What Would Cause LiFeP04 Battery Voltage To Spike During Charging ? XW Pro

[patsfan1986]

Schneider XW Pro Inverter hooked up to 4 12vdc 200ah series config batteries.

Been on the phone with Schneider for about 4 hours and we still cant figure it out.

When the XW Pro starts bulk charging... the voltage climbs..... 56....57....58..... then all of a sudden the voltage will jump to over 65+ volts hitting the High Battery Voltage Cutoff.

I keep adjusting the bulk charge rate from 57.6 all the way down to 56 .... Ill adjust the charge current from 40 -> 20 -> 10 etc.. and no matter what I'm always hitting the voltage cutoff.

Spoke with 2 Schneider techs via phone ; been tweaking the battery charging settings but still not having any luck.

Any ideas on what may be causing this?

Appreciate any advice.

 

[timselectric]

Just a guess.
But if one of the battery BMS's disconnected charging. I could understand a short duration spike. Before the charger adjusted.

 

[BentleyJ]

Yes, what timselectric said is typical behavior for the Schneider if the battery capacity is too small to accept enough current or the battery gets disconnected during a charge cycle. Sounds like 1 or more of the 12V batteries BMS is disconnecting on HVCO limit.

 

[patsfan1986]

Thanks for the info I appreciate it ! How do you recommend I proceed? Should I try and remove the BMS and give the charge another try ?

 

[Shimmy]

Best approach is likely to trend jar voltages and see if you have a problem with one. This is the problem with having multiple BMSs in series rather than parallel. Beyond that, about all you can do is individually charge each jar...

 

[BentleyJ]

How do you recommend I proceed? Should I try and remove the BMS and give the charge another try ?

The BMS is there to protect the individual cells in the battery from being damaged. Don't remove it or use the battery without a proper BMS.
This is my recommendation.
1) Disconnect the cables between the batteries.
2) Check the voltage on each battery and make sure its in range.
3) Ideally you could remove the top of each battery and check each cell or if the BMS has Bluetooth with a phone app that would be very helpful.
4) Top balance each battery individually at 14.0V to 14.2V and let them Float at that voltage for 24 to 48 hours to give the BMS time to rebalance the cells.
5) If at anytime during charging the BMS disconnects, its necessary to find out why. If one of the cells is hitting the HVCO then the voltage needs to be turned down until this doesn't happen. Then slowly increased until the battery is balanced.

 

[cs1234]

I'm having good luck balancing my individual 12v lifepo4 batteries with this relatively low cost 12v battery balancer. It might take a few days for it to make a difference as it only seems to move around 10amps at a time, but it's helped me with my 12v batteries that weren't staying balanced in series.

It made it real easy to see which batteries were going into high voltage disconnect also, you can see at a glance which one has shut down the charging input because the display for it on the balancer will show a much higher voltage vs all the other still charging batteries.

 

[Luxpower_Gilbert]

Try setting your bulk to 55.2v…

 

[patsfan1986]

Try setting your bulk to 55.2v…

I Changed the bulk & absorption to 55.2v and it looks like it completed the charge cycle successfully. However , per my battery manual a 100% SOC is (13.5*4 = 54v). That new setting seems to only have charged the batteries to 53v which is around 70% SOC.

Should I keep increasing the bulk slowly (55.3........55.4..... etc.. and see what the max is before I hit the HBVC?

@BentleyJ Ill give your advice a try this weekend.

 

[Quattrohead]

Your battery's appear to be inadequate for the inverter, and having four BMS in series is always a bad idea. Are you struggling for battery capacity overnight and that's why you want to squeeze more out of them? You definitely could start inching the charge voltage up 0.1 volts at a time but I would also recheck all of your connections because your batteries / meter / inverter do not seem to be agreeing on voltages.

 

[TomC4306]

Your battery's appear to be inadequate for the inverter, and having four BMS in series is always a bad idea.

Yep, yep, yep.
You spent the money on the Schneider, buy a real 48 volt battery.

 

[740GLE]

You’ve already spent the money on the current setup mind as well spend a little more for a balancer.

It may take some time to bring everything back in check but hopefully once corrected it won’t drift too much the balancer can’t keep in check.

 

[callmeburton]

Had a similar issue, turned out to be a very loose connection. If you are taking the previously stated advice of disassembling and testing each battery you might end up "fixing" it when you reassemble it all

 

[patsfan1986]

Quick update.

Let the SOC drain down to 50% then started the recharge cycle at 57v 40a.
It looked like it completed the cycle getting the charge to around 85%. However, anyone have any idea as to why the charge cycle started again the moment stage 2 ended?

 

[Shimmy]

anyone have any idea as to why the charge cycle started again the moment stage 2 ended?

Battery voltage stabilizes/drops when charging stops, so you can see a spike afterwards to top off that delta.

 

[HRTKD]

Is a voltage of 60 on the high side? 58.4 volts would be the upper limit for a LiFePO4 battery.

 

[Consumerbot3418]

Is a voltage of 60 on the high side? 58.4 volts would be the upper limit for a LiFePO4 battery.

On the chart, that was the current getting that high, not voltage. He had it set to 57.6, and it only went to 57.2 or so, according to the charts.

It looked like it completed the cycle getting the charge to around 85%.

Glad to see that less aggressive charge settings helped--I'm hoping to implement something similar, glad you shared your experience here!

 

[Tomthumb62]

On the chart, that was the current getting that high, not voltage. He had it set to 57.6, and it only went to 57.2 or so, according to the charts.


Glad to see that less aggressive charge settings helped--I'm hoping to implement something similar, glad you shared your experience here!

I had a similar problem as OP and was recommended a similar approach and it worked. For my 12v system, I set the AC charger to "power supply mode" and charged to 13.8V, no BMS cutoff, yeah! Then 13.9, same, then 14.0 and it triggered. Back to 13.9V for another day, then tried 14.0V again and it triggered again. Back to 13.9V for another day (maybe I set for 13.95V that time, can't recall), back to 14.0V and it didn't trigger this time. I think I kept at it until 14.2V and called it good enough for the time being. Apparently this method helps gives the cells more time to get balanced by the BMS. Then I turned the charger back to regular charging mode. I also adjusted my SCC to match the new voltage that doesn't trigger BMS protection. It's a bit time consuming, but no more voltage spikes now.

 

[TomC4306]

On the chart, that was the current getting that high, not voltage. He had it set to 57.6, and it only went to 57.2 or so, according to the charts.


Glad to see that less aggressive charge settings helped--I'm hoping to implement something similar, glad you shared your experience here!

More battery will achieve this nicely. LOL