hmmm...I'm not so sure I follow your train of thought here. The ground strap is not spec'd for the maximum load through the main fuse (50A on our Ultra's) but the max current with the starter under load. Take a look at the starting circuit on our bikes, notice there is no fuse on the starter? So what is the current draw of the starter under load when you hit the switch? I don't know for sure myself but I do know the CCA on my LiFe battery is around 320A. If I had to guess I'd say I might draw 60-75% or more of that when I hit the starter switch (192-240A). In my case I'm not worried about the ground strap not handling the load (I only have a single 720W RMS amp) but as a guy that has done some serious audio upgrades to his ride YMMV (you have multiple high output amps). What I am worried about is what happens if that ground strap fails? I sure don't want that starter load making it's way back to the battery via my amp ground that's run directly to the battery! Even if I used a heavy gauge amp ground that was able to survive that current load I'm betting the internal circuitry of the amp won't. This is why I'm dead set against running any accessory device ground directly to the battery. It might not be safe under a failure of the main ground strap.

 

I do run multiple amps in my bike. Currently running a Mmats 6150, requires 4g cable and 80a fuse. Also have an SD 3000.1 that calls for 2g wire and 150a fuse. I also utilize an SD 800 that calls for 8g wire and a 40a fuse. Lastly an SD 250 with a 30a fuse.

With the amount of possible draw at any given time, I personally don’t trust the ground strap from the battery to frame to carry the load. While I understand that starter draw is considerably high, it’s only drawn for a very short time (seconds at best).

If you actually read Arc Motos manual, they even recommend grounding the 720 directly to the battery in a motorcycle application. I would choose to follow the manufacturer’s recommendations in most cases.

 

We've been down this road before. I'm not here to change you or anyone's mind about how they have already run their amp ground(s). I just want to make sure that someone with no knowledge that comes along asking the question of where to ground their amp (or anything aftermarket for that matter) doesn't get the idea that the "right", or only, place is the negative post on the battery. IMO (and many others a lot smarter than I) there is a safer and equally good, if not better, ground available through the frame.

The damage caused by an inadvertent or accidental ground path is pretty much instantaneous, "seconds at best" is a very long time with high current.

Regardless of the potential for problems, Arc Moto isn't the only company out there making that same guidance and I don't understand why. I know of at least 2 good reasons why you should not do it, I'd really love to know their technical justification(s). Perhaps I might learn something.

If I didn't think my ground strap could carry the required load I would improve the strap. I would never attach the ground to the battery directly.

Some time back I challenged Teedoff to simulate a failed ground strap by removing the ground strap, leaving the amp ground attached to the battery, and hitting the starter. AFAIK he never took me up on that and I don't blame him. Even though the chances are good that everything would be fine you'd be a fool to try that intentionally, it'd be like playing Russian Roulette. Why would you leave yourself open to the chance of it happening accidentally? It just makes no sense to me knowing what I know and with my experience with DC power systems.

 

I’m not trying to convince you to change your process either. If it works for you, roll with it. I’m just rolling what has historically worked for me. I am certainly no electrical engineer by any stretch, but I assume that the designers and engineers at electronics companies are. If recommendations or instructions from companies like Arc Audio and Rockford Fosgate say to do it, I put my confidence in their statements.

My original position on this topic actually began with several on the forums expounding on grounding their amps in the fairing. I absolutely disagree with that process as the path to ground is dependent on the connection made through the neck, triple trees and head bearing.

I only advocate for what has worked for me over the years. If your process works for you, have at it. I’m not arguing with you, just debating the available options. To me, conversation leads to learning. I have learned a lot on this forum over the years. I’m thankful for everyone that contributes to educating on this hobby of ours.

I will say I’d be willing to try your experiment of disconnecting the ground strap, but I don’t see a reason to do so. I don’t believe anyone is advocating for that practice. I think folks are looking for adding stability to grounding, not weakening its practice. Again, I’m no electrical engineer but IMHO the ground strap is there predominantly for the starter. The starter has no other path to ground, but the chassis floating ground. It is not hard wired back to the battery.

 

Nope, I'm sure most of us are running some kind of distribution block. I run 4 gauge power and ground directly from the battery to distribution blocks in the fairing, 8 gauge to the amps from their.
Getting ready to upgrade to 2 gauge from the battery to the fairing on this winters upgrades.

 

It's no secret the majority of us have had great success grounding directly to the battery. It is quite often recommended by amp manufacturers. I would guess grounding to the battery would suffice in order to keep your warranty in tact, as per manufacturer. That being said, for high wattage and multiple amp systems I do see recommendations from respected install shops to upgrade the main ground strap as a precaution. I also see recommendations to run to the chassis ground post on the ground strap vs the battery on multiple amp systems, if for no other reason, than to limit the octopus of cables tied into the battery.
personally I connect directly to the battery, but am considering upgrading the ground strap, and connecting my ground at that particular chassis ground this winter along with my amp upgrades. I feel it is cheap insurance with a SD 2400.4, a SD 1600.1, and a 400.4 going into the bike. For the average 1 or 2 small amp systems, you would be fine with the factory ground, and either connecting to the battery or the main chassis ground.
I wouldn't just ground any where in the fairing.That has long since been ruled out as a poor option.