Hello,
could anyone propose an Integrated Circuit which offers battery protection (mainly cell balancing, if possible : overvoltage-undevoltage-overcurrent) for a custom 2series-2parallel battery pack (Li-Ion batteries,nominal voltage of pack 7.2 ,min :6V max :8.4V, capacity:5.2Ah)) ?

NOTE : The pack cannot open to protect each cell individualy.

 

If you need to do cell balancing, the terminals of each cell must be accessible.
If accessible, there are lots of "2S" Li Ion charge controllers that do the job.
Google for "2S Li Ion charge controllers" and select one based on your cell capacity.

 

If you need to do cell balancing, the terminals of each cell must be accessible.
If accessible, there are lots of "2S" Li Ion charge controllers that do the job.
Google for "2S Li Ion charge controllers" and select one based on your cell capacity.

It looks to me like he is looking for the other type, the type that works with each individual cell.
This type monitors the voltage and as it reaches the full charge point (normally around 4.20v for regular cells) it starts to bypass the current so the cell no longer charges. Since this does not affect the other cells in the pack, the other cells can either continue to charge or also bypass the current. Eventually they all switch into bypass mode so the pack is fully charged.
Myself, i prefer to monitor each cell with a single controller but that could require a lot of wires and connections when there are a lot of cells involved.

I would think this is something Google could still help with though with a simple search or two

 

As cell balancing requires each cell terminals to be accessible (as you told and it is not accessible in my case, only the two terminals of the package are accessible) , is there maybe something providing the other protections ( overvoltage-undevoltage-overcurrent )for my case?

 

As cell balancing requires each cell terminals to be accessible (as you told and it is not accessible in my case, only the two terminals of the package are accessible) , is there maybe something providing the other protections ( overvoltage-undevoltage-overcurrent )for my case?

Oh you mean the pack you are starting with has already been constructed so you cant get inside of it?
That's a problem, but do you know what kind of cells they used inside? There are different types of Li-ion some have protection built in, but you would have to be sure.

 

As cell balancing requires each cell terminals to be accessible (as you told and it is not accessible in my case, only the two terminals of the package are accessible) , is there maybe something providing the other protections ( overvoltage-undevoltage-overcurrent )for my case?

Some packages come with the charge controllers built-in. If you know the package details, it may be possible to confirm if it has a built-in controller.

 

Oh you mean the pack you are starting with has already been constructed so you cant get inside of it?
That's a problem, but do you know what kind of cells they used inside? There are different types of Li-ion some have protection built in, but you would have to be sure.

Yes the pack is alreade constructed.

 

Well the package i refer to is this : https://gomspace.com/UserFiles/Subsystems/datasheet/gs-ds-nanopower-bp4-27.pdf
with configuration 2s-2p. Each cell is described here : https://gomspace.com/UserFiles/Subsystems/datasheet/gs-ds-nanopower-battery_2600mAh.pdf

 

Well the package i refer to is this : https://gomspace.com/UserFiles/Subsystems/datasheet/gs-ds-nanopower-bp4-27.pdf
with configuration 2s-2p. Each cell is described here : https://gomspace.com/UserFiles/Subsystems/datasheet/gs-ds-nanopower-battery_2600mAh.pdf

The battery cells themselves look pretty much standard except maybe high reliability, but the pack is quite advanced. It looks like you should contact the manufacturer for more data such as a schematic because the pdf on the pack does not seem clear enough to make any decision as to how to charge this pack.
It even looks like there could be individual wires to each internal cell, but from the pdf it's not clear enough to be sure so you'd have to get more info or do some extensive testing.

 

The battery cells themselves look pretty much standard except maybe high reliability, but the pack is quite advanced. It looks like you should contact the manufacturer for more data such as a schematic because the pdf on the pack does not seem clear enough to make any decision as to how to charge this pack.
It even looks like there could be individual wires to each internal cell, but from the pdf it's not clear enough to be sure so you'd have to get more info or do some extensive testing.

Unfortunately, it is a little bit difficult to contact the manufacturer and as i know they cannot provide more infirmation. From what i know there cannot be individual wires to each cell, only two wires of the whole package.

 

I contacted Texas Instrument and they proposed me to use this IC. But i am in doubt if it suits my ocassion.

Mod: added datasheet.E

 

I contacted Texas Instrument and they proposed me to use this IC. But i am in doubt if it suits my ocassion.

Mod: added datasheet.E

Look at the diagram of the chip on the first page, what do you see?
What i see is several terminals of that ic going to several battery cells. The cells might be in series, but they still have individual wires going to each cell, so every cell terminal has a wire.
But aside from that, the data sheet says "3 to 20 cells" (in series) while you are using just 2 in series.

But take a look yourself, do you see anything different?

If you can not contact the manufacturer of the cell pack you probably should turn to a different pack, but if you cant do that then you should do some testing so you can know how the terminals of your battery pack function. As a minimum, you have to know what all the terminals are for. If yoiu dont, you can never use the pack correctly or at least be sure you are using it correctly.
So in the absence of a good schematic i would say you should do some testing to find out the function of each terminal on the battery pack.

 

Look at the diagram of the chip on the first page, what do you see?
What i see is several terminals of that ic going to several battery cells. The cells might be in series, but they still have individual wires going to each cell, so every cell terminal has a wire.
But aside from that, the data sheet says "3 to 20 cells" (in series) while you are using just 2 in series.

But take a look yourself, do you see anything different?

If you can not contact the manufacturer of the cell pack you probably should turn to a different pack, but if you cant do that then you should do some testing so you can know how the terminals of your battery pack function. As a minimum, you have to know what all the terminals are for. If yoiu dont, you can never use the pack correctly or at least be sure you are using it correctly.
So in the absence of a good schematic i would say you should do some testing to find out the function of each terminal on the battery pack.

Yes, i agree. The diagram doesn't seem to agree to the configuration of my battery pack (cause it assumes that we can access each individual cell of 3 or more series cells) and that's why had my doubts when they proposed it.

 

Yes, i agree. The diagram doesn't seem to agree to the configuration of my battery pack (cause it assumes that we can access each individual cell of 3 or more series cells) and that's why had my doubts when they proposed it.

Maybe you could provide a real life picture of your pack.
Did anybody ask yet, how many wires do you have coming from the pack, or how many terminals?

 

Maybe you could provide a real life picture of your pack.
Did anybody ask yet, how many wires do you have coming from the pack, or how many terminals?

Nobody yet. I will contact them again and refer to the number of wires coming from the pack. I think it will help.

 

IDK about controllers - sounds like a scam although I don't doubt they are used to cheapen cost of production.

If your in parallel you can use diodes to prevent backflow. That's about all you can ACCOMPLISH in a failing situation to prevent a MELTDOWN / explosion. You can't remediate the missing battery and if your device can be damaged due to a missing cell: your f'ed. you need to cut all power when ampheres drop - which a controller won't do.

If your in series then every bat must be able to withstand the highest voltage - they add but not incrementally. If one fails voltage will drop, and you'd have to detect it to know. You could still use diodes to insure power flow goes only one way.

The problem with diodes is they cost more and don't shut off the power: and they run hot and consumer battery.

Power supplies are of course one of the chief costs of any GOOD electronics and this is why.

You'll note that many devices wire together batteries without such protection. Look at all those Li power tools at HomeDepot. None of them use "protection". They are fire hazards. But somehow ... it tends to work and is allowed.