2nd Battery charging cable size

F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
7
0
Hello all! I am installing a 5kW sub amp w/two 10s, w/an extra deep cycle battery. I have a concern...

If my sub amp requires two 0/2 positive leads and two 2/0 negative leads to my secondary battery, do I need two 2/0 positive leads between both batteries (and battery isolator) and two 2/0 ground/chassis connections on each battery, or can the charging cable for the secondary battery be just big enough to charge the battery? I don't want to bottleneck my system. Any and all help is greatly appreciated! Thank you!!! I don't want a car-B-q!
 

hispls

CarAudio.com Veteran
5,000+ posts
10+ year member
Sep 10, 2009
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I hope this isn't any kind of legit 5K amp as only 1 additional battery isn't going to cut it.
 

F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
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  • #4
I hope this isn't any kind of legit 5K amp as only 1 additional battery isn't going to cut it.
It is Mr. MusicMan new compact 5kW Amp. The builder said I wouldnt even need an additional battery.
 

F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
7
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  • #5
Would be way better off doing an alternator upgrade first. Which amp do you have?
MrMusicMan mini 5kW
Would be way better off doing an alternator upgrade first. Which amp do you have?
 

some dude

CarAudio.com Regular
Sep 7, 2020
113
46
Quick YouTube search showed a 3.8k doing 4200 watts at 1ohm. Looks like a legit amp. I've never heard of the brand.


What are you going to wire your subs at Ohm-wise?
That effects your electrical road map.
 

djdilliodon!

CarAudio.com Well Known
Nov 12, 2021
334
239
I was looking at a SkyHigh 370A H/O alternator build for older Ford model. I guess that's where my next $1k is going!
i have no experience with that amp but let’s say it’s a true 5k rms, you will 1000% need a new alternator cause the stock one won’t even be close to cutting it! An amp that does 5k rms with decent efficiency will pull around 450 amps plus by itself of current playing tones. With music it would pull around 350 ish amps all assuming you are playing it at high levels. You will need an upgraded alternator, upgraded battery in the factory location, and at least 1 extra battery added. The actual battery setup to go with will depend on how much run time you want them to have. Of course those of us with limited space can’t just be throwing 4 batteries in the back so we must come up with the best compromise. You will also want to run all 1/0ga ofc wire at the min.
 

metalheadjoe

Unapologetic prick
10+ year member
Oct 21, 2007
1,257
613
Hello all! I am installing a 5kW sub amp w/two 10s, w/an extra deep cycle battery. I have a concern...

If my sub amp requires two 0/2 positive leads and two 2/0 negative leads to my secondary battery, do I need two 2/0 positive leads between both batteries (and battery isolator) and two 2/0 ground/chassis connections on each battery, or can the charging cable for the secondary battery be just big enough to charge the battery? I don't want to bottleneck my system. Any and all help is greatly appreciated! Thank you!!! I don't want a car-B-q!
Since no one else answered the question... The highest current flow is between the rear battery and the amp, so double runs there is a good idea. Sizing between the front and rear batteries depends on current capacity of each battery and alternator output. For a stock alternator and typical front battery, a single run will be fine. You can never have too much conductivity, so more wire is always better.

In my vehicle, I have two runs of 1/0 from the rear battery to the amp and one run of 1/0 from the front battery to the rear battery, and it works great. I would start with that. You can always add more if needed.

Don't bother with a battery isolator unless you plan on running it long with the vehicle off. They are meant to prevent you from draining your starting battery and being stranded.
 
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F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
7
0
  • Thread Starter Thread Starter
  • #10
Quick YouTube search showed a 3.8k doing 4200 watts at 1ohm. Looks like a legit amp. I've never heard of the brand.


What are you going to wire your subs at Ohm-wise?
That effects your electrical road map.
I'm wiring 4ohms.
 

F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
7
0
  • Thread Starter Thread Starter
  • #11
i have no experience with that amp but let’s say it’s a true 5k rms, you will 1000% need a new alternator cause the stock one won’t even be close to cutting it! An amp that does 5k rms with decent efficiency will pull around 450 amps plus by itself of current playing tones. With music it would pull around 350 ish amps all assuming you are playing it at high levels. You will need an upgraded alternator, upgraded battery in the factory location, and at least 1 extra battery added. The actual battery setup to go with will depend on how much run time you want them to have. Of course those of us with limited space can’t just be throwing 4 batteries in the back so we must come up with the best compromise. You will also want to run all 1/0ga ofc wire at the min.
Thank you for your input. I seriously appreciate it! 🙏
 

F-137 Kong Ramch

CarAudio.com Newbie
Jun 23, 2021
7
0
  • Thread Starter Thread Starter
  • #12
Since no one else answered the question... The highest current flow is between the rear battery and the amp, so double runs there is a good idea. Sizing between the front and rear batteries depends on current capacity of each battery and alternator output. For a stock alternator and typical front battery, a single run will be fine. You can never have too much conductivity, so more wire is always better.

In my vehicle, I have two runs of 1/0 from the rear battery to the amp and one run of 1/0 from the front battery to the rear battery, and it works great. I would start with that. You can always add more if needed.

Don't bother with a battery isolator unless you plan on running it long with the vehicle off. They are meant to prevent you from draining your starting battery and being stranded.
This is what I was hoping. Thank you very much for your detailed response. I appreciate it!
 

some dude

CarAudio.com Regular
Sep 7, 2020
113
46
So at 4 ohms your amp is putting out around 1200 watts?
I'm thinking 1 run of 1/0 gauge OFC would be more than enough. You can use 4 gauge OFC and be fine. Someone chime in to confirm.
 

metalheadjoe

Unapologetic prick
10+ year member
Oct 21, 2007
1,257
613
I'm wiring 4ohms.
Why not wire to one ohm? You could achieve the same output with a smaller amp wired to one ohm. If you want the big amp for future planning, you can still wire your subs to one ohm and turn down the gain to a level your subs can handle. There are no drawbacks to wiring to the lowest load your amp can handle (others disagree, but I've yet to hear a valid counterargument).
 

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