# Help me match up parts to use for Synkromotive



## IchibahnSLC (May 22, 2015)

Just figured out that I can use them in series in order to boost the max voltage. Excellent. Now just need an answer for my terminal question.

Also would any 4/0 awg welding cable work?

Thanks guys.


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## onegreenev (May 18, 2012)

I can help you with your Synkromotive. Send me a private message. I just sent you one. 


Pete


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## dougingraham (Jul 26, 2011)

IchibahnSLC said:


> The plan is a 144v system running a max of 700A. I will be running 4/0 cable.


I am running 2/0 at 1000 amps and this is overkill. If I did it over I would just use 1/0. The only place you might want heavier is in the motor loop. You see higher currents there than between the controller and the battery. 4/0 is heavy and difficult to work with in addition to being expensive. If you were running 2000 amps I would suggest 4/0. In the real world you only run your max current between the motor and controller for a few seconds and the difference in performance between 1/0 and 4/0 at 700 amps is going to be difficult to detect in the real world. Even 2/0 is going to be overkill in a street EV.



IchibahnSLC said:


> Also should I be crimping or use soldering pellets for the connections


You should use tin or nickle plated copper lugs intended for the size of cable you end up with. Best practice is to use an anti oxidation grease. Something like noxoid. This will prevent corrosion issues a couple of years from now. A proper crimp will be more reliable in the long run than a soldered joint.

Pete can probably answer any of your Synchromotive specific questions.


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## IchibahnSLC (May 22, 2015)

dougingraham said:


> I am running 2/0 at 1000 amps and this is overkill. If I did it over I would just use 1/0. The only place you might want heavier is in the motor loop. You see higher currents there than between the controller and the battery. 4/0 is heavy and difficult to work with in addition to being expensive. If you were running 2000 amps I would suggest 4/0. In the real world you only run your max current between the motor and controller for a few seconds and the difference in performance between 1/0 and 4/0 at 700 amps is going to be difficult to detect in the real world. Even 2/0 is going to be overkill in a street EV.


I think I have access to some free 4/0 or 2/0 THHN wiring. Would that work well for the conversion?



dougingraham said:


> You should use tin or nickle plated copper lugs intended for the size of cable you end up with. Best practice is to use an anti oxidation grease. Something like noxoid.  This will prevent corrosion issues a couple of years from now. A proper crimp will be more reliable in the long run than a soldered joint.
> 
> Pete can probably answer any of your Synchromotive specific questions.


Even with the soldering pellet? I figured that the soldering pellet will make it solder much more reliably then any crimp. 

I appreciate the input!


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## dougingraham (Jul 26, 2011)

IchibahnSLC said:


> I think I have access to some free 4/0 or 2/0 THHN wiring. Would that work well for the conversion?


You want Orange insulation on your high voltage cables. This is the color the first respondents know what to do with as high voltage so they don't injure themselves and others when trying to extricate a person in a crash. Also you want it to be fine strand flex cable. An Orange welding type cable with a 600 volt insulation value is what you are looking for.

Isn't THHN insulation normally used on building wire?




IchibahnSLC said:


> Even with the soldering pellet? I figured that the soldering pellet will make it solder much more reliably then any crimp.


Solder is less reliable in a vibration environment than a proper crimp. The problem with solder is it wicks up the wire and you have a stress riser at the end of the solder flow. After a few weeks or months of vibration the wire breaks at this point.

I have not used soldering pellets but I don't see how this would give you a better connection than a crimp. Solder is not as good a conductor as copper and without crimping most of the current will pass through the solder unlike a good crimp. But the difference will be difficult to measure. The pellets will take longer to use as you have heating time and cooling time to contend with. The vendors have probably done their homework and the correct size lug with the proper size pellet will probably not wick too much. And like crimps you have the heavy heatshrink to act as a strain relief at the end of the fitting.

Good luck with your project!


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## IchibahnSLC (May 22, 2015)

dougingraham said:


> You want Orange insulation on your high voltage cables. This is the color the first respondents know what to do with as high voltage so they don't injure themselves and others when trying to extricate a person in a crash. Also you want it to be fine strand flex cable. An Orange welding type cable with a 600 volt insulation value is what you are looking for.
> 
> Isn't THHN insulation normally used on building wire?


It is usually used in buildings. I'm not sure if there are any fundamental differences minus the fact that the wiring is only rated to 90 C . 




dougingraham said:


> Solder is less reliable in a vibration environment than a proper crimp. The problem with solder is it wicks up the wire and you have a stress riser at the end of the solder flow. After a few weeks or months of vibration the wire breaks at this point.
> 
> I have not used soldering pellets but I don't see how this would give you a better connection than a crimp. Solder is not as good a conductor as copper and without crimping most of the current will pass through the solder unlike a good crimp. But the difference will be difficult to measure. The pellets will take longer to use as you have heating time and cooling time to contend with. The vendors have probably done their homework and the correct size lug with the proper size pellet will probably not wick too much. And like crimps you have the heavy heatshrink to act as a strain relief at the end of the fitting.
> 
> Good luck with your project!


I will go for crimp connections unless someone else would like to chime in? I like the way the solder connections look but if the connection quality won't be as good or solid I don't want it. What is a good crimping tool? I'm guessing something basic like LINK won't work?


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## onegreenev (May 18, 2012)

> I'm guessing something basic like LINK won't work?


Yes, they do work. I prefer them over the expensive hydraulic crimpers if you are only doing a single vehicle. If you go into business then invest in a very high quality hydraulic crimper.


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## IchibahnSLC (May 22, 2015)

onegreenev said:


> Yes, they do work. I prefer them over the expensive hydraulic crimpers if you are only doing a single vehicle. If you go into business then invest in a very high quality hydraulic crimper.


Excellent video. I will be ordering a brute force crimper then. 

As for the wiring needing to be orange for first response is that referring to both ground and power? How do you guys keep the wiring separated if they are the same color? Or are you only referring to the + cable wiring?


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## dougingraham (Jul 26, 2011)

IchibahnSLC said:


> As for the wiring needing to be orange for first response is that referring to both ground and power? How do you guys keep the wiring separated if they are the same color? Or are you only referring to the + cable wiring?


Yes both cables are orange. As a polarity indicator I use colored heatshrink over the lugs. But this is not as clear as you might think. I have two battery boxes. One cable connects between the boxes. What polarity does that cable have? Well it is negative on one end and positive on the other end.

If there is any possibility of a mix up label clearly and take care.


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## IchibahnSLC (May 22, 2015)

dougingraham said:


> Yes both cables are orange. As a polarity indicator I use colored heatshrink over the lugs. But this is not as clear as you might think. I have two battery boxes. One cable connects between the boxes. What polarity does that cable have? Well it is negative on one end and positive on the other end.
> 
> If there is any possibility of a mix up label clearly and take care.


Yeah, that is my concern as well. I'm looking at running 10 batteries in the trunk and 5 under the hood so I was wondering about labeling. I'm sure I can keep it straight using colored heatshrink. I will just order a big bundle of orange 600v cabling (This LINKwork?). Probably will go for the 2/0 gauge. I was going to go with 4/0 due to the excessive heat here in the summer but I will probably be ok.


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## dougingraham (Jul 26, 2011)

IchibahnSLC said:


> Probably will go for the 2/0 gauge. I was going to go with 4/0 due to the excessive heat here in the summer but I will probably be ok.


Look at it this way.

4/0 resistance per foot = 0.00004901. Loss per foot at 700 amps = 24 watts
2/0 resistance per foot = 0.00007793. Loss per foot at 700 amps = 38 watts
1/0 resistance per foot = 0.00009827. Loss per foot at 700 amps = 48 watts

That is your worst case and unless you are doing something extreme this will be a few seconds at most. Assuming a 180 volt nominal battery and a cruising power of 18000 watts this gives 100 amps for your cruise current. for 4, 2, and 1 ought cable the losses at 100 amps are 0.49, 0.77, and 0.98 watts per foot. Considering 18000 watts and assuming 25 feet of cable this is pretty insignificant. The cruising losses with 1/0 cable are going to be 0.77*25 = 19 watts. As a percentage of power 19/18000 = 0.1%. Losses in the motor are probably closer to 10%. Changing to 4/0 will make your typical cruising losses go down to 0.06%. In the grand scheme of things none of this matters.

Run 2/0 between the controller and the motor and 1/0 everywhere else.


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## azdeltawye (Dec 30, 2008)

IchibahnSLC said:


> I think I have access to some free 4/0 or 2/0 THHN wiring. Would that work well for the conversion?
> ...


THHN or equiv. building wire is no good for an EV - It's way to stiff. Use fine-strand welding or marine cable. 
Flexible cables are needed for a high vibration environment such as an EV..


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