XW only works during the daytime

Re: XW only works during the daytime

First, according to the voltage, your batteries are pretty much flat. Apparently both the Inverter and Volt Meter agree on that fact. You really don't want the resting voltage below ~46.3 volts (20% state of charge) as you run the risk of permanently damaging some of the sells (cells that go to zero volts and actually become reversed charged by the rest of the cells).

The Hydrometer reading should give you a resting voltage of ~49.7 volts which should be ~80% charged (sg=1.225).

So, you need to get the battery bank charged to >~75% state of charge (>49.6 resting voltage). You want to do this quickly--Batteries sulphate (hard crystals form) and will reduce the battery capacity the longer they spend below ~75% state of charge.

How will you be recharging the bank? Generator, grid power, solar, etc... What amount of current will your system be supplying to the battery bank?

As you get the batteries recharged (reach ~58 volts under charge and hold for a few hours--ideally until the cells reach 100% charge / specific gravity (whatever is the reading for your cells).

While this is going on, take a volt meter and move around each cell/battery in your bank and measure the voltage at each point... You are looking for differences... Under load, you are looking for the low cell/battery (i.e., is there one failed cell/battery and the rest are good?).

Under charging, you are looking for cells/batteries that don't act like the rest... Low voltage, possibly a shorted cell (or otherwise dead cell). High voltage, possibly an open or fully charged cell (for some reason).

I guess you have three parallel strings of batteries (8x 6 volt 530 AH in series, x3 strings in parallel for 24 batteries). Ideally, you want around 5-13% rate of charge (starting rules of thumb):

• 3x530 AH * 0.05 = 79.5 amps minimum
• 3x530 AH * 0.13 = 206.7 amps maximum

Can you do the above?

After you get the bank on charge--you can read a few threads about batteries. And a couple battery FAQ's:

NAWS Battery FAQ
www.batteryfaq.org

Also, do you have a DC Clamp Current Meter (this is a cheap one that will do the job--just a rebranded version of this one)? It will make monitoring your battery bank much easier--You want to measure the current in each parallel battery string and ensure that they are properly sharing charging/discharging currents. It makes finding open/shorted cells much easier (as well as bad electrical connections).

Something is going wrong here... Is your Hydrometer Accurate/good quality (measure your car's battery sg)? Tapping to remove bubbles from float? Batteries really cold? Are you measuring all cells or just a pilot cell (i.e., the cell you measure is OK, but there is one or more cells that are very low SG)?

-Bill

Re: XW only works during the daytime

You have 4 dead batteries at the moment. You want to get those charged right away. Mark them and keep track of them. They may never be right.

The others certainly need charging as soon as you get a chance.

It is going to take 5-10 reasonably sunny days with no loads for just solar power to recharge your bank (doing this from my phone, so my estimate may be off a bit).

-Bill

Re: XW only works during the daytime

Something is wrong with the wiring and/or programming on the charge controllers...

Measure the voltage at the charge controllers and at the battery bank--It should be within a few 1/10ths of a volt of each other (what is the gauge and length of the wiring from the charge controllers to the battery bank?).

And what is the charging voltage and absorb timer settings? Should be somewhere around 58-59 volts and 2-3 hours of absorb timing.

How much current are your controllers outputting to the battery bank (each/both)?

Do you have a Remote Battery Temperature Sensor? The voltage reading from the XW charge controllers (if I recall correctly) is temperature corrected to 77F (i.e., if the batteries are very cold, the XW will read lower voltage; if the batteries are very hot, the meter will read higher than battery voltage).

As the bank is charging, see if there is one or more cells/batteries that is reading high voltage in your string... If you have an open/high resistance battery, it will stop that string from recharging.

Also, check the voltage drop across each wire and connection point... If you read anything more than a few millivolts (1/10th or volts), you have a you may have a bad connection.

Also, check all the cells with a hydrometer and write down the value of the SG for each cell.

Something is not going right with your charging.

-Bill

By the way, equalization should only be done (is meaningful) after the battery has been properly charged and most of the cells have stopped increasing SG during charge (and are bubbling pretty well).

Equalization is typically performed when the cells' SG is ~0.030 or more difference from each other.

EQ pumps extra voltage/charging current through all cells, over charging the "full cells" so that the extra current can recharge the "weak cells.

EQ should be stopped after all cells stop rising in SG (check every 30-60 minutes). EQ is very hard on a battery bank and should only be done when needed (what you are doing is probably not equalization). Normally EQ is done every 1-3 months.

By the way, how long has your bank been in service? Have you needed to add water yet (typically, need to refill ~2 months if batteries are being properly charged).

-Bill

Re: XW only works during the daytime

Cpfarr wrote: »

I just checked each battery and they are all reading at 6.2 volts except for the one that is coming in at 0.0 volts now. I think I'm going to drop one string out of the equation till I can get that one replaced. The sg for this battery is 1.225. How can the voltmeter read 0.0 and the sg be 1.225 at the same time?

Was going to joke that the meter is set to AC range--but you are probably not laughing right now.

If you pull a string out of service, take the 4x "not right" batteries out of the connected strings and replace them with "good batteries" you have pulled with the one "bad string" (if you need to).

Do you have a 6/12 volt charger you can try on any of the "bad batteries"? See if you can get any current flowing through them and see what the SG does eventually become (haul the batteries to a place with grid power?).

I have about 16" of #6 awg going from each cc to the terminal blocks then it jumps to 4/0 to go to the batteries which is a 10' run.

According to a generic voltage drop calculator, you are looking at ~0.11 volt drop on the 16" cables and ~0.14 volt drop on the 10' cables (assuming 60 and 120 amps).

The charge voltages are set as follows;
Eqlz - 62.0 volts
Bulk - 57.6 volts
Absorb - 58.4 volts
Float - 54.0 volts
Absorb time is set at 120 minutes per Rolls and Dave's recommendation. I did set it to run for 240 minutes this morning before the sun came out to see if that would change anything but it did not so it's back to 120 min now.

Set the bulk to 58.4 volts for now.

Interesting that during the eq none of the batteries bubbled at all?

Batteries are less than ~80-90% full right now.

With the solar pushing max current (at least for today):

• What is the current flow into the battery bank?
• What does your volt meter read at the Charge Controller terminals and at the battery bank
• What do the two charge controllers read as output voltage?

-Bill

Re: XW only works during the daytime

I always like to recommend that people use a heavy and short cable from the charge controllers directly to the battery bank and not to share a single cable from several controllers over a long run to the battery bank.

It is possible that controllers can confuse each other with "noise" on the shared cable run.

This is more or less a guess on my side. There have been reliable reports here of inverters causing confused MPPT charge controllers. And the pulses from desulfators too (Bluesky and Outback are the two families I remember the reports about). The electrical noise appears to cause the controllers to not output as much power to the battery bank as they could (confuse MPPT tracking?). These problems may be rare--but it is hard to know (if your controller's output was down 20-30%, would you know?).

Is this case... I have no idea--but at this point the problem is severe enough that I don't think shared 4/0 wiring is the primary problem here-but 10-12 feet from the charge controller and sharing a 4/0 cable to the battery bank is something I would recommend avoiding if possible.

One possible check would be to shut down one of the shared charge controllers and see if the output current of the second controller goes up (or controller voltage readings change).

-Bill