Schneider Conext SW 4024 Help

cdabilly · September 2019

I sent Schneider some questions and while they were helping me the answers finally stopped and I am hoping someone here has some help for me.

The battery manufacturer for my batteries recommends that if the batteries are to sit for an extended time then once every 6 months you apply a boost charge. Their exact text is:
"If a boost charge is required; the recommended charge is 24 hours at a constant voltage equal to 2.40V per cell."

I have 24 cells, so my numbers tell me that I need to do a charge of 57.6v for 24 hours straight.

I emailed Schneider about this and they got back to me with:

The easiest way to maintain a high voltage for an extended period is to set the Batt Capacity to 0Ah (to stop the exit amps from ending the charge) and then set the max absorb time to the desired time. This will cause an extended absorption charge. 57.6V is the default absorption voltage if your battery type is set for flooded, so this works out well. However, the max absorb time can only be increased up to 480 minutes, or 8 hours, so you'd have to start the charge 3 times to complete this. 24 hours is quite a long time to keep the batteries at such a high voltage, so I would confirm with the battery manufacturer that this is necessary before proceeding.

What I am trying to learn now, and have not been able to get a response to is how to set to 0AH. My batteries are AGM and when using the control panel my lowest setting even for a custom bank is 50AH. So first and foremost I wonder how I can set it to 0AH.

Also, I wasn't able to figure out how to set the voltage of my Conext to 57.6V the highest it would go was about 35V.

If anyone can help me with those things I would appreciate it.

Estragon · September 2019

It sounds like it's set for 24v nominal bank voltage (not 24 x 2v cells = 48v).

Someone more knowledgable with Schneider may be able to help with the 0ah thing.

If you do the "boost charge", be sure to use temperature cpmpensated voltage. If the batteries get hot, hitting them with highish uncompensated voltage for a long time may not be a good idea. Do they suggest checking to see if (eg) resting voltage is close on the idle batteries to indicate if the boost is required? Doing a 24hr continuous charge off-grid can be a problem anyway, requiring a non-pv power source.

MrM1 · September 2019

Setting the Ah to 0 does NOT stop the exit amps from terminating absorb portion of the charge. Be nice if it did work that way, but it don't. I've tested it (unless the did a firmware update that fixed it).

About the only way to get an extended charge is to set bulk same as absorb same as float... Then it will change at whatever volts u set all 3 indefinitely. Then use charge block to terminate.

BUT remember at some point after charge block blocks charge to manually turn off the charger OR it will start charging again at the set time to end charge block.

MrM1 · September 2019

Oh BTW... I just tried to set my SW 4024 to Battery Bank Capacity = 0Ah, and as I expected it errored and said 50 Ah is the lowest setting. So Another strike against Schneider support. It doesn't do that.

MrM1 · September 2019

I'm confused.... Why are you trying to charge a 24v bank at 57.6v? Highest voltage u should be using is 32.4v (+ or - depending on battery brand) for EQ, and then only when monitoring Temps pretty close every hour.

Estragon · September 2019

In fairness to Schneider support (and certainly deferring to those who know Schneider stuff far better than I do), it's possible the device itself will accept a 0ah bank size and behave as described, but not all interfaces will accept that value. They may have assumed use of an interface that will.

Dave Angelini · September 2019

An XW will set to zero amp hours. The tech at Schneider made a mistake. Nice that no one on this forum ever does

The CSW even at 50 AH is about perfect for running the full absorb time you enter or terminating at 2% of 50 AH which equals 1 amp, whichever comes first.

MrM1 · September 2019

Dave on my 435ah bank when set to 50 Ah it terminates at about 8 amps. I wish there was a way to set it to time OR end amps. This has always been a frustration for me. But I have learned so much lately that I don't think that early termination is that bad. I'm still learning

Dave Angelini · September 2019

Well what is your absorb time? Increase it until it terminates at 1 amp if that is what you want to do. If you have max absorb time and it still does this, then it is your battery that is the issue.

Right now a couple old US navy (now Cal Fire) S2 trackers flew over my roof and so someone is on fire, again...Friday!

MrM1 · September 2019

Absorb time is set to max but the SW has done this since the batteries were new. I've tried all kinds of things. But charge block seems to work best. Just not the most automated

Dave Angelini · September 2019

Hmm to 480 minutes absorb time, something is wrong. How old is firmware?

Schneider Conext SW 4024 Help

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