MCM4 HS custom battery with Spot Welder

[Battling]

Got it ! 1000km with my MCM4 HS double custom battery. So I think it's safe and I can share the making of

1st episode, I had to make a spot welder (there's a lot of tutorials and videos on the net)

Required components :

- Oven transformer without it's secondary winding
- An Arduino (I used both Uno and Nano)
- A Solid State Relay http://www.aliexpress.com/item/Newest-solid-state-relay-SSR-25DA-25A-actually-3-32V-DC-TO-24-380V-AC-SSR/32583056369.html
- A foot pedal switch http://www.aliexpress.com/item/foot-switch-stomp-foot-switch-Length-20cm-Material-Plastic/477130569.html
- 2m of thick electric cable (mine seems to be a 3AWG)
- A power supply cable
- 1 resistor of 1K/10K
- A box if you want to secure it

- Once the transformer extracted from the oven, I saw and removed all the secondary copper wires (the thin part)

- I made 3 coils with the thick electric cable.The SSR is used as a switch in the primary winding connected to the 220V. The SSR is drived by a digital pin of the arduino. The foot pedal switch is also connected to a digital pin while the resistor is used as pull-down one. A simple sketch detects when the foot pedal is pressed and close the SSR for 40ms and open it for 500ms close it again for 90ms and open it. I did a few tests before giving this values which don't make the cells heat and which gives a good strength

- I used 2 strands as electrodes and 2 pens as handles

In a second version, I used this needles http://www.aliexpress.com/item/1-pair-SUNKKO-709A-Spare-part-welding-head-welding-needle-replacement-for-battery-18650-welding-machine/32385534829.html?spm=2114.13010608.0.77.OevRPi

Nothing difficult if you have the components and basic tools.

[Battling]

2nd episode : Panasonic NCR18650PF 340WH Battery

Tools and components :

Links on Ali :

200mm Heat Shrink Tubing : http://www.aliexpress.com/item/PVC-Heat-Shrink-Tubing-220mm-Diameter-140mm-New-High-Quality-Color-Selectable/32603497299.html
220mm Heat Shrink Tubing http://www.aliexpress.com/item/200mm-diameter-127mm-PVC-Heat-Shrink-Tubing-Battery-Wrap-Mould-Parts-ROHS-1-Meter/32557485097.html
Nickel Strip : http://www.aliexpress.com/item/1-PC-1M-8mm-x-0-18-Pure-Ni-Plate-Nickel-Strip-Tape-For-Li-18650/32526880149.html
Insulation Gasket : http://www.aliexpress.com/item/Insulating-gasket-meson-3-2-18650-lithium-battery-pack-and-series-18650-hollow-flat-gasket-insulation/32588215589.html
JST SM 2Pins Connector : http://www.aliexpress.com/item/Best-Sale-10Pairs-15cm-Long-JST-SM-2Pins-Plug-Male-to-Female-Wire-Connector/32574619357.html
BMS : http://www.aliexpress.com/item/16S-unicycle-lithium-ion-battery-BMS-60V-li-ion-battery-protection-circuit-board-for-solowheel-battery/32256690244.html
XT-60 Bullet Connectors : http://www.aliexpress.com/item/Wholesale-5-Pair-Of-XT60-XT-60-Male-Female-Bullet-Connectors-Plugs-For-RC-Lipo-Battery/32308831172.html

Cells are from Nkon.nl

 

It's easy to assemble the cells using this insulation gaskets. No need to apply hot glue first

Quick try :

Real time thermistor testing

It's important to electrically isolate the 2 packs with cardboard for example

Testing in EUC before covering

First heat shrink tubing placement. We don't see it here, but on both edges, I also used cardboard

The second

Heating with a rework soldering station

Double side tape for increasing the firmness

 

 

 

[US69]

Wow!

respect! But was this a lot cheaper than buying a 340wh pack??

all parts for the spot solder, BMS, and batteries? How much was that?

[Jason McNeil]

@KingSong69 not everything is life can be reduced to cost  What about the innate sense of joy that every man secretly has in completing some DIY project, or just the challenge?  

Edited August 9, 2016 by Jason McNeil

[Battling]

Thanks.
It's cheaper but the most important for me was the ability to make my own batteries when I want ( I'm posting the third episode with the second battery), with my own security criteria as I had a bad experience with my previous EUC battery whose cells died after 2 months and the seller (Gearbest) refused to apply the warranty.

As for the costs :

- MCM4 HS with no battery : 460€ from Ali
- Spot Welder : I had all the stuffs and bought only the SSR, the foot pedal switch and, for the second battery, the copper needle : about 14€
- Panasonic 340Wh Battery : 132€ for the cells and about 30€ for the other components ~ 160€
- LG 420Wh Battery : 171€ for the cells and about 30€ for the other components ~ 200€

For 840€ I had an MCM4 HS with 760Wh battery, so Yes, it was cheaper. Now, this wheel is cheaper : when I bought it, the 132Wh model was about 550€ and now it's about 500€, so the 760Wh DIY version would cost 790€.

 

[Hunka Hunka Burning Love]

Nice job @Battling, and beautiful cat you have there!  I hope that cable it's gnawing on isn't powered!    What sort of range do you get on a full charge now?

[Battling]

@Jason McNeil, you're totally right, I always prefer buying tools and making by myself, and when I see @electric_vehicle_lover I would go further. Big fun here.

Thanks @HunkaHunkaBurningLove. Every time I open my components drawers, he jumps on my desktop. No risk, it was the thermistor, no voltage.
About the range, I'm around 50km because I go very fast. My weight : 70kg.

[Hunka Hunka Burning Love]

I think your cat was an electronics technician in a prior life.    He likes to supervise your work.

Have you done a test pull on the double upped nickel tabs from a cell with a pair of pliers to verify the contacts?  Do you have an old, dead cell to experiment on?  Looking at the photos your spot welds look very nice, but I'd be curious especially with two layers of tabs how well they are spot welded to the battery terminal metal.  Are you able to apply some pressure to the tab as you are welding or do you think that isn't necessary as long as the tab is fairly flush with the terminal end?

Edited August 9, 2016 by HunkaHunkaBurningLove

[Battling]

I think too, he also participates sometimes.

Yes, I did several tests with my fingers, with pliers and even with another battery like here

You can see the the marks on the strip and batteries.
These tests allowed me to fix the durations of the SSR commutation at what I think was the optimal values for my configuration.

At the end, my strips were more hardly fixed that the laptop ones I used for my tests.

Edited August 10, 2016 by Battling

[Battling]

3rd episode : LG INR18650-MJ1 420Wh

Different cells, but same tools and same method 

This BMS uses IRFB3607 in place of the domestic MOSFETs (HY3010P) used by the blue previous one

As you can see, I replaced all the JST SM by T Plug

 

Edited August 10, 2016 by Battling

[esaj]

Very nice job!

Does the microwave-oven transformer drop the voltage? Ie. is the idea to use (very?) small voltage with high amps? How much amps does that put out during welding, hundreds?

I'd be interested in building one, but don't have a scrap microwave oven, plus I'm not very confident when it comes to working with mains voltages (230V RMS)  

[US69]

10 hours ago, Battling said:

Thanks.
It's cheaper but the most important for me was the ability to make my own batteries when I want ( I'm posting the third episode with the second battery), with my own security criteria as I had a bad experience with my previous EUC battery whose cells died after 2 months and the seller (Gearbest) refused to apply the warranty.

As for the costs :

- MCM4 HS with no battery : 460€ from Ali
- Spot Welder : I had all the stuffs and bought only the SSR, the foot pedal switch and, for the second battery, the copper needle : about 14€
- Panasonic 340Wh Battery : 132€ for the cells and about 30€ for the other components ~ 160€
- LG 420Wh Battery : 171€ for the cells and about 30€ for the other components ~ 200€

For 840€ I had an MCM4 HS with 760Wh battery, so Yes, it was cheaper. Now, this wheel is cheaper : when I bought it, the 132Wh model was about 550€ and now it's about 500€, so the 760Wh DIY version would cost 790€.

 

Again: Respect!

And this is also much Money safed, as i can see now...

I didn't exspect the cells and BMS to be under 240-260 Bucks!

10 hours ago, Jason McNeil said:

@KingSong69 not everything is life can be reduced to cost  What about the innate sense of joy that every man secretly has in completing some DIY project, or just the challenge?  

Didn't you read the first 2 words ....Wow and Respect ;-) ???

As an EUC Enthusiast with 3 wheels just  in a half year i know some things are not "only costs" :-)

Was more interested if i can do this, too.....AND saving some Money  aaaah: I have to take some Pictures of my KS18 fan modding....showing my DIY Projects....

 

[US69]

@Battling The other BMS is also from aliexpress? Do you know the specs? Especially will this BMS cut out if under a certain voltage?

[Chriull]

@Battling: Great Work documented by you!

Just in case you plan once to parallel some of your packs :  http://forum.electricunicycle.org/topic/4870-ks-16-680wh-jittery-ride/?do=findComment&comment=54542

So then you should "cascade" your packs, shorten the reverse voltage protection diodes on the second (following) packs and as a safety measure choose a BMS with more than one Mosfet for "overvoltage/charge" protection. (Or just the space to solder some more mosfets in...)

Also as posted here  http://forum.electricunicycle.org/topic/2247-decrease-charging-time-5a-high-current-charger-mod/?do=findComment&comment=29975 and in the following posts there are many parameters for shutoff/safety conditions controlled by the BMS. Maybe it would be worth to find a BMS which can be programmed?

 

[Battling]

Thanks @esaj.

In deed, this transformer is modified for dropping the voltage. With 3 coils, I'm at 2.31V

Regarding the current, I really don't know its value as my Ampere-meter doesn't exceed 20A!

The transformers have a good efficiency so Power in the primary almost equals Power in the secondary. So Pin ~ Pout

I've just measured the current in the primary : 1.68A

So Pin = 230 x 1.68 ~ 386VA
Iout = 386/2.31 ~ 167A

The needles are safe, I used to manipulate them by hands while welding, so, if you make a case, there's no risks.

On the other hand, when opening the oven, you have to take care at the big capacitor which could stock energy for a while. You had to discharge it or disconnect it with protected pliers for example.

[Battling]

@KingSong69 again, thank you. It seems EUC manufacturers make also money with batteries

Another advantage for European buyers : you don't have to wait after your EUC with batteries. I received mine via PostNL in 3 days.

I forgot the links to the cells :

Pana: http://eu.nkon.nl/panasonic-ncr18650pf-3-7v-2900mah.html
LG : http://eu.nkon.nl/rechargeable/18650-size/lg-inr18650-mj1.html

The new BMS was from the same seller, ther's a link to another store with all the specifications :

http://www.aliexpress.com/item/16S-60V-or-67-2-V-unicycle-lithium-ion-battery-BMS-60V-li-ion-battery-protection/32700654093.html

@Chriull thanks for the links, I read some of the posts, but I assembled the 2 packs in real parallel because for me cascading was impossible as it's risky if one pack become faulty or if a wire is cut...Over-voltage/charge protection is less impacting for me, that's why I shunted one of the 2 BMS.

There's about 800Km with these 2 packs in parallel and never had a single incident, fall, cut off, whereas I ride very fast, I have several hills on my daily work path. The rode in my city is terrible.

I agree with you, the best BMS would be a DIY one.

Edited August 10, 2016 by Battling

[Chriull]

1 minute ago, Battling said:

...Over-voltage/charge protection is less impacting for me, that's why I shunted one of the 2 BMS...

That only gets important once the cells age and start to fail - then theoretically one/some cells could get overcharged...

1 minute ago, Battling said:

...I agree with you, the best BMS would be a DIY one.

Or at least self configured - so one knows the limits and can set them oneself.

[Battling]

A recent add concerning the charger : Initially, the charging time was about 5H.
Thanks to @esaj's links http://www.aliexpress.com/item/1set-GX16-3-Pin-Male-Female-Diameter-16mm-Wire-Panel-Connector-L71-GX16-Circular-Connector-Socket/32658447630.html, I could now use my old TG F3 charger in parallel. The charging time is now about half

I'm thinking about putting the Y in a box with a relay controlled by an attiny85 with a voltage or current detection (voltage divider or ACS712)

 

[Ronni Seaver]

Well check http://welderreview.com/handheld-spot-welder-machine-use-precision-welding-batteries/ as well....

[SereneCry]

Hey. Made a spotwelder and finished my new batterypack. I forgot the cardboard insulators underneath the very last row though! How important is that? Do I need to tear off the nickelstrips and put insulation underneath and re-attach? Won't the batteries get weaker if I do another spotweld on them? Also there was a spark when I plugged in the charger and it looks like the light on the charger glows brighter than when I charged the old batterypack. Everything seems to work but haven't had a testdrive yet.

Edited June 23, 2017 by Cryptonitor
Another question

[US69]

what is this batterie type?

and for what wheel will it be used?

Edited June 23, 2017 by KingSong69

[SereneCry]

@KingSong69 Cells are 18650, 3,4Ah 3,7V. Max discharge just 8A but they were so much cheaper than 40A discharge cells that I can replace the pack 4times before it costs as much as a 40A max discharge pack. Wheel is Esway E3 MarsRover. Batterypack fully charged and now there is no spark or sound when i plug in the charger. Sealed up the pack with glue and thinking about just heatshrinkwrapping it and do a testride. So strange that there would be spark when I plugged the charger in first time though! Afraid I'll damage the motor/electronics/charger.

EDIT: Tried connecting everything and tilting the wheel (driving forward) and there seemed to be alot more torque and more rapid acceleration. May be that I've gotten used to the old worn out batteries

Edited June 23, 2017 by Cryptonitor
Decimalpoint error corrected

[US69]

Really important question:

Is this "Soshine 3400mah" cell the "protected" Version with a small pcb upside? is one of this cells a liiiitlebit longer than the normal or old 18650 version?

And: Did your Esway E3 run on only one of this 16series packs?

[SereneCry]

@KingSong69 yes they are the protected version that are slightly bigger. The wheel ran on just one 16-pack. Assembled and tried to testride but I couldn't even get on before it died! Had to plug in charger to be able to turn it on again. Same problem second time. Have I blown my BMS or something? Thinking about that spark when I plugged in charger first time... Or maybe the safetykajigger built-in to the new cells have blown?

EDIT: tried just tilting the wheel again after plugging in the charger so I could turn it on. I could run it along wih my hand but immediatly after I stepped on it cut off and died again.

EDIT: Starting to take it apart again to hack off those protection circuits. Crossing fingers!

Edited June 23, 2017 by Cryptonitor

[US69]

Ok,

 i can only WARN you very heavily to use this -sorry please- selfmade crap combo!

Reasons: Behind this Soshine cell is a panasonic cell that is only capable of max 6 Amps! 

Because of this Soshine protects this cell with a PCB....

But Pcb protected cells have NOT to be in seriell config with BMS, where the BMS overtakes all protections...

Think about just one or two cells shuttiing down....then the BMS shuts down! And you fall!

 

You HAVE to use minimum 10 AMP capable cells in a an EUC wheel, and in an EUC wheel only running on one 16pack...i would go for MINIMUM 15, better 20 Amp cells.....and these have to be unprotected!!

 

You have to tried to save money on the wrong end.....that could have as worst case make you faceplant very bad!

Sorry, strong words, but it was dangerous what you have done!

By rolling by hand no amps are reached, but with your weight this all dont work as 7-8amps are reached easilly!

Edited June 23, 2017 by KingSong69