Is it a problem to have the positive and negative cables run side by side with no air gap?

[The_Josh_Bear]

I don't have much to add besides agreeing with @u2slow that you should run the positive cable straight to the starter, and from the starter back up to your OE hook ups. Of course you can delete the positive on the driver's side and bolt that negative to frame or tie into the passenger side ground.
Also this seems like a lot of work to avoid spending $300 on some stock batts $400 on two group 31 batteries and hack the trays. I just googled around, and good Lord, group 31's are significantly cheaper than decent group 65's these days!! How stupid is that!?!?

 

[u2slow]

I just googled around, and good Lord, group 31's are significantly cheaper than decent group 65's these days!! How stupid is that!?!?

I'd love that (what my dodges use) but it's not the case around here. 65's are cheaper, and available at more places. Last I checked, Walmart nor Costco carries a group 31 cranking battery.

 

[divemaster5734]

you should run the positive cable straight to the starter, and from the starter back up to your OE hook ups.

That's where my ocd kicks in.
All fuse or other overcurrent protection is calibrated to protect the wire, this is true in every circuit on the planet.
If he has a 600 - 800 amp protection device on the batteries that won't do anything to protect the little 8 gauge jumping from the starter to the accessories or start relay.
8 AWG needs 50a protection, or 80 if you want to toss the 20% rule and go next higher.
If there's a short, say it rubs on the frame, or melts on the exhaust, that little 8 will melt the insulation off from the short to the starter, and become a glowing red hot fire source until it either burns in half, with the hot half hopefully dangling harmlessly in the air, or it will find other exposed metal to short out on, it's kind of doubtful it would ever blow the battery fuse before causing other havoc.
Inline 60a circuit breakers are cheap and easy to install, but that only protects from that point downline, so unless it's installed right at the starter it won't be fully protected.
Installed at the starter could cause long term functional issues.
This is why they have the OEM cable with a terminal tap built into the cable that's one piece from the left battery through to the right and ends at the starter, with the short accessory jumper built in.
Mine was frayed with half the strands on the outer wraps no longer attached, and just taping it doesn't make a wrench tight connection, which is why I made each jumper separate and terminated with a copper lug instead of lead, as copper is a better conductor.
I'm planning on installing a terminal buss for the accessories and power with a relay, then only leave the always live 12v distribution that's required, door locks, interior dome lights, power step, security, and ignition switch.
All that said, these trucks have been running with no main battery or accessory protection for decades, and I'm sure only a few hundred thousand have actually burned up due to electrical fire in that time.
I'm a total newb on all this diesel stuff, if it wasn't for all you guys here there's no way my two projects would have ever made it this far.
Unfortunately, I' have a sever defect, if I can do a thing, then I can sure as heck overdo it just as much.
Being retired doesn't help, got too much time to invent catastrophic events in my head....

 

[The_Josh_Bear]

That's where my ocd kicks in.
All fuse or other overcurrent protection is calibrated to protect the wire, this is true in every circuit on the planet.
If he has a 600 - 800 amp protection device on the batteries that won't do anything to protect the little 8 gauge jumping from the starter to the accessories or start relay.
8 AWG needs 50a protection, or 80 if you want to toss the 20% rule and go next higher.
If there's a short, say it rubs on the frame, or melts on the exhaust, that little 8 will melt the insulation off from the short to the starter, and become a glowing red hot fire source until it either burns in half, with the hot half hopefully dangling harmlessly in the air, or it will find other exposed metal to short out on, it's kind of doubtful it would ever blow the battery fuse before causing other havoc.
Inline 60a circuit breakers are cheap and easy to install, but that only protects from that point downline, so unless it's installed right at the starter it won't be fully protected.
Installed at the starter could cause long term functional issues.
This is why they have the OEM cable with a terminal tap built into the cable that's one piece from the left battery through to the right and ends at the starter, with the short accessory jumper built in.
Mine was frayed with half the strands on the outer wraps no longer attached, and just taping it doesn't make a wrench tight connection, which is why I made each jumper separate and terminated with a copper lug instead of lead, as copper is a better conductor.
I'm planning on installing a terminal buss for the accessories and power with a relay, then only leave the always live 12v distribution that's required, door locks, interior dome lights, power step, security, and ignition switch.
All that said, these trucks have been running with no main battery or accessory protection for decades, and I'm sure only a few hundred thousand have actually burned up due to electrical fire in that time.
I'm a total newb on all this diesel stuff, if it wasn't for all you guys here there's no way my two projects would have ever made it this far.
Unfortunately, I' have a sever defect, if I can do a thing, then I can sure as heck overdo it just as much.
Being retired doesn't help, got too much time to invent catastrophic events in my head....

Very good thoughts, and you answered them yourself. I appreciate the open thinking to help bring us along for the ride. I use those automatic resetting breakers for anything I might need to keep working on the side of the road after taping up the short just to get home: trailer brakes, e-fuel pump main power, and I have one for cab power from 15 years ago during my honeymoon when the stupid fuse link cracked on me! Took me 3 DAYS to track that down with my bride not super happy with me. Eventually I was able to convince her that it's the TRUCK having problems, I wasn't the problem.

I did have a 12 gauge wire foolishly un-fused once ground out on my 88 300-6. STUPID... thankfully the only thing I had to replace was my shorts after the smoke cleared and I was able to pull the ground wire off. That was pretty scary on a gasser, it could legitimately burn through a fuel line in that case. Only needed that lesson once!

 

[divemaster5734]

I did have a 12 gauge wire foolishly un-fused once ground out on my 88 300-6. STUPID... thankfully the only thing I had to replace was my shorts after the smoke cleared and I was able to pull the ground wire off. That was pretty scary on a gasser, it could legitimately burn through a fuel line in that case. Only needed that lesson once!

I use the resettable inline CB's whenever possible.

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Have had this one on my camp trailer for the power w i n c h for at least a decade.
I use it as a disconnect as well.
They censored that word.
My first car was a '65 Galaxy 500 2 door coup, 390ci w/ holly 700 quadrajet / c6. 15 yrs old, paid $100, and promptly smoked some of the wiring along with my brand new 8 track deck.
Still remember that moment of abject terror as smoke was pouring out from behind the dash, just before I reached under the dash, grabbed a handful of wire, and ripped it out. Luckily happened to grab the same wire I had just put in.

Figures I'd become an electrician..

 

[IDIBRONCO]

They censored that word.

Pretty funny. "Artificial intelligence" that spells the word wrong. The one that it wanted to censor is spelled with an e instead of an i.

 

[nelstomlinson]

For AC you absolutely want the two wires running side by side, as close as possible, to reduce impedance. It's a code requirement to have the hot legs and neutral in the same conduit.
For DC it doesn't really matter.

 

[divemaster5734]

For AC you absolutely want the two wires running side by side, as close as possible, to reduce impedance. It's a code requirement to have the hot legs and neutral in the same conduit.
For DC it doesn't really matter.

Indeed, it's for harmonics.
Otherwise it's phase imbalance.
You sound like a Sparky.

 

[nelstomlinson]

Electrical engineer.

 

[parkergn]

All that said, these trucks have been running with no main battery or accessory protection for decades, and I'm sure only a few hundred thousand have actually burned up due to electrical fire in that time.

Old thread, but this is what I've been over thinking recently...

I'm currently replacing all my battery cables in my van. All started with taking out batteries for warranty, then replace the DC-DC charger on my cable, finding good deals on welding cable, and now have ripped all the 40 year old cables out of the van and working on installing fresh, 4/0 (posi starter) and 2/0 (parallel connect, and grounds).

my question is FUSES? Should I protect the new cable from short circuit in the engine bay? They lasted 40 years with no shorts, go another?

if so, I'm using Eaton MRBF Terminal fuses for my DC-DC 25' cable (75amps), and alternator (150-175amps). I could easily add another 250-300amp fuse between the batteries, but what about the 5' starter cable?

 

[nelstomlinson]

It's normal to NOT fuse the starter cables. I'd guess our starters have a surge current of 600+A and a steady current close to 400A. Has anyone measured those currents? Whatever the real numbers are, I doubt a 300A fuse would work.

I'd follow standard practice, and not fuse it.

Where did you find that good deal on cable?

 

[Nero]

I have yet to see any type of fuse between a starter and a battery on any vehicle, automotive or heavy duty. Not saying they don't exist, but it makes sense not to have one. Surge amperage.

 

[franklin2]

All fuses have a common problem; Voltage drop. A very good reason not to use them in the cable to the starter.

If it eases your mind, you do have a fuse of sorts, seen it happen a couple of times. If you have a dead short on one of the large cables, it usually melts the lead terminal right off the battery till the cable end falls off and opens the circuit.

Good wiring practices make this a very rare occurrence.

 

[divemaster5734]

Old thread, but this is what I've been over thinking recently...

I'm currently replacing all my battery cables in my van. All started with taking out batteries for warranty, then replace the DC-DC charger on my cable, finding good deals on welding cable, and now have ripped all the 40 year old cables out of the van and working on installing fresh, 4/0 (posi starter) and 2/0 (parallel connect, and grounds).

my question is FUSES? Should I protect the new cable from short circuit in the engine bay? They lasted 40 years with no shorts, go another?

if so, I'm using Eaton MRBF Terminal fuses for my DC-DC 25' cable (75amps), and alternator (150-175amps). I could easily add another 250-300amp fuse between the batteries, but what about the 5' starter cable?

There are three important factors to selecting the correct wire.
Insulation, Conductor Count, and Conductor Type.
For our purposes in trucks we should only use Copper conductors, which leaves two other factors to consider.
Strand count,(higher is better) and insulation, (rated for application).
Welding cables have high flexibility, and a high strand count.
They are usually Neoprene, EDPM, or a PVC mix CPE. The drawback for auto use is the insulation, or "jacket", is soft, which is more susceptible to vibration damage and cracking in freezing temps.
Purpose made battery cables have a more robust jacket that gives added protection against vibration and impacts, and doesn't break down as badly as welding cables in extreme temps, hot or cold.
They usually have the same or higher strand count then welding, 1100+ vs 972.

NEVER use CCA auto cables, (Copper Clad Aluminum), as the Al doesn't conduct as well as the CU, and you have to derate by 1-2 wire sizes to equal the same CU load ability.

A wire I've used is called MTW, ( Machine Tool Wire)
It also has a high strand count, it's used for industrial equipment, and normally sold as AWM, (American Wire Manufacture, compared to AWG, (American Wire Gauge), AWG is sold in hardware stores for consumer use.
High strand count is critical for performance.
The higher the strand count means more surface area.
While this is vital in AC circuits, the increased surface area also works for DC circuits, especially when you're generating AC at your alternator, which generates EMF's that can cause a resistance to the flow of electrons.
The reason you should never use a 4/0 AWG cable is it only has around 76 strands, vs 4/0 MTW, which has at least 972 depending on manufacture, or CPE that start around 1100 strands.
To be honest, I've taken wire out of large commercial chiller and used to make cables for my hot rod that worked for years until I sold it.
A welding cable will work, but you'll need to be careful about routing, and very importantly, strain relief.
I would make a "Chinese Sock", type of Kellems Grip for any hanging vertical drops, (battery to starter), to help keep the wire from slapping around and destroying the insulation.

New EV cables have other properties that we don't need to address for our OBS rigs, and you don't need to spend the extra money.

I tried to keep it simple, but wanted to give you a decent idea of you options and risks.

 

[parkergn]

Where did you find that good deal on cable?

Here in Toronto I we have Canada Welding Supply. Got “ToughFlex” welding cable by Kalas. 4/0 6’, 2/0 16’ all for $190 CND.

I tried to keep it simple, but wanted to give you a decent idea of you options and risks

Thanks for the all the insight! I’m fairly confident on the cable I bought, EDPM Class K wire, plus no refunds. I’ll be sure to run it securely. My van has a few hangers like you described I can reuse, I’ll add some extra harness tape to soften them up, the factory rubber is worn.

My cable has 30 gauge wire. So I should be up to the +900 wire count like you mentioned.

I have yet to see any type of fuse between a starter and a battery on any vehicle, automotive or heavy duty. Not saying they don't exist, but it makes sense not to have one. Surge amperage.

Copy that! I’ll only be fusing my 3G alternator and DC-DC charger. Leaving the starter and accessories factory setup. Thanks!

Also last question. The starter trigger wire, is there an amp draw, I have plenty of 14gauge wire for this, looks like factory is about 12g, wondering if it’s even pulling amps, if so how much