Opening the Sealed Type Drop-in Lifepo4 Battery

[goboatingnow]

I agree too balance needs to be done near the “ top knee” otherwise the correlation between. Cell voltage and actual Soc allows way too much cell variation

I fully agree re drop in. The market simply isnt there yet. You have to have cell access.

[SOLAR SUPPORT]

Originally Posted by wholybee

In order to balance a battery, regardless of passive, active, or doing a manual top balance, you MUST get charge higher than 90% and it needs to stay there long enough for the balance to occur. If you balance at a lower SOC, it simply will not work. Charging to near 100% isn't as bad as you seem to think. Don't overcharge them, and don't store them at 100%, but charging to 100% (or very close to it) to balance them is normal maintenance.

There is also no need to isolate the battery, nearly every BMS will successfully balance a battery during the normal course of daily charging (during the final few % SOC) while also powering loads.

If you open up your drop-in, perform a full top balance with a bench-top power supply, then put it back together and start charging it to 14V everyday, you will probably not need the active balancer, and never need to balance it again.

We should stay away from all kinds of factors that shorten the life of the batteries. You can find many studies on the internet that deal with the reduction of the promised life cycle numbers of Lifepo4 batteries, which are used close to SoC 0-100% levels.

Battery manufacturers also state that the life time or cycle numbers they promise will be valid if you use the Lifepo4 batteries they produce in the 20-80% SoC range. There is sufficient information and warning in the healthy SoC% range public regarding the use of Lifepo4 batteries.

We know very well that when the potential balance between the series connected cells in the batteries is disturbed, this affects the battery life quite negatively. In that case, it is necessary to focus on the bms, which is responsible for maintaining the balance, and to examine to what extent it can do the balancing task.

If the bms is able to charge the passive cell equalization above 3.55Vpc, then it is necessary to charge the battery above the SoC 80%. If the charging voltage has to approach the upper limit for passive balancing to be effective, it can be said that there is an inverse correlation between the passive balancing charge and the longevity or cycle numbers of the battery.

For active balancing, which stands out as a passive balancing alternative, between cells, it is sufficient for the cell voltage to be above 3.3 vpc. 3.3vpc is a good level because it is possible to balance cells without going past 80% SoC.

It is necessary to observe to what extent the balance between cells is realized by starting the active balancing automatically from 3.3vpc and continuing until it reaches 3.5-3.6vpc.

If cell balancing can be achieved without exceeding the 3.6vpc level with active balancing, then forcing the cells to charge more than this voltage level will not contribute much in terms of capacity but it will reduce the number of life cycles of the cells.

If there is no difference between balancing the batteries without separating them from the boat electrical infrastructure and balancing by isolating the battery in terms of balancing time and balance precision, of course, an effortless way is followed. Is it possible to balance the cells in the battery at 0.001vpc while charging and/or discharging continues simultaneously or separately? Gotta try this.

[Pete7]

Ok, so what are you going to do with your LFP batteries? Open them up or return them?

Personally, I would open them up, replace the BMS and perhaps add an active balancer. You have nothing to lose and putting them back into a new box which are cheap would solve the problem.

Pete

[SOLAR SUPPORT]

Originally Posted by Pete7

Ok, so what are you going to do with your LFP batteries? Open them up or return them?

Personally, I would open them up, replace the BMS and perhaps add an active balancer. You have nothing to lose and putting them back into a new box which are cheap would solve the problem.

Pete

My seven month old batteries are fine now. Since there is no certain problem that requires making a warranty application, no result can be obtained with such an application.

In terms of future improvement, assuming the current warranty is gone, what I'm going to do is add the smart active balancer without taking anything away from the existing battery.

I will open the battery boxes soon and planing to use them again after the balancer upgrade. I haven't received the active balancers yet.

[SOLAR SUPPORT]

I just opened Pandora's box. It was a heavy plastic cutting process that required extra care not to damage the stuff inside. I added the smart active balancer. What surprised me was that the cells that had been resting at 3.3V for a long time were quite stable. After two hours of charging with AC-DC charging, the active balancer started to work when the cell balance exceeded 0.02 volts. Now I have closely followed the Lifepo4 cells..

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

I noticed that my BMS did not or could not do the cell voltage balancing task. I guess the problem with Drop-in Lifepo4 batteries can be solved by doing active balancing. I have not made the necessary intervention for this because the smart ACBs I have purchased have not yet arrived. Once these are available I will share information on progress.

You might be right about the charger. However, it is not the solar charger that makes the balancing charge of the cells in the battery, but the bms in the battery. With any Mppt or PMW charge controller, you can charge the batteries by bringing the charge to a certain level and without exceeding 90% SOC. The recommended Lifepo4 battery charge for long-term healthy use is not to exceed 90% Soc already.

You don't have to do the cell balancing charge every day. Every user who likes to make cell balancing charge as often as you should know that for a healthy balancing charge, the battery must be isolated from the electrical infrastructure to prevent it from being discharged during this time.

could you please post a link of the smart active balancer you use. only aware of the Neey which is really smart and start balancing at a programmable value but they are very expensive.

[SOLAR SUPPORT]

Originally Posted by CaptainRivet

could you please post a link of the smart active balancer you use. only aware of the Neey which is really smart and start balancing at a programmable value but they are very expensive.

https://m.tr.aliexpress.com/item/100...gloPc2turMsite

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

https://m.tr.aliexpress.com/item/100...gloPc2turMsite

You know that Daly active balancer cell values are known to be off, so again you have no idea what your real cell voltages are.
2nd the Daly only starts balancing when all cells above the threshold set but if you have a runner it does nothing.

No drop ins have no issue if charged properly according to manufacturers spec with chargers capable of LI.

[PaulCrawhorn]

This sort of confrontational posting is not helpful to anyone

hurts the overall forum community most of all

and certainly reduces the credibility of those involved

[Pete7]

Originally Posted by PaulCrawhorn

This sort of confrontational posting is not helpful to anyone hurts the overall forum community most of all and certainly reduces the credibility of those involved

Agreed. I have edited and deleted the last few posts. Gentlemen, there is a "Be Nice" rule for the forum, please obey it. You may disagree and challenge something that has been posted, but please do so nicely.

Thank you

Peter

[PaulCrawhorn]

Personally, I find it best to simply state "my truth" as I believe, addressing errors of fact where I see them, and keeping the focus away from the people involved.

Saying "xyz is not true" "abc is reality" works better than anything like "you are wrong".

[ers61]

Originally Posted by SOLAR SUPPORT

I just opened Pandora's box. It was a heavy plastic cutting process that required extra care not to damage the stuff inside. I added the smart active balancer. What surprised me was that the cells that had been resting at 3.3V for a long time were quite stable. After two hours of charging with AC-DC charging, the active balancer started to work when the cell balance exceeded 0.02 volts. Now I have closely followed the Lifepo4 cells..

i wonder what brand were your batteries ? i'm suprised that the bms of your drop in was daly brand

also how did it go at the end ? did active balancer fixed your problems?

[SOLAR SUPPORT]

Originally Posted by ers61

i wonder what brand were your batteries ? i'm suprised that the bms of your drop in was daly brand

also how did it go at the end ? did active balancer fixed your problems?

Battery brand is Ritar which imported from China. Before I cut open the box from the top, I didn't know about the cells inside and the bms brand. The problem was that during charging the bms was triggering the hvcutoff, not allowing the average cell voltage of the battery to rise above 3.45 volts. This is because the %Soc of one cell is higher than the other three cells.

After adding the Bluetooth Smart Dally Active Balancer, I applied an intermittent charge with a current of 0.03C and 1.5% above the average cell voltage. Thanks to the active balancer, I followed the balancing of the cells on my mobile phone. After each balancing process, which took about 5-10 minutes, the bms hvcutoff voltage was slightly increasing after the charging phase. The battery is fully charged with 14.5 volts when the active cell balancing is completed with a controlled charging that continues in the form of charging and then balancing, lasting a total of two hours.

[HeywoodJ]

Sounds suspiciously analogous to an absorption phase. The mechanics of bubbling electrolyte and active balancing are different, but in the end the purpose is the same - holding the batteries at maximum voltage to ensure that all cells are at the same state of charge at the end of charging

[ers61]

Originally Posted by SOLAR SUPPORT

Battery brand is Ritar which imported from China. Before I cut open the box from the top, I didn't know about the cells inside and the bms brand. The problem was that during charging the bms was triggering the hvcutoff, not allowing the average cell voltage of the battery to rise above 3.45 volts. This is because the %Soc of one cell is higher than the other three cells.

After adding the Bluetooth Smart Dally Active Balancer, I applied an intermittent charge with a current of 0.03C and 1.5% above the average cell voltage. Thanks to the active balancer, I followed the balancing of the cells on my mobile phone. After each balancing process, which took about 5-10 minutes, the bms hvcutoff voltage was slightly increasing after the charging phase. The battery is fully charged with 14.5 volts when the active cell balancing is completed with a controlled charging that continues in the form of charging and then balancing, lasting a total of two hours.

i'm suprised that the dally bms didnt do its work and you had to cut off the battery. normally its a good brand for a bms.