Schneider CSW4024 Battery Charging Fault

Nitr0

New Member
I recently connected my new Schneider Conext SW2024 and I'm having issues getting it to charge my BigBattery 24v Powerblock. I think that I have all the settings to the proper rates to charge the battery based on the battery specs on the website but I still get an error a few minutes into charging.

49 - DC Over Voltage: Cause: Voltage at the DC input terminals is above the High Battery Cut Out Setting. Solution: Clear the fault and attempt restart. Ensure battery voltage is 21-33 VDC (default settings) at Conext SW terminals. Check all other charging source outputs, and battery cables.

The charger shows the battery at 28.4v when it cuts out and I have the "High Battery Cut Out" set at 29.2v since that is the max on the battery specs.

Battery Specs

Detailed Battery Specs:​

Chemistry: LiFePO4 (New)
Configuration: 8S (Series)
Voltage: 24V
Ah Capacity: 170Ah
kWh Capacity: 4.352kWh
Wh Capacity: 4352Wh

Performance Specs:​

Max Continuous Discharge Current: 175A
Max Continuous Power: 4480W
Max Discharge Peak Current: 350A (6 Seconds)
Voltage Range: 19.6 – 29.2V

Charging Specs:

Suggested Charge Voltage: 29.2V
Max Charge Current : 175A

The inverter/charger is currently set at the following

Charger Settings
Charge Cycle: 2 Stage
Force Charger State: Bulk
Max Charge Rate: 30%
Bulk/Boost Voltage: 29.2v
Max Bulk Charge Current: 90A
Bulk Termination Voltage: 28.8v
Bulk Termination Time: 180s
Absorption Voltage Set Point: 29v
Max Absorption Charge Current: 90A
Absorption Time: 120m
Float Voltage Set Point: 26.85v
Max Float Charge Current: 90A

Battery Settings
Battery Type: Li-Ion
Battery Bank Capacity: 170ah
Battery Temperature Coefficient: -42 mV/C
Recharge Voltage: 29v
Low Battery Cut Out: 20v
Low Battery Cut Out Delay: 10s
Low Battery Cut Out Hysteresis: 2v
High Battery Cut Out: 29.2v

I've read through the manual, different forums, and tried to contact BigBattery but I haven't found the right settings yet.
 

GVSolar

Solar Addict
I'll need more information on your system setup before I can weigh in meaningfully.
1. Do you have a solar charge controller SCC? Panel Watts? Temperature at your location?
2. Is the battery charging from AC input or solar or both?
3. What does the balance of system look like? Wiring diagram? other units?
4. I have a combo - not a Gateway - Combox generates graphs of charge/discharge under System Performance/Battery Bank Daily Summary - check gateway for similar graph and post that graph of your charge history during disconnect period.
Check your CSW manual for the error code explanation - and further detail in manual - and post please. I'll take a look at mine as well.
BTW the voltage as shown on the SW can be higher/lower than the actual Battery Bank Voltage if there is voltage drop in the system cabling. I also would not charge to 29.2 for those units - but might start with a lower voltage setting to keep from hitting the limits of the BMS disconnect on runaway cells... at least until you get a good handle on the operating characteristics of that battery.
best.
sample graph
 

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Nitr0

New Member
So I just confirmed all my battery settings one by one with BigBattery.com and they state the battery is fine and its something on the inverter end. Here are the answers to your questions.

1. The unit is currently only battery backup with not solar tied in at the moment. My solar is Enphase and into my main panel. The critical loads panel this is feeding is a constant 1600w at the moment but in an grid-fail would be about 1000w max but not constant. The temperature where everything is located is 68 degrees F
2. Battery is charging from AC input from my main panel which is grid fed. Solar is currently turned off (snow covered anyways)
3. Grid > Main Panel (200a) > 30a 2 pole 240v breaker to Schneider SW AC Breaker Panel 120/240V 30a 2 pole 240v breaker > SW4024 inverter > 30a 2 pole 240v breaker in critical loads panel. Both legs of the 240v are balanced to based on the breaker loads. 6a L1 and 10a L2
4. The error is ID 49 which means the DC voltage is above the High Battery Cutout.

I've attached an image of the last charge attempt when I was working with BigBattery's technical support. It goes to 28.9 changes to absorption and kicks out with ID 49. High Battery Cut out is set to 30v which is what BigBattery told me to set it to. Here are all my settings that BigBattery told me to use. I have a case open with Schneider but no response.

Charger Settings
Charge Cycle:2 Stage
Force Charger State: No Float
Max Charge Rate: below 50%
Bulk/Boost Voltage:29.2v
Max Bulk Charge Current:90A
Bulk Termination Voltage:29.2v
Bulk Termination Time:
Absorption Voltage Set Point:29.2v
Max Absorption Charge Current:90A
Absorption Time:
Float Voltage Set Point:29.2v
Max Float Charge Current:90A
Battery Settings
Battery Type: Li-Ion
Battery Bank Capacity: 170ah
Battery Temperature Coefficient: -42 mV/C
Recharge Voltage:29.2v
Low Battery Cut Out:21v
Low Battery Cut Out Delay:10s
Low Battery Cut Out Hysteresis:2v
High Battery Cut Out:30v
 

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GVSolar

Solar Addict
Bear in mind I'm not there, but based on my reading of your chart/description, here is what I think may be happening:
Battery cuts out at approx 45amps charge/29.2v. Schneider Absorption exit amps are based on Charger/Battery Bank Capacity settings - charger will exit at 2% of that capacity setting - if you entered 170ah - then SW would exit absorption as soon as it only takes 3.4amps to maintain 29.2 volts, which will happen VERY quickly at 90amp bulk charge current, if the battery is at a high SOC. The exit amps are a protection against overcharge. The inverter is doing what is designed to do - exiting absorption at the predetermined % of capacity. More detail is in the manual.
I use a CUSTOM battery setting: 3 stage profile. Much more control and (IMHO) better overall profile for LFP.
BULK: where you want it.
ABSORPTION: where you want it.
TIME: again where you want it, but I would start small/short.
FLOAT: no higher than 26.6 (especially when charging from AC - and without large variable loads)
RECHARGE: 26.4
If you float LFP higher than 3.33 per cell (26.64) on steady AC - THAT IS A BIG NO-NO - you will certainly overcharge your battery overtime and do damage.
Three suggestions: Use a 3 stage profile as above. Raise Battery Bank Capacity to 340ah which will make exit amps higher (6.8a) and reduce the max charge current to 45 amps - REDUCE FLOAT TO 26.6 MAX. Then see what happens. BUT IT LOOKS TO ME LIKE THE BATTERY IS FULL.
Again, I would be leery of charging to 29.2 consistently - especially if you are not discharging in any meaningful way.
PLEASE FORGIVE THE BOLD ALL CAPS - but I would hate to see you burn up your battery.
BTW - I can't tell from your description if your SW is driving the critical loads all the time or not - is it just standby - or actually feeding the loads?
YMMV. My advice is free and worth what you paid for it. Best.
 

Nitr0

New Member
I'll try your settings and see what the results are. My critical loads are only lighting and my furnace at the moment so I can do testing. Bigbattery said the BMS will protect the powerblock through most of this testing.
 

GVSolar

Solar Addict
Still not clear to me... are the critical loads being fed by the SW - or by the grid? UPS, standby or constant feeding from battery/SW?
 

Nitr0

New Member
The critical loads are fed by the SW. The SW is charged by the grid. Right now the SW is active and says AC passthrough.

I have a spreadsheet Im tracking all settings in and sharing with Bigbattery till it's resolved
 

Nitr0

New Member
I have the charger turned off until I test the settings again because when it errors charging it drops load. I'll test the settings this evening.
 

GXMnow

Solar Addict
I have a Schneider XW-Pro. It is a bit different, but I will bet the software is similar. I was getting flaky batt high volt shut downs when I first set it up. What Schneider told me was to set the high battery cut out voltage up to 64 volts on my 48 volts system. Evidently there is an offset built into the system, and this number does not function as expected. In my case it was tripping about 4 to 5 volts early. So just try setting this value under the "inverter settings" tab to 32 volts on your 24 volt system and see what happens. Obviously monitor the battery volts and make sure charging is properly stopping at the setting under "Absorb Voltage Set Point" in the charger tab. I am using the "Custom" Battery setting, and some of the values just seem to be ignored. The "Li-Ion" selection did not work well for me. The "Bulk Termination Voltage" would only go up to 54 volts, but the "Bulk/Boost Voltage Set Point" and "Absorption Voltage Set Point" both allowed me to dial it up to my desired 57.2 volts, and it now switches from bulk to absorb at 57.2 volts as it should. Obviously my voltages are about double yours. Absorb only seems to run about 20 minutes on these batteries. I am also set to "2 Stage No Float" so once the absorb current falls below 8 amps it stops charging completely and goes to standby pass through mode.

I would also lower the charge current a bit while testing. I only run 25 amps into my 48 volt 360 amp hour battery bank. It puts 7 KWH into the battery in about 5 hours. Try just 25% max charge rate until you get a handle on this. Measure the voltage with a separate meter on the terminals of the SW. The read outs in my XW-Pro show a little higher than my Fluke meter, but it's typically within about 3/10ths. 57.2 volts in the Schnieder is giving me about 57 volts flat at the battery terminals. Once you know the true voltages at the battery bank, you can adjust the values in the SW to get the desired voltages due to any offset or scale error. I am only going to 85% charge on mine and they only ran below 45% when the power was out with no solar power for a whole day.
 

GVSolar

Solar Addict
"What he said..." All good stuff from @GXMnow - thanks - Schneider is very powerfully flexible - but the manual is a "deep read" - As GXM said the bulk termination settings are derived from an offset from the maximum bulk charge. It's in the SW manual - took me a while to get a handle on that one. And I completely concur on keeping your max amps on the lower end to start - less potential for an "oops". Best.
(notice the offset in the chart from the manual - Preset Bulk vs. Bulk Termination Voltage) Bulk Termination Voltage is accessed in the Advanced Settings menu.
 

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Nitr0

New Member
Ok, so I've come in the middle between GV and GXM. I assume when the battery charge is good the status is "No Float"? I was under the impression the max charge rate made the determination of the percentage of the 90A max rate. I think that is true since I have been using 30% and 50% while testing. I moved my High Battery Cut Off to 32v and everything else between 27v and 28v. Everything seems good now.
 

Nitr0

New Member
I guess my one last question is on the absorption charge. BigBattery told me to set this to the lowest value which is 1 minute. I have it current set to 5 minutes and when I walked away 30 minutes ago it was on "No Float" and now it says absorption charge again. Is this going to be a normal off and on thing for the battery. Its never had a load on it and BigBattery told me it was likely already at 100%.
 

GVSolar

Solar Addict
Glad to hear it working better. I use 3 stage - I don't run two-stage no float so I can't comment. @GXMnow now should know. At some point you'll want to simulate a power shutdown and test the inverter/battery's set-up in a backup scenario. Best.
 

Nitr0

New Member
I answered my previous question myself. I had the recharge voltage set to 27 instead of 26.4 like you had suggested. What is the benefit of the 3 stage with the float as you noted previously? I do lose power a lot, something like once a week for anywhere from 1 to 10 minutes.
 
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Nitr0

New Member
I'm also a little concerned about the 26.4v recharge. Is that too soon to recharge again? In 30 minutes its already down to 26.8v just sitting there. Does it hurt to set it low or is that the risk of not having a full charge when you need it?
 

GXMnow

Solar Addict
Since you are just using it for backup, you do want to keep the batteries topped up. LFP cells do tend to dip down a fair bit after the charge current stops. Fully charged at rest will dip back to about 3.4 volts per cell. So 8S should rest about 27.2 volts when fully charged at no load. Half charge is about 3.2 per cell, or 25.6 volts. So recharge around 25 would be when the pack is down to under 50%. But 26 volts, just one more, could be nearly 80% on some LFP cells, because their charge curve is so flat. Does the BMS report a "State of Chare" you can monitor? See what voltage you are at when it is down to 60% and start around there. If you don't have a power failure for a while, you can just trip a forced charge cycle to top up the pack anytime.
 

Nitr0

New Member
The powerblock only has a voltage meter so I don't know what the SOC is. I checked the last two days since I connected the battery to the SW and it seems to sit at 26.43 to 26.5. I'll set my recharge to 26v for now and see where I'm at. I didn't get a chance to change out of bypass tonight so I'll test tomorrow.

I will eventually connect my Enphase combiner into the critical loads panel but I have a lot of wiring work prior to that.

Thanks for all the info. I think just tuning it in at this point. Spent the evening reading about LifePo4 charging.
 
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