Low voltage Cables How do people do it?

[leman2112]

Trying to keep stuff plug and play as much as possible, however its getting kinda too pricy. Think I am going to have to start to build my on 12v wiring harnesses eventually. I know damian says that we can use cat5e networking cables like that of an ethernet cable? Just wondering about really good brands that I can trust. I hear belden makes really good cables and I am going to be using them on my bms. Fine stranded, shielded, strong, good quality.

Is it ok to use larger cables for my 12 volt system? My bms cables are 16 awg? Will this work for my 12 volt system?

Is it ok to use shielded cables in place of non shielded cables?

The only networking cables at home depot are really tiny like 24 awg? Would that be ok? I kinda want to use my bigger cables for durability because I plan on building an offroad rig that is going to get wheeled extremely heavily, hopefully!

[arber333]

Trying to keep stuff plug and play as much as possible, however its getting kinda too pricy. Think I am going to have to start to build my on 12v wiring harnesses eventually. I know damian says that we can use cat5e networking cables like that of an ethernet cable? Just wondering about really good brands that I can trust. I hear belden makes really good cables and I am going to be using them on my bms. Fine stranded, shielded, strong, good quality.

Is it ok to use larger cables for my 12 volt system? My bms cables are 16 awg? Will this work for my 12 volt system?

Is it ok to use shielded cables in place of non shielded cables?

The only networking cables at home depot are really tiny like 24 awg? Would that be ok? I kinda want to use my bigger cables for durability because I plan on building an offroad rig that is going to get wheeled extremely heavily, hopefully!

My favourite signal cable is Liycy or similar signal cable with multiple 0.5mm2 or 0,75mm2 lines. Usually those cables have lines clearly marked by numbering. Then it is simple to draw your schematic and follow your connectors. You just cut the cable to length and connect to where you need.

However if you need twisted pair i decided against LAN cables. They are really thin and LAN crimping system just isnt good for high vibration intensive enviroment which car is.
I make my own CAN twisted pair from two previously mentioned marked lines. I put one end into my battery drill and the second end i fix in a drill press or somewhere solid. Then i give it a twist . Usually i crimp connectors on it after i mount it in a car.

[ZooKeeper]

Trying to keep stuff plug and play as much as possible, however its getting kinda too pricy. Think I am going to have to start to build my on 12v wiring harnesses eventually. I know damian says that we can use cat5e networking cables like that of an ethernet cable? Just wondering about really good brands that I can trust. I hear belden makes really good cables and I am going to be using them on my bms. Fine stranded, shielded, strong, good quality.

Is it ok to use larger cables for my 12 volt system? My bms cables are 16 awg? Will this work for my 12 volt system?

Is it ok to use shielded cables in place of non shielded cables?

The only networking cables at home depot are really tiny like 24 awg? Would that be ok? I kinda want to use my bigger cables for durability because I plan on building an offroad rig that is going to get wheeled extremely heavily, hopefully!

The answer depends on the circuit and current, not voltage.

- For 12v POWER circuits in a vehicle, 16ga with appropriate fusing is fine
- Signal & sensor circuits (throttle, Fwd/Rev, VCU-Inverter) can be almost any wire gauge
- CAN should be "twisted pair" and certainly CAT5 cable or similar would be appropriate, shielded is best

My bench testing is using Telco wire, it's SMALL, like 26ish gauge. The only "heavy" wire is the +12v & -12v supply to the VCU and Inverter, which are 16ga & internally fused by the power supply @ 5A.

[DaveH]

You don't need to shield CAN wires. I have never seen an OEM use shielded cable for CAN. Just run the wire next to the body - the body is your shield and your ground return for the CAN high and low signals.

To avoid long-term reliability problems with vibration, temperature changes etc, I would not use wire smaller than about 20 gauge outside of electronic enclosures.

[leman2112]

So is it ok to use my belden shielded 16 guage cables for CAN? Or should I order Cat5 cables that are 20awg? Is that even possible I wonder?

[leman2112]

Also just considering using the Liycy. just kinda still trying to figure out the measurement system.

https://products.lappgroup.com/online-c ... liycy.html

Is this the one I need?

2 x 0.75 6 38 53

Number of cores and mm² per conductor

2 x 0.75

Outer diameter [mm]
6

Copper index [kg/km]
38

Weight [kg/km]
53

[jalovick]

Part of getting the low voltage cabling right is making sure it's routed, terminated, and protected properly. I've been looking towards Motorsport wiring guides to get an idea of how they do it well on ICE vehicles. The principals for the low voltage wiring are essentially the same.

I've found these YouTube videos series useful:
Dave from Haltech wiring VLOG (Haltech is an Australian ECU manufacturer and tuner):
- https://www.youtube.com/results?search_ ... Vzd2lyaW5n

HP Academy (A NZ Motorsport group) training videos:
-

Even though they cover ICE ECU wiring, the tools and processes are similar.

Jamie

[arber333]

So is it ok to use my belden shielded 16 guage cables for CAN? Or should I order Cat5 cables that are 20awg? Is that even possible I wonder?

20awg...is that 0.5mm2? I use 0.5mm2 to 0.75mm2 cables for CAN. Just to have more integrity. I see OEMs use 0.5mm2 usually.
I dont shield them, because nothing is gained from shielding differential signals.
What i learned also with twisted pair for BMS was to NEVER rout 12V power among communication cables. It can cause all sorts of issues that you never need to filter out if you put those power cables a foot apart from signals.

You use Liycy cable, which is shielded cable to pass NONDIFFERENTIAL signals like resolver or single ended 12V push pull signals. For those i recommend to count the number of signal lines and add power supply pair. So for 7 signal lines i use 9 or 10 pole Liycy cable. I ground only one end of cable mesh at the receiver end and observe. If i am required to ground at both ends i decide later.

CAN cables i rout separately from power cables and i try to use 2P connectors along the way. So i can connect in the middle and connect my PC with transciever to listen to traffic.

[DaveH]

It's fine to use shielded cable for CAN, just don't worry about connecting the shield to anything. It does need to be a twisted pair though.

[leman2112]

Will 16 gauge work for my Can Lines? Or should I buy the thinner Liycy cable .5mm² or .75mm²? I guess it is just a metric unit of measurement? Maybe 16guage is pretty similar in size to .75mm². I better check out the conversion charts on the interwebz really quick. Just want it to work.

[ZooKeeper]

Will 16 gauge work for my Can Lines? Or should I buy the thinner Liycy cable .5mm² or .75mm²? I guess it is just a metric unit of measurement? Maybe 16guage is pretty similar in size to .75mm². I better check out the conversion charts on the interwebz really quick. Just want it to work.

That will be fine, from my limited experience smaller area wire works better at higher CAN speeds, but even @500k 16ga works well.

I will take issue with much of what is posted on the 'net about vehicle wiring because it utterly fails to account for duty cycle, any true semblance of actual EE standards and fails to drive home the point that the purpose of a FUSE is to protect the WIRING from overload damage, not a component.

[m.art.y]

Am I right in thinking that vechile chassis ground = 12 V battery "–"? So essentialy I run 12 V positive wire to feed the inverter (prius gen3 in this case) and negative for the inverter I can connect to vechile chassis or do I need to run it directly from the negative terminal of 12 V battery? Also if I use shielded cable for resolver/encoder I can connect the shield to the same negative wire that connects to vechile chasis? And at the same time I can connect DC/DC output from the inverter to the same 12 V positive that feeds the inverter and inverter case connected to vechile chassis will act as ground (negative)? Or does DC/DC + output need separate wire straight to the battery positive?

[arber333]

Am I right in thinking that vechile chassis ground = 12 V battery "–"? So essentialy I run 12 V positive wire to feed the inverter (prius gen3 in this case) and negative for the inverter I can connect to vechile chassis or do I need to run it directly from the negative terminal of 12 V battery? Also if I use shielded cable for resolver/encoder I can connect the shield to the same negative wire that connects to vechile chasis? And at the same time I can connect DC/DC output from the inverter to the same 12 V positive that feeds the inverter and inverter case connected to vechile chassis will act as ground (negative)? Or does DC/DC + output need separate wire straight to the battery positive?

Just be sure to use a suitable fuse on inverter input. Never connect any load to 12V source without a fuse online unless you use big cables.