A new classic 150 owner with a lot of questions.

[my t30]

Hi guys, My name is Philip and I am setting up a solar system for my Dad. I have some questions that my local dealer didn't really know how to answer so he said to post them here. So thanks for reading and I hope I didn't take up too much of your time.
The setup i have is:
(5) 130w Sharp panels (in series because of a 200ft wire run).
(5) 109ah Trans-Canada batteries (running at 12v, local dealer says that they are just marine deep cycle batteries. Wanted to go for better ones but couldn't because of space requirements).
(1) Midnite solar classic 150 ( which btw i really like the quality of but i need some help setting it up).

So i will number my questions to make them easier to read.
1. During a full day of sun the cc goes through Bulk, Absorb and then Floats for like most of the afternoon. But when i check the batteries with a hydrometer says that they are only at 12.40 volts when in float.and when the sun goes down the batteries drop down to 12.4 and are at 12.0 by morning without any heavy load. (The way we were charging the batteries before was with a truck alternator hooked up to a Honda engine. with that charger when the batteries were full they would still be at 12.9 in the morning after running it the night before.) I thing it has something to do with the amount of time it stays in absorb but i cant find any of the correct settings online for the batteries that i have. I did go through the wizard for setting it up but it isn't working properly i think?
2. What are the best EQ time and voltage?
3. What is the difference between Solar mode and Dynamic Solar?
4. Can i run my backup charger(which goes up to 14.5 volts) with the classic hooked up? I assume i would have to turn it off.
Cant remember any others right so thanks for taking the time to read and answer them.

[Westbranch]

Please post the specs for those panels.  that info is needed to see just what you should be producing.
From what you have said so far those batteries are being undercharged or there is a mystery load.

What was the voltage showing for the batteries on the Classic when it was charging the batteries. It should be in the range of ~ 14.4 volts
how have you wired 5 12 volt batteries?  5 batteries is not a good number to ensure they are all being charged evenly.
Have you checked the specific gravity of each cell? have you checked all the cable connections? Tight?

there is lots more but this will get things started.

[Vic]

Hi Philip,

I am going to assume that your Sharp PVs are similar to this:

Sharp ND-130UJF Electrical Characteristics
Maximum Power: 130 Watts
Voltage at Pmax: 17.4V
Current at Pmax: 7.5A
Short-circuit current: 8.2A
Open-circuit voltage: 21.9V

You might have an invoice for the PV modules with their part number,  and there will be a label on the back of each PV stating the above important abbreviations and numbers.

Is this information guess correct ?

Five PV modules in series may well be a fine configuration.
Five 12 V batteries in parallel is almost always TROUBLE,  usually,  BIG trouble,  as it is almost impossible to get charging currents equally shared between each batt.  AND,  if you are lucky  and they are balanced now,  they will certainly change as batteries age.  Many batteries in parallel can seem attractive,  as one can feel that this is a simple and inexpensive way to gain more capacity.  In reality  it is usually a fairly easy way to shorten the lives of the batteries,  as one lagging batt,  will drag down its neighbors.   The bank will never really be any better than the poorest batt.  More on this later.
And your guess may be correct,  that there may be too little time that the CC spends in the Absorption stage.

Here is a link to the latest manual for the Classic:
http://midnitesolar.com/pdfs/classicManual.pdf

There may be a newer version of Firmware for the Classic,  depending on when the Classic was made,  and weather any FW updates have been done.

More later,  Vic

[boB]

>>But when i check the batteries with a hydrometer says that they are only at 12.40 volts when in float

Do you mean check with a voltmeter ?  If so, in float, the voltage should be more like 13.6V.  This is
adjustable in the CHARGE --- VOLTS menu.

Was there a load on (inverter ?) when you saw this voltage ?

Also, what is the Absorb voltage set for ?   And minimum Absorb time ?  You might want to set the
minimum absorb time longer.... Especially if it is set for 1/2 hour which it might be by default.

>>2. What are the best EQ time and voltage?

EQ time and voltage depends on the batteries.  Time is usually for a few hours.  But always check
the water level when EQing.  Check the water level periodically anyway of course.

>>3. What is the difference between Solar mode and Dynamic Solar?

Dynamic is just another optional mode.  It moves around slowly.  That mode is in there
because others were doing this kind of tracking mode for a while. Usually SOLAR will work better.
Also, Legacy works pretty well.

>>>4. Can i run my backup charger(which goes up to 14.5 volts) with the classic hooked up?

Yes you can.  Just leave the Classic turned on.
If your external charger brings the battery voltage up above the Classic's set point
voltage, the Classic may go to resting though.  This is because the Classic can only try to
raise the battery voltage...  Not bring it down from whatever else is charging the batteries.


Westbranch is correct about checking the Absorb voltage.   If you used the old "wizard" from
the menu, just go to the CHARGE menu to adjust things.  Also, are you using battery temperature
sensor ?

boB

[niel]

those other questions can be good to get answered to refine your setup, but yikes, it almost sounds like somebody forgot to flip the breaker switch to on for those voltage readings are not of a battery bank receiving a charge. you did not tell us of what the present voltage settings are on for the classic or what it is you may have observed while it's operating. did your installer set any parameters or did he just connect it with default parameters?

[my t30]

Thanks for the answers, sorry if I didn't put enough info in my first post.

Hi Philip,

I am going to assume that your Sharp PVs are similar to this:

Sharp ND-130UJF Electrical Characteristics
Maximum Power: 130 Watts
Voltage at Pmax: 17.4V
Current at Pmax: 7.5A
Short-circuit current: 8.2A
Open-circuit voltage: 21.9V

You might have an invoice for the PV modules with their part number,  and there will be a label on the back of each PV stating the above important abbreviations and numbers.

Is this information guess correct ?

Five PV modules in series may well be a fine configuration.
Five 12 V batteries in parallel is almost always TROUBLE,  usually,  BIG trouble,  as it is almost impossible to get charging currents equally shared between each batt.  AND,  if you are lucky  and they are balanced now,  they will certainly change as batteries age.  Many batteries in parallel can seem attractive,  as one can feel that this is a simple and inexpensive way to gain more capacity.  In reality  it is usually a fairly easy way to shorten the lives of the batteries,  as one lagging batt,  will drag down its neighbors.   The bank will never really be any better than the poorest batt.  More on this later.
And your guess may be correct,  that there may be too little time that the CC spends in the Absorption stage.

Here is a link to the latest manual for the Classic:
http://midnitesolar.com/pdfs/classicManual.pdf

There may be a newer version of Firmware for the Classic,  depending on when the Classic was made,  and weather any FW updates have been done.

More later,  Vic

Yes those are the panels i have. Why would 5 batteries in parallel be bad? Because they have to be an even number of batteries or i have to connect them in series?
I am checking my firmware version now.
The charging voltages are all default.
Absorb 14.4, Float 13.2, EQ 14.4  Absorb charging time is set to Min 1:59 Max 2:00, End amps is 1.2A.
If i test with a voltmeter these are the voltages on the batteries while charging.
Thanks again guys.

[Westbranch]

here is a good source about multiple battery bank, it does a good job explaining the issues.

Just thinking, it might be best to just hook up one battery and see what the system does with that battery.  this will ensure the settings/connections area proper.   After that you can add 1 battery at a time looking for similar results.  If one battery/ connection is bad it will show...

Edit: missed out the smartguage link:  http://www.smartgauge.co.uk/batt_con.html

[Vic]

Hi Phillip,

Thanks for the added information on the PVs.  With five of them,  you have no other practical way to connect them and use all five.  This IS pushing the input voltage to the Charge Controller,   BUT,  you appear to have more significant problems just now,  so will leave this one be for now.

To me,  your charger settings appear OK for voltage,  but it does appear that these and the 3 hour Absorption stage is not getting the job done.  You might consider increasing the A.sorb time to five hours,  by increasing the Min and Max times by 2.00 hours.  You may well run out of sun in less than five hours,  but looks like you need more time.

When you mentioned that the Hydrometer read 12.40 volts,  you may well mean that the SG (Hydrometers measure SG -- the density of the electrolyte in this case).   This is not awful,  but it represents less than full charge.

Do you know the size of the wiring that connects each battery to the other,  and what is the size of the wire,  and approx length for the run between the output of the CC and the batteries?  It is very important that the length of the wiring connecting each battery be identical,  and ideally,  short.

Regarding the End Amp setting,  it seems low,  but think that it will be ignored due to the way the A.sorb times are set.   Normally,  this setting is 1-2% of the total AH capacity of the batteries.   So when used,  this COULD between about 5 and 11 Amps,  but this a bit of a more advanced setting just now.  You can ignore it.

Normally system design is based on the total power consumed by all of the loads on the system,  and at times the maximum of the largest load.   This would dictatate the amount of PV needed.  And,  the number of days that one needs to run on batteries often dictates the amount of battery capacity that is needed.

The absolute best design strategy is to obtain the battery bank's capacity in a SINGLE STRING of batteries connected in series,  if needed,  but not in parallel.  IMHO  two strings of batts is the maximum to ever use,  even that is often difficult to manage.
ENUF for now,   Is this application an RV?  Are you running an inverter?  Thanks,   Vic

[boB]

One of the problems with multiple battery strings in parallel is that the battery cells have a better chance of getting un-balanced.

The good thing about your installation is that they are only 12V each.  6 X 2V cells in series for each battery.  AND each
battery will have the same voltage across them.  This is good.  5 paralleled 12V batteries will be much easier to
manage than say, 5 strings of 48 V batteries in parallel.

I would say that as long as you cross-wire the plus and minus battery cables so that each battery has the
capability of seeing the same current in and out, you should be OK.

Using your hydrometer to check the SG of each cell once in a while will ensure they are indeed balanced.

Let us know how it goes.  If there are eventually problems, (it could take a very long time for that), and
you want to stay with a 12V system, you ~could~ opt to go with a set of 6 of those HUGE L-16 2V cell
batteries that are sold these days by various manufacturers.  Rolls for instance.

boB

[Vic]

Phillip,

I would NEVER argue with boB.  And,  we all run what we have,  until it fails to meet expectations/needs.

When I first moved to this,  Center Of Nowhere site,  I bought a travel trailer from a friend/neighbor.  It had a 12 V system,  and an MSW Inverter.  The batt bank was seven 12 Deep Cycle batts in parallel,  a 100 watt PV,  and a shunt controller,  IIRC.  Ran this for a couple of years.   The bank was never totally discharged by one errant battery,  I just could not run the Microwave oven from the batteries,  ever.  But that bank went for a total of about four years or so,  getting more and more feeble,  but it never did fail,   really.

So,  do not let perfectionists like me rain on your parade.  Run  What U Brung,  for as long as it will do the job for you.  Good Luck,  Vic

[boB]

Vic,   I forgot that if one battery goes bad in such a way that it drags the others down then
that could certainly be a reason for  not using lots of batteries in parallel.  But hopefully
you would figure that out very quickly.  I suppose one current monitor on each battery
in parallel could easily let one know when one battery out of several is not doing what it
is supposed to do....   BUT that means you just have a bad battery.  It would probably
have gone bad if it was in series with other batteries being used in say, a 48V system.
Then what do you do ?  That's the case for a battery balancer that makes sure that
each battery has the same voltage across them in a series string.
Placing them in parallel also makes sure they have the same voltage across them but
not each 2V cell unfortunately.

Let's try an experiment...  Let's take something like 20 X 12V batteries and put them
in parallel and see what happens !

boB

[Vic]

Hi boB,

A neighbor has a auto service business.   He has a get away cabin near me.  Historically,  he buys stale, new 12 V starting batts from a batt distributor.  Just about every time he comes to his cabin,  he brings yet another batt,  and two cables with him, and places the "new" battery in parallel with the others.  This often works.  On occasion,  he arrives to find NO POWER available.  A short or something has brought the entire bank to its knees,  and he starts over.

This works for him.  Have not seen the system he has,  but have heard that there ar about a dozen 12 V starting batts in parallel,  of varying ages --  one big happy family.

The worst situation that I've seen is one person who has six strings of 8D Gell batts on a 48 V system.  No way to tell SGs,  and way too many strings  THis guy is constantly fiddling with things.  Believe he has culled the best 12 batts into three strings.   In this case,  he felt that the "no maintenance" feature of SLAs would save a lot of time,  and heartache fiddling with batts.   He thinks,  now that this was a mistake.  This bank cost over $20K,  and has struggled to get about 2 years out of them.

To me the largest issue with battery banks,  is to pay attention to them.  One needs a relationship with their batteries.  They do speak to us,  and we need to be there to listen.

Measuring SGs is important, especially with multi batts/strings in parallel -- monitoring batts and making smallish changes to try to accommodate the changes that are needed.

Another thing that seems to happen is that few people place the necessary fuse/circuit breaker in each string to protect against fault currents in the unlikely event of a cell shorting.

The 7 parallel string that I inherited with the trailer mentioned above,  started out great (as reported to the person selling it to me),  and continued to loose capacity over time.  Quite a lot of this loss was probably caused by poor current sharing on both charge and discharge  twix the batteries.  It was adequate for some time,  just not up to the task of running heavy loads.

Just opinions,   Vic

[boB]

The worst situation that I've seen is one person who has six strings of 8D Gell batts on a 48 V system.  No way to tell SGs,  and way too many strings  THis guy is constantly fiddling with things.  Believe he has culled the best 12 batts into three strings.   In this case,  he felt that the "no maintenance" feature of SLAs would save a lot of time,  and heartache fiddling with batts.   He thinks,  now that this was a mistake.  This bank cost over $20K,  and has struggled to get about 2 years out of them.

Maybe what happened there was that he did not have enough charging energy or power to keep that huge string fully charged and then it sulfated ??
Just a thought.

What we have seen in the past is that people usually do not have enough solar or wind or whatever to charge their batteries fully and they go bad.

And connecting old 12V starting batteries up together probably isn't a good idea to power a house with.  It would be fine for starting a big engine maybe.  But as you know, the car alternator must always run pretty much to keep them up.  My car battery will  self discharge if I let it sit.

Actually, my truck battery went completely away after letting it sit for months.  Oh !  I forgot !  I was stolen along with the wires clipped off !

boB

[my t30]

Thanks Guys for all the replies. Yes the system is in an RV out in the middle of nowhere. I do have an cheapo motomaster inverter but i rarely use it because most of the loads are 12 volt. I did a firmware update and am  playing around with the absorb settings. I also cross connected the charger and loads to the batteries like i'm supposed.  (thanks westbridge for the link)
Today was the first day of good sun since i last posted so i tested the batteries with the hydrometer at the end of the day and they were better but still not perfect. Also i noticed that some of the individual cells were uneven in SG. I'm supposed to EQ to fix that right? If I am I'm still not sure what EQ voltage and time to use.

Today I noticed that the batteries were charging in absorb at 14.9v while I have it set to 14.4v. The only thing that I can think of is the temperature compensation raises the voltage because it was cold this morning and the batteries were at 10 C. Is this right because it's just a wild guess?

Also i noticed that once in a while during full sun the panel voltage drops from 100ish volts to 13ish, and the 12 volt current goes from 20ish amps to 2ish, for about 20 seconds and then back up to full power. I can also hear a faint buzzing/beeping noise in the charge controller during this time. Is it supposed to do this?
Thanks
Philip

[boB]

Thanks Guys for all the replies. Yes the system is in an RV out in the middle of nowhere. I do have an cheapo motomaster inverter but i rarely use it because most of the loads are 12 volt. I did a firmware update and am  playing around with the absorb settings. I also cross connected the charger and loads to the batteries like i'm supposed.  (thanks westbridge for the link)
Today was the first day of good sun since i last posted so i tested the batteries with the hydrometer at the end of the day and they were better but still not perfect. Also i noticed that some of the individual cells were uneven in SG. I'm supposed to EQ to fix that right? If I am I'm still not sure what EQ voltage and time to use.

Today I noticed that the batteries were charging in absorb at 14.9v while I have it set to 14.4v. The only thing that I can think of is the temperature compensation raises the voltage because it was cold this morning and the batteries were at 10 C. Is this right because it's just a wild guess?

Also i noticed that once in a while during full sun the panel voltage drops from 100ish volts to 13ish, and the 12 volt current goes from 20ish amps to 2ish, for about 20 seconds and then back up to full power. I can also hear a faint buzzing/beeping noise in the charge controller during this time. Is it supposed to do this?
Thanks
Philip

If the batteries were sitting at 10 degrees C instead of 25 degrees C, at -5mV per degree C per cell of temperature compensation, that
would come out to about 5mV * 6 (6 cells) = 30 mV per degree C for the 12V battery.   30mV times 15 degrees C of difference
(25 - 10) would should add about 0.45 volts to your setting.   That's  14.4 + 0.45 =  14.85 V which is just about what you found.

The beeping and buzzing is probably the "Low Max"  (LMX tweak)  doing its thing.  Since you have quite a high PV voltage,
you could probably get by disabling that LMX in the TWEAKS menu if you like.

boB