Creating custom Li-Ion charger for Galaxy Note 10.1

[nas-r]

Long story short, my galaxy note 10.1 stopped charging because I used a dodgy cheap cable. I've tried different cables, replacing the battery and flashing the stock firmware and kernel with no luck. It will not charge. The cables definitely work, as I flashed the stock rom over USB to my PC. It just won't charge the battery.

It gets the 5v from the USB port but none of that ever gets to the battery. (checked with multimeter)

Now I thought it would be a shame to let a great device die due to such a small problem. My current solution would be to combine some Li-Ion charging IC that could operate over USB input voltages with (perhaps) a balancing IC as the battery is 2-cell Li-Ion.

If it's significant the battery has 5 wires exiting the battery to the device, 2 red, 2 black and one blue.
I have no idea what the blue one does.

Due to my severely limited knowledge of electronics i'm not sure if the balancing IC is really necessary. To be specific I opened one of the batteries and found one of these inside:

MP24AG: http://eng.it-m.co.kr/cnt/prod/tep_5l/MP24AG.pdf

From what I can understand it provides current and voltage protection, but will it also balance the cells?
If so could I get away with a simple single cell linear IC such as: http://cds.linear.com/docs/en/datasheet/405442xf.pdf
Or would something more like this still be required? http://www.ti.com/lit/ds/symlink/bq24123.pdf

Does the second one (TI-bq24123) handle the cell balancing by itself?

I'm new to this forum but have an ongoing passion for electronics so I hope to be here for a while. Currently studying software engineering and like to have a couple of side projects going.

Any help is greatly appreciated.

Regards,

Nas

 

[(*steve*)]

Welcome to Electronics Point.

OK, let's go right back to the beginning.

1) Why do you think the dodgy cable was to blame?

What are the voltages across the red and black wires? Across the red and black wires if paired differently? Across the red wires? Across the black wires?

No, that chip (MP24AG) will not balance the cells.

Balancing is probably required for long battery life.

If there is access to each cell individually then you can change them independently, but almost certainly NOT at the same time (especially if you're charging from USB)

 

[nas-r]

Thanks for the reply.

1) I think it was the cable because it converted micro-usb to the proprietary samsung 30-pin connector and as soon as I plugged it in the tablet entered a boot-loop and would no longer charge. It's possible that it was a coincidence that the first time I tried the cable this symptom appeared, I'm not honestly 100% sure.

The voltage across combinations of black/red wires from the battery is 3.75V
in the battery there are terminals labeled B1+ B1- B2+ and B2-
with corresponding connections to the relevant pole/cell.
Between these terminals is located the MP24AG and then hidden in the plastic are the wires which eventually emerge as 2 black, 2 red and a blue wire.

The battery is rated at 3.7V 7000mah 29.5Wh

RE: your last paragraph, I should have been more specific. I don't ever intend to charge this over PC USB. It will likely be charged using USB adapters that supply between 1-2A at 5V.

I mean I've just done some preliminary searching for adequate li-ion charging ICs so I don't really know what I'm talking about lol.

From what you've told me I'm beginning to think I'll need balancing since this tablet will hopefully go through another 500 or so charge cycles over the next 18 months. So I'll need a balancer and a charging IC.

Questions:

i) if I use a balancer, will I still required a charging IC (linear perferably) that supports multiple cells or will one like the LTC4054-4.2 suffice to simultaneously charge both cells using the balancer?

ii) do you have any recommendations? Am I perhaps going in the wrong direction?

Thanks again for replying.

 

[(*steve*)]

It certainly sounds like that adapter did something to your hardware. If it shorted something out it is not inconceivable that the charging circuit in the tablet could have been damaged.

So yeah, I'm with you on the charge the battery outside the tablet idea.

OK, I need a little more specific information (multimeter in voltage mode).

With the black multimeter lead on the B1- and the red multimeter lead on the B1+ you get 3.75V?

With the black multimeter lead on the B2- and the red multimeter lead on the B2+ you get 3.75V? (exactly the same, or a couple of millivolts different??)

With the black multimeter lead on the B1- and the red multimeter lead on the B2- you get...?

With the black multimeter lead on the B2- and the red multimeter lead on the B1- you get...?

With the black multimeter lead on the B1- and the red multimeter lead on the B2+ you get...?

With the black multimeter lead on the B2- and the red multimeter lead on the B1+ you get...?

If the batteries are in series you will only be able to charge one at a time from a USB adapter. They are almost certainly in series. The answers to the above will tell us.

i) you probably need a balancing charger, so yeah, charging and balancing.

ii) let's get some data and see where it takes us.

 

[nas-r]

I'm pretty sure they're in series as I did test those combinations and always got a voltage of 3.75 - 3.76 or 0. But where I got 0, usually all I had to do was swap the wires to get a voltage.

Unfortunately I have no opportunity to test this during the work week, I'll get some proper numbers on Friday.

 

[(*steve*)]

Is your meter digital or analog?

If digital, the display may show a negative voltage if you connect the leads the "wrong way", but swapping them will not make it go from zero to positive.

It is important that I get an understanding of how the batteries are wired, so please run those tests when you can.

 

[nas-r]

It's digital and you're correct, don't know where I got zero from.



Those are the results. The values of 2.935 are just points were the result would continually switch between 2.93 and 2.94. Otherwise the results were fairly stable.

 

[(*steve*)]

That's excellent. It tells us that B1+/B1- connect to one cell, and B2+/B2- to another cell.

It also tells us that there is no connection between them.

This means that you can charge both cells simultaneously from whatever pair of chargers you can find.

Beware that the cells are possibly not protected so make sure that any charger you get will honour the voltage limits for the cell chemistry.

 

[nas-r]

Thanks steve!

What about the results led you to that conclusion? Not disagreeing just curious in case I need to do something similar in the future.

The battery does have a chip that is designed to protect against too much voltage or current

 

[(*steve*)]

If the battery was a single cell, or 2 cells in parallel (with 2 outputs for some obscure reason) then you would only get a single cell voltage. In your case you got two distinct voltages. Those voltages tell me that there's 2 cells.

If the cells were connected in series, you would see double the cell voltage at some point as well as the cell voltage in more places. You don't see this, so I know the cells are not connected.

BTW, great job at putting the results in a table. It made the the answer stick out like dog's balls.

 

[nas-r]

Ah of course! They're definitely not connected in series. I think they are actually connected in parallel however, and that my multimeter isn't the most accurate thing in the world. I say this simply because today I tore the spare one apart a little bit more, and the two red and two black wires that exit the body of the battery are actually soldered onto the board together. This would confirm the conclusion you came to, that they are definitely not wired in series.

This I hope simplifies my situation further, since I can now just purchase something like this off eBay: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=231206236475
It will charge it slowly (7mAh capacity charging at max 1A...) but it will charge. I'm thinking of putting in a switch and using both batteries, charging/discharging them separately.

Thanks a lot for your help steve, I'm glad I could avoid throwing out a genuinely useful device!

 

[alexdoc]

does samsung tab 10.1 now work? I have the same problem. thanks

 

[nas-r]

Yep. I used a 1A Li-ion charging board off eBay, soldered wires from the exposed battery leads to the charging board and charge the battery through that. Downside is you have to power cycle the tablet to update the battery % after charging but apart from that, it works fine.

 

[Kenneth Tan]

I had the same problem. The solution is to short the D+ and D- wires on the tablet side. (or in the charger output side ) More elegant is putting also two resistors in series, 82KOhm each, between 5v and gnd and then connecting this D- and D+ in the middle. Worked fine on my Note 10.1 until I had a firmware lockup. But thats another story.
Now you can charge it from any usb source.

 

[nas-r]

I'm going to give that a shot some time soon. I thought the charging circuit in the tablet carked it, but if this works its certainly more elegant than my current setup.

Thanks for the tip!

 

[Kenneth Tan]

I actually made an usb male-female adapter with the short and resistors inside. Now I can use it on more devices that have trouble charging from non-same-brand chargers.
You should search for these resistor setups. They seem to be different for brand and even charge current.
82KOhm is used in the Galaxy S4 to achieve 1.2A charge current. But my S4 charges @1A even when only the data wires are shorted.
Ofcourse by now you should understand that the cable cannot be used for data transfer.....