big 3 upgrade

I have a 2004 Toyota Siena LE. I put an amplified sub to fill the low end spectrum of music. 600W supposedly. Now, I don't think I need a big 3 upgrade, but I have some power cable (Gauge 4 KnuKonceptz) left, so i thought I would play a little bit more. The issue I came across is the one of the ground. I found the original grounding cable from the negative of the battery attached under the battery. I thought this would be a chassis ground, but I found the following link on youtube, where the car audio guy grounds to a similar point and says it is the engine block ground. That would mean grounding to chassis somewhere else (he grounds to the strut column which is inaccessible in my vehicle, but I can find a different spot). Please look at the pic I took, the red arrow marks the spot in question and let me know: is this considered a ground from the battery negative to an engine block or to a chassis? Here is the link to the video on YouTube: http://www.youtube.com/watch?v=p82xRzCr-lc and this is my photo: http://www.flickr.com/photos/118530903@N07/12732867534/ Now, if this is a chassis ground point, would this bolt be a good grounding point to an engine block? http://www.flickr.com/photos/118530903@N07/12732630373/ Thank you for all your input.

It must be my week for the big 3. At least that youtube is better than the other crap I've just seen, but I do have a few comments: - do not touch car metal when disconnecting the battery +12V. That's true if the battery -ve is still connected, but that -ve should NEVER be connected when fitting or removing the +12V terminals (beware of secondary batteries) and hence IMO that warning is misstated. - the 0G from the alternator has no effect except as follows: Fat cable is important if it's a single-wire alternator (D+) but that looks like it is a 2 or more wire type - ie, it has a Sense connection to the battery +12V. Hence voltage drops across the alternator to battery cable have no impact unless that cable gets too warm or melts, or you are powering things direct from the alternator (which may not handle the higher voltage) or the alternator is pushing its highest output (at that RPM) and you want that extra bit of power (ie, less i2R losses). I'd rather a smaller more flexible cable with copious capacity - ie, maybe a 0.1-0.2V drop at most during full output current. Otherwise the video seems ok in principle - ie, you want to ground to chassis (frame) rather than body panels. I have concerns about how those leads are bolted in, and I'd prefer dedicated bolts etc (ie, only one GND or only GNDs - not other mechanical components dependent on bolt torques or not having angle grinders scar threads), but your mounting points seem ok. 600W is only ~60A - it's not a huge system. The major OEM GND is from batt- to the engine block because the starter-motor has the highest current demand (excluding 400A catalytic converters etc). That is usually sufficient for audio systems unless the alternator has a similar current rating (noting that starters are short term and therefore that GND could be underrated for full time use). Some vehicles might go from the batt- to the chassis and then to the engineblock but most seem to have batt- to block and batt- to chassis ie, 2 cables from the batt- terminal. I usually add an engine to chassis GND under the engine - eg, from unused spare block threads else engine mounts to a nearby chassis point. That's usually the shortest and subject to least vibration and heat, hence more reliable etc. And both should be able to use substantial bolts - ie, fatter than turret bolts etc. It also means a lower GND voltage because of its lower mounting. (Just kidding re that last sentence.) But the wiring order shouldn't matter - ie, batt- split to block & chassis or batt- to block to chassis to batt- to chassis to block. If they are all copiously fat enough, there should be negligible voltage drop and that's the point of the big 3. Note that those two cables ground THREE things together. One simple improvement is the add a third cable to the missing section. EG - my block to chassis adds redundancy and lowers the resistance of my OEM split batt- to block & chassis wiring. (It also boosts the batt- to chassis from its thin cable to the fatness of the batt- to block to chassis cabling.) I'm not sure if that answers your question?     Incidentally the following is NOT how to do it... Admittedly that's not for audio but (believe it or not!) improved engine performance! That's courtesy of the NicoClub as discussed on mp3car's Grounding kit in cars.

Oldspark, thank you for exhaustive explanation. When you say my grounding points seem ok do you mean that the one in the first photo is to the chassis and I should go with the other one directly to the engine (second photo)?

As I say, battery -ve to engine block (starter motor) is usually the most important and biggest OEM ground. But there is no absolutely correct way - it can go batt- to chassis to block, but usually is batt- direct to block so it does not depend on any intermediate connection. Some go batt- to block to chassis so that if the batt- to block fails, they have no chassis GND and hence can't engage the starter and hence can't melt throttle/choke/speedo cables, sensor grounds, body mounted (alternator) regulator ground wires, etc. Of course that is rendered useless if there is any other substantial batt- to chassis GND path. I prefer to double up on block to chassis GNDs (redundancy) and include a batt- to chassis (plus batt- to block) GNDs to avoid the above meltings and disasters.    From what I can see your arrowed ground points look ok. If you have bigger bolts lower on the block or chassis, use them instead - or as well. In a way it would seem strange to use bolts of equal or smaller diameter than its attached cables (because bolts have lower electrical conductivity than copper) but that assumes the bolt is doing all the conducting or that the bolt itself is not a catastrophic fusible link (just as lead battery terminals can be).

OK, thank you. I will try it and will post the results.