Konion Makita LiMn battery care and feeding by Doctorbass

[parabellum]

True. I don't know if the cells Doc provides are lose or in the packs ?

Guess I should pm him for details.

Regards

Jerry

Those are Makita power tools packs, if you open it you will see neat 5s2p pack. I opened 20 packs for 200 cells between yesterday and today, about 12 cells dead, take about 12 more that are not so good as the rest and they are still about 176 cells that reads around 1500mah at 3C discharge rate, from 4.16-4.17V(in my understanding they kind of settle at this voltage after charging ) to 3.1V (it is my adjustment for discharge).

 

[John in CR]

True. I don't know if the cells Doc provides are lose or in the packs ?

Guess I should pm him for details.

Regards

Jerry

Those are Makita power tools packs, if you open it you will see neat 5s2p pack. I opened 20 packs for 200 cells between yesterday and today, about 12 cells dead, take about 12 more that are not so good as the rest and they are still about 176 cells that reads around 1500mah at 3C discharge rate, from 4.16-4.17V(in my understanding they kind of settle at this voltage after charging ) to 3.1V (it is my adjustment for discharge).

I hope you left them in factory pack form as much as possible, only removing the bad cells. If you did then I hope you have a tab welder, because otherwise not only did you create 10X the work, but also greatly increased the future risk of cell failures.

 

[jerrysimon]

John so far I have purchased one pack off ebay and opened it. As you say I have also come to the conclusion that leaving them connected in their pairs is the easiest thing to do. Seperarting each cell makes for a lot of extra work.

I already have three packs of 12s1p, A123 cells. Initially I got those new with individual tags and joined them myself. There are now suppliers that provide brand new cells welded up into the configs that you want. My last two 12s1p packs of those were like that and all I had to do was add taps and power leads. For my short five mile each way ebike commute, a 12s1p A123 pack of new cells welded up as I want them costs me about £60/$100 which to my mind makes it not worth buying/using suspect s/h cells from old drill packs from ebay. Buying usuable Makita packs off ebay also seems a little bit hit and miss so unless you have someone here like Doc who you know will test them for you and not sell completely dud packs, it could get expensive.

Its a shame simliar sources for buying new Konions don't exist. I am beginning to think I will just stick with my A123 cells, although I would love a 10s4p pack of Konions which would not weigh a lot more than my 12s1p A123 pack and could be used for longer rides. The alternative is to just carry a couple more of my 12s1p, A123s when I go out

Regards

Jerry

 

[parabellum]

True. I don't know if the cells Doc provides are lose or in the packs ?

Guess I should pm him for details.

Regards

Jerry

Those are Makita power tools packs, if you open it you will see neat 5s2p pack. I opened 20 packs for 200 cells between yesterday and today, about 12 cells dead, take about 12 more that are not so good as the rest and they are still about 176 cells that reads around 1500mah at 3C discharge rate, from 4.16-4.17V(in my understanding they kind of settle at this voltage after charging ) to 3.1V (it is my adjustment for discharge).

I hope you left them in factory pack form as much as possible, only removing the bad cells. If you did then I hope you have a tab welder, because otherwise not only did you create 10X the work, but also greatly increased the future risk of cell failures.

Yes. I do not remove cells if not totally necessary. Was just trying to resume without getting to deep. If any pair is removed for any reason, I try not to damage tabs to solder on them later.
Question:
If I need to solder on positive tab and plastic under it melts It easily can short to negative, right? I was thinking to cut out and insert a fish-paper separator in between. Any other and/or better idea?

 

[John in CR]

I always tried to avoid soldering on the tops of tabs, and instead solder on the side that was against the dead cell or the bottom of the extra tab going at the +/- ends of the original pack. Accomplish that by first flattening the extra tab, and the folding it over on the cell getting the connection to expose the bottom. When given a choice, always put the joint over the negative cell end. This way gives you an insulating layer of air vertically, so to get hot enough to melt the plastic at the dangerous positive end, the heat of soldering has to travel the length of the thin tab, which is slow and fast cooling. Another benefit is a nice clean look with few solder connections showing.

I recently opened some almost 3 year old packs, most with well over 1k cycles, that were totally sealed with only pos and neg leads out of the ends of the duct taped packs. Out of the 20s packs containing 880 cells (V and VT cells, and Makita and Bosch packs), I had 1 dead V cell pair caused by which based on the solder blob at that connection must have been a connection I spent too much time and heat on, and it was a positive end. One V cell pair was totally worn out but still alive, just in need of replacement, which luckily I found a capacity match replacement in my odds-n-ends left over cells. A 200 cell VT pack had 10 dead cells, an entire parallel group that was dead, and that was the only pack I did parallel connections, so one solder heavy connection at a positive end killed a whole group. I'm going to get some pics and do a thread summarizing the end result of almost 3 years of use.

We recently made 28 10s strings of Konion VT's laid out lengthwise, so due to so much soldering required we did paper donuts to go under the tabs of all of the positive ends. It was a crazy amount of work that we'll never do again, but should prove a durable pack(s) that will also be the structure of the bike frame. If you plan your layout to only needing a few solder connections on top of the positive end, then paper rings would definitely be worth the effort.

John

 

[docnjoj]

Hey John!
Do you ever mix V and VT cells in the same pack?
otherDoc

 

[Doctorbass]

Hey John!
Do you ever mix V and VT cells in the same pack?
otherDoc

You can do that.. but each parallel string must have the exact same number of V and VT cells

ex:
String 1: contain 10 V cells and 3 VT cells all in parallel
String 2 contain 10 V cells and 3 VT cells all in parallel
String 3 contain 10 V cells and 3 VT cells all in parallel

etc...

(String mean Paralleled cells group)

 

[Doctorbass]

Assembling cell one by one is not really difficult and complicated as some would suggest

I have made ALOT of makita based pack and personally it's always a pleasure to do.

If you follow the exact recommanded method i have posted here, it should work as expected for you.

BTW.. NO NEED TO REMOVE THE WHITE STICKY stuff on the spotwelded nickel... becuase if you follow my method, you will see that you flip them.. so you can solder directly on the nickel.

Plus, the heat from your solder iron is not really transfered to the cell tab due to the path the heat need to travel thru the fliped nickel stack :wink:

That way i recommand has proven to be really reliable and satisfying, according the the numberous Pm and email i got from the makita pack buyers over the last years.



Here is the thread i recommand to read before making your makita based battery:


http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=28285&hilit=making+makita


Here is the right way to solder the cell tab:

charging these 5x 1.3Ah Vt cells to CC-CV 10A 4.20V give around 6.5Ah

Real test.. Real results!

around 6.5Ah from 5 cells parallel... and.... 3.8miliohm!.. not bad for these auto balancing 18650VT cells!

That's 24Wh out of 5 these used VT cells

At 5$ per packs ( for the VT 1.5Ah makita pack) that give 4 to 5 cells each... let say 4 cells that's 6.25$ per 24Wh = 0.26$ per Wh

Just 5 of these cells in parallel can sustain 50A continuous and 100A burst... just like a 18$ headway cell

3.8 miliohm resistance for 5p pack! ... = to the high power headway cells... BUT DONT NEED BMS :wink: .. They self balance !

Doc

 

[999zip999]

If you are to use johnCR method I cut with sissiors the part of the tabs that hang over on the pos. side of the cell so as not to contact the neg. case.

 

[docnjoj]

Hey John!
Do you ever mix V and VT cells in the same pack?
otherDoc

You can do that.. but each parallel string must have the exact same number of V and VT cells

ex:
String 1: contain 10 V cells and 3 VT cells all in parallel
String 2 contain 10 V cells and 3 VT cells all in parallel
String 3 contain 10 V cells and 3 VT cells all in parallel

etc...

(String mean Paralleled cells group)

Thanks Doc!
otherDoc

 

[John in CR]

Hey John!
Do you ever mix V and VT cells in the same pack?
otherDoc

Sure, just not within series strings. Back when I first got my Bosch packs, I did combine a 12p10s VT string with a 10p10s V string and they matched up quite well, but it was 2 separate packs in series. You can do it, but you have to monitor balance between the 2 packs, and that kills the biggest benefit of Konions, which is install and forget. Just charge and use.

Those Bosch fatpacks we picked up so cheap new 3 years ago are aging faster than my used Makita V cells that were from DoctorBass in the same period. The Boschs are down at least 20% in capacity and the V cells are only down about 10%...still not bad for an average of 2 fairly shallow cycles a day for almost 3 years.

 

[999zip999]

I think the your luck comes from dod and not testing the limits ah.

 

[parabellum]

John, Doc thank you very much! I really hate to reinvent the wheel.

 

[parabellum]

John, before I forget, what voltage do you charge them to, per cell?

 

[John in CR]

I think the your luck comes from dod and not testing the limits ah.

It's foolish to test the limits of batteries other than purely as experimentation. Instead, I was exploring the limits of convenience and reliability. Of course my shallow discharges, conservative charge voltage, and broad packs are what got me to well over 1500 cycles on most of my Konion packs, and they'll live at least another year on the lower power scooter ebikes I'm rehabbing. However, there's no luck involved in getting over 10k miles with homemade battery packs without a single minute of downtime due to batteries, nor a second spent in almost 3 years on checking, balancing, plugging, unplugging or any of the inconvenient nonsense people tolerate...No puffing cells, no BMS's killing cells, no plugging connections wrong, and no fire worries...just pull in the carport, plug the charge cable, hit the switch, and come back later after it beeps to unplug and turn off. Oh and don't forget that at the time they were the by far the most economical lithium option.

Wait till I build a bike that almost never has to get plugged in, just park it for a good angle to the sun, and be able to put the key in and it's always ready to ride.

 

[John in CR]

John, before I forget, what voltage do you charge them to, per cell?

My chargers seem to vary a bit with temperature, but 4.05-4.1V per cell.

 

[parabellum]

Is there any sense to have balance wires on this packs?

 

[999zip999]

If that parelle of cells has a bad one it will discharge faster ( load ) and charge faster if you have bad cell ( cells ) or show a little low or something to let you know to repalce it. Most people don't have access to check there cells for balance as they are sealed up except for the balance wires plus to bring up or lower the cell group.

 

[marty]

A bit of History:

Back in the begining of 2007 I introduced these cells from Makita battery pack to the E-bike world.

I am not the very first person who used them other than for powertools. The RC crowd.. mainly from Germany already used them as great powerfull cells ( the 186650V). That's from one of their link that i finally found the specs in 2008. Also, The Bionx Lithium battery are using them too. finally Bosh are also using them but they use the lower capacity model ( 18650VT)

Since it happened. The popularity of them grow up alot and became a great solution for simple, cheap and low maintenance lithium battery.

How they came to the E-S ?
After my uncle that work from Makita gaved me few used and deffective battery i tested them alot and finally made my firsts ebike battery pack.

I still get some from him that i share with the E-S and to thanks him about that generosity, i built him an ebike with some of these cells.

The qty i can get from him is really interesting and i can supply and share my overstock to the E-S when i can.

I am one of the big supplier of these used or deffective packs.

As i said, these packs i get are all returned from custommers because they are deffective.

Some have just few cycles on them and some have over 400 cycles... But i asked my uncle to only give me the one that have 100 cycles of less. He have the special computerized makita tool to test them. By that way that ensure all cells had their burn-in and have more chance to work for their entire life compared to brand new cells.

These cells are called : KONION i have to say.. i really dont know why they call them like that but i know it come from the german wensite.

They are made by SONY since around 2005-2006 and still exist today

They are lithium manganese and exist in two models:

18650V and 18650VT.. some rare 26650VT model exist but they are difficult to find)

18 is for 18mm diameter and 650 for 65.0mm lengh


They come in different pack on the market:

The 18650V are used in:
-The BL1830 makita pack of 18V 3.0Ah
-The BionX electric bike battery of 24V and 37V 9.6Ah

The 18650VT are used in:
-The BL1815 makita pack of 18V 1.5Ah ( but they have 1.3Ah real)
-The Bosh 36V slim and fatpack


Here are their specs:

18650V: ( the most popular for ebikes)
( same as the Sanyo’s UR18650W)

-Voltage range: 3.0 to 4.2V
-Nominal voltage 3.7V
-Capacity: 1500mAh(10C) to 1600mAh(1C)
-Max Discharge C rate: 10C ( 15-16A)
-Max Charge C-rate: 1.5 to 2C depending on the cooling
-Cycle life: 700 cycles to 75% initial capacity ( from BMZ manufacture)
-Cycle life claimed by Makita: 1200 cycles
-Internal resistance 30miliohm per cells
-Released in 2005... still existing in 2011



18650VT:

-Voltage range: 3.0 to 4.1 or 4.2V
-Nominal voltage 3.76V
-Capacity: 1030mAh(10C), 1080mAh, ( 1C) to 1300mAh(0.1C)
-Max Discharge C rate: 15C ( 17-20A)... and 30A for 30 sec
-Max Charge C-rate: 3C depending on the cooling
-Cycle life: 500 cycles to 90% of initial capacity, at 2A discharge ( from BMZ manufacture)
-Cycle life claimed by Makita: 1200 cycles
-Internal resistance :initial is 25 miliohm ( 26-28 miliohm of used cells)
-Gravimetric energy94 Wh/kg
-Released in 2005... still existing in 2011

Here is the specs from BMS compagny: ( see the attached file) ( please note that the Wh of the 18650V at 1C is not 3.61Wh but is 5.61Wh.. this is an typing error in the specsheet


BMS ??

These cells are well appreciated because they do not require balancing wich normally cost time and money to acheive on diy battery.

The 2010 and older Makita packs and the Bionx pack dont have any balance circuit in them.

it's not magic but it's still something we dont really understand.

While they do not require balancing, they must have something that will cut the current like a LVC to protect overdiacharge.. and also to be protected against overcharge.

When assembling them into a DIY battery they MUST all be at the same voltage before to parallel them and to charge the pack.

Info: Here is a document from the NASA Aerospace Flight Battery Program that tested some of the VT cells:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100028067_2010030204.pdf

Why the Konion?

- Because they are cheap when bought as used packs, ( around 30 cent per Wh)
- Because they can give high power
- Because they dont NEED balancing
- Because THEY ARE SAFE chemistry
- Because you have a great source :wink:

They dont like: heat above 50 celsius.. it damage permanently them
that's why i recommand to keep the nickel strip already spotwelded on them and to solder on these nickel parts... dont solder directly on the cell tab! that will produce damaging gas inside that will act as an insulator between the layers and will oxidize them.


Getting some:
From now it probably exist over 200 persons that made battery using them on the E-S and as far as i know, you all appreciate them.

Some that got some from me in 2008 are still asking to get more to build more pack.


My Konion packs

In 2008 i decided to build the biggest ebike pack ever built.

It have 432 of the 18650V cells and is divided in 4 independent packs of 6s 16P ( i updated it to 18P few month later

Today in 2011 i still use it and still never need to balance it.

To give you a teaste of what look like one of my diy pack made with makita:

Got Hyperion EOS 1420i NET3 Charger connected to Meanwell SP-750-27 Power Supply. Power supply fan is annoyingly loud. Got some basic set up questions. Lets suppose I am charging one VT cell to learn about these used Makita cells.
BATT TYPE LiIo as in Lithium Ion
BATT VOLTS 3.6Vpack (1S) 3.6V = Nominal Voltage. 1S = 1 cell in series.
BATT CAPACITY 100 - 50000 mAh Doctorbass says "18650VT cells are -Capacity: 1030mAh(10C), 1080mAh, ( 1C) to 1300mAh(0.1C)" What should I set mAh at in units of 100? 1100 mAh?
CHARGE CURRENT 1.1A Copy from instructions: The common CHARGE RATE (set in next screen) for lithium is 1C of capacity (equal to 0.7A for a 700mAh setting). Should I change this?
TEMPERATURE CUT-OFF 50°C I got no temperature sensing probe. Will just keep my finger on the battery while it charges.
SAFETY TIMER 20 - 300 MIN How many minutes should I set this safety cut off timer at?
TCS CAPACITY 100% TCS = Terminal Capacity Selection. I am thinking just leave TCS at 100%
TCS END ACTION CONTINUE Please disregard this setting.
TVC = YOUR RISK! +0mV (4.100Vc/C) TVC = Terminal Voltage Control NO CHANGE THIS!
DISCHARGE AMPS 1.1A Hoping to discharge with CBA III Computerized Battery Analyzer. Please disregard this setting.
DISCHARGE VOLTS 3.0V Hoping to discharge with CBA III Computerized Battery Analyzer. Please disregard this setting.

The 3 settings that I am not so sure about are: IN RED
BATT CAPACITY
CHARGE CURRENT
SAFETY TIMER

 

[Doctorbass]

BATT TYPE LiIo as in Lithium Ion
BATT VOLTS 3.6Vpack (1S) 3.6V = Nominal Voltage. 1S = 1 cell in series.
BATT CAPACITY 100 - 50000 mAh Doctorbass says "18650VT cells are -Capacity: 1030mAh(10C), 1080mAh, ( 1C) to 1300mAh(0.1C)" What should I set mAh at in units of 100? 1100 mAh?
CHARGE CURRENT 1.1A Copy from instructions: The common CHARGE RATE (set in next screen) for lithium is 1C of capacity (equal to 0.7A for a 700mAh setting). Should I change this?
TEMPERATURE CUT-OFF 50°C I got no temperature sensing probe. Will just keep my finger on the battery while it charges.
SAFETY TIMER 20 - 300 MIN How many minutes should I set this safety cut off timer at?
TCS CAPACITY 100% TCS = Terminal Capacity Selection. I am thinking just leave TCS at 100%
TCS END ACTION CONTINUE Please disregard this setting.
TVC = YOUR RISK! +0mV (4.100Vc/C) TVC = Terminal Voltage Control NO CHANGE THIS!
DISCHARGE AMPS 1.1A Hoping to discharge with CBA III Computerized Battery Analyzer. Please disregard this setting.
DISCHARGE VOLTS 3.0V Hoping to discharge with CBA III Computerized Battery Analyzer. Please disregard this setting.





The 3 settings that I am not so sure about are: IN RED
BATT CAPACITY
CHARGE CURRENT
SAFETY TIMER

BATT CAPACITY : 1400mAh ( mac cell cap is 1300 so to ensure it will not cut before just put 1400. With this value it will calculate at wich current it cut the charge . It is usually at C/20 so if you put 1400mAh it will end the charge process when current is as low as 70-mA = ( 1400/20)

Yuo can charge these cells to 2.5C no prob ( 1300 x 2.5 = 3.2A per cell in parallel)


These celsl are safe. The safety timer is calculated to be a delay that is a bit longer than the charge time... let say 125% of the charge time.


The konion VT are not 3.6V.. they are 3.7V nominal but you can use lilo seting to charge them at 4.1V wich prolong their life


Doc

 

[999zip999]

What can I charge my 15s 10p pack at 61.3v and what amps ?

 

[Doctorbass]

What can I charge my 15s 10p pack at 61.3v and what amps ?

no prob for 4.08V per cell ( with 61.3 and 15s)

10p with 1.5Ah cells is 15Ah and 2.5C is 15x2.5 = 37.5A max charge current ( if cells have good airflow!)

Doc

 

[999zip999]

?? Wow 37a . That's over may budget. I guess I'm can get that kingpan 1200w charger. My house might knot like a 1200w. Or is a 1200w a 900w ?

 

[Doctorbass]

?? Wow 37a . That's over may budget. I guess I'm can get that kingpan 1200w charger. My house might knot like a 1200w. Or is a 1200w a 900w ?

It is not necessarely 37.5A... yo can cahrge at a lower current too! :wink: .. the 37.5Ah is the max... not the recommanded ideal current wich is 1C

Doc

 

[nebriancent]

im just over 2300 km and 90 or so charge cycles on my pack and i have noticed no real decrease in capacity
i burst at up to 5c and my continuous now is about .75-2c depending on terrain so they do seem to hold up pretty well

i had to replace 2 paralleled strings due to my own mistake of overdoing the c rating in -15c weather and not checking the balance but the rest of the cells are within 20mv after 90 cycles with no balancing

i suggest from my small amount of exp with these cells to check the balance once every 4-5 cycles and if you notice your voltage looking a little low during your run check it then and there

side question to doc
i have done a shunt mod via a voltage divider to the current sensing circuit on a 12 fet infinion running 4110s
im getting peak amperage registered on the ca at 107.8 amp
im not sure what the phaze current multiplication is on these controllers or if its dependent on the motor its feeding

is this sustainable on a 9c 8x8 aka 2808 or am i risking popping my fets? if i need to tone it down it shouldn't be a problem as i have a 22 turn pot on the one side of the vd circuit