Last update 26/03/2026 ( I managed to reduce the cell delta to 15 mv ,and the delta is still decreasing, by changing the requested chargeing voltage to 56 for 1 week and keep it balanceing )

I’m experiencing significant cell imbalance with my 48V 350Ah battery. The imbalance is most noticeable in the last seconds of charging, and the differences start to decrease once charging stops, even without discharging the battery.





It seems that the battery’s built-in balancer is very slow, and charging stops when any single cell reaches 3.6V. Balancing only occurs during charging, which makes the problem worse.





I tried keeping the charging voltage slightly lower to allow more time for balancing. I even disconnected the BMS cable and set a float charge around 58.8V. However, charging still stops when the battery reaches this voltage, so the balancing process halts as well.





In other words, there’s no way to keep balancing active for several hours.





One potential solution could be installing an active balancer, but opening the battery would void the warranty.

Has anyone dealt with this issue? What would be the best way to improve cell balancing without risking the warranty?



Thanks in advance.

Edited March 26Mar 26 by esmail-kassir
Update

2 hours ago, esmail-kassir said:

I’m experiencing significant cell imbalance with my 48V 350Ah battery. The imbalance is most noticeable in the last seconds of charging, and the differences start to decrease once charging stops, even without discharging the battery.





It seems that the battery’s built-in balancer is very slow, and charging stops when any single cell reaches 3.6V. Balancing only occurs during charging, which makes the problem worse.





I tried keeping the charging voltage slightly lower to allow more time for balancing. I even disconnected the BMS cable and set a float charge around 58.8V. However, charging still stops when the battery reaches this voltage, so the balancing process halts as well.





In other words, there’s no way to keep balancing active for several hours.





One potential solution could be installing an active balancer, but opening the battery would void the warranty.

Has anyone dealt with this issue? What would be the best way to improve cell balancing without risking the warranty?



Thanks in advance.

What is the pack voltage when a cell hits 3.65v? Also how old is the battery?

8 minutes ago, Stefan Cornelissen said:

What is the pack voltage when a cell hits 3.65v? Also how old is the battery?

55.9

Just now, esmail-kassir said:

55.9

You can always try to use voltage settings for a while and charge the battery to 55.5 for a week and then slowly every week up it by a 0.1v.

I have done this for one a set of batteries before with a pacebms and it balanced fine.

But you need to disable coms and set float and charge voltage the same

Edited March 18Mar 18 by Stefan Cornelissen

20 hours ago, esmail-kassir said:

Has anyone dealt with this issue?

I have:

Its a LEOCH 48100-S. I have no coms and use inverter settings for bulk and float charge voltages according to specs of the battery manufacturer. According their recommendations the bulk charge remains for 1 hour to allow for balancing. However it looks like it has no effect. Averge refuses a guaranty claim by arguing that the pack still has full capacity according to specs.

1 hour ago, Beat said:

I have:

Its a LEOCH 48100-S. I have no coms and use inverter settings for bulk and float charge voltages according to specs of the battery manufacturer. According their recommendations the bulk charge remains for 1 hour to allow for balancing. However it looks like it has no effect. Averge refuses a guaranty claim by arguing that the pack still has full capacity according to specs.

the same situation I have

Hi there,

Thank you so much for providing the details and sharing those helpful screenshots it really helps us understand the situation with your Felicity FLA48350TG2 battery 51.2V nominal, 350Ah, around 17.5 kWh. This is a well regarded model for home and small commercial solar systems, and it includes a smart BMS with RS485/CAN communication, built in WiFi monitoring, aerosol fire protection, and the ability to connect up to 15 units in parallel. The pattern you're describing where the cell voltages show more difference toward the end of charging, then settle a little during rest, and charging stops when one cell reaches around 3.6V is something a few other owners have noticed with this type of battery too. The built in balancing is passive very gentle, low current , and it mainly works during charging when cells are in the higher voltage range starting around 3.4–3.45V per cell. When a single cell reaches the protection limit first, the overall charging process stops sooner, which can limit how much balancing time is available. Here are some, straightforward steps that have worked well for others and stay completely within warranty guidelines:

1. Gentle adjustment to the charging settings this is usually the easiest and most effective place to start.
   If your inverter is communicating with the battery (via CAN or RS485), the BMS sometimes sets a higher bulk voltage, but then stops early to protect the cells. You could try switching to a user defined or lead acid charging mode for a while you can disable communication temporarily if needed and use these settings.

   • Bulk/absorption voltage: 55.2–56.0 V (roughly 3.45–3.50 V per cell) this tends to keep the cells in the balancing friendly range for longer without any cell hitting 3.6 V too soon.

   • Absorption hold time: as long as your system allows (ideally 4–8 hours or more each day if possible).

   • Float voltage: around 54.0–54.4 V.

   • Charge current: keep it gentle, around 35–70 A (0.1–0.2C).
     Many users find that giving the battery this longer, lower voltage time helps the internal balancer do its job more gradually, and cell differences often become smaller over a week or two.

2. Regular full charges:
   It can be helpful to bring the battery up to 95–100% SoC fairly often. The balancing mostly happens when cells are above about 3.4 V, so regular time spent there tends to keep things more even.

3. Monitoring with the built-in tools:
   The Felicity EDMS software available through their support or website, usually with a simple USB/RS485 connection lets you see individual cell voltages, track how the differences change, and check if there's a newer firmware version available. Keeping a log of a few cycles can be really useful, and if you ever want to share those logs with Felicity support, they've been able to offer guidance or small updates in similar cases.

4. Non-invasive external options:
   For setups with a single battery, external pack level equalizers connected only to the main terminals are sometimes used certain 48V types exist, though they're more commonly helpful when there are multiple batteries in parallel. In parallel systems, devices like Victron Battery Balancers can assist with evening things out between packs.

If after trying the charging adjustments for a couple of weeks the differences are still noticeable, you're very welcome to reach out to Felicity support or your local distributor with your cell voltage screenshots and logs. Sometimes these situations relate to the initial setup of the cells or a small BMS setting, and they've been able to help with service or advice. You're doing a great job troubleshooting this already your idea of lowering the voltage to allow more balancing time was really thoughtful. If you're comfortable sharing a bit more such as, the settings you're currently using, a rough idea of the biggest cell difference you see, or whether communication is enabled, we'd be happy to offer more tailored thoughts.

Some of the members have already contributed insightful contributions to your thread.

There's also a dedicated Felicity discussion thread here on PowerForum where local users share their experiences.You're not alone with this lots of folks work through it successfully.

Also here are some other threads related to felicity solar batteries.

https://powerforum.co.za/topic/15778-felicity-solar-lpbf48250-pv-wake-up-line (good for wiring/charging specifics)

https://powerforum.co.za/topic/11615-5-star-felicity-solar-lpbf48200-battery-with-sunsynk-inverter (discusses rebranding and compatibility)

I hope this helps.

On 2026/03/18 at 2:44 PM, esmail-kassir said:

The imbalance is most noticeable in the last seconds of charging, and the differences start to decrease once charging stops, even without discharging the battery.

That behaviour is quite typical at the top of charge. What you’re seeing: Delta increases in the last moments of charging then reduces again once charging stops

That usually indicates:

●Cells reaching full at slightly different times

●The BMS starting to balance at the top

●Surface charge exaggerating the voltage differences during active charging

Key point: If the delta comes down on its own at rest, it’s generally not a true capacity mismatch, but normal top end behaviour.

What I would still suggest let the battery sit at full (absorption) a bit longer to allow balancing. Then check the delta again after 15–30 min rest.

Next step (if you want to be thorough): Do a discharge log (Voltage vs SOC vs Load)

That will confirm whether any cell actually falls away under load or if this is purely a top-end balancing effect. The 49mv Delta needs some attention but not a critical imbalance.

@TaliaB

The cells are well balanced and behave identically under high load, even near the lower end of their capacity. I’ve also verified this down to around 44.8V.

The voltage delta only appears when the battery is at full charge, and it drops back within seconds once charging stops.

12 minutes ago, esmail-kassir said:

@TaliaB

The cells are well balanced and behave identically under high load, even near the lower end of their capacity. I’ve also verified this down to around 44.8V.

The voltage delta only appears when the battery is at full charge, and it drops back within seconds once charging stops.

That behaviour is normal for LFP at the top end. During the final stage of charging, small differences between cells get exagerated as they reach full at slightly different times, especially while current is still flowing. The highest cell hits the voltage “knee” first, which creates the temporary delta you’re seeing.

The key point is that the delta drops again within seconds once charging stops and the cells behave evenly under load across the rest of the SOC range. That rules out capacity mismatch or a weak cell , it’s simply normal top-of-charge behaviour, not a fault.

7 minutes ago, TaliaB said:

That behaviour is normal for LFP at the top end. During the final stage of charging, small differences between cells get exagerated as they reach full at slightly different times, especially while current is still flowing. The highest cell hits the voltage “knee” first, which creates the temporary delta you’re seeing.

The key point is that the delta drops again within seconds once charging stops and the cells behave evenly under load across the rest of the SOC range. That rules out capacity mismatch or a weak cell , it’s simply normal top-of-charge behaviour, not a fault.

So, do you think most LFP packs will perform similarly, but the absence of an active balancer here emphasizes the issue?

8 minutes ago, esmail-kassir said:

So, do you think most LFP packs will perform similarly, but the absence of an active balancer here emphasizes the issue?

What you’re seeing is mainly due to the steep voltage curve near full charge, where even very small SOC differences between cells translate into noticeable voltage differences while current is still flowing. That happens regardless of the brand or pack size.

The absence of an active balancer can make it a bit more visible or slower to settle, since passive balancing only trims the higher cells gradually. But in your case, since the delta collapses quickly once charging stops and everything stays aligned under load, it’s still well within normal behaviour and not something that indicates a problem.

Must say that pack is pretty well balanced. I regard the Felicity battery quite highly. I have only seen good things in the examples I have seen in the field.

The situation is exaggerated as @TaliaB has noted. LFP stretches it's legs at the top and the bottom of the charge curve. An active balancer as fitted to Orion's on the FW keeps pack in synch and you don't see this level of delta. But the passive (ghandi) balancer takes time and strategy in keeping it floating slowly towards 100% SoC. Still effective but every OEM has a different strategy. So it takes time to learn what the OEM wants and then to practice it at least once a week to keep things healthy.

17 hours ago, Steve87 said:

Must say that pack is pretty well balanced. I regard the Felicity battery quite highly. I have only seen good things in the examples I have seen in the field.

The situation is exaggerated as @TaliaB has noted. LFP stretches it's legs at the top and the bottom of the charge curve. An active balancer as fitted to Orion's on the FW keeps pack in synch and you don't see this level of delta. But the passive (ghandi) balancer takes time and strategy in keeping it floating slowly towards 100% SoC. Still effective but every OEM has a different strategy. So it takes time to learn what the OEM wants and then to practice it at least once a week to keep things healthy.

@TaliaB

I have charged it up to 100% and then slightly discharged it by exporting to the grid several times today. This led to a noticeable, though slight, improvement. At least this shows that the balancer is working. However, during the winter period, I didn’t allow it to charge to 100% very often.

Honestly it doesn't get better than this. Anything else will be a new product from the Factory. Lowest cell at 3.47 is very close to a full cell.

This type of top float balancing can even be done once a week. In the high end Commercial installations these batteries carry out 2 Cycles a day due to 2 peaks (morning and evening) and once a week keeps them in good shape.

I agree with @Steve87 all good.

@TaliaB @Steve87 Thanks for help

Love the vibe here! Info's on point and the convos are lit 🔥. Appreciate the help!

2 hours ago, Steve87 said:

Honestly it doesn't get better than this. Anything else will be a new product from the Factory. Lowest cell at 3.47 is very close to a full cell.

This type of top float balancing can even be done once a week. In the high end Commercial installations these batteries carry out 2 Cycles a day due to 2 peaks (morning and evening) and once a week keeps them in good shape.

But I have to mention

But gotta say, I've seen Felicity batteries with better balancing, like my neighbor's one for example

@TaliaB @Stefan Cornelissen @Steve87 @Beat

I’ve changed the requested charging voltage from the battery side to 56 volts. Since then, I’ve noticed an improvement. It appears that the BMS only balances the battery when there’s charging current, and the battery SOC isn’t 100% (maybe).

Now the delta dropped significantly