headlights dimming no voltage drop

I used 1/0 guage wire for my big 3.that was with a 500watt rms as well.Overkill.. maybe i didnt need that big but for future upgrades that i have done it sure has paid off-A vision without a plan is just a hallucination-

IMO you can never have "too thick" copper when low resistance is desired. Though that is from the lowest-resistance POV - not necessarily an economic or practicable POV. So what if I use 4-times the "required" gauge (wire size) and thereby quarter my voltage drop along it?    What's good about it? 1/4 the voltage drop. 1/4 the power loss. What's bad about it? Weight (acceleration, fuel). Cost. Remember that wire ratings are often for their SAFE current capacity (for given conductor, sheathing, bundling, etc) else what comeone considers reasonable heating or maybe an acceptable voltage drop (per length). They are not rated the lowest voltage drop in your application wrt performance gain, cost, relative effectiveness etc. (A 0.1V loss for halogen lamps may be negligible. The same loss for audio can be (apparently) quite significant.) Alas I tend to design by voltage drop; then check I do not exceed cable ratings. And don't forget the ground paths - in particular engine to body/chassis - especially with high(er) current alternators. Your 160A alternator at full output will have 1.5 times the (eg) ground-cable voltage drop compared to 110A full output. That engine-body ground is shared by MOST circuits in your vehicle, so doubling or quadrupling its conductor area will halve or quarter its loss for most circuits. [ Viz: If the ground and power cables WERE the same gauge & length, that means a 25% or 37% voltage drop reduction in that alternator-load cabling (ignoring fuses, connectors, etc). Do the +12V power cable as well, and it's a 50% or 75% reduction. ] The same applies to the engine-battery or battery-body/chassis ground when the battery supplies the load. [ Ideally batteries do not power vehicle loads except when not charging (battery recharging and slow reacting alternators excepted). ]     Alas many overlook the grounds when upgrading the hot cables (the so-called "upper bling" lol). Furthermore - excluding possible ground-loop noise issues and (AFAIK) single-wire alternators - extra ground cables/straps should be added to protect equipment should one or more grounds go high-resistance. This is not uncommon - corrosion, dirt, heat, vibration, etc all conspire to break the grounds so that alternator voltage will increase and blow your equipment to make someone rich(er).   [ This probably does NOT occur with D+ type single-wire alternators. ] [ Heard of mass on-board equipment destruction since nuclear testing ceased? Has it been due to a bad alternator to battery ground? ] Extra engine/gearbox to body grounding is hence also good insurance, as is the occasional checking of each connections resistance or loosen/re-tighten else disassembly & cleaning to overcome hi-resistance joints. I may even triangulate the grounding - ie, engine to body, body to battery-, plus the extra battery- to engine, though that's usually only on standard setups without redundant engine-body & body-battery- cabling. And FYI - the Big-3 (or 4) upgrade I have seen on 12volt describe ADDING extra cabling - not replacing it. This supports redundancy as well as NOT interfering with standard wiring (hence should not void vehicle & equipment warranties etc).    As for vehicles with chassis-body constructions (as opposed to monocoque construction).... But enough for now.... It was merely my opinion - which as you know, you ALL have a right to!   

Oldspark with your last post and from the best of your knowledge you think finishing up the Big 3 or possibly the Big 4 will fix my problem ?2003 Modded Mustang GT

I'm going to say YES(although it is an assumption but...)...You need to do it anyway...You have already upgraded the alt wire...Although that may need to be increased as well...Someone once said..."its like sucking a golfball through a garden hose"...Always makes me laugh...Kirchoffs law...The sum entering must equal the sum leaving... or ...what you do on one side must be done on the other...M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Wot?! You expect ME to READ something else? What the...! Yes - DEFINITELY! Especially if it's "finishing it up". If you've done some, do it all. Besides, when is Tommy wrong! The "Big 3" was something I never heard of until this site. But it's exactly what I figured out years ago, and tried to explain to others, albeit not so elegantly. The Big-3 sounds more important yet more concise than main "Power Distribution" etc. It doesn't matter what you do, if the power route (Big 3 etc) is limited, the whole system is. Sure, you can throw on a bigger battery and alternator, but that also means bigger losses. So why not MINIMISE the losses first, THEN increase the size of the system. You probably have to increase the distribution size anyhow AFTER you increase the power source(s), so why not do it first BEFORE you start a fire. The BONUS is that you might find it solves your problems so you don't need a bigger alternator or battery!    (Is it akin to upgrading brakes BEFORE the more powerful engine? The bonus is - when racing - the later braking probably gains more than a better engine. It is certainly cheaper, and it may be enough to win.) My previous reply's ramble merely paraphrased the Big 3. I was trying to highlight the potential (pun intended) big simple gains - though that's like that battery reliability - you aren't so much increasing voltage, but rather halving voltage losses on certain sections. Some time ago I was trying to get someone to measure voltage drops across each path segment in order to reduce his large 2V drop. Alas he still thought a bigger battery or alternator was the solution. It wasn't you... Nah(?!!). [ I don't remember the detail of your earlier thread, but I recall thinking your 13.8-ish volts was uncomfortably low; ok, but low. But it seemed stable, hence not "the" problem. And if it was a 2 or 3 wire alternator, it could be tricked into a higher output voltage. It was probably just a low-set regulator voltage. ] FYI - I had a similar problem. My rear-tray mounted aux battery had a largish voltage drop from the front battery/alternator considering it would only have been charging (10-20A?) and used heavy telco DC cable - plus 2 circuit breakers, relay, Anderson Connectors etc. I found a 1/2 Volt drop between the main battery +12V and the first 50A breaker - a distance of about 4 inches! I replaced the intercon-cable with a new one. Much better! I don't know what caused the 1/2V drop - maybe corrosion between the crimped eyelet ends & the copper - it wasn't obvious and I didn't care (for a once off) - I just eliminated a 0.5V drop between 2 batteries. (That leads to undercharging of the aux battery and hence premature failure.) Yet again I have managed to expand a little on the reply of "YES". But hopefully I have imparted some experience, confirmed the brilliance and wisdom of the others hereon, and maybe paraphrased again to clarify the fog. Otherwise take it as a "bash the info in" exercise. If you don't do it, we'll bash you into submission. Maybe not physically, but we will keep bashing our keyboards.   (Eh Tommy?) Just pretend to "see the light" or cooperate - don't let your ego fight it. As a wise one once said... "Resistance is Futile". (I prefer to paraphrase that - "Resistance is a Voltage Drop".) For some things, accepting and doing not only keeps you out of hospital, but after observing the effects, the explanation falls into place. Of course, maybe everyone else is wrong (that's what I find so different being here - major agreements; else education etc), but hence my techno-ramble to empower understanding else contra-discussions etc. (I like finding I'm wrong.) And in your case, with the extra voltage and other things NOT dipping, the dipping headlights strongly suggests the Big 3, else some other "shared" power path. It might be a slow-reacting alternator or low voltage/capacity highly sulphated battery (from previous "under" charging??), but let's eliminate the common & cheapest cause. The Big-3 is rarely wasted anyhow - it always brings some improvement.... BTW - I liked your asking me "from the best of your knowledge". It worries me when I'm looked upon as some experienced expert etc. Whilst maybe conceptual and capable, I lack the hands-on experience of the other contributor here. I demonstrated that this morning with my ignorant questioning of a 24V starter in a 12V motorcycle. Sometimes I can be way off (whether the technology mentioned, or just way off this planet i general), but that's where others are good at correcting, else sometimes confirming (aka - phew!).) And "the best of my knowledge" reminds me of that legal out "to the best of my ability". lol Cheers, P. PS - YES!

I know the Battery Warehouse I use always suggest a lead to lead(thats lead like what blocks x-ray's) connection(Deka/East Penn Manufacturing)...Ive only seen lead connectors with factory replacements though...But have always found then to be big enough...Not sure if it will fit all the wires in your case but there only about $2-$5...And could be a  factor...!M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

"Military" Battery TerminalThe one on the bottom looks like a GOOD size one...Just some examples of the lead/some are brass coated...etc...M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Alway's love your posts oldspark...!!! (bash a keyboard...nah...)M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Ha! YOU love MY posts! You have no idea... not so much that I get a kick plus "experience" from yours, but the support else acceptance & challenge etc I find here. Where are all the tall poppie killers? Maybe like dog invented Jap bikes to keep dikheads off Harleys, dog invented my former (local) involvements to keep DHs of these and similar forums! [ FTR - I love Jap bikes - but it's an old joke from before Harleys became "trendy" - I guess we used to have insecure Harley riders (lol). It's also a joke I paraphrased into Australia & USA, but that one has certainly come home to roost. Bluddy Karma! And there are certainly some amazing Aussies here, but I can understand our reputation for bashing tall poppies. ] Back to work... Battery terminals - how ironic. I found some excellent "satin forged" terminals that were made in USA, were a work of art, and cost little more than primitive alternatives.... VIZ: Not that pic does them justice, but other pics I found as at projecta.com.au/catalogue/cid/50/asset_id/80 weren't suitable.... And I think mine were "PT" series??? But what I loved was its dual auxiliaries, various main cable sizes (gauge ranges) as well as rugged construction (though better replacement bolts may be useful). And they looked great - satin or brass plated (as if I'm cosmetic!). Alas no multi-taps in the negative terminals that I could find. So why the irony? Because after eons without these saviours, within one year of fitting them (and I bought several spares for other vehicles!!), I decided to modernise my electrics and use a 3 flink battery-terminal mounted box (flink = fuse-link)... viz: And Musty, er, Sir Mustang - I'm not sure what you mean by the "aux power supply" beside the battery.... Maybe it's a CAPACITOR - I read somewhere that they "create" power... Though I'll assume its some charger or cold-climate plugin etc (no - we don't have sump or coolant heaters here, nor washer water heaters etc. But we do have electronic kangaroo repellers - albethey unfortunately not as effective as the shark repellers, nor poppy killers). Thanks Mustang. Definitely let us know. I wanna hear the good news. Even though I expect it, its nice to know. After all, it might just be....