp breakers.  SO, with that said, now that it is running in series parallel, do I need to resize these two breakers for each series string?

If you have your PV wired 2S2P for the 60V input to the Classic you should disable LOMAX.

I'm a little confused with how you had the Combiner box wired. You said you had two(2)positives and two (2) neg coming OUT of the Combiner. Not sure how that came about.

You should series connect 2 panel outside the Combiner box. Pos to Neg and have a pos from one panel and the Neg for the other panel run into the Combiner. Do the same with the other two panels. You now have two strings with 2 panels in series. When the positives of both strings are connect to the two breakers in the Combiner they are paralleled as the breakers are bussed together. All negatives go to the Neg buss bar in the Combiner. Coming out of the Combiner should be a single positive from the breaker buss bar and a single negative from the negative buss bar.

That said with both breakers in the Combiner ON and the Pos out of the Combiner connected to a PV Breaker at the Classic and the other side of that breaker connect to PV + at the Classic and the Negative from the Combiner connect directly to the PV -  at the Classic you should see around 60V as the Voltage on the PV + and -  terminals of the Classic when you have some sun on the two strings of panels.

Sorry if this is so confusing I should have just drawn a picture. A picture would have saved all the words.

Vic can correct me if said something wrong trying to write it out.

[Westbranch]

robbert, here are a couple of schematics, 1 parallel and the other series.... they are for the KID but just look at the panels and circuit breakers part..

hth

Parallel http://www.midnitesolar.com/pdfs/Kid_12V_2p_Par_REV_B.pdf

series http://www.midnitesolar.com/pdfs/Kid_24V_2p_Series_REV_B.pdf

[ClassicCrazy]

There are some good pictorials in the Kid owners manual on how to wire panels in series  / parallel configuration .
http://www.midnitesolar.com/pdfs/Kid_24V_4p_Series+Par_REV_B.pdf

Larry 

[ClassicCrazy]

ha ha - great minds think alike Westbranch !