Introduction: Hackable Battery

Picture of Hackable Battery

*Disclaimer: This contains Li-On Batteries, they can be dangerous but so are power tools. Please Respect Electronic and their wonderful nature, as Im not held responsible if you do something stupid*

First and foremost, I didnt make it, however I did want to share it will the community, because to me, this Battery Ive found seems to be VERY hackable for other purposes. Heres the Specs:

Input Voltage: 15-24V DC 2.5A Max
Output Voltage:12-24V DC 4A 70W Max
Specs on the box say its 52Wh
Max output is 72W.
Operating time:4hrs depending on load
Charge time: 3 to 8 hrs.
Weighs in around 418g

I found it on walmart.com (where else!) For around 8 bucks. I figured, Hey, This has to be useful in something else other than what it was designed for. Its originally for laptops but given the Input/Output voltage and Other specs I couldnt resist from buying it. My initial thought was that it would contain NiMh batteries, But today when I looked on the back, it says it contains Li-On Cells. Hmmmm. This is Begging to be hacked. 

On to the photos. I couldnt keep my hands off this thing. I knew there was a way inside, but how? Not surprisingly I test fitted it to my netbooks power supply and it doesnt fit. Gee what a surprise (sarcasm).

Photos 1 and 2 Show the outside of it.

3rd photo shows just a peek of the inside as I was opening it up..and a peek to what was hidden. Lithium Batteries you say? I found it interesting..

4th Photo is self Explanatory. Hmm Li-On batteries made by samsung. A quick search on the web brought me here (clicky). 2400mAH. The Cells are wired in Series-Parallel. Im gonna guess its something like 4800mAH per Dual Cell @ 11.1V total. Dont Forget, that voltage is boosted even higher...

5th and 6th photo show me trying to get a look at the underside of things, trying to determine Where that Input Connector Goes. Sucks that I have no charger to put the adapters that come with. Hack on My Friend, hack On .

Last photo shows the whole thing, as it fell out of the package. Opps. No cells where harmed in the making of this Slide Show.

This is quite wonderful. My mind is alight with Ideas on what to do and how to Improve it. The Fets are epoxied to a piece of Aluminum. Improvement there? You bet. Arctic Silver my Fellow hackers. I feel at some point it probably would have overheated. Im actually thinking of replacing the whole boost converter circuit, with something..Smaller and who needs 4 Amps of current anyway? Im sure 1amp would be enough (in terms of output-The board doesnt look as if it has anything to do with charging, but I could be wrong).

The most amazing thing I find about this is that the input voltage is Pretty much exactly the same as what a Solar Panel Puts out to charge a 12V Battery. Free, Cheap Energy Anyone? Again, the whole thing cost a bit under 10 bucks (including shipping). Could I have found Li-On Batteries for the same Price? Maybe, but with integrated Charger and Boost Converter? Nope.

Oh I wont Link the product here, It is probably considered spam :)

Update: I soldered on some wires to the bottom of the charging port and it works! Of course now I find that I have a spare tip that will fit the thing, so I didnt have to go through the trouble of soldering. Oh well. Also, 2 of the 6 cells gets Hot, well warm. Around 35C warm.

Comments

ironsmiter (author)2012-02-07

Update time.
  Both packs finally dies. Turns out it was the first two cells, in both packs(surprise, right?) So, bad cells replaced. and the circuit works fine again.
Now onto the fun stuff.
   I COULD put them back together as external packs, but I had a better idea present itself. One of my 24V NiCd drill/saw/light batteries died. Multiple cells showing 0Volt.
Things in my favor : 
    24 volt available from both battery packs.
    2Ah from the nicad, 2.4Ah from the Li-ion(replaced old ones with matching capacity cells)

and since the 6 18650 cells take up FAR less room than the 20 NiCd... there's room in the battery case for all the circuitry AND the connectors :-)
Think I'll put the charge port on the top of the battery, where it'll be covered when in the tool.

The only things I think I'll add are a switch, to dissconnect the charge/discharge circuit board from the li-ion protection circuit, and a pair of diodes, on the battery terminals. Diodes, to keep me from blowing anything up, if the battery accidentally gets put into a normal charger.
(NiCd charging current/voltage, flowing backward into the output circuit may or may not do very bad things. Trueblood is good for vampires, bad for vampire circuitry)


That should keep the pack from going flat in a couple days, like it did originally.
Don't know WHAT clown designed the circuitry, but they seem to have forgotten a few fundamental facts when it comes to batteries.

Nerdz (author)ironsmiter2012-02-08

I should have bought more of these as its no longer available. It would have been a good source of Li-On Batteries. Oh well. I still have mine, I just havent decided what to do with it. Part it out? Its not surprising the 2 Front batteries died first. Chinamen designed it :P. The only thing that might be useful would be the protection circuitry in that case, that is if it functions correctly.

Its probably even better to Just rip out the boost converter, Hack it for parts and then Rebuild it using our own design (hell there are tons out there that have shutdown pins and only use 1mA or less when in shutdown mode).

Maybe I'll rip the thing apart but the batteries will probably be shelved. But those first 2 cells, if you let them heat up what-so ever you reduce their life drastically. Who designed the Charging circuit? I think Monkey's did, as Clowns would know better :P.

Actually you know what. Just rip the batteries out. Keep the Protection Circuitry but Buy a Charging IC for Charging Li-Ion Batteries. Their pretty cheap and easy to solder. Try MCP73831, Its a SOT-6 package and can provide up to 500mA to charge Li-Ion Batteries. Ive used it before and its good at its job. Not to hard to solder either (even with a cheap Radio Shack Iron).Its MUCH better than the wack job charger in this thing by default. There are ones out there that have temp monitoring. You technically *should* use this but ive gotten away with using my fingers and watching it every hr.

To your comment below: Or a reed switch. Magnet and a reed switch would work better. Although your just switching the load on or off anyway, Theres already a switch to turn the tool on :)

ironsmiter (author)Nerdz2012-02-08

:-) like the reed switch idea. but then i'd have to modify all my tools as well.
all 6 of them. dremel out the magnet pocket, epoxy in the magnets...

If i use a momentary push switch, it'll turn the battery "on" whenever inserted.
And NOT on, when in the nicd charger( you'd have to see it)

I'm thinking that the switch will go between the protection circuit, and the main board.
May That way, even if my plan doesn't work, and somehow it gets into the nicd charger and the unhooked circuitry fries from the voltage... I still have a working battery pack and protection module :-)

With my current plan, of using the whole shebang, just recased with an added switch... I'm out exactly zero dollars. If I start re-designing the charge/supply circuitry... then I'm gonna be buying ic's, etching boards... whole lot of not fun, for a $40 battery/charger

Thanks for the thoughts, and added info though.

Nerdz (author)ironsmiter2012-02-08

That Charger IC is actually pretty cheap around $0.60 each. Shouldnt cost more than $ 2 total (you could make a Adapter and then use through hole parts-then it will be even cheaper), that is assuming your making PCBs yourself.

Oh and you cant use a NiCD charger on These batteries, Unless you meant using the powersupply to charge them, which you can.

I ripped the whole thing apart. Desoldering these IC's are impossible, my iron doesnt go up high enough, it seems they used Lead free solder. I managed to ruin a Nice FET though trying to pull it out. Oh well. I think Im going to run them all in parallel for more capacity, 14.4Ah total.

GL.

ironsmiter (author)Nerdz2012-02-09

Yep. sorry if i wasn't clear.

I WAS charging the intact packs, using an old laptop power supply.
My plan is to continue using it to charge my new Li-Ion drill battery :-)


Which IC were you talking about?
As good as I am... surface mount chips are a little beyond my skill.
my hand just isn't steady enough to use the usual techniques.
I can usually do the larger SMC resistors, capacitors, and sometimes smd led's... but up the pin count, and count me out.
I know my limitations.


Good to know that those cells are going to use, instead of landfill :-)

If you really want to get those bits loose... try a toaster oven!
Most lead free solder will give up and go fluid around 450F.
and that's not TOO hot for most IC's to survive for a short duration.
PROBABLY the big problem you were having was heat-sinking.
For small solder irons, sometimes even just the heavy copper traces on the circuit board are enough to thwart your efforts.

Since I'm still in the middle of this project, I'll let you know, but my little 15Watt pencil iron from RadioShack(yes, it's older than their new name "The Shack") did just fine desoldering the interconnecting wires between boards, and batteries.

Another thing to try is... drop a bit of melted leaded solder onto the solder joint.
Not only does it add hot thermal mass(like putting a solder tip twice the size on) but, it also lowers the melting temp of the solder that's already on there.

Nerdz (author)ironsmiter2012-02-24

MCP73831. Its not too hard even with a Radio Shack Iron (15W), even a 40W can do it if you mod the tip ;). Adapters are relatively cheap too to make it fit into a DIP socket (or to breadboard it).

ironsmiter (author)Nerdz2012-02-25

hmm, that one is interesting. One of the first chargers I've seen that was rated at 4.2 volt(the -2 chip I mean. the -3, -4, and -5 obviously have higher terminating charge voltages.). for some reason most charger IC's what to charge up to 4.25. I've even seen 4.4!!! Personally, I'd much rather slightly undercharge the battery pack and add more cells to make up the lost capacity, if it turns out it was needed.

Looked at that data sheet pretty throughly.
Should work very well with your 1x6 arrangement.
for everything EXCEPT how LONG it will take to charge.
That puppy is only rated at 550mA!!
If you do a 1x6 and charge with that chip... you'll be waiting...
wait, that's only 30 hours for a full charge.
that's not so bad.
I guess.
Not FAST, or even "over night" but pretty good, considering you can get that speed of charge out of a usb port!

Nerdz (author)ironsmiter2012-02-26

You have to use the 4.2 Chargers with these. Any Higher and they'll explode and catch fire. The higher Voltages Are for different cell's (although I havent seen any on the market that take them yet). You could probably get away with charging to just 4.15 or 4.10 to get a higher life cycle out of them. But this device wasnt engineered with that in mind ;)

Yea for charging time its Capacity / Charge current. Most batteries should be charged either 1C or 0.5C. The lower current you charge it with the better off you are, you also extend its life. Id probably go with 0.25C (C meaning the capacity, ie 2400 mAH for these cells). So if I wanted 0.25C, that would be 600mA BUT As you noticed the IC is only rated for 500mA, which is actually quite fine but, since its a linear charger we would want to make VCC as close to Vbatt as possible (like 5V) so it doesnt dissipate a lot of power. 30hrs isnt bad, especially since I was going to use them in some sort of LED flashlight.

Theres larger Charger IC's out there that could use external FETs for up to god-knows what current (limited by your FET and probably a current sense resistor).

The only thing I dont like about Lithium Ion batteries is 1) They cant take abuse and 2) Their Temp rating. If I wanted to leave batteries outside these wouldnt cut it. have a look at LiFEPO4 Batteries. They just have a lower voltage but their *almost* the same battery. I bought a few of these. Their very nice to keep around for emergency purposes.

Nerdz (author)Nerdz2012-02-08

Ive successfully identified 2 of the IC's on the Chip, ofc after burning out one of the current sense resistors. Disconnect the battery before working on this thing. I pulled the batteries off as soon as I smelled smoke (opps).

First one is quite obvious: BQ2000T which is a multi-chemistry charger. This little IC goes for $4 alone in single qty's.

2nd one is a bit harder, with the output port Facing Forward and the board turned upside down, its a bit south of that port but a bit north Of the furthest FET. Its the SMPS Controller IC 3842B. This is a fairly common IC. If it's input voltage was a bit lower, it would be useful (7.5v is the lowest it will go). Still, considering all these batteries together ouput 9.6V, I guess we could rework this whole thing.

Im still identifying the other IC's. Most are probably FETs or Diodes, along with a comparator and 5V regulator.

ironsmiter (author)ironsmiter2012-02-07

Looks like there will be plenty of room to add the fuel gauge!

And MAYBE, if i take out some of the battery case ribbing, to upgrade from a 3S2P pack and make it a 3S3P pack, for even longer runtime.(with li-ion, adding cells adds MORE runtime than what is listed on the cell. Some technomumbojumbo about a lower draw per cell = longer usable voltage levels. 3s1p=X runtime, 3s2p=2.1X runtime, 3s3p=3.3Xruntime, 3s4p= 4.6 runtime, etc.)


Finally, thinking maybe making the on/off swith a MOMENTARY switch, that gets activated when the battery is in the tool(there are a number of locations where the battery pack completely touches the tool body). What do you think... just one more thing to go wrong? or a very cool safety device?

sam D (author)2011-09-10

Its interesting seeing inside. You might be interested to see the pack I soldered up from mobile phone hates. http://samdidgaf.blogspot.com/2011/08/soldering-mobile-phone-batteries.html

Nerdz (author)sam D2011-09-10

Thats awesome, how did you get a hold of that many batteries?

Im really thinking of reworking this thing. The two Cells nearest to the protection PCB get warm. I hooked up a MCP9700 to measure temp and they were around 35C on the outside, ambient being around 25C. If I do rework it, I'll defiantly keep the protection PCB but use a more suitable Charger. Seems they only took 4 hrs to charge, and my input current was 1.75A, so with losses they are charging with around 1.5A or less which means each parallel battery pack should be getting 0.5A each, and each individual battery 0.25 each.

Then again these cells were depleted. Measured less than 3v overall. Ideally they should be trickle charged and brought up slowly. I cant seem to find a flaw in this thing for 9 bucks.

ironsmiter (author)Nerdz2011-09-24

Thanks for the find! Less than 5 days later, my package of 2 arrived.
    The one i took apart so far, does seem to have suffered the usual battery pack trouble.
   One cell out of the batch is overly discharged, and is pretty well toast. The others all recharged fine(using aligator clip leads off a 1 cell li-ion 18650 charger. 
    
    The second pack had a charge(2.9V) and so, looks promising, for using As-Is. 

Probably end up powering a set of led running/biking lights.

For those who worry about such things, these are made in Korea, rather than China.




My plan for the one I disassembled is, make it BIGGER! (MORE POWER! Muhahahah)
I'm going to take some of my old laptop cells, pick the best balanced sets i can and turn this puppy into a 12 cell battery pack.
Hoping to get a good 4-6 extra hours out of my netbook when hooked in.
I'm going to have to look up the sepcs on the IC's, and see if they can handle it, but i may go as high as 18 or 24 cells! Sure, it'd take all day to recharge, but might be worth it. 6S2P, 6S3P, or even 6S4P?
Especially since my 12volt auto trickle charger has a matching plug to one of the laptop power supply jacks! Should be good to run my camping lantern/radio for a good solid weekend non-stop.

Nerdz (author)ironsmiter2011-09-24

I do wish these batteries were of the newer kind, Lithium Iron Phosphate (LiFePO4). With those batteries you dont have to worry about safety as much, their pretty much indestructible but get As close to the power density as Li-On's (not exactly the same but close enough).

I just looked last night and they went down to $4! I guess I made them popular as their not in stock online anymore.

Ive last charged them on sept 10th and its the 24th Now. Im curious to know how the cells have faired after 12 days. Ideally they should read somewhere near 3.8V-4.0 (Most read around 4.0 or 3.9). Ive also noticed the Boost converter Runs even with nothing connected. This shouldn't waste too much power as theres nothing on the output.

Ive thought of one thing to do with it: 1000 Lumen (or more) Light. With the math Ive worked out (assuming the LEDs consume 1.5Amps) It should last around 4hrs.

Currently Im working on a Solar Panel That will go along with it (finally!)

ironsmiter (author)2011-09-24

and for those interested, here's the link to the PDF for these batteries.
http://www.cellboost.com/img/manual/irecharge_laptop_manual_1.pdf

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