Outback system not charging my batteries

surveyor1

Hi Guys,
I have a system with 7k of pv, 2 outback fm 80 charge controllers, a radian and 1200 Ah battery bank. i consume a constant 700 watts during the day and about 1200 watts during the night. However, during the day while charging my batteries and running the system, my CC is only taking my batteries up the 56.6 volts and might hold it at that voltage for no more than 1.5 hrs before it goes into float. when i run the numbers, i don't think that my batteries are getting fully charged.
Can someone advise me as to what i can do to atleast get the CC up to 57.6 volt absorb charge? What other settings should i have to ensure that my system gets the battery fully charged?
thanks in advance for your help

Plowman

Re: Outback system not charging my batteries

Sealed batteries? If not, check specific gravity to verify state of charge.

surveyor1

Re: Outback system not charging my batteries

these are AGM batteries.....24 -2 v making a 48v system

vtmaps

Re: Outback system not charging my batteries

surveyor1 wrote: »

Hi Guys,
I have a system with 7k of pv, 2 outback fm 80 charge controllers, a radian and 1200 Ah battery bank. i consume a constant 700 watts during the day and about 1200 watts during the night. However, during the day while charging my batteries and running the system, my CC is only taking my batteries up the 56.6 volts and might hold it at that voltage for no more than 1.5 hrs before it goes into float. when i run the numbers, i don't think that my batteries are getting fully charged.
Can someone advise me as to what i can do to at least get the CC up to 57.6 volt absorb charge? What other settings should i have to ensure that my system gets the battery fully charged?
thanks in advance for your help

Is this entirely off-grid?
What have you set the absorb voltage to?
How have you set the absorb to terminate (by timer, or end amps)?
Do you have a remote battery temp sensor, and what is the temp of your batteries?

--vtMaps

surveyor1

Re: Outback system not charging my batteries

this is an entirely off grid system.
my absorb voltage is 57.6 per concorde manual. however, the highest i have seen on the mate is 56.6 during absorb
i had it to terminate by either timer or end amps.......this has no effect. the time set for absorbing is not being reached
yes i have a rbt sensor plugged into the radian. the temperature of the battery is 32c. i am using the outback mate and also has the flexnet dc battery monitoring system installed.
i can see the voltage temperature correction and even then the temperature voltage dont reach the 57.6v.

i have disabled the advance flexnet dc charge termination, have adjusted the charge factor downwards, have increased the bulk time, but none of this has caused any improvement in the CC staying in absorb longer than 1.5 hrs.

what am i doing wrong?

SkiDoo55

Re: Outback system not charging my batteries

Might give the array setup, panel model, panels in strings and number in,parallel. Input voltage at cc's when output 56.6 VDC Ambient temp etc. More info helps them help you.

surveyor1

Re: Outback system not charging my batteries

I have 27 Helios 255w panels setup as 9 string of 3 panels. one of the cc has 4 strings while the other has 5 strings. the system is in a building by itself with windows always open so i guess the ambient temp would be about 28 C . the CC would be reading in their low 80 volt range when in absorb stage.

vtmaps

Re: Outback system not charging my batteries

surveyor1 wrote: »

I have 27 Helios 255w panels setup as 9 string of 3 panels. one of the cc has 4 strings while the other has 5 strings. the system is in a building by itself with windows always open so i guess the ambient temp would be about 28 C . the CC would be reading in their low 80 volt range when in absorb stage.

troubleshooting time.

How about a little experiment... unplug the battery temp sensor... see if your voltage goes higher. Stay near and monitor voltage and battery temp... don't let it get away from you.

Next, get out your digital voltmeter (with fresh batteries) and check the voltages on each of your 2 volt cells. It would be good to have voltages while resting as well as during charging and discharging (the higher the current, the better). Can you run the system with a generator for a few hours while you rest the batteries?

Make sure the voltage of the battery as a whole (measured in the battery box) matches the voltage shown on the Mate... this must be checked while charging or discharging (the higher the current, the better).

Speaking of charging, do you have a DC clamp ammeter? If so, confirm that you have the expected current from your arrays and to the battery. Is the battery current (after loads) high enough to charge those batteries?

If all of the above is OK, then it might be programming.

--vtMaps

niel

Re: Outback system not charging my batteries

32 c is a bit hot. that has to be cutting the charge voltage down because of how hot they are. why are your batteries that hot is the question?

SkiDoo55

Re: Outback system not charging my batteries

32C isn't Hot, my current free air temp is 35.6C/96.1F. Small battery in float showing 35C? On display of XW MPPT60-150 from BTS.
had over 40C for yesterday! Sure that some of the AZ temps are higher.

niel

Re: Outback system not charging my batteries

yes, but it will pull down the voltage going to the batteries some.

mtdoc

Re: Outback system not charging my batteries

You need a Flexnet DC to track your batteries amps in and amps out (state of charge) and to be able to use end amps (aka return amps) to end your absorb only after fully charged.

Add: I see from one of your posts that perhaps you do have a Flexnet DC? If so, make sure it is correctly set up (see HERE- You likely have a Mate3 so the procedure may differ slightly but the idea is the same)

Get the return amp setting from your battery manufacturer's specs.

SkiDoo55

Re: Outback system not charging my batteries

niel wrote: »

yes, but it will pull down the voltage going to the batteries some.

yes it will! Compensate charging curve. I don't have total capacity when it's 40C ++😳

surveyor1

Re: Outback system not charging my batteries

Hi GUYS,
I tried vtmaps suggestion and removed the temperature sensor. This was an eye opener. My observations: (1). I realized that the volt meter reading of the batteries and at the charge controller were different. So i had to calibrate the CC. (2). once this was done, the absorb voltage did rise and i saw the 57.6 volt on the batteries. (3) I allowed the batteries to absorb and they did that for about 3 hrs. As suggested, I had a thermometer within the battery bank to keep an eye on the temperature. The temperature remained at 32c throughout. that's a good thing. (4) at the end of the day the bank was reading 52.1v without load. I then allowed the bank to rest for 1 hr and the voltage went down to 51.8v. I then checked the individual cells and they were reading an average of 2.15v. (5)The battery manufacture literature says that a voltage above 2.13v suggest the batteries are full. So far so good!!

I will use them over night and try again in the morning!

Question: (1) when the OB mate 3 is charging, do it use the temperature compensated voltage, or the actual battery voltage.
(2) because am using my radian on the batteries while they are being charged, should i also add the load amps to the battery end of charge amps as per manufacturer to get the final end of amperage value for input into the mate?

vtmaps

Re: Outback system not charging my batteries

surveyor1 wrote: »

I tried vtmaps suggestion and removed the temperature sensor. This was an eye opener. My observations: (1). I realized that the volt meter reading of the batteries and at the charge controller were different. So i had to calibrate the CC.

That's very worrisome!! Before you calibrate the charge controller you MUST FIRST look to see if the reason for the discrepancy is a voltage drop in the wiring.

While bulk charging (high current) measure the voltage at the battery terminals with your voltmeter. Then use the same voltmeter to measure the voltage at the output terminals of the controller. If they are different it means you have a voltage drop in the wiring.

If you do have a voltage drop, two consequences:

1) the bad connection (or partially broken wire) makes heat or may arc. this is a fire danger. While charging you can use an infrared thermometer to look for hot spots.

2) you can ruin your batteries. Voltage drop is proportional to current flow. If you are losing a volt at full power it may take a long time to get to absorb, but as the current tapers off the voltage drop is reduced and the actual voltage at the batteries will rise towards the actual voltage of the controller. By calibrating your controller to put out a higher voltage (if that's what you did) you may be putting your batteries at risk of seeing that higher voltage.

btw, I'm not saying that calibrating your controller was the wrong thing to do... I don't have enough info to make the diagnosis. But you must be certain to eliminate the possibility of a voltage drop.

When I suggested that you remove the temp sensor, I was troubleshooting to see if it might be defective. It has an important role, especially with AGM batteries. When your batteries are warm, their tolerance to voltage goes down. AGMs do not tolerate overvoltage well. You need temperature compensation to protect them when they are warm. At 32° C, your battery voltages should be a bit less than the specified voltages.

surveyor1 wrote: »

Question: (1) when the OB mate 3 is charging, do it use the temperature compensated voltage, or the actual battery voltage.
(2) because am using my radian on the batteries while they are being charged, should i also add the load amps to the battery end of charge amps as per manufacturer to get the final end of amperage value for input into the mate?

1) The actual charging voltages that the controller uses are the temperature compensated voltages. That's the whole point of having temp compensation. The actual battery voltage and the output voltage at the controller should always agree (as measured with a voltmeter), if they don't it means you have a voltage drop.

2) you don't need to to account for load amps... you have a flexnet DC. It can measure battery current... it doesn't need to subtract loads from production to guess at battery current. Also, you have two controllers... I don't think end amps can be coordinated with two controllers without the flexnet DC.

--vtMaps

jcheil

Re: Outback system not charging my batteries

vtmaps wrote: »

btw, I'm not saying that calibrating your controller was the wrong thing to do... I don't have enough info to make the diagnosis. But you must be certain to eliminate the possibility of a voltage drop.
--vtMaps

I am not 100% sure on this, but I "think" the calibration doesn't actually change anything related to the charging. It just calibrates the "meters" on the different devices to make sure they all "see" the same voltage. Now, does that is some way "indirectly" effect the charging rate? I do not know. I know I had to calibrate mine in that the voltage the CC "saw" vs the voltage the mate3 "saw" vs the actual battery bank voltage at the terminals were off a few 10th's of a volt each. If I recall, the CC was low by .1v of the "actual" voltage of the battery bank and the Mate3 was low by .2v or something like that.

But I also would really like to know for sure what it does and if I/we are using it properly.

solar_dave

Re: Outback system not charging my batteries

SkiDoo55 wrote: »

32C isn't Hot, my current free air temp is 35.6C/96.1F. Small battery in float showing 35C? On display of XW MPPT60-150 from BTS.
had over 40C for yesterday! Sure that some of the AZ temps are higher.

About 42C here yesterday, 45C not unheard of, record high 50C.

SkiDoo55

Re: Outback system not charging my batteries

Yes I know how hot it gets there. Have worked in It Tucson and Gila Bend area many summers in past years, keep wrenches etc in a bucket of water so you can handle them type of heat!😰

surveyor1

Re: Outback system not charging my batteries

vtmaps wrote: »

That's very worrisome!! Before you calibrate the charge controller you MUST FIRST look to see if the reason for the discrepancy is a voltage drop in the wiring.

While bulk charging (high current) measure the voltage at the battery terminals with your voltmeter. Then use the same voltmeter to measure the voltage at the output terminals of the controller. If they are different it means you have a voltage drop in the wiring.

If you do have a voltage drop, two consequences:

1) the bad connection (or partially broken wire) makes heat or may arc. this is a fire danger. While charging you can use an infrared thermometer to look for hot spots.

2) you can ruin your batteries. Voltage drop is proportional to current flow. If you are losing a volt at full power it may take a long time to get to absorb, but as the current tapers off the voltage drop is reduced and the actual voltage at the batteries will rise towards the actual voltage of the controller. By calibrating your controller to put out a higher voltage (if that's what you did) you may be putting your batteries at risk of seeing that higher voltage.

btw, I'm not saying that calibrating your controller was the wrong thing to do... I don't have enough info to make the diagnosis. But you must be certain to eliminate the possibility of a voltage drop.

When I suggested that you remove the temp sensor, I was troubleshooting to see if it might be defective. It has an important role, especially with AGM batteries. When your batteries are warm, their tolerance to voltage goes down. AGMs do not tolerate overvoltage well. You need temperature compensation to protect them when they are warm. At 32° C, your battery voltages should be a bit less than the specified voltages.

--vtMaps

Hi vtmaps,
Thanks for your timely advice. When i did the calibration, the system was at idle with no loads. The voltage reading on the CC was displaying a few tenth Higher than what i was reading with the volt meter at the battery terminal and cc terminal. the voltage display on the mate was also a few tenths higher than the battery reading. So i adjusted downward both mate and CC.
Before the charging cycle started this morning I reconnected the temperature sensor. Today turned out ok. I think, but i will await your input! The batteries reached 100% and it was a bit overcast. I did several voltage measurements and the CC display is now in sync with my readings a both the CC terminal and the battery terminal. I looked at the mate and i saw how it applied the temperature corrected voltage. So although the CC was sending out 56.8 volts, the temperature corrected voltage is 57.6. Thus it seems like the batteries are now getting their due. additionally, the unit gave me an absorb charge for 4 hrs today. The longest i have seen. This is in line with what the manufacture say to expect.

I will give you another update tomorrow.

BB.

Re: Outback system not charging my batteries

You also have to be aware of what different mfg. display on their meters. Some display the "raw" voltage, others will display the temerature corrected voltage (25C nominal voltage).

Most will temperature correct their charging voltage set points, but some (few, many, all) will not temperature correct their Equalize voltage set point.

A good/accurate DMM is very handy to figure out what the heck is going on.

-Bill "a person with one meter, knows the voltage; a person with two meters is never sure" B.