Q8 modding

[hank]

As an aside, you can get silver (or silver-plated-copper) electrical braid too:
https://www.google.com/search?q=silver+electrical+braid

Turns out there’s an ASTM standard specification:

Standard Specification for Silver-Coated Braid and Ribbon Flat Copper Wire...

ASTM B971 - 10(2014)
Standard Specification for Silver-Coated Braid and Ribbon Flat Copper Wire intended for use in Electronic Application

Active Standard ASTM B971 | Developed by Subcommittee: B01.04

Book of Standards Volume: 02.03

And hey, whaddaya know, there’s also a shear strength standard for nonferrous bolts:
https://www.google.com/search?q=ASTM+standard+metric+screw+electrical

[Tom_E]

@Tom Tom

… The poor springs have an up-side, the will act as fuses (collapse) at excessive current levels , for those who e.g. put a cell in backwards. Djozz was correct in preferring good springs, but some people need to be protected from themselves. Once you improve the tail yourself, you must take responsibility. Seems like a decent compromise.

I proved the fuse thing already . Fortunately I got spare springs and no apparent harm done - to the light or cells. I had only 2 GA cells in at the time, one upside down - noticed no light blink or flash, then saw a nice little stream of smoke.... The springs turned blueish and collapsed - usual thing. I've seen this before.

I'd like to see I took one for the team and tried it, but...

[Lexel]

you could cut the traces and put there 0603 0 ohm resistors they also act like a fuse

[Lexel]

@Schoki

I would make the 4 LED footprints the same size, so you can buy LEDs the same size and put them where you want.

its good to have 2 bigger pads
you can always reflow a 0603 on a 0805 pad

[Etex]

AlexGT, looks pretty darn direct, to me. Hey if it works for 1/24 scale slot cars (from the 60’s), it works for me.

Hmmm, maybe slot car contact braiding (ie., contact brushes) would be something to look into.

[TheOnlyDocc]

I now use the temp control and set it to a new tem. Worked like a charm! Thanks Tom and Lexel!!! But i have another question. I checked the datasheet from the VTC-6 and they can be discarged way below the 3,0V. Is there an option to set also the LVP levels?

[Tom_E]

Well, only in the code - there's a setting for that, but in reality, how many mAh are you gaining? If you look at it, not much is left below 3.0V. Some wanted to use a higher cutoff even.

[TheOnlyDocc]

The VTC-6 are going down to 2,0V. I do not know how many mAh i would gain if the cutoff is set to 2,5V but i have a heavy modded TN-31 and the cutoff there is set to 3,2V/cell. If i use the cells than in a light without LVP i got quite some extra runtime untill the cells are below 2,5V. So it would have been nice to be able to get this extra runtime by setting this cutoff via the modes. But so i have to wait for the next bigger mod (when i have the time to flash the mcu with changed values.
I will definitely ask you again how to when the time comes. So far i am really happy. And i am impressed how long it took to get to 60°C headtemp ~22A on turbo. That speakes for the design!
With the Luxeon V this time will be much shorter (@~35A :smiling_imp: )

[Lexel]

it is possible to set LVP to any value you want if you can flash the MCU

[Tom_Tom]

@Lexel

you could cut the traces and put there 0603 0 ohm resistors they also act like a fuse

’Twas discussed, ad nauseam, fusible traces, SMD fuses, etc, but too complicated to introduce into this design, from scratch. Complexity and cost, for something that hopefully may never happen to most. And bearing in mind selling price. Fusible springs (intentional or otherwise) will probably do the job well enough. If you beef them up, you take the responsibility to operate the torch safely.

[Zulumoose]

Has anyone considered that the resistance of the springs comes from the gaps, that if the springs were compressed more OR the gap filled, there would be no gain from bypassing.

How about simply feeding braid onto the spiral of the springs so that when compressed there is a crushed braid under the battery, no need even to solder? Viable?

[AlexGT]

@Etex

AlexGT, looks pretty darn direct, to me. Hey if it works for 1/24 scale slot cars (from the 60’s), it works for me.

Hmmm, maybe slot car contact braiding (ie., contact brushes) would be something to look into.

Thanks for the tip Etex, I just purchased some on Ebay, it looks way better than the soldering braid, will keep it for future projects… :+1:

[Tom_Tom]

@AlexGT

I soldered copper braid on the spring but instead of soldering to the battery PCB, I just made a hole in the center of the braid and screwed it in directly contacting the aluminum body, it bypasses the PCB and screw and just makes direct contact with the aluminum around the screw hole, I sanded, polished to a mirror shine and then used DeOxit and Progold on both the braid and the polished aluminum surface around the screw hole, I think is a more direct path for the current than through the screw…

Very neat. Good use of de-solder braid (I think that’s what you used ?) Prettier than my usual efforts.

[hank]

AlexGT:

screwed it in directly contacting the aluminum body

Q8 modding

I soldered copper braid on the spring but instead of soldering to the battery PCB, I just made a hole in the center of the braid and screwed it in directly contacting the aluminum body, it bypasses the PCB and screw and just makes direct contact with the aluminum around the screw hole, I sanded, polished to a mirror shine and then used DeOxit and Progold on both the braid and the polished aluminum surface around the screw hole, I think is a more direct path for the current than through the screw…

I don’t understand and can’t tell from the picture what you mean. Did you drill and tap holes in the battery tube?

VWPieces:

will not find anything under 100pc per size needed. Sell off kits of quality hardware to others.

I’m hoping someone will sell off kits with quality right screws to me, actually. As I don’t know for sure what I’d buy by the hundred.

why buy 5-10 priced each when you can get 100 for the same price.

Too much of anything becomes a burden for one’s survivors, after enough decades of accumulating stuff. My estate sale will make hardware junkies happy.

[Tom_E]

I can't follow the copper braid mod either - don't understand where the screws are. My method is not dependent on the screw as well. Literally about 1 mm, maybe, is used on the PCB. The ring around the screw hole is soldered so it sits above the solder mask, making contact to the bare aluminum of the battery tube.

[Rob_K]

He made round opening in the braid and put it between body and the board and then screw finished the job by going thru the board and the braid

[Tom_E]

Ahh, ok - similar to my mod then - going direct to the screw hole. Not a fan of copper braid though.

[AlexGT]

@Rob_K

He made round opening in the braid and put it between body and the board and then screw finished the job by going thru the board and the braid

Exactly that! I might open the tailcap again just to take pics… :weary:

[Etex]

He sandwiched the braid between the alum battery tube, and the PCB, with a hole lined up in the braid for the screws to clamp it down directly.

Edit: whoops, to slow.

[The_Miller]

@AlexGT

@Rob_K

He made round opening in the braid and put it between body and the board and then screw finished the job by going thru the board and the braid

Exactly that! I might open the tailcap again just to take pics… :weary:

and you made the tail pcb into a flower, yeah we need to see more pics