4/0 SHCA tinned OFC

[jarrad67]

Will a 15ft run of SHCA 4/0 tinned OFC be enough to safely power two Fosgate t2500-1bdcp's? I have a 320a HO alt, big 4, group48 XS battery, 10 farad cap bank.  My front stage is on a separate run of 1/0, Fosgate t600.4 for the doors and t400.4 for dash and tweeters.  Currently running two SA8-v3s 4ohm DVC wired to 1 ohm on a T1000-bdcp, but looking to upgrade.  Havent decided on subs yet, but possibly the new Sundown Z8s when the come out.  

 

What and how many supplamental batteries would you recommend? Also could I fuse the 4/0 at the front with a 600, then split off at the back battery to each amp? 

[revoracing247]

Looking at the specs of the t2500, they recommend a fuse of 300A. Then looking up several sources for 4/0 copper current capacity, they range from like 230-380A.

So 600A+ through one 4/0 would be a on the sketchy side. If you did, you'd potentially get about a 1V drop in the 15ft and be generating ~600W of heat through the cable.

I think i saw Meade has a single 4/0 run to the back of his Cadillac. But I think that's to a rear battery bank, so the current draws are smoothed out in that setup.

Or maybe my googling is off somewhere lol but hope this helps give more context

[jarrad67]

So if I ran each T2500 on a run of 4/0 it should be no problem?

[revoracing247]

Tough question haha short answer is, "it should!" And the Engineer answer is "it depends!" it feels like overkill when they just have 1/0 terminals right? It's about perspective and knowing the limits of your system and how you designed it.

Here's what the t2500 lists in the specs

 

and the ampacity charts that mainly come up on a google search is for electrical codes for housing or the power grid and what not, so they're way more concerned about 100% duty cycle draw on the cable and making sure it won't ever fail when used within specs. Which basically turns into the game of heat dissipation of the wire and where the insulation integrity starts to fail. (which i wish SkyHigh provided data sheets for their products so we knew exactly their specs)

But in an effort to be helpful rather than just tell you to go do the math and research:

The easy answer is to run a 4/0 to each amp with a 300A fuse and you can almost definitely sleep at night because you're fused per the amp specs and within accepted guidelines for ampacity on 4/0. And worse case each wire is effectively a 185W heater (with a 0.52V drop) and i don't think your current electrical could supply 750A long enough to start having the wire actually become the issue.

But how often are you actually just listening to a full volume sin wave for minutes at a time in the summer heat anyways? So if it was my system and thus taking full responsibility for any decisions based on internet advice..... I would run a 2/0 to EACH amp on the current electrical.

OR, a single 4/0 with the cap bank and an extra battery or two at the back. So hopefully the theoretical 700A that the amps could draw wouldn't be coming across the 15ft 4/0. And again you only have a 320A alternator and single battery upfront, so that seems pretty unlikely you'd be able to supply that current long enough for the 4/0 to be an issue. I'd fuse the 4/0 at like 350A and if that blows then you know you need to rethink the configuration as you're pushing the limits of the cable to the back. But more than likely with typical daily driver usage I'd bet that fuse wouldn't pop. I'd still clamp the line and watch the voltage drop at the amp to see, just in case haha

Also with the electrical at the back, if you did 1/0 3ft runs to the amps from the battery bank, then worst case at 350A they'd become a 75W heater (with a 0.21V drop). And honestly you'd probably be fine like that. But now you have to put a lot of thought to get such short runs of 1/0. The best answer is to just calculate different ideas yourself and get a feel for what level of sketchy you're okay with where.

Thinking back to Meade's setup, i think his 4/0 was coming from his battery bank up to the Orion DC/DC converters, which he had 4 of at 50amp. So he's looking to do 200A, and thus safely within the single 4/0 ampacity charts.

Hope that helps

[revoracing247]

another note on my theoretical rear electrical bank setup vs dual 4/0 from the front.

4/0 15ft: at 350A is a 185W heater. but that's 12.3W/ft of heat dissipation
1/0 3ft: at 350A is a 75W heater. and that comes out to 25W/ft of heat dissipation

I'm not sure i like that 25W/ft number. but i also am not confident on my reference point for heat dissipation per ft on large copper conductors lol I don't have a lot of experience trying to calculate out temp rise in systems like this.

If we could get expected temperature rises from SkyHigh wire at different currents, then we could get a lot better picture of how this system would perform. But again this is just looking at worse case, which you might never even see if you just want to play music and for short periods of time.