DIY Electric Car Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter · #1 ·
For those of us who have batteries front and rear, where do you run the HV cables connecting them?
What are the concerns if you run them through the passenger compartment or outside along the frame rail?
I ask because I’ve seen several pro built conversions that have cable conduits running along the frame from front to back like this Porsche. Wouldn’t running them through the tunnel, or down the center of the car, be safer? These just look dangerous to me, but are they?
Thank you.

Car Automotive parking light Wheel Tire Vehicle
 

·
Registered
Joined
·
7,977 Posts
I ask because I’ve seen several pro built conversions that have cable conduits running along the frame from front to back like this Porsche. Wouldn’t running them through the tunnel, or down the center of the car, be safer? These just look dangerous to me, but are they?

View attachment 123799
What does an old 911 have for a tunnel? With a rear engine and no liquid coolant, there's no need for a tunnel and there might not be an easy route. But those conduits, although better than exposed cables in that location, look like an amateur hack to me.

I'll also note that getting paid to do a conversion does not imply having professional qualifications to do automotive engineering.
 

·
Registered
Joined
·
3,101 Posts
Not good if "professionally built". How's an emergency responder supposed to know there's 400V in what looks like a cooling or HVAC line?

Stuff's supposed to be Home Depot orange, not galvanized shiny metal Lowes
 

·
Registered
Joined
·
7,977 Posts
What does an old 911 have for a tunnel? With a rear engine and no liquid coolant, there's no need for a tunnel and there might not be an easy route.
After a quick Google image search for "911 floorpan", it appears that an old 911 doesn't have a usable tunnel, or a backbone like a Beetle. If they're going to use conduit and can't find a better location than that, they could have run the conduit through the interior.

How's an emergency responder supposed to know there's 400V in what looks like a cooling or HVAC line?

Stuff's supposed to be Home Depot orange, not galvanized shiny metal Lowes
Good point - standards exist for a good reasons. Even if conduit is appropriate and the location is safe, it would be easy to properly colour-code it. Of course then the hack location would be more obvious...
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #5 ·
Good points: Color and First Responders. How are they to tell those are not HVAC lines? Sure looks like them.
So given a blank slate, what’s the best way to connect a front and rear pack?
Down the center? Inside, outside?
Would you use a conduit, even if inside the car?
On my list already: It’s gotta be Orange if it’s HV.
Thank you.
 

·
Registered
Joined
·
3,101 Posts
IMO the metal conduit is a two edged sword. If you were to, say, toss a rock with the wheel of the Porsche into the pictured-here-car's conduit a) the conduit might protect the insulation from otherwise being pierced at the impact point b) might pierce the cable inside, electrifying the conduit, but not pop a fuse. We don't have "ground" for the conduit to pop a fuse if such a breach occurs, like we do for building wiring. Feeling lucky?

Then there's first responders - in theory they should be able to access a disconnect before they try to get you out of the wreckage. But they need to know where the HV lines are, or where it's safe to cut up the little beauty you spent the last two years of your life building. Orange is necessary, IMO, damn the aesthetic (done right, it could be an accent feature).

On the plus side, conduit might keep rodents and human toddlers (at the risk of being redundant) from gnawing on your hv cable insulation.

Tesla runs naked HV cables under the back seat of the Model S, iirc. I don't recall any armor or barrier plate there or in the runs in the quarter panels, where fiberboard covers the cavity. I definitely wouldn't run naked HV cables anywhere they could get stepped on, touched, or kicked, so outside is ideal, given a choice. Out of foreseeable reach is the next choice - none of Tesla's trim panels covering cavities that run cabling are interlocked as far as I remember (verify for yourself). A DC Jacob's Ladder is last means of safety deterrent
 

·
Registered
Joined
·
28 Posts
Those external lines on the 912 pictured are for coolant running up to a radiator inside the the front fender area.
Originally, Porsche 911/912s used these pipes for oil run to a heat exchanger up front.
HV 2/0 cables are run through the tunnel (yes 911/912 have a tunnel like a VW), in conduit, free from any abrasion or intrusion from outside elements.
Most modern EVs have HV cable inside the passenger compartment, just remember to fuse both cables at one end or the other.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #8 ·
Thank you for clarifying this Porsche's setup. Having physically seen a few conversions that route HV cables along the frame, the VW Speedster sold on BAT last year and my own 68 bug included, I was perplexed that a pro shop that's been doing conversions for years would route HV cable like this. This makes so much more sense now. My apologies to the shop for my ignorance.
Good advice to run HV lines in conduit even when inside the car. Tesla may be able to run naked lines but most of our conversions don't have five star crash ratings.
Thank you for all your comments.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top