Building battery from MAKITA Konion PACK

[John in CR]

agreed, to a point.. these cells remain ballanced very well, but by grouping P groups first, then series those you can monitor the voltage of each group as a single display. instead of each string seperately.. if you care to monitor.. and you should..

Yes.. i'm i the group of person who preffer PARALLEL FIRST and than serie...
This was debated alot and John, in the industrie you will NEVER find any "serie first and than parallel"
Too many seperate induvidual cell without any monitoring!!
Only LiMn and nicad MUST be done the way you suggest due to the particular chemistry.

Doc

For those who want to parallel each level it's still less than half the work if you don't take them apart. Plus you only need to solder the parallel connection where the tab is at the negative cell end, so you don't risk melting or weakening the plastic protector at the positive end. I cringe when I see people break these packs into individual cells, because I know the work that they've created for themselves, along with the cell matching they've lost. You don't break up the 2p V packs, so why do it for the 1p VT packs?

As far as monitoring at the cell level, it's not done on hundreds of millions of lead acid car batteries, and these LiMN cells self balance through the same mechanism, so I don't see much point unless you're running your pack at stressful levels.

A required step not mentioned though is capacity matching.

FWIW, the 2000+ Konion cells that I've built into packs for myself and others haven't had a single failure. Some of those packs are over 1k cycles, including those on my daily rider that has seen 2 cycles on a typical day for over 2.5 years, so dismissing my easy build build method as incorrect is unwarranted based on real world results. If pack building was really as hard as some make it, then I wouldn't even build my own packs. These cells don't burst into flames like Lipo, so there's no real risk building them in a less than technically ideal manner, and the time I save is worth more than the pack itself.

[Doctorbass]

John,

I'm glad to see we offer two good solutions for the future pack builder

Doc

[beast775]

im sure this is my next step in a battery.thanks for all the posts to make it easier-john-drbass,ive been using 18650 in high drain hobby applications for years and have never had one go bad.there seconds from 2nd tier battery suppliers.so i can imagine the sony are alot better.how many packs will i need for 48v 12ah drbass?

[Doctorbass]

.how many packs will i need for 48v 12ah drbass?

HOW MANY CELLS DO I NEED FOR A BATTERY OF X ah and Y volt ?

It is simple to calculate:

12Ah ?.. ok... divide 12 by 1.5Ah if you choose the V cells or divide it by 1.3 if you choose the VT cells

ex for the VT: 12 / 1.3 = 9.2.. so we round that number to 10.. for 13Ah

now you want 48V.

Generally we talk about NOMINAL voltage.. that mean this is the voltage the cell have at 50% SOC. ex a makita cells have 3.7V at nominal(50%) and 4.2V full (100%) and 3.0V at 0%

This is not a direct proportional relationship with the voltage due to the discharge curve shape.

so for 48V you calculate 48 / 3.7V = 12.9.. we generally round that number to 12 because it is more common to have 12 cells and more compatible for some measuring device.

12 x 3.7 = 44.4V

but you can still choose 13 x 3.7 = 48.1V if you wish

now you know how many cell in parallel you need ( 10 cells parallel) and how many of these parallel block of these cells in serie you need (13)

so you need 10 x 13 = 130 VT cells

generally i recommand people to get 10% more cells to have some spare to replace damaged cells during the construction or other replacement needed.

Doc

[beast775]

thanks drbass, i kinda got what you said .so i think there is 10 cells per pack? i need to go study a bit on these packs and look at your youtube channel.seems like i might need a shitload of packs! merci mec J'apprécie votre aide que je vous dois un mec .

[999zip999]

Yes both ways work. But with Doctorbass I could put a balance wires on for easier monitoring on a cell level in parelle first. Gald to hear these cells are so versible.

[999zip999]

JohnCR, How do check cell balance and charge the strings before assembly ?

[marty]

x
-Before to use the pack flully charge ALL the cells to 4.1V or 4.2V.. (4.1 will prolong the life of these cells but will give you a bit less capacity)
x

JohnCR, How do check cell balance and charge the strings before assembly ?

I got a CBA III - Computerized Battery Analyzer to check cell capacity.
http://www.westmountainradio.com/cba.php

What charger should I buy for my used Makita Lithium-Ion battery building experiments? Should I charge each cell separately or in parallel groups?

[Doctorbass]

x
-Before to use the pack flully charge ALL the cells to 4.1V or 4.2V.. (4.1 will prolong the life of these cells but will give you a bit less capacity)
x

JohnCR, How do check cell balance and charge the strings before assembly ?

I got a CBA III - Computerized Battery Analyzer to check cell capacity.
http://www.westmountainradio.com/cba.php

What charger should I buy for my used Makita Lithium-Ion battery building experiments? Should I charge each cell separately or in parallel groups?

Any RC charger would do the job.. check on hobbyking. Or a lab powersupply you can buy on ebay that can ve adjusted at 4.20V.. so any power supply with adjustable current and voltage up to 5V would be ok.

Before to put all cells in parallel group, you should ensure that the voltage difference between all cells you want to parallel is not too high.. let say 200mV or less is acceptable.. otherwise the lower cell will charge too fast and be damaged. to charge them, I suggest to put all cells in group of voltage.. all group with less than 200mV between the higher and the lower cell.

( this is just to charge them).... when you'll make your parallel group, I suggest to randomly choose cells and to group them. that will average all your group of paralleled cells for your pack.

Doc

[marty]

To build a big battery pack from Makita cells, what do you think about using a whole bunch of these plastic holders. Eliminate all the labor of soldering.
14.8V 4 x 18650 Battery Holder Case Box with Leads
http://www.dealextreme.com/p/14-8v-4-x- ... ads-103855

[ambroseliao]

The problem will be the thin springs that make contact with the positive terminals. They're not nearly thick or strong enough to support the max current most ebikes will need. You will also have to deal with the shocks that come with a bike mounted pack. You'll need to strap the Sony/Konions in pretty firmly to prevent them from coming loose.

I'm sure they're fine for static, low drain applications.

[amberwolf]

IIRC, Leamcorp did some testing with springs in his solderless cylindrical battery case threads.
http://endless-sphere.com/forums/viewto ... =14&t=8660
viewtopic.php?f=14&t=17912
I dont' remember them working very well.

[Doctorbass]

Spring tend tobe too thin fo rthe current demand...

I used already some copper braid... wich is a little soft and conduct alot more!

What i suggest to prople who dont want to solder or spotweld is to use soft copper braid and a little foam under it to keep pressure on the copper braid.

These braid can be used like a buss bar to parallel and serie them.

For testing cells before the assembly i made some neodium magnet test lead for testing the capacity at 1C of each cells. this is a really quick connect way and still conduct more than i expected.

you can solder on the chrome layer on the magnet.. but dont heat them too much to keep their magnetism.

Doc

[marty]

Magnets. Good idea!
Find this picture here:
Handy RadioShack Test Lead Set
http://digital-diy.com/products-and-har ... d-set.html

mag_probes_for_batteries600w.jpg (36.09 KiB) Viewed 524 times

This guy makes his own with 1/4" security system magnets. I got a bunch of them. They are chrome plated and about 3/4" long. Very strong magnets.
Find this picture here:
Magnetic Personality Test Leads
http://www.hometoys.com/htinews/aug07/a ... /leads.htm

fig3.jpg (11.3 KiB) Viewed 524 times

[Teh Stork]

I'm building a rather large pack, capable of around 1500 whr. (18s16p) It will be placed inside the bicycle frame. Using glue I'll make a permanent huge pack witch sits nicely once it's in.

I wrote some code to my arduino which does:

1. Saturate Mosfet. Cell starts discharging through a 1 ohm resistor.
2. Once the (sagged) cell hits 4V. Start timer.
3. Once the cell hits 3.7V. Print timer.
4. Shut off mosfet. Small delay. Print voltage sag. Usually in the 0.1V range.

Trouble is: these data correlate better between capacity and IR than what Doc's data does. I do not have a spreadsheet, but judging from a initial IR test - I can tell if this is going to get a good time or not.

Soo, should I change my methods to measure capacity at 0.5C and from full charge? Or should I simplify things very much and group cells judging from IR?

I plan on running my pack between 3.65 and 4.15V max, for longer trips - I'll add a 1000whr booster pack.

Opinions would be appreciated

[999zip999]

Why don't you run the pack at 3.4v-4.1v or so.

[Teh Stork]

Why don't you run the pack at 3.4v-4.1v or so.

Well, I could allways do that. Just that there is little capacity below 3.6V. The pack is so big that I'll rarely really drain it. When I'm going for my 60km round trip - I'll have around 2500whr of battery capacity And with the option to charge half-way

I look forward to getting everything fitted up and checking the actual capacity I get out from the pack while running. I've got a asphalt hybrid racer of some sort, so no huge tires sagging me down

[Teh Stork]

I'm planning on using glue to make a permament pack with my cells. A close friend of mine, in the plumber industry - suggested I should use Tec7. It is a form of silicone for everything in the bathrooms - but w/o silicone. (It doesn't stain the backside of mirrors amongst others (no vinegar)). The glue won't hold the full load during riding - but i want it to be structurally elastic and strong (no cracking).

Have anyone tried something similar?

I'm also in the finishing stages of a battery tester based on a AVR It can handle 8 cells at the same time. Or 8 konions in my case. My current setup uses irfp2907's (huge hexfets), a breadboard and a shit ton of small wires. Clearly not ideal, but a nice proof of concept. Going to etch my first pcb soon, maybe it's going open source if it doesn't screw up somehow

[marty]

Here Doctorbass uses tape.


Here Doctorbass uses the plastic seperators from the Makita packs.


Here is a web photo gallery of Doctorbass battery building projects. This is from 2009. Sure that he has perfected his methods by now.
http://voltev.com/doctorbass/

Glue would be a horrible mess if you ever needed to disassemble a large battery pack.

[granolaboy]

I'd still like to know where people are finding dozens and dozens of these power tool packs. I've phoned around all the recycling places, and the local dewalt representative, and nobody has any, or is willing to part with them (well, aside from buying them new or used in working condition of course, which is ridiculous)

[marty]

I tried dealing with this place.
http://www.recycle.net/
Click on Battery Recycling / Other Battery Recycling / Lithium Content Battery Scrap OR Lithium Ion Battery Scrap / View Listings
Forget exactly how that place is set up but I paid $50 for [Pay Per Lead Service: 50 Credits]
Looked at Credits Spent at recycle.net Think I used all my credits?
Long story short. Unless you have $$$$$$ for 50,000 pounds or so of used batteries and more money to transport them, Just forget it.

[Doctorbass]

I'd still like to know where people are finding dozens and dozens of these power tool packs.

My uncle is working for these places

I have a good familly

Doc

[Teh Stork]

I'd still like to know where people are finding dozens and dozens of these power tool packs. I've phoned around all the recycling places, and the local dewalt representative, and nobody has any, or is willing to part with them (well, aside from buying them new or used in working condition of course, which is ridiculous)

I contacted makita customer service norway (my country), and after some 10 emails - I could pick 100 used packs up from the local makita workshop. I gave them a quick intro in what i was doing, + that packs often had 2 out of 10 cells broken. Adding that I'm a student definitely didn't hurt either. I'm sure dewalt, bosch and others could offer me even more cells, but my 680 working cells will hold for my pack, my booster pack, and a wiffy ebike in time

[mistercrash]

I plan on building a 14s14p battery pack with these Konion cells. Do I need a special charger to charge this pack once it's done? Can I charge it with the charger I use now for my 48V SLA? Or can I charge with a RC charger like the CellPro 10S I have?

Thanks.
Ray

[Doctorbass]

I plan on building a 14s14p battery pack with these Konion cells. Do I need a special charger to charge this pack once it's done? Can I charge it with the charger I use now for my 48V SLA? Or can I charge with a RC charger like the CellPro 10S I have?

Thanks.
Ray

Never use SLA charger for charging lithium!.. they are not stable and don’t have constant current and constant voltage generally.

A for 14s, a Meanwell power supply is better ( if you attach one of these current limiter board it’s better)

I know that some europeen are selling 14s RC charger.. and also one of the hyperion is 14s capable too, ask Ggoodrum

Doc