XW 4024 DC Under Voltage warning (W 48 )

Re: XW 4024 DC Under Voltage warning (W 48 )

If you have a volt meter--Check the voltage of each cell under load, and check the voltage at the input lugs of the inverter.

The batteries should be able to support ~23.0 volts, and the inverter could have its low voltage cutoff as low as 21.0 volts (allow for up to 2.0 volts drop across wiring--wprse case).

At this point, looking for "differences"... A bunch of cells with normal voltage, and one or two cells significantly less.... A voltage drop across a cable or connection that is higher than anywhere else (corrosion, loose connection, etc.). Or a "hot" connection/wire (again, loose/dirty/corroded connection).

What is the battery bank/room temperature? Did the system every "work correctly"? Are these new or older batteries, etc...?

-Bill

Re: XW 4024 DC Under Voltage warning (W 48 )

How are you measuring XX% state of charge? Battery Monitor? Hydrometer?

The second measurement set at 92% SOC would seem to indicate that the bank is less than 92% state of charge, or is beginning to sulftate.

Large batteries that are cycled below 80% SOC can need a fair amount of current and time to recharge--And sometimes higher voltage levels.

How often are you having to replace water (distilled or equivalent) in the battery bank... Having to add some back every couple of months is probably about right. If you never have had to add water, they may be under charging.

To fully charge a battery bank, you need to hold ~29 volts (depends on battery mfg. instructions) for 2-6 hours (2 hours if you don't discharge very deeply, 6 hours if deeply discharged). Some folks have found that they may need to add 0.5 volts to 2 volts to really get the battery bank fully recharged (again, depends on chemistry/battery construction).

Check and log the temperature corrected specific gravity for all cells. And monitor one cell as you discharge and see what the S.G. levels are doing... Are you really using 10% of the battery state of charge, or are you cycling deeper than you expected.

Battery variations (alloying with lead) can change behaviors... Batteries designed for Fork Lifts (very deep cycling) can use a lot of water and moderate voltages. Batteries designed for float service and low water usage (calcium) can need higher voltages to complete charging.

A couple of good ways to tell when a lead acid battery is getting fully charged... As they approach 95-100% SOC, the battery will begin to "boil" or "fizz" (like a carbonated drink). If you have little gas being produced while the there is good current flow (over 2.5% of battery AH capacity), then it is not fully charged yet.

Another is to monitor the battery charging current when holding absorb voltage (~29 volts)... You will see the charging current slowly drop over a couple of hours--To ~% to 1% or less of AH capacity (660 AH = 13.2 amps to 6.6 amps or less) and then "Level Off" (plateau) or stop dropping... At this point the battery bank should be full.

If nothing like the above is happening, then you probably need more charging time or current. Are you using solar panels to charge or the XW Inverter/Charger connected to mains or generator to recharge the bank)?

What is the size of your array (Vmp-array voltage, wattage, charging parameters -- Absorb Voltage, Absorb Timer, etc.)?

Assuming all else is well--It sounds like dropping the LBCO voltage and checking how will the batteries are charging (specific gravity, charging parameters) are the two avenues of investigation I would suggest.

-Bill