12v DC "Ring Main"?

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   I have 4 amps and 2 batteries in my VW T4, along with various other bits n stuff. The 2 batteries are on opposite side of the rear, each in a compartment above a wheel arch. I'm just about to install a couple of larger monoblock amps, and it's getting to the point where star wiring with heavy gauge power cable isn't making sense to me. Is there any problem with me making a ring joining everything with a 100a blister fuse between the main players?

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Lucasdude Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 16 March 2013 Location: London Status: Offline Points: 821	Post Options Post Reply Quote Lucasdude Report Post Thanks(0) Quote Reply Topic: 12v DC "Ring Main"? Posted: 22 March 2022 at 6:52pm
	I have 4 amps and 2 batteries in my VW T4, along with various other bits n stuff. The 2 batteries are on opposite side of the rear, each in a compartment above a wheel arch. I'm just about to install a couple of larger monoblock amps, and it's getting to the point where star wiring with heavy gauge power cable isn't making sense to me. Is there any problem with me making a ring joining everything with a 100a blister fuse between the main players?

DJ-Dulux Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 24 August 2009 Location: Kenilworth, UK Status: Offline Points: 378	Post Options Post Reply Quote DJ-Dulux Report Post Thanks(0) Quote Reply Posted: 22 March 2022 at 7:19pm
	Volt drop is the thing you got to watch, in principle a ring is fine if properly fused etc, main outgoing and then sub fuses as you step down in cable size. But, the cable size will start to get large pretty quick. I did a 12V ring in a lab, 70mm2 cable around, had to buy crimps, crimp tools etc, 100A fuse holder and then a way to split off the ring to other devices, got expensive pretty quick to do it right. Dupe...
	Dupe...

Lucasdude Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 16 March 2013 Location: London Status: Offline Points: 821	Post Options Post Reply Quote Lucasdude Report Post Thanks(0) Quote Reply Posted: 22 March 2022 at 7:27pm
	Thanks Dulux. I already have all the crimps and fuse holders etc. The system is currently (sic) wired with 16mm cable from the alternator to the first battery, then 1.5m across to the second battery and also to the 1kw sub amp. So really all I will be doing is continuing the same 16mm cable on to the 2 new 500w mono amps with 100a blister fuses between them, then back to the first battery. The alternator is 120a, and every cable has a 100a fuse at either end.