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Old 24-11-2022, 03:33   #1
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Opening the Sealed Type Drop-in Lifepo4 Battery

I had heard about the deterioration of the balance of the cells in the sealed Drop-in Lifepo4 batteries over time, but I realized that I did not understand this issue very well and did not care enough. Thanks to fellow sailors whom provided information about the cell imbalance in the forum discussion topics and drew my attention to this direction.

As with the DIY concept of Lifepo4 batteries, it's a good thing that the battery cells are easily accessible. I have to admit that I wasn't knowledgeable enough to make my first Lifepo4 batteries seven months ago. I preferred the batteries to be in a watertight box as it was more suitable for the way I use my sail boat.

The most common method used by drop-in Lifepo4 battery manufacturers to get ahead of other competitors in the intensely competitive market is to use low quality bms. I think Bms' are still in the near stage of being perfect and being well accessible era. For this reason, when purchasing a Drop-in Lifepo4 battery, the bms inside the battery should be examined very well. BMS must have bluetooth feature, which is very important in order to monitor and eliminate the imbalances between the cells.

My Drop-in Lifepo4 battery's internal Bms has a passive cell balancing feature, but this is not being enough in long term. Lifepo4 battery Bms trigers Hvcutoff at 13.8-13.9 volts. HVCutoff was 14.1 volts when I first charged them seven months ago. So I have to cut them open from the top to get an idea of ​​the health of the batteries and the balance of their cells.

It is not possible to communicate with the existing Bms' in my batteries. I'm waiting for newly purchased smart bluetooth active balancers (ACBs) to arrive by the int. cargo in two weeks. Thanks to the ACB's bluetooth feature, I will be able to monitor the cells in the battery any time by using cell phone app installed.

After the cut&opening the batteries one by one, I will add only smart bluetooth ACBs without touching the bms inside. The current situation is so bad because I have had no idea of the states of the individual cells in the sealed battery. I will have a chance to follow Lifepo4 battery cells individualy after I install two smart ACBs that will change this situation.

Before I start the top balance charge process, I must bulk charge both batteries first, until the Hvcutoff is triggered by the bms. I also think that I have to isolate each battery from the boat's electric infrastructure before starting to top balance its individual cells. I am going to use the new 0.01 volt precision dc-dc charger to reach the target voltage stage steps after the each active balancing stage completed of the cells. I think I must be carefull when connecting two batteries. The voltage levels of the batteries should be close to each other, otherwise the current between them may be at a level that the bms cannot handle.

I hope that top balancing charge process will not last too long. It is winter time so I am not bothering about the time would be spent to make batteries more healty. I am sure this small upgrade investment and works will prolong the Drop-in Lifepo4 batteries' service life time. On the other hand I am not afraid of that I will lost their warranty by cuting and opening their sealed box since I am sure they will not serve as promised by the manufacturer.
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Old 24-11-2022, 06:17   #2
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Whilst you will lose the warranty opening them up, if they are way out of balance now, solving that may give you a much longer battery life.

How about changing the BMS whilst you are at it?

If you are happy to order on Ali Express etc, you can buy empty battery boxes in a variety of sizes. Since its winter and you have time to order some new boxes which are quite cheap and would be good. Then find a way of using a gasket to seal them but rather than glue, fit with hinges or spring clamps, so you have access in the future.

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Old 24-11-2022, 07:54   #3
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

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Originally Posted by Pete7 View Post
Whilst you will lose the warranty opening them up, if they are way out of balance now, solving that may give you a much longer battery life.

How about changing the BMS whilst you are at it?

If you are happy to order on Ali Express etc, you can buy empty battery boxes in a variety of sizes. Since its winter and you have time to order some new boxes which are quite cheap and would be good. Then find a way of using a gasket to seal them but rather than glue, fit with hinges or spring clamps, so you have access in the future.

Pete
It doesn't make sense to spend 10 years of service life for a two-year warranty. If the capacity drops within two years, the warranty is of no use. I want to use the batteries for many years without sacrificing their performance and capacity.

BMSs are fulfilling their main duties. After the smart active balancer addition, there is not much left in the battery from an advanced bms. I will not change the bms because their capacity is sufficient.

I think the current discount campaign can also be a good opportunity, but before the discount campaigns, the prices of many products increased more than the discounts applied in the campaigns.
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Old 24-11-2022, 09:35   #4
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

If you want good longevity, do not try to save money in your up front investment

and do not buy drop-ins that you need to then modify.

The biggest problem is the fact that just like a cheap crappy BMS they are using poor quality cells.

Out of all the LFP cell model / brands available to consumers, only a very few are from makers that are purchasing high quality chemicals and components.

And to the extent they have good QA processes in place, it is very often the rejects that are getting sold off to the smaller / cheaper distribution channels.

Investing the time and energy to identify the right cells to buy and the reliable sources to buy decently matched Grade A instances

is where you will get your highest ROI in extended lifespan - that and caring for them properly, preventing "unexpected events" that can instantly render scrap

Obviously if you already made the mistake, you make the best of it, do what you gotta do.

But personally, if I could recoup say 70% of my investment I'd start over...
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Old 24-11-2022, 09:48   #5
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Here is where you can download the manual for a particular BMS (overkill solar bms).
I post it here for the good information in it on how to perform a top balance, the process of which is the same regardless of what BMS you use. If you are going to open your drop-in batteries (I think that is the smart thing to do) you would be best to remove all the cells from the case, and follow the top balance directions in this manual.

https://overkillsolar.com/support-downloads/

And another good resource for balancing cells(mostly the same procedure but written by someone as from above)

https://diysolarforum.com/resources/...ly.65/download
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Old 24-11-2022, 10:06   #6
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

I believe that vendor relabels BMS made by JBD / LLT

and yes well respected maker, at least among the cheap Chinese competition

Avoid Daly, poor QA
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Old 24-11-2022, 11:40   #7
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Quote:
Originally Posted by wholybee View Post
Here is where you can download the manual for a particular BMS (overkill solar bms).
I post it here for the good information in it on how to perform a top balance, the process of which is the same regardless of what BMS you use. If you are going to open your drop-in batteries (I think that is the smart thing to do) you would be best to remove all the cells from the case, and follow the top balance directions in this manual.

https://overkillsolar.com/support-downloads/

And another good resource for balancing cells(mostly the same procedure but written by someone as from above)

https://diysolarforum.com/resources/...ly.65/download
Thanks, I downloaded the file with information about DIY battery construction and balancing charging.

After plugging in the cables that need to be connected to the new smart active balancer, I have nothing else to do with the inside of the battery. I'll try to seal the plastic battery boxes again when I'm done. I'm thinking of making a top-opening and leak-proof cover assembly to be able to open the batteries when needed.

I guess the cells inside the battery are in good condition. I will try to make top balancing charge with smart ACB and fine tuned dc-dc charger.

After the balance between the cells is ensured in this way, I do not plan to remove the cells and the bms in the battery box unless if it is necessary. If I can't get good results with using the ACB to rise and balance cell voltages to their maximum voltage then I will remove the cells from the box and try to connect the cells in parallel after charging the cells to the same %SOC separately. I hope this part of the scenario won't be needed.

Since smart bmses produced in China are still being developed, it seems that it will take some time for this technology to be used in all batteries in its most perfect form.

I think many people who make tests on these topics on the YouTube channel contribute to the development of bms technologies. Thanks to them, I learned a lot and still continue to learn. For those who have the time, I recommend watching these videos published in these channels as it is the fastest way to understand and learn this battery technology.
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Old 26-11-2022, 16:03   #8
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

why is the hvc so low even when new? you should be charging at like 14.2v . all the drop ins I've seen are 14.2 - 14.4v charging. hvc should be much higher. for example the battleborn hvc is 14.7v

if you are only charging in the 13v range, that is probably why they are not getting balanced.

for example here is the battleborn note

"Balancing of Cells
A passive balancing process is activated by the BMS at the top of each charge cycle when the battery voltage exceeds around 14.2V. This ensures that all the cells remain at the same state of charge, which helps pack longevity and performance. "

I was hoping to see the pictures of the opened batteries when I opened this thread...
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Old 26-11-2022, 21:18   #9
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Or JK BMS…a good one too with integrated 2A active balancer.

But before cutting open try if you can get it balanced by methods Paul, other and me posted, all will work if the cells are not damaged already. If damaged try your warranty.
If you get that balance sorted, sort your „MPPT“ and replace with a real 3 stage MPPT and this most likely caused the imbalance.
Only if nothing of this is working cut open the battery and Highly recommend changing your BMS, yours in drop in doesn‘t do his duties in any way. Your problem is the BMS and not them being out of balance as this is a result of the crappy BMS or/and MPPT.
Patching up a crappy BMS with active balancers which are not steered via the BMS will make things even worse, not better.
Same with your MPPT as many told you to get a 3 stage one…but you just accuse us we don‘t understand your problem.
We actually do but you don‘t want to listen…
My last post here too…
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Old 26-11-2022, 21:30   #10
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Quote:
Originally Posted by smac999 View Post
why is the hvc so low even when new? you should be charging at like 14.2v . all the drop ins I've seen are 14.2 - 14.4v charging. hvc should be much higher. for example the battleborn hvc is 14.7v

if you are only charging in the 13v range, that is probably why they are not getting balanced.

for example here is the battleborn note

"Balancing of Cells
A passive balancing process is activated by the BMS at the top of each charge cycle when the battery voltage exceeds around 14.2V. This ensures that all the cells remain at the same state of charge, which helps pack longevity and performance. "

I was hoping to see the pictures of the opened batteries when I opened this thread...
I have heard that the batteries produced are charged around 50% SoC and put on wholesale. It is not possible to know what kind of balance they have at the end of the first charge and how many months they wait in the warehouses until they are sold at retail. Because the production dates are not written on the box.

The initial voltage measurements of the two batteries I bought were identical, 14.0 volt. The first charge of my Drop-in Lifepo4 batteries did not exceed 14.2 Volts. This is what I observed when I charged the batteries before starting to use them with my AC-DC regulated device with 0.1 V Sensitivity. I didn't pay much attention to this situation as they passed the capacity test. Hvcutoff decreased in seven months to 14.1v, 14.0v and most recently 13.9v.

I know that many drop-in batteries do not have an active balancer. I'm guessing that drop-in Lifepo4 batteries have passive balancer with the idea that bms should be the base standard. Passive balancing tries to discharge all other cells to bring the voltage of other cells closer to the lowest one. This balancing is at the level of very small milliamperes. Passive balancing energy is converted into waste heat energy in the bms card inside the battery.

Suppose that the passive balancing works on over 3.55V cell voltage for 4S@14.2 volts like "smac999" mentioned. Then it becomes certain that the passive balancing in these batteries has not worked at all for seven months.

Active balacer is automatically activated when the cell voltage is 3.3 volts (13.2V@4S) or more. I think this is the effective balancing act that should happen. During the active balancing process, a different and more effective method is used than the passive balancer.

Active balancer measures the energy of the cell with a higher voltage than the others with 0.001V sensitivity and transfers it to the cells with lower voltage. The transfer currents between cells are much higher than passive balancing. Therefore, active balancing takes place in a much shorter time and without loss of energy than passive balancing. Active balancing ischemia continues until all cells reach the target equilibrium value.
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Old 26-11-2022, 21:41   #11
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Quote:
Originally Posted by smac999 View Post
why is the hvc so low even when new? you should be charging at like 14.2v . all the drop ins I've seen are 14.2 - 14.4v charging. hvc should be much higher. for example the battleborn hvc is 14.7v

if you are only charging in the 13v range, that is probably why they are not getting balanced.

for example here is the battleborn note

"Balancing of Cells
A passive balancing process is activated by the BMS at the top of each charge cycle when the battery voltage exceeds around 14.2V. This ensures that all the cells remain at the same state of charge, which helps pack longevity and performance. "

I was hoping to see the pictures of the opened batteries when I opened this thread...
That’s what several of us wrote and also several methods how to get it back to balance without opening. If that’s not working a or multiple cells already damaged or the BMS so instead cutting open request exchange on warranty. Like this he can see if that warranty is actually worth anything too.
But he decides to ignore all this and ordered active balancers and wants to cut batteries open…
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Old 26-11-2022, 22:06   #12
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

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Originally Posted by CaptainRivet View Post
Or JK BMS…a good one too with integrated 2A active balancer.

But before cutting open try if you can get it balanced by methods Paul, other and me posted, all will work if the cells are not damaged already. If damaged try your warranty.
If you get that balance sorted, sort your „MPPT“ and replace with a real 3 stage MPPT and this most likely caused the imbalance.
Only if nothing of this is working cut open the battery and Highly recommend changing your BMS, yours in drop in doesn‘t do his duties in any way. Your problem is the BMS and not them being out of balance as this is a result of the crappy BMS or/and MPPT.
Patching up a crappy BMS with active balancers which are not steered via the BMS will make things even worse, not better.
Same with your MPPT as many told you to get a 3 stage one…but you just accuse us we don‘t understand your problem.
We actually do but you don‘t want to listen…
My last post here too…
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.
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Old 27-11-2022, 17:55   #13
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

I tried the overkill bms for a couple of weeks, and wasn't getting the balance I wanted. I added a 1 amp active balancer, and everything was fine within 36 hours. I then unplugged the active balancer to save parasitic losses, and everything has remained balanced for 18 months
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Old 27-11-2022, 19:41   #14
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

Quote:
Originally Posted by SOLAR SUPPORT View Post
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.
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.
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Old 28-11-2022, 00:25   #15
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Re: Opening the Sealed Type Drop-in Lifepo4 Battery

I bought a couple of expensive Victron drop ins and through the 50% charged at new, their standing in the retailers warehouse for eighteen months and my ignorance re lithium batteries and the terminals not being sealed where they pass through the case lid, one of the internal BMSs suffered water damage and thoroughly discharged them both.

Only one of them recovered and after being totally rejected by both the retailer and Victron I decided that since I owned the battery and they had no interest in warranty matters I could take the top off it and see what might be wrong.

I subsequently removed the lid and found the water damaged BMS and that to achieve 100 amp hours capacity they had used four pairs of parallel 50 amp hours cells in series. The failure was caused by the collapse of a single cell. Having now gained access to the individual cells I was able to restore seven of the eight cells.

In response I rewired the cells as a 50 amp hour battery and purchased a Daily BMS for it.

I will never again purchase a drop in battery and will always implement DIY with cells and generic BMSs.
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