Battery relocation ground...
 

Hey everyone-

So I put my battery box in... Best I could get for a ground from anywhere on the chassis to any other point on the chassis was 0.2 ohms.... So I chose the strut tower; and got 0.2 ohms from the negative terminal to that & anywhere I could get to on the chassis.

http://farm4.staticflickr.com/3814/8...f3469c_b_d.jpg

Just wondering if 0.2 ohms is okay... I've never done a battery relocation before.

Thanks!

Mikle

0.2 ohms is plenty. Technically, the continuity check doesn't mean much here (Testing a piece of headphone wiring will give you 0.2 ohms). In this case, it's all about using the path of least resistance. You'll want to connect to a pre-existing bolt in the vehicle frame. Do NOT drill holes in the frame; if necessary, tap a pre-existing hole. Remember to use a negative/ground cable wire size equal to, or larger than, your positive cable wire size. To ensure a solid electrical connection, remove any paint or rust from your frame electrical connection point. Best of luck to ya!

I used the bolt that the spare tire uses to get bolted down

Best place for it. Out of sight and the way...

Sounds good. Thanks guys! You can see it in the picture connected to the tower brace...

IIRC both wires are 1 or 0-gauge. Although I tested the spare tire bolt hole, I elected not to put it there because I still may throw a doughnut in there in case of pinch ;)

AAA or towing through insurance is a spare tireless man's best friend...

^^Got roadside service. But the thought of sitting on the side of the road in my baby waiting on some dude to change a tire w/no appreciation for what I have into this makes me cringe :D

Here is another question regarding the power wire... I'd like to run it thru the RH upper frame rail; and have it pop out & enter the bay behind the coolant reservoir. However, there is the bundle running down the strut tower that goes to the ECU harness... I know for stereos, running the remote line too close to the power can cause weird shit... However- Is it okay to run the main power cable next to other engine bay wiring?

I'd probably keep that thing away from any wires, especially anything shielded, just to be on the safe side, ya know? I'm not trying to answer this as a fact, but that's just what I would do to eliminate any future gremlins. You know the ones that you would look back on after 6 months of tearing shit apart with a face palm and a pack of smokes.

If it's properly insulated wire you shouldn't have to worry. Alot of newer cars for space run a 6-8 gauge battery positive wire next to the normal wiring loom/ high/low CAN systems for interior use.

what about running it through the firewall and down the frame rail. safer placement in a wreck.

Mike on my sr I ran it along the right side, out the stock body hole all the way to the right of the firewall, up my wheel well and back down under my headlight. It's doesn't run anywhere in the bay. My engine harness runs along that as well. Just make sure a fuse is in the back with the battery. Weather along the wheel well or frame rail in the bay, a 240 will not hold up in a wreck and that wire will get piched real quick

I ran it thru the body, up the wheel well, thru the frame rail and into the bay. I don't need a fuse inline because I tied it into the OEM wiring location; so it is still protected by the main power fuse. Also, it is 0-gauge & completely immobile everywhere it could possibly be susceptible to chaffing.

http://farm8.staticflickr.com/7429/8...3f68f1_c_d.jpg

http://farm8.staticflickr.com/7426/8...0cffc1_c_d.jpg

http://farm8.staticflickr.com/7450/8...131a20_c_d.jpg

http://farm3.staticflickr.com/2887/8...f323b2_c_d.jpg

Done deal. Car powered up nicely. Very much appreciate the inputs, guys!

BTW, in a front-end collision, pinching the power wire would be the least of my wories ;)

Nice.. Just curious why more weight on the driver side?

Same reason I added 20lbs of sound deadening, kept the factory A/C system & everything else. Also, I was able to run the vent using the factory drain hole behind the LH rear tire ;)

BUT- I already gained a bit by moving it to the trunk. I don't drift; and I will never realistically push it on the touge/circuit/backroads hard enough for this to be a problem.

AND... This way, I have very easy access to the fuel pump carrier without having to struggle with the carpet. Trying to balance aesthetichs, performance & maintenance-friendliness~

Mike, I would run the power wire either inside the cabin and do a through firewall connection for the battery, or run it like you wanted too, through the frame rail. If it is outside of the car and not protected inside the frame rail there is a risk of it getting damaged or hooked on something you may run over in the road and potentially hurting something. Just something to think about. I have an extra through firewall/bulkhead mount if you want it. I'll shoot you some pictures of how mine turned out.

Bad idea. The spare tire hold down is only attached with a few spot welds. This is not a place any ground should be attached to.

Work? Yes.
Recommended? Absolutely not.

A Pro Audio installer friend of mine made me move my rear audio ground off this location. He said "Spot welds make 5hitty grounds."

Pretty sure I'm good. It comes off the battery, thru the cabin, out of the fenderwell grommet; and thru the frame rail all the way into the bay. The exposed section in that one pic is mega-immobile; and protected by the other loom & fender brace. I re-read my other post... Prolly could've been a bit more clear lol

No offense, but the entire car is spot welded together and seam sealer fills the cracks...

Mike- you may want to throw a 100amp breaker on it. Even if you blow a fuse to protect the factory wiring, you'll still have power up to that point. God forbid in an accident if that wire gets cut and you have flammable fluids leaking, you have no way to kill power and things could go up in smoke. It's a safety precaution that's all. Looks good though, I didn't see your post as I was writing mine earlier.

^^Truth... Added a bunch of seam sealer to the bay while everything was apart... Amazing how many 'holes' are left after the manufacturing process is complete=)

I will add a circuit breaker to the list.

^this is what I was talking about. No one likes my input :( lol

Uh, so what? I am referring to the spot welds on that part specifically, and them being insufficient for use as a ground.

Dev71893- Actually it was a good thought- just not sure you realized that my system is tied to the OEM fuse... and I didn't contemplate a CB until jr_ss elaborated a bit.

Even so, a CB will be on the 'to do' list for after she gets tuned.

^^Dude, I tested every point imaginable in search of a decent ground... The spare tire post had the same 0.2ohms as everytihng else- Spot welds or not it is fine for use as a ground. Whoever you are getting your info from was probably basing what they told you from experience dealing with typical S13 rusted out spare tire bays where the spot welds there are falling apart. Your original post said that it was "not good because it is only held in place by a few spot welds." Using that logic, nowhere on the car is a good ground... BTW- the multimeter doesn't lie ;)

If there is solid metal-to-metal contact & continuity to anywhere else on the chassis; it perfect acceptable to use. My choice to not use it had nothing to do with acceptability as a ground and everything to do with keeping the install clean.

I see you don't read my build as much as you say :P CB is aaaaaaawesome. I'm piped into the factory wiring too, but not disconnecting the battery to do something makes it incredibly worth it. Push the release, car is cold. Done.

And I just hit the spare tire spot with the dremel to bring out ze shiny metal, grounds just fine.

^^Yes I fucking do haha!!!

70-something pages of build, random pics, conversations & videos; I can only remember so much~

I asked my audio guy and he said, and I am quoting "No one serious in any audio competition would EVER use that for a ground - what does that tell you?" Sorry, I am listening to his 25 years in auto electronics experience over yours.

Anything bolted to the frame (like my audio is now) is not relying on spot welds. Over and out.

Easy there, killer. First of all, I'm not planning on ever getting into audio competitions. Second of all, anywhere on a 240 you can think of is only held together with spot welds (which is why serious racers go back thru and add stitch welds to the entire structure)... Third- I have a degree in Avionics Systems technology, an FCC certification & 20+yrs of aircraft electronics systems maintenance under my belt; so I am not [completely] talking out of my ass. Even so, I strongly encourage you to listen to those whose experience you know & trust vs. a bunch of faceless Joe Schmos like us on a forum=)

Now, with that said: What I personally got from your guy's quote is that he probably (and very rightly so) knows more often than not that the spare tire bay in 20yr old cars is usually in pretty sad shape... or the underbody below it is- in which case, the spot welds there will vibrate loose when subjected to a billion watts of BOOM BOOM BOOM from a competition stereo setup. Most of us will never have competition stereo systems installed; and therefore would never really need to consider this when choosing a place to ground the battery (or our non-competition amps lol).

My only concern was 0.2ohms being good enough for a ground... but this turned out to be a fun discussion... and thanks to y'all I am convinced to go ahead and add a CB to the system.

Thanks again everyone :)

Mike

hey guys the guys that did my 1uz swap in my s14 relocated my battery to the trunk according to them car gets spark and fuel and cranks but wont turn on voltage drops from 12v to 4v when cranking theyre using my trunk latch as a ground from the battery , could that be my problem?

Jesus holy Batman bump. I had to re-read this whole post to make sure my dumbass didn't say anything dumb 5 years ago [emoji23]. As far as your issue, if it was fine before the relocation, then that's probably what caused your no start. You said voltage is around 4v, where are they taking a reading? More importantly have they done voltage drop testing to pinpoint where the loss is? Also no I wouldn't ground to the trunk latch, I'd ground to the rear strut tower. What gauge of wire was used? What size battery? There's a lot that could've been done wrong. Start with moving the ground to a better spot and voltage drop test from there.

Sent from my SM-G955U using Tapatalk

thanks for the reply, i barely got the car towed back from the shop that did the swap for me they said they tested the battery and it was fine . im going to try to get a better ground hopefully that helps looks like 2 guage but i could be wrong looks decently thick , and they also put a breaker switch that switches off when the cable gets hott and yea voltage drops down from 12v down to 4v when trying to crank