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Team Nissmo
2011.12.23, 11:28 AM
I upgraded my Fets to 6x 4562`s and tested the wiring circuit for volt drop before replacing.

My stock wire lost 0.2 Volts at 5Amps(my 70T stock motor draws 5A stalled and my mod motor draws 5A norm)
5 wires at 0.2v = 1 Volt drop :(
http://thumbs.webs.com/Members/viewThumb.jsp?siteId=38926445&fileID=246522028&size=thumb

The MR-03 switch lost 0.07V@5A
http://www.wlmr.co.uk/photos/Fets/vd%20switch%203.JPG

The upgrade motor wire lost 0.02V at 5A
http://thumbs.webs.com/Members/viewThumb.jsp?siteId=38926445&fileID=246522023&size=thumb
20 AWG wire:
http://www.wlmr.co.uk/photos/Fets/vd%20mod%20motor%2020.JPG

5 wires at 0.01v = 0.05 Volt drop :cool:
http://thumbs.webs.com/Members/viewThumb.jsp?siteId=38926445&fileID=246522024&size=thumb


To carry out this Volt drop test I used:
A variable voltage supply set at 5A to put a load through the wire.
A Volt meter with the probes either end of wire being tested (parallel)
An Amp meter with the probes between the wire being tested and the supply (series)

color01
2011.12.23, 02:55 PM
While I don't think each one of your stock wires drops 0.2V (they're different lengths = different resistances), that's quite an interesting find. Perhaps there is some merit after all to replacing the car's wiring... I think a lot of us only take out the switch. :D

Team Nissmo
2011.12.23, 09:14 PM
The length of wire makes a difference, longer equals more Volt drop.

A stock AWD has 6 wires so the Volt drop would be higher
My stock AWD switch lost 0.4V@5A
http://thumbs.webs.com/Members/viewThumb.jsp?siteId=38926445&fileID=246522022&size=thumb

The AWD upgraded below now only has 4 wires so only 0.04 volts lost.
http://thumbs.webs.com/Members/viewThumb.jsp?siteId=38926445&fileID=250220899&size=thumb

I have tested a lot more stock wire since the high results on my MR03 and found the amount of
Volt drop is between 0.08 and 0.32 Volts at 5 Amps (0.90V norm)

If I had the worst stock wire tested on my AWD a total of 1.92V would be lost.
If I had the best stock wire tested on my AWD a total of 0.48V would be lost.
With the 20 gauge wire tested on my AWD total of ____ 0.04V would be lost.

Team Nissmo
2011.12.23, 09:27 PM
Done some tests with same length wires :)
Xmod Gen 1 switch:
Looks better than the kyosho AWD one I tested...
http://www.wlmr.co.uk/photos/Fets/vd%20switch%20x.JPG

Xmod stock battery bridge wire:
http://www.wlmr.co.uk/photos/Fets/vd%201%20stock.JPG

Xmod bridge with 20 AWG wire:
http://www.wlmr.co.uk/photos/Fets/vd20.bmp

Xmod bridge with 16 AWG wire:
http://www.wlmr.co.uk/photos/Fets/vd16.JPG

Xmod motor plug stock wire:
http://www.wlmr.co.uk/photos/Fets/vd%20motor%20plug.JPG

Xmod motor plug 16 AWG wire:
http://www.wlmr.co.uk/photos/Fets/vd%20motor%20plug%2016.JPG

Micro dean plug:
http://www.wlmr.co.uk/photos/Fets/vd%20dean.JPG


Xmod stock wire hanging by a few threads and 20 AWG upgrade:
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/20%20g%20power-1.JPG

On the next wire upgrade I do I could join all the bits removed and about to be fitted to get a true reading of the total circuit.:D

z3zinho
2011.12.24, 06:18 AM
While I don't think each one of your stock wires drops 0.2V (they're different lengths = different resistances), that's quite an interesting find. Perhaps there is some merit after all to replacing the car's wiring... I think a lot of us only take out the switch. :D

Since not much of the current passes thru the switch, I never bodered to take it out, but I do change the wires. :rolleyes:

color01
2011.12.24, 06:28 AM
I have tested a lot more stock wire since the high results on my MR03 and found the amount of
Volt drop is between 0.08 and 0.32 Volts at 5 Amps
This seems like a much more reasonable number. :eek:

Of course, the other figure to be wary of is the 5A -- I don't know any Mod motor that actually pulls 5A constantly. The hottest "usable" 130 motors I know (Plasma Dash hybrid) pulls about 2A constantly, which constitutes a proportionately lower voltage drop vs. 5A. 5-10A is a reasonable stall/startup current for these motors, definitely not normal running current draw though (batteries would be searing hot and leaking juice if they truly discharged at 5A average).

Could you redo this test at 2A instead of 5? Just to be in a closer range to real-world values. :) Thanks for your work (and Merry Xmas)!

Team Nissmo
2011.12.24, 10:31 AM
As startup/pulling away from standing on the track with my mod. motor draws 5 Amps every time I accelerate, I choose this from my first round of tests. I can do the tests at 2A for your constant Amp draw?. But this is what my AWD with a mid range mod motor (Stock R) draws form startup with the wheels off the floor :eek:

The upgrade should not give you any more top speed only pulling away as the Amp draw is only greater on acceleration. As the stock wire warms up it could increase in resistance reducing the top speed.

My tamiya speed checker showed it gave me an extra 1 KPH from cold.

color01
2011.12.24, 04:41 PM
I'm really curious to know, so if you could it'd be great. :) Thank you (on behalf of all the other curious people as well)!

At some point I need to borrow an infrared thermometer to figure out how hot the other electrical contacts get as well -- what about the clamped junction between the battery terminals and the PCB power wires? What about the batteries to the terminals themselves? Lots of places to lose voltage.

Again, this is great work, thank you! :)

Team Nissmo
2011.12.29, 11:01 AM
I upgraded an AWD and tested all the wires removed.
Stock wire AWD
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/ag%20stock.JPG

AWD switch (no.2) + stock wire Volt drop@2A loosing 0.189 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/2a%20sw.JPG

AWD switch (no.2) + stock wire Volt drop@5A loosing 0.481 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/5a%20sw.JPG

AWD stock wire circuit Volt drop@2A loosing 0.596 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/2A%20vd%20all.JPG

AWD stock wire circuit no safety Volt drop@2A loosing 0.310 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/2A%20vd%20no%20cap.JPG

AWD stock wire circuit Volt drop@5A loosing 0.674 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/5a.JPG

AWD stock wire circuit Volt drop@7A loosing 1.003 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/7a.JPG

AWD stock wire (no switch) Volt drop@10A loosing 1.076 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/10A%20no%20switch.JPG

Team Nissmo
2011.12.29, 10:23 PM
As z3zinho stated on the Kyosho 2.4 board the power does not all go thru the switch but on some 27mHz boards it does. I do not like the idea of the siginal side to the fets loosing any voltage as this could effect the power flow so I replace them all.

AWD switch (no.2) repaired and upgraded with 20 AWG wire Volt drop@2A
A saving of 0.119Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/2a%20sw%2020g-2.JPG


AWD switch (no.2) repaired and upgraded with 20 AWG wire Volt drop@2A
A saving of 0.331 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/5a%20sw%2020g-2.JPG


AWD 20 AWG wire circuit Volt drop@2A
A saving of 0.225 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/2amp-2.JPG


AWD 20 AWG wire circuit Volt drop@5A
A saving of 0.496 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/5amp-2.JPG


AWD 20 AWG wire circuit Volt drop@7A
A saving of 0.765 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/7amp-2.JPG


AWD 20 AWG wire circuit (no switch) Volt drop@10A
A saving of 0.931 Volts
http://memberfiles.freewebs.com/77/47/38974777/photos/Fets/10amp-2.JPG

TheSteve
2011.12.30, 03:27 PM
If worried about voltage drop don't forget to remove the PTC on stock motors.

z3zinho
2011.12.31, 12:13 PM
As z3zinho stated on the Kyosho 2.4 board the power does not all go thru the switch but on some 27mHz boards it does. I do not like the idea of the siginal side to the fets loosing any voltage as this could effect the power flow so I replace them all.


Besides the Iwaver boards, all the kyosho boards work this way. You can see that the ground and Vcc on the fet pad's goes directly to the battery terminals and don't go over the switch ;) The current that goes into the receiver part of the board is so small that the voltage drop in the switch is not important. Believe me.

It's way more important to change the wire that connects the left side of the chassis to the right side of the chassis on 2wd cars, there is a lot to gain from that litle wire ;)

Team Nissmo
2012.01.11, 08:08 PM
Besides the Iwaver boards, all the kyosho boards work this way. You can see that the ground and Vcc on the fet pad's goes directly to the battery terminals and don't go over the switch ;) The current that goes into the receiver part of the board is so small that the voltage drop in the switch is not important. Believe me.



On the Kyosho MR-03 and dnano boards all the power to fets goes through the switch.
Believe the pic it shows pin 3 of the fets wired to S2 ;)
http://www.wlmr.co.uk/photos/Fets/03pt2.JPG

z3zinho
2012.01.12, 10:00 AM
:eek: I've never looked at the mr03 board with much detail... I only changed fet's on one of my cars and it was just prior to going to the UK for the PN Qualif ;):D. I was in such a hurry I didn't notice that. Thanks for pointing that out. I have no idea why did kyosho went this route after all this time. Poor design choice in my opinion.

Switch is definitely coming of on all my 03 cars! The power our mod cars use is way to much for that litle flimsy switch. Although they are not the same, I've seen melted switches on some Iwaver boards when using mod motors :eek: