My XW6848 inverter/charger won't charge the battery bank more than 20 amps.

paulcheung

Hi guys,
I am new here. my XW6848 won't charge the battery bank more than 20 amps. I have set the max. charge rate at 50 amps on both bulk and absorb. Floating at 30 amps max. is there other setting I need to look at? my battery bank is 48 volts 370 amps. hours FLA.
Thanks.

BB.

I have never seen an XW... But some things that may affect the system:

• Many times, charging current is 120 or 240 VAC amps input (I.e., the AC branch circuit rating), not the DC output amps. (i.e., 30 AAC * 240 VAC = 7,200 Watts; 2,400 Watts / 58 VDC charging = 125 ADC charging to battery bus)
• Do you have 120/240 VAC fed to XW+, or just 120 VAC?
• Have you checked the battery bank AH rating in the XW? I don't remember if it limits charging current to XX% of battery AH capacity, or simply uses to display XXX% state of charge.
• Have you measured the voltage at the battery bus and see what it is really? Also, double check the DC wiring from the battery to the XW Vbatt output and make sure is good, no big voltage drop, etc.).
• Does the XW+ display (nearly) the same VDC for Vbatt as your meter? Some inverter-chargers can be calibrated if the internal meter readings are off.
• XW+ set for battery type (flooded cell, AGM, etc.)?
• Is the Remote Battery Temp Sensor wired up and reading correct battery temperature?

Anyway, no expert, but that is where I would start.

-Bill

paulcheung

The input AC is 230 volt split 115 volt each line. The DC volt is fine between 50 volt to 62 volts. It has set at 53 volts on grid support. The charge controllers and the Combox display the same voltage. The connection should be good as it export to the grid through XW6848 with around 100 amps DC sometime during the day, sometime it draw more than 50 amps from the battery bank.
Thanks.

BB.

I should also ask--What is the state of charge of the battery bank (type of batteries, specific gravity if flooded cell, temperature, etc.)?

And, are you discharging the battery bank and then looking for charging current? More or less, you may not see full charging current from a battery charger until the battery bank is ~80% or less state of charge... If the battery bank is >90% SoC, you will generally see much less current (tapering to ~1% or less rate of charge as you approach 100% SoC).

Do you have any other 48 VDC battery bus loads (another standalone inverter, some other DC loads)? Or is the XW+ your only battery bank load?

In very general terms, these are the expected rates of charge for a 48 VDC flooded cell deep cycle lead acid battery bank). Note Rate of Charge is based on battery bank 20 Hour capacity rating. Voltages are for typical FLA batteries at ~25C/75F (as lead acid batteries get hot, their charging voltage should fall a bit). And, as always, try to find the Mfg's specifications/operator's manual:

• Float Charging (no other DC bus loads) ~2% rate of charge maximum (near end of life). New FLA batteries are probably in the ~0.1% to 1% rate of charge (or less). Float voltage is ~54.4 VDC (very rough)
• Bulk Charging: Typically for solar, we suggest 10-13% rate of charge (relatively gentil charging rate). For AC (or genset charging), you can pump upwards of 20-25% rate of charge (typically will only see at less than 80% SoC and less than ~59.00 VDC battery bus voltage). 
• Absorb Charging" is the transition from Bulk to Absorb charging (bulk=current limited charging; absorb=voltage limited charging). Generally, Absorb would be ~59.00 volts held from ~80-90% SoC to full charge. For FLA batteries, absorb is roughly 2-6 hours (deeper discharge, longer time)--For time based Absorb cycle. For % of charge, around 1% rate of charge, then transition to float.
• EQ Charging: Controlled over charging at ~60 - 64 volts for FLA batteries (depending on brand/model of battery, industrial batteries can be towards the high end for EQ charging). Typically done once a month (for some vendors), and/or when high to low cell SG is >~0.030 SG units difference). Typically around 2.5% to 5.0% rate of charge (nominally battery bank is supposed to be at 100% SoC, then start EQ--Cannot start EQ on a less than full battery bank)

Short answer is you will not see "maximum" charging current unless the battery bank is significantly discharged (typically 80% to 50% SoC) and/or you have significant DC battery bus loads other than the XW+ Inverter.

-Bill

paulcheung

The SOC on the bank should be around 50 to 60% at the time when I turn on the charger. It is off all the time with grid support. the charge rate I used to use is around 10% at ~40 amps. when I use the Magnum 4448PAE inverter. 

BB.

Are you actively cycling the battery bank (typically, 50% to 80%+ SoC every day)? Or are you letting the system run "standby" and just recharge to ~90%-100% when the battery bank hits 50%?

Active cycling, that is fine.... Letting a battery bank set below ~75% SoC for days/weeks/+ at a time--That is generally not good and will cause sulfation of the plates and an "early" battery bank death.

Some folks set the charger(s) to not recharge until the battery falls below ~80% - 75% SoC, then initiate charging. Taking a deep cycle battery from 90-100% SoC (no deep cycles), is usually considered "not good" (there are float service batteries for UPS type applications, but does not sound like your bank). If you have standard FLA deep cycle batteries, some folks here suggest cycling to below ~80% SoC at least once per month.

One question we usually ask--How do you know you are down to 50% SoC? Many Battery Monitors can be less than accurate. Typically, specific gravity (for non-sealed cells), is the 'gold standard' for SoC.

-Bill

paulcheung

The battery bank used to cycle daily with grid assist with the Magnum inverter for over 6 years, the bank is at it's last leg because the under charge most of the time in the first 2 years. I have only 6 original battery in the bank since the installation from 2012 August. 16 of them. Two parallel bank 16 of them, from 740 AH to 370 AH single bank. Now it is on stand by six days a week and one day cycle to around 50% SOC at 47.5 volts under load at around 10 amps discharge rate. 

BB.

What is the battery bus voltage a few minutes (or hour) after you "enable" the XW+ charging? Does it it rise quickly to >54.5 volts to 59.00 volts (if sulfated, quickly enters absorb charge mode) or does it stay at lower bus voltage for a few hours (bulk charge)?

Has the XW+ ever worked "correctly", or this behaviour since installed?

Actual Bus Voltage measurements at different SoC/charging modes would be very helpful... But, otherwise, I am probably about at the end of what I can do to help (usual stuff above, look for excessive voltage drop between XW+ Vbatt terminals/output to battery bus, etc.).

On occasion, there has been fixes to "unexplained" behaviours by resetting to factory defaults and then reprogramming. (in other "computers", I have seen this work if there was a firmware upgrade and confusion with old database/bad DB conversion)...

-Bill

paulcheung

I have not use XW+ to charge the battery much since the battery bank is been charge by the solar controllers. I just try to charge it 2 to 3 time since I installed the XW+ from Feb. this year. I am just wonder if there are other setting I over looked. well it is not big deal since I am not real depend on it to charge the bank. I also still have the Magnum as backup.
Thank you. 

I have another problem with XW+, maybe I should start a different thread as it is a different issue. it has stuck on AC by pass few time in the morning since I installed about 4 months back. It stay on AC by pass in the morning didnot use the power from the battery bank + solar. The block sell set at 5 pm to 7 am. it still on by pass at 9 am and the battery voltage gone to 60 volt+ and the support voltage set at 53 volts. I have to disable the grid support and enable it back in order for it to use the solar power and started to sell to the grid. is it normal? 
Should I start a new thread or continue on this one?
Thanks again.

BB.

Paul,

I would suggest you keep to this thread.  Everyone that would have "useful information" in one thread, would probably have information for the second thread.

If things do diverge/go down the rabbit hole, for one segment of the discussion, then splitting to a second thread to avoid "cross posting" between problems in this thread--Then I would split.

But, it is your choice. And lets give it a couple days for others to reply. We are all volunteers here, so it may take a bit to get feedback.

Paul, I guess you are done towards Jamaica? Local support might be a bit thin (Schneider appears to be trying/using a product support model through distribution->retailers/installer->customer; And a customer may have some difficulty getting direct support from Schneider).

-Bill

mike95490

What do you program the Xanbus with ?  SCP ? Combox?    You need to set the battery bank size properly in the 6848, as I think it will assume a C10 max charge rate. (I have the xw6048, the older cousin) and there are several interlocking settings that have to be correctly set.

mcgivor

What is the AC input breaker value set at in the settings, if too low a value say  that would limit the charging current, just another thing to check.,the default should be generous, usually ~30A.

Dave Angelini

The default is 60A on an XW. These problems are almost always about proper configuration. The OP needs to start reading.

t00ls

unless you can show a video of the settings in each menu....no one will be able to help on this problem

as dave said, read the manual and get some understanding of the terms used in it...now if you are confused in the terminology....we can help

paulcheung

The AC input is set at 29 amps. I thought the charge current, time and voltage all should be in the charge controls settings. they all there but it seem just not do the thing they should. 
in the Custom battery setting. The Battery temperature Coefficient set at -108 mV/oC. could that be the problem?

paulcheung

mike95490 said:

What do you program the Xanbus with ?  SCP ? Combox?    You need to set the battery bank size properly in the 6848, as I think it will assume a C10 max charge rate. (I have the xw6048, the older cousin) and there are several interlocking settings that have to be correctly set.

I use the Combox with a small laptop. I try to set it to C8 max charge rate. 

Estragon

paulcheung said:

The AC input is set at 29 amps. I thought the charge current, time and voltage all should be in the charge controls settings. they all there but it seem just not do the thing they should. 
in the Custom battery setting. The Battery temperature Coefficient set at -108 mV/oC. could that be the problem?

Yeah, you might want to check that setting vs battery makers recommended value.  That said, temp compensation mostly affects absorb voltage and would have no effect on current in bulk (< ~80%SOC).

mcgivor

Having all settings correct for the application is critical to the overall performance, particularly when interactive with the grid , one wrong setpoint could have a cascade effect on others. There are other factors such as ballance of system hardware which could influence transition, for example the conductor size between the controller and batteries. Since the charging source uses voltage at the controller which could be significantly different, if the conductors are undersized or at high current, than actual battery voltage, resulting in early transition.

The condition of the batteries is another factor, if known to be on their last legs as stated, the capacity may be significantly less than the value programed into the charging sources, further complicating things. Battery voltage itself is not an accurate measure of state of charge, which is particularly important in grid interactive systems, a battery monitor would be a better way because it calculates what goes into and out of the battery as well as uses voltage at the battery itself as a reference to make the decision when charging is complete.

Changes made to setpoints need to be made very carefully so as not to conflict with other parameters, multiple changes can lead to confusion as they are often made to compensate for some other errors made and so on.

paulcheung

Thank you guys for your time to reply. As I said before. since there are not clear known answer for this problem I won't make it bother me any more as I still has the Magnum inverter to charge the battery bank if necessary. I am more concern about the sticking part in the morning when it should start power the load from the solar and battery and sell to the grid when the voltage go higher than the set point on grid support voltage. 
The battery bank is way under size now as I pull the dead batteries from the two bank left just one bank working. I am considering to get a grid tie 3kw inverter to cut the charge current to near half in order not to toast the battery bank when the grid is over frequency or under voltage.

BB.

What is the battery bus voltage st 20 amp charge?

Bill

paulcheung

From 52 or 53 volts way under 59.2 volts I set the absorb voltage.

BB.

Does sound like something is limiting charging current... 

-Bill

mike95490

What is the quality of the AC source powering the charger ?

The XW line is very picky about the "quality" of the incoming power.  Grid is usually not a problem, but generators are being so cheaply made and have a lot of distortion in their output - bad generator waveform could be an issue.

paulcheung

It is the grid power I did use to charge the battery bank. The night after I use load shave try to use some battery power so I can recharge it with some large current to stir up the electrolytes. only to follow by a dark cloudy day. so I turn on the charger using the grid to charge battery bank. The grid power was qualified by the inverter so it should be good.