# Building my own battery packs out of samsung 18650 cells



## Andreas H (Aug 1, 2015)

Hello,
I got my Yinding LED light and 10 brandnew Samsung 18650 2000mAh cells a few days ago. Everything works fine and now it is time for some changes.

You can't _switch off the green LED shining all the time at the backside(can you??)_...exept you build (a voltage controlle +) small switch near the battery at your bike.
At first I have to tell that the battery I am going to use will be shared with 2 other small lights(front and rear light for street use).

_My first thought _was to build packs similar to the org. Yinding battery - this would be nice, because I wouldn't have to buy a new charger.

Does anybody know what is inside the org battery? I think there will be a small pcb??

_On the other hand _as weight is no problem I think building two larger packs would also be great:

like 2s3p with balancer leads and I also think about a Imax B6 to buy and some more 18650 cells, many 2s and 4s balancer leads(for charging 4 18650 cells in series(not welded together) with the imax) and xt60plugs, battery holder ...this way one can also use the 18650 with my DIY powerbank which arrived without any cells.

So my first question was
_if Icould use the org charger for selfmade battery and what elso do I need?
_
I hope my research about Li-Ion Batteries and charger was successful(I never used them before nore did I know anything:

_Could you please check if this is right and could work._

I want to use about 10-12 (18650) cells to biuld my own battery packs 2s2p and 2s3p with balancer leads, charged with an Imax B6. I will plug discharge protection on the balancer lead after charging.

I also want to use some 18650 for other things(powerbank) and want to charge them with this charger in series. 4s1p....balancer leads soldered between every cell.(taje one of this black battery holder with springs...
_

This should be fine...what do you think? _

_Please understand that english is not my native/first language and I have problem to find the right words especially with technical stuff....and all this battery, charger, RC and light stuff is absolut new to me.
_
but thanks you and many greets


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## ledoman (Apr 17, 2012)

You can use original charger as long as there is 2SxP pack setup ie. 2S2P and 2S3P are fine. Using protection circuit is nice but not neccesary if you do regular balancing with hobby charger or any other way ( charging each set separately, but it's impractical).

You might take a look my last battery pack review to get some ideas.

And remember you must NOT use 4S1P pack with your Yinding due to high voltage. It is designed for 2S packs (ie. 8.4V max.)

"You can't switch off the green LED shining all the time at the backside(can you??)...exept you build (a voltage controlle +) small switch near the battery at your bike."

Well you can remove green led from the driver or simply mask it with some dark tape internaly over the led or externaly over the button. What about red light, do you still want to see it when battery voltage is low? If so, then mask out only green led internaly on the driver.


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## Andreas H (Aug 1, 2015)

Thank you for your help...good news that the original charger will charge the 2sxp packs.

the 4s1s setup would only be used to charge single 18650 cells...4 at a time, balanced with a lipo charger.


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## watts888 (Oct 2, 2012)

Personally, I wouldn't use the stock charger if you had the option to use a better one. It sounds like you're knowledgable about batteries and chargers, so why not use the good stuff. A good balance charger is worth the cost if you're building batteries.

For clarification, are you planning on running 3 lights simultaneously off one battery pack? I'd rather use dedicated battery packs for them. I've had instances on a bike trail when my light went out, and it scarred the heck out of me. going down rocks and roots and suddenly not being able to see is not a good time. If everything is going through one battery, if it goes, all your lights are gone.

For the status light, if you want the green light off when the light is not in use, a simple battery disconnect switch or unplugging the battery would work fine. Once the light is turned on, I barely notice the green/red led on the back of the light unless I'm purposefully looking at it. The reflected light out the front end completely overwhelms the small amount of light the green/red indicator led makes.


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## Andreas H (Aug 1, 2015)

What bothers me is the green LED. 
If I let the light permanently on MTB, then it would certainly consume the battery. 

Perfect would be:
Battery full: no LED
Battery (almost) empty: red LED

I'm going to have a look at the lamp from the inside today.


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## watts888 (Oct 2, 2012)

the LED is pretty low energy, and the circuit is still using some even if the lightis off. If it's just for a day, the status light won't do much to your charge. I've left one of my lights hooked up after a 3 hour ride and after a week, the light still worked fine for another hour (about what I expected based on normal run times). If it really makes a difference, I'd go with a simple in-line slider or rotary switch or unplug the battery.


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## ledoman (Apr 17, 2012)

You can see internals here: https://fotki.yandex.ru/next/users/kirvelo/album/365720/view/749285
I agree with watts888 about low consumption, but if you REALY want you can simply remove the green led.


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## tigris99 (Aug 26, 2012)

With what im reading the 2 issues I see is:

Forget the 4s thing. All your going to rid doing is shorting things out due to over voltage. 4s is 16.8v. Cant use as a power bank to recharge, you'll literally cause the 8.4v packs to explode.

Charging voltage to the batteries must always match the voltage of the battery being charged. Too low then wont charge completely, too high you can and more than likely will cause a fire.

Other than that everything is correct. Making a pack with balance leads is very simple. Protection circuit is a good idea as it also protects against over discharge which will ruin batteries. Over charging them is what causes fires (and trying to charge over discharged packs can cause toxic leakage and a list of other problems)


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## Andreas H (Aug 1, 2015)

I think you've misunderstood me.

I don't want to connect something with different voltage. same for charging.

I mean powerbank like these, they are for charging mobile phone, the cells are connected parallel

LCD Mobile Power Bank Akku USB Ladegerät DIY 18650 Batterie Case Universal HANDY | eBay


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## Andreas H (Aug 1, 2015)

I am back ;-)

After I tried two headlights corresponding to the German regulations, I have decided to use (only) the Yinding. They seem to me as if they were broken.

But now there is the next problem. I am using Busch&Müller LED backlight, which works with 8,4V(I have tested it). The last headlights had a switch and it also turned on my backlight.

Is there any chance to get some power from the Yinding....so when I turn on the Yinding it also should start the taillight.

When I open the link ( https://fotki.yandex.ru/next/users/k...20/view/749285 ) ledoman has posted, I would guess that I have to solder the cable to the 2 spots right under the switch....is that right?


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## tigris99 (Aug 26, 2012)

You have to solder to the switch on the yinding and the switch on the rear light. Will require drilling into the case of each which will require special attention to seal the cable so it doesn't allow water inside.


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## ledoman (Apr 17, 2012)

Can't see the picture of the driver right now, but I think you would get just the power, same as you would use Y cable out of battery pack. Turning on/off would be separately for each. Of course if you are talking about spots where red and black wire came in.
Or you are talking about switch legs? You should be more precise. Possibly post the picture (taken from net), mark the points and punlish it here.


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## Andreas H (Aug 1, 2015)

Edit: added some links and removed misspellings

The rearlight has no switch. There are only 2 slots for the cable. That's it.
If I want to switch it on, I would have to put a small switch near the battery bag which is in a bag under my saddle.

@Ledoman: You have posted the link with the internals which was

https://fotki.yandex.ru/next/users/kirvelo/album/365720/view/749285
There is the switch and below the switch there are two spots of tin.
These are my best mspaint-skills^^

Zwischenablage02.jpg - directupload.net
I think this would be the right place to solder my cable, isn't?
I soon will go to work , after that I will take the Yinding and my multimeter and have a look if that is right.

@tigris99: as i just wrote, the rearlight has two slots for stuck inside a plug or you can solder the cable. It is really simple:

Busch + Müller TOPLIGHT Mini Plus LED-Rücklicht kaufen | Bike-Discount

I will look to get a very thin one, so that I dont have to drill a hole in the Yinding housing.
But I will use sealant for the place where the cable goes (together with the other cable) through the housing.

I think it will work this way? or do you see any problems?


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## ledoman (Apr 17, 2012)

Archie might tell more, but I think this won't work. The switch in Yinding is momentary ie. it just give impulse to the other elements on the board.

Two spots you are talking about are connected, so no go. Input lines (V-, V+) are more to the left edge on that picture. One (V-) is at the switch corner and the other (V+) is same on both spots you are talking about. If you connect V+ and V- to the rear light it will be same as having Y cable out of battery pack. And I think this would be the way to go and leave Yinidng intact and sealed. My opinion, though. Your rear light would be lit on as long as you have connected it to the battery unless you insert the switch.

Another solution is to make electronic switch (connected to yindings momentary). Read more about solutions HERE and HERE.

PS. After you edit your post showing on the picture I understand you are talking about switch legs. Those you would want to connect in the last solution with electronc switch. Otherwise no go as there is very low current going throug just for the moment you press (or hold) the switch (hence - momentary switch).


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## Morten Schmidt (Apr 25, 2014)

What ledoman said. No, it won't work. Momentary switch. You could perhaps tap power from the leads going to the yinding LED board, but I think it is a bad, bad idea for several reasons. Look into crafting an external switch of just use a Y splitter cable and unplug the tail light when needed.


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## Andreas H (Aug 1, 2015)

Yes. I understand now...I do not have much experience with electronics and I had never seen the Yinding directly from the inside. Only on pictures. But this is the reason I asked this question here. 

At first I thought the switch would only switch on and off. I do not know why... a stupid idea because he actually cycles through the modes.

Ok, then I will have to build a second switch somewhere else. Thanks you!!!


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## Andreas H (Aug 1, 2015)

Yesterday I got two battery packs (Ansmann 7,4V with 1600mAh for Sony camcorder or something like that) and of course I opened them to see what's inside. ;-)

There are 4 cells inside. "S A1 ICR14430/650 KA01 KG23",
but one of the 4 cells is marked.... KG24 ".
2 cells are connected in parallel. then in series.

Of course there are some eletronics inside. It looks as if the cells are ballanced, because there is one Ballance lead. (I'm not sure if it is called like that. I never have used my english for electronic stuff). 
At a 2S accu that would make 3 connections, but there are 4 connections. (You can see it at the third and last picture).

I used my multimeter to get the voltage, but no matter how I tried to measure, it was always 0.0V(left side and right side =0,003-0,005V).

So I measured directly at the cells: all together 3,88V, next was the 2 parallel and there I got 3,88V and 0V. 
This is all very strange to me. It Looks like something is wrong. What do you think?

I am going to build a small adapter and charge one of them with the Yinding charger.

I wanted to use these batteries to make one big battery pack: 7.4V and 3200mAh.

First 4cells connected parralel and then 2 of them in series.

Should be no problem?


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## ledoman (Apr 17, 2012)

The one with 0V out of two pairs is faulty. You shoud not use it anymore. The other pair with 3.88V might be still usable. Don't charge this good pair with Yinding charger! It can be dangerous. Charger is 8.4V and batteries are 4.2V at max. You need to learn a lot about li-Ion and similar batteries -> Sharing Battery Knowledge Essays & Feedback - Battery University including chargers, using and storing.

"First 4cells connected parralel and then 2 of them in series."

Make a sketch how you would like to connect them. I'm not shure if I understand you. Sounds to me like you want to make a short, sparkles, ..... You should connect them just like in the pack on your photos. This is tipical 2S2P setup we mostly use.


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## Andreas H (Aug 1, 2015)

> "First 4cells connected parralel and then 2 of them in series."





> Sounds to me like you want to make a short, sparkles, .....


I think I explained this wrong. I want to take *8* cells. Then I connect 4 cells parallel(all + get connected(+ to +) and all - get connected), next 4 cells the same. when this is done i have 2 packs with 3,7V. The next step is to connect these 2 packs + to - to get 7,4V...no sparkles or shorts^^
I think me english is just bad, so you misunderstood me.

I have now also opened the 2nd Pack:

0,889V then I checked the 2 cell pairs that are connected parallel and I got 0,195V and 0,693V

These two battery packs are completely new and have never been charged (by me).
Strange that they should be bad. I have Ansmann AA cells that are really old and are still working. I thought you can trust this manufacturer.

What can I do?
I have the Yinding charger and I have an old Nokia (mobile phone)charger rated with 3,7V 355mAh. I could break the packs and charge each cell until they have the same voltage(4,1V-4,2V) and then check if there is a bad one, especially the two with 0V.
I have read many times that people get this kind of battey for their mtb lights because it has the right voltage(8,4V). My knowledge is not good enough for understanding what the 4 connections are made for. I understand that from this board there a 3 wires, to + and - and one to ballance the battery.

Do you think, that with the right charger(the one from Sony, which was made for this and the original Sony battery) you could charge the battery and it would balance itself?


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## ledoman (Apr 17, 2012)

So you want to build 2S4P pack. Now I understand. English is not my native, too.

When you finish your pack you can charge it with Yinding charger. Please note 8.4V is the top voltage and 7.4V is an average on any 2SxP Li-Ion pack (using 4.2V (3.7V) cells).

Regarding other cells you have measured they are all bad. At least they won't hold their capacity. Any lower than 2.5V indicates some sort of a problem. Some might work at lower capacity and have bad performance. If you ask me I wouldn't bother with those. I would rather use new ones. Read this thread and you would learn some things you are asking for.

Sony circuit might be usable, but you would need to check how it works. 3 connections from the pack to the circuit are sufficient.


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## Andreas H (Aug 1, 2015)

Yes, 2s4p. I should have writen this.

I am just carefully charging these battery packs with the yinding charger.(8,5V)
At the beginning I was checking the Voltage and temperature all the time, it seems to work. I will check it 1-2 times and in 1 or 2 hours I will stop charging.

It will turn out if it worked or not.

I will write down all the voltages before I go to bed. Again in the morning and after work I will turn on some lights and look if there is some useable energy inside. I will post it here.

thanks for your advice ledoman


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## ledoman (Apr 17, 2012)

Check voltages of each pair of batteries after charging and after resting for some time, for example after one day. See if there is noticeably difference. Idealy they should all have same voltage, but I doubt this would be the case. The voltage is only one indicator, internal resistance would be another.
Report then back the situation.


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## Andreas H (Aug 1, 2015)

So I checked everything. I also charged one of them today for two more times for 1h. 
this is what I got:

first pack:
4,23V
4,24V

second pack(the one with 0V), did not change because of two times charging:
4,24V
3,84V

unbelievably that they sell this crap in a very big and wellknown electro store as new.

I got 2 more today but they are totally different(outside is same, same printing)
but no round cells, more like a cube divided into 4 flat pieces, cover is aluminium.
voltage is fine.
First thought was lipo because of not round???
I soldered wires to all four. I will check the next days how long they will work.


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## Andreas H (Aug 1, 2015)

I had another idea: I really have a lot of used (but good and reliabel) Bosch (Blue) 10,8V accus. Inside there are three green 18650 Samsung cells(series, but balanced).

Of course if the voltage is 12,75V* it is too much for the Yinding, this is the reason why I want to use a DC-DC converter(Step down). 

*3S1P = 3x 4.25V. just theoretically, I will test a charged one soon.

input 10-12,75V
output 8-8,5V
power: only for the Yinding and my 2 lights because of the german law.(small front and rearlight, both LED)...not much.

Ah, sorry, frontlight(not the Yinding) can work with up to 42V, so only the Yinding would need the Converter.

I want to place the accu and converter in a saddlebag, could this be a problem because of heat? Can someone help me with this idea?? Are there other projects like this online? 

English is not my native language, that's why it is really difficult to search for things you don't know how they are called ^^

thank you


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## ledoman (Apr 17, 2012)

Andreas H said:


> first pack:
> 4,23V
> 4,24V
> 
> ...


They could be new in terms of use, but old in terms of production. Batteries are aging over the time regardless they have been used or not. Depends also where and at what stage they have been stored. As said read Batteryuniversity web pages.

Check voltages of those packs tomorrow. If they pretty much holds the voltage there are chanches they are usable. It is only question of capacity and voltage sag.


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## Andreas H (Aug 1, 2015)

Today I replaced the accu-pack with the broken accu-pair against a new one.
Juhu "now I can solder everything and tape it together to a 8-cell accu" I THOUGHT. damn, the new one also has two cells parallel with 0,0V. 
what the fuc. are they selling in this shop Oo
naa...cut it and make one working out of to broken ones. 
I think this is like robbing people. Most users will put the accu inside their cameras, charge it once and then begin taking pictures or videos and are not fetching their multimeters and knives and cut the damn thing, they just bought for 30-60€, open.
(I didn't pay this prices, but MM is selling this crap for 39e, the lipoly for 53,99) each.

Ok, so now I think I have enough working battery packs: 

-original Yinding
-8 cell Lipoly 3200mAh
-Li-ION 3200mAh. 
-I would still have the 18650, but the packs above have protection (and so on) already build in. it's the easiest way to go. also no problem to charge them with the Yinding charger. It even stop charging when it's full.


The Lipoly has a funny board. There are only 3 accessible contacts. 
I took "+" and "-" for charging. Then I took the multimeter to check the voltage at the same contacts. I got a strange number of about 1,5V, so i fetched two more multis but there is really only 1,4V at the contact which are accessible without destroying the plastic cover. As it is already broken, I took it off and checked the voltage directly on the cells(before the board) and there it is perfect. from 4,23 to 4,25V between all four cellpairs. so charging works perfectly, even with two battery packs parallel with the yinding charger.
But now I will have to solder 4 wires at each battery pack. 2 for charging and 2 for plugging on the lights.


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## tigris99 (Aug 26, 2012)

Oh please tell me your not trying to use a Li-Poly and a Li-ion battery pack in parallel while charging or using together in parallel for the lights?!?!?!?



Or charging a Li-Poly battery on the yinding charger???? Li-Poly battery packs are far more dangerous than Li-Ion and should only be charged with a balance charger that's rated for Li-Poly batteries. That's also the reason the li-poly pack has the 3 contacts, third is for balance charging. And mixing the 2 packs so they are connected to each other in your saddle bag is a good way to get killed.

Sorry, no disrespect, but you need to STOP experimenting with lithium batteries before you get yourself hurt or your home burnt down. Do the research and learn every detail about both battery types and research what happens when you do something wrong and each one fails.


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## Andreas H (Aug 1, 2015)

@tigris99 I wrote a very long posting only a few hours after yours. I don't know why it is not here.


I think there are some misunderstandings. 
Of course I don't charge lipos and Li-Ion with the same(yinding) charger. 
I don't even have a Lipo. It was a mistake to call the cuboid accu a Lipo. I did this because the shape looked like the RC lipos and at first it reminded me to a lipo. This was technicaly wrong. 
I checked some sources before charging it.
The black plastic cover I removed at the beginning says Li-Ion Battery...no doubt this is also Li ion.

A half year ago before I bought the bike with the Bosch motor and battery pack I did a lot of research about Lipos and the different possibilities to build a motor to a bike. At this time I also played with the idea to build a lightweight bike using my specialized stumpjumper fsr and lipos. this would have been a terrible mistake^^
I have to charge my 400Wh Bosch battery pack 5-6 times a week but this means I just have one plug to put to my bike and after 3 hours it is full and ready to use. a nightmare to charge the lipos this often.
I even bought one more accu because one of them had two cells which did not go over 3,8-3,9V.

Maybe some parts of my postings sounded as if I have not much knowledge, but it is really hard to express one self or phrase questions if one does not know the technical words in english.


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## Verb_Darby (Aug 30, 2015)

I keep 2 oranges attached to my handle bars for night rides, my Baghdad battery lite has never failed me. Makes a nice treat after my ride too. ( Baghdadbattery.com). If your worried about aerodynamics- mag lite /duct tape Diy time - 23 seconds on trail. But for the California midnight enduro race every year I've won with a wind up flash lite geared to my pedals forces me to keep going. (Am scared of the dark)


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