Battery Replacement in 10000mAh Power Bank: Electronics Compatibility, Charging & Housing Options

Hello everyone, I will write briefly what I mean. Well, I have a power bank with a capacity of 10,000 mAh, however, his good times are behind him. I am planning to replace the batteries with new ones. The housing has 5 pieces. Here comes the question. Well, will the electronics withstand and charge the whole set or will it be damaged or will not fully charge the new set? I am considering an alternative in the form of putting 2 sets of 2 pieces into the housing, which sets would be loaded separately, while the loading and discharging would depend on the switch that would be installed in the housing. Please advise on the above-mentioned topic. Thank you and best regards.

vicio_32 wrote:

Replacement for 5 with a capacity of about 5 thousand MaH is planned.

They do not exist. As far as I know, there are 18650 cells with a maximum capacity of about 3500mAh. The rest are just fakes. Unless you have a different type.

vicio_32 wrote:

Well, does the electronics withstand and charge the whole set, or will it be damaged or will not charge the new set to the end?

Electronics can handle it.

If you ask, it means that you don't know much about it all. In electronics, you cannot use proportional or linear dependence of parameters, it's not just mathematics.

The charging system of cells is adapted to the parameters of the cells used in terms of current efficiency. Usually, such systems use charging with nominal currents, and even higher ones corresponding to the cell capacity in order to optimize the charging time. Direct application of such charging conditions for capacities that are twice as small will result in damage to the cells used, and a drastic reduction in their lifetime.
Make the measurements of your charging system and make the necessary adjustments to the settings, if the electronic design allows it.

The use of a packet switch is a bad idea - the switch will only be an element causing additional losses during longer operation and creating the possibility of defects, complicating the operation.

My guess is that these 5 cells are to be connected in parallel? Honestly, I advise against it for 2 reasons: charging such a powerbank will be very long, about days and the life of the cells is short, even if you buy branded cells with real capacity. Strong powerbanks are based on other flat cells, probably Samsung, where one cell can have 6-10 thousand. These mAh cells are expensive, so such power banks are not cheap. The fewer cells, the better in a device with such poor control electronics. Example: 2 18650 cells with different capacity connected in parallel will fall after 100 charges where they would normally withstand 1000 charging cycles.

It would be ok if you wrote it down properly. What batteries, what does it mean to replace with 5 with a capacity of 5000mAh? Are they supposed to have so much together or each separately?

I think that each one will give about 25,000 mAh. Here you already have an issue settled by a colleague Miecho18. There are no batteries with a capacity of 5 Ah. Max is probably 3.5 Ah. That's why you write about counterfeit products that will at best have around 2000mAh, and knowing the Chinese, they can also have 1000mAh or less.

It's best to buy branded Samsung or sanyo cells that have about 2200mAh and most importantly, this capacity will be real. If you have a lot of money, you can buy these 3500mAh, they will take longer to charge, as long as we are talking about connecting everything in parallel.

I do not know why colleagues are discussing about 18650 cells? Where did the author define the type of cells?
In fact, very little specific data was given beyond the capacity values.

In general, there are also alternatives such as:

-20700, 21700, 26650, PL-7250115-2C, PL-7548168WR, PL-9059156WR, 7872196, PL-8570170WR, PL-8570170-2C.

On the other hand, returning to the merits of the matter, is it worth replacing the cells, remaking the electronics system, dividing the batteries into two, since you can buy, for example, a product such as:
- Power Bank PV120 5100mAh Black 2.1A, Powerbank Intenso ST10000, or Power Bank SUNEN 4000mAh in the amount of 2 - 3 pieces if needed?
The economic calculation supports such a solution.

Due to the numerous responses that I did not expect, I enclose photos of the interior of the power bank which I use and which is mentioned in the post.

So this is what we expected 5 18650 cells in parallel.
This solution is far from ideal because with time it will have more and more self-discharge due to different capacities of individual cells (they will charge each other). Better to think about 1 or 2 cells of greater capacity. Here is an example link 10 thousand. mAh Link

The above-mentioned product has dimensions 197 mm x 73 mm x 7.6 mm and package 18650 approx. 65.6 x 82.5 x 18.5 mm?

There is no need to combine, if you want to resuscitate the system, you need to use the appropriate cells available on the market, and that's it.


Most cheap power banks do not have a balancer and work somehow. It seems that the installed cells from the same production series, charging with a sufficiently large current, as well as the discharging of the package are selected (not discharged to the limit parameters) so that the package has uniform parameters during the assumed operation.

Nothing stands in the way of making additional outputs for connection balancer , but it makes the operation of a device like a power bank much more complicated.
As a last resort, the balancer can be used periodically.

E8600 wrote:

This solution is far from ideal because with time it will have more and more self-discharge due to different capacities of individual cells (they will charge each other).

What are these strange theories? Can you give me a link to your experiences or measurements confirming what you are writing about?
You can easily connect the cells in parallel, it is only important that the cells have the same voltage during the connection, preferably that they are discharged to the minimum voltage allowed by the manufacturer.

aaanteka wrote:

Most cheap power banks do not have a balancer and work somehow. It seems that the installed cells from the same production series, charging with a sufficiently large current, as well as the discharging of the package are selected (not discharged to the limit parameters) so that the package has uniform parameters during the assumed operation.

Nothing stands in the way of making additional outputs for connecting a balancer, but it makes the operation of the device, such as a power bank, much more complicated.
As a last resort, the balancer can be used periodically.

But who needs a balancer in a powerbank in which the cells are connected in parallel?

Piotrek#G wrote:

You can easily connect the links in parallel,

Of course, nothing will happen, but the cells will age faster. Manufacturers use such connections because it pays off for them, e.g. for a laptop battery, you have a shorter warranty, so they do not care too much. If you do not know how to choose the cells, at 5 there will always be something like a change in capacity in relation to others. And as you know, a li-ion cell should have a limited current after charging, but in such a package it will not happen because the rest is fully undercharged. A friend may have exaggerated with the balancer, but it would be useful to separate the cells during the charging process, because that's what I mean with aging. I deal with electronics as a hobby, but I think that a zener diode and a resistor for each cell would do the trick (or another simple electronic component). Branded cells of screwdrivers, where the warranty is up to 3 years, their durability is due to the perfect electronics that take care of the charging process. Poor electronics will damage the best cells very quickly in the subject.

aaanteka wrote:

Most cheap power banks do not have a balancer and work somehow

Do you know the construction of these most power banks?
You probably have never seen one like this before and that's why you write such fairy tales.

There is one link or several, but always connected in parallel, and this is the case in 99.99% of power banks. So why a balancer? What is it for?

Don't make unnecessary confusion.

To keep the cells in proper condition? How is charging performed?
Not all products have the package structure that your colleague presents.

Be sure to review Xcellon, OXA, Sandberg, and others to see that the merger isn't always the way the colleges present.

Unfortunately, but Freddy is right most of them are connected in parallel to make things easier for the producer and reduce costs. For powerbanks with a really larger capacity, other cells are used and usually it is one cell or a maximum of two, each charged separately. Therefore, branded powerbanks with a real capacity of 10-20 thousand, mAh do not cost PLN 40, as do Chinese experimental constructions where I even saw 10 18650 cells in parallel without any separation when charging. People are very eager to buy it only later, it turns out, despite inserting 10 cells with a capacity of 2000mAh each, the total capacity of such equipment is max 7-8 thousand, mAh instead of the 10 x 2000mAh = 20000 mA. Soon someone will say that they put old cells in with new branded ones, after several dozen cycles, the capacity will be similar with electronics and parallel packing of cells without security measures. This was the case with the author of the topic, which is why he is thinking about exchanging cells. I would rather look for a power bank on one link, preferably Li-po.

What you threw in is 2 x 2 parallel links, definitely a better solution than 5 in parallel, but you can see for yourself that the manufacturer has saved and the balancer is gone. But is it a powerbank, it looks more like a 18650 cell charger and then the balancer is not necessary because you replace the cells and swap them places.

Most of the cheap ones, yes, but that was previously discussed in post # 9.

Of course, another alternative technical solution was also presented.

The example shown is only a counter argument to "99% parallel connections" and that's exactly what it is - a cheap, simple circuit that uses a mixed connection, not a parallel one.

Serial connection with balancing is commonly used in power banks with the ability to power laptops, notebooks, cameras.
Most of them have a properly matched mains charger.
Let's not limit ourselves to products loaded only from the USB port.

The topic is "Replacing the battery in the power bank", not "How to convert the factory powerbank".
So why this discussion about balancers?

The author's level of knowledge is quite low and I doubt that he will be able to make such a modification.
Quite low, because he does not know that there are no 18650 batteries with a capacity of 5000mAh in practice. The author wants to take out the old (probably 2000mAh) and put in a new one.

vicio_32 wrote:

Well, will the electronics withstand and charge the whole set or will it be damaged or will not fully charge the new set? I am considering an alternative in the form of putting 2 sets of 2 pieces into the housing, which sets would be loaded separately, while the loading and discharging would depend on the switch that would be installed in the housing. Please advise on the above-mentioned topic.

18650 series batteries with a capacity of 5000mAh they exist just that they have such parameters .
But this has also been written above .

E8600 wrote:

Therefore, branded powerbanks with a real capacity of 10-20 thousand, mAh do not cost PLN 40, as do Chinese experimental constructions where I even saw 10 18650 cells in parallel without any separation when charging.

Why do Tesla use packages where 74 cells are connected in parallel, without any separation during charging? Why is such a serious company still using 18650 (currently 21700) and not larger cells?

Piotrek#G wrote:

Why do Tesla use packages where 74 cells are connected in parallel, without any separation during charging? Why is such a serious company still using 18650 (currently 21700) and not larger cells?

You have to ask at Tesla, because they only know.

The simple answer is the price of 18650 cells is the most favorable. Additionally, these cells have membrane protection to prevent fires. The durability of the cells can be taken care of in various ways, apparently TESLA has a different patent for it that everyone can find because the company TESLA, as the only brand known to me, renounced the income from its patents and made them available to all people free of charge, thus wanting to support the development of electric drives and popularize electric vehicles . Electric drive is the future, which I am not happy about as a motorcycle fan I wonder how it is with the OC rates in electric vehicles.