Battery in trunk

[Steve885]

My car came with the battery in the trunk . I bought a brand new battery but it won't stay charged..it's grounded to the truck latch receiver that seems to be bolted to the body..does any one know a better place to ground..I noticed the wire from the engine bay is 4 gage and connected to the original batter post.. Let me know if u need more info. Thanks guys

 

[curtis]

You need to run a wire from the Ground on the battery all the way up front to the fender well fire wall etc and then run grounds to the engine trans etc. Mine is from the battery to the trunk floor then daisy chained to the subframe connectors then to the ground next to the ecu then to a nut thats welded to the inter fender well. That nut has a battery post connected to it on the engine side then I have grounds running everywhere. Something else to do is run multiple or a larger wire to the little fuse block on the hot side to the alternator and you can also run a larger wire to the starter. The aftermarket battery box kits are BS. They put a short ground so they don't have to buy 15 feet of extra cable to sell in the kit. Do a search for battery relocation this has been covered before.

put battery +relocation -Re: in the search box this will pull up all posts with battery relocation and none of the replies from other members so faster to read through them.


Now think of the ground like this. You have to have a good ground for current to flow. Shouldn't the neg side have the point of least resistance just like the positive side of things that you added the large cable to. By having bolted down in the trunk all the ground side of things have to flow though a bunch of spot welds to make it up front to the engine. It needs a ground to run and from the factory the ground is just barely adequate anyway and most times is corroded on the ends and into the covering a few inches. If you want to go cheap measure out what you need to use and raid the junkyard for neg cables from the battery to the block, alternator cables etc from the newest cars you can raid. 10 bucks should take care of this if that much. Most junkyards will say you can have it.

 

[turbowop]

IMO, what Curtis suggests is overkill. While that much wire and ground connections is all for good measure, I don't believe it's required.

I have had one single 2awg wire from the battery in my trunk to one of the rear upper shock mounts. I made sure the connection was to bare metal and it's been working fine for a decade now. I've measured resistance with a digital multimeter and it's negligible. It's literally the same from the rear shock mount to any ground point in the engine bay as it is between any other ground point within the engine bay. I can show idle, cruise, and WOT datalogs that show voltage output is perfectly fine, even with AC, in hot weather, etc. Car fires up everytime as well.

Guys have argued with me in the past, but have yet to show me why the overkill method is better when my car works perfectly fine the way it is. I think those little spot welds must be working pretty good.

Now if you have a hoopty rust bucket that's falling apart due to corrosion, you may need to use the overkill method. But then, a car like that most likely needs more than just ground wire upgrades.

 

[EMX5636]

I'm sort of splitting the middle of you guys. I have an HKS grounding kit (got for free so don't hate) that grounds the block/alternator/and engine mounts to the frame up front with clean metal connections. Then the rear just has 2 ground cables, one to the trunk floor, and one to the strut tower (bare as well). I've had a Odyssey race battery and now a 51R (Honda size) Yellow top for the last 4-5 years no problems.

 

[ktmrider]

Quoting Steve001:
My car came with the battery in the trunk . I bought a brand new battery but it won't stay charged..it's grounded to the truck latch receiver that seems to be bolted to the body..does any one know a better place to ground..I noticed the wire from the engine bay is 4 gage and connected to the original batter post.. Let me know if u need more info. Thanks guys

If you're actual problem is a battery drain the ground location/numbers won't cause it. Figure out what circuit is live after turning the key off for that.

On the ground thing new(er) cars love proper grounding. Our OBD1 models are not quite as sensitive to voltage drop ( or increased resistance due to crappy ground points or wire diameter ) however IMO there is no such thing as Too Many or Overkill. Again OBD2 and the latest CANBus electrical systems are more dependent on ground systems but don't leave your car in a lurch doe to bad wiring.

FWIW I buy a spool of 8-gauge wire and a pack of weather resistant connectors then make my own ground harness. Wife's 2009 Pilot was horrible! OEM battery died, found ONE 12-gauge wire from the negative terminal to the front rad support. That's it. And the paint was not removed from the contact point either so the 6mm bolt threads were all that grounded the entire system. Cleaned everything up, ran a few new straps, and the car ran better than ever.

 

[Steve885]

..I went out and bought 20' of ground wire. I'm going to create a few more grounds ..I moved the original one to the shock tower after grinding away some of the paint.. I was able to drive it today a few times,it didn't leave me stranded any ware so I know the alt is working.. But I'm thinking I have a open circuit draining that batt. I'm not sure where to start with that .. Thanks guys for all the help...this is a awesome site!!!!

 

[EMX5636]

If you have access to a digital volt meter that will read amps, just hook it to the battery and pull fuses until the amperage drops. Just be careful because you can pop the fuse in the meter when you first hook it up if it's only 10A and the key or doors are open.

My car had a couple goofy door switches that would leave the dome light on sometimes. Just something to look out for.

 

[theevozero]

There are too many chiefs in the thread. The BEST way to do it is like what Curtis said, with the correct gauge wire on both ground and (fused)power. Also adding a separate charge back wire of the correct gauge with a fuse(close to the battery), to the alternator is the PROPER way to run it in the trunk, in order to have a proper power cycle. Then again, the true proper way is to have it is under the hood closest to all the accessories as possible, like it was designed to be.

Everyone is gonna have there own opinions and comments, but opinions suck! Facts are key. Understand how electricity works and this issue simplifies itself. I heard someone speak of resistance, did you take voltage drop or current into account? If you're running a single wire, your current has to be through the roof, thus heating that wire and eventually losing conductivity.

I was in the same boat when I bought my car. Having charging and starting issue. All problems went away when the battery when back to the front. Simple.

 

[turbowop]

So my post was opinion? /ubbthreads/images/graemlins/roll.gif

No offense to Curtis, but I'm pretty sure his car doesn't even run currently, and hasn't for a long time. He is one of the many JSB's on this site. My car runs, and has since I first purchased it in '98. You want facts? I gave them to you based on my EXPERIENCE with a car that has had the battery in the trunk for well over ten years and has been running perfectly the whole time. So that is Curtis' theory vs. my personal experience regarding the battery in the trunk of a GVR4. Anybody that wants to blow time and money on overkill is welcome to. I just don't feel the need, and I don't exactly half-ass my car. But hey, wtf do I know?

I respect Curtis, I just don't agree with him on battery relocation requirements. But to say my post was opinion is ignorant. It's pretty hard to dispute the FACT that my car has no charging issues.

 

[mitsuturbo]

After exploring battery relocation ideas with this forum, and some of the members even involved in this thread, i decided to use 0AWG ground wire to one of the seatbelt mounts under the back seat. It's non intrusive, it was easy to grind paint away, and i should not have to worry about corrosion or rust. It's a nice fat cable, with a nice clean, large contact patch. I'm not the least bit concerned it won't work properly. My last relocated battery didn't have near as good a ground, and i never encountered any issues because of it.

My battery does die a bit after a couple weeks, and i have to put it on a charger. But that's because i keep the clifford alarm armed 24/7, and the car is sitting in the garage without being driven or run.

Having said all that...

Rather than argue about what's the best way to mount a battery in the trunk, how about addressing the original concern?

OP has a car with the battery in the trunk, and it won't stay charged.

Okay, now let's not assume it's simply because of the location of the battery, or the ground, for that matter. Now that the grounding point has been beaten to death, let's explore some other ideas.

Is the car driven often?
Does it have an aftermarket alarm, or any other potential power sapping devices installed?
Does it discharge even while it's running, or just after it sits for a while?
Do the headlights dim significantly when the heater is turned on full power?
Do the headlights dim when the turn signals are flashing?
Has the charging system been checked, at all? (VatoZone does this for free, as do other parts stores)

 

[theevozero]

I wasn't necessarily pointing the finger at you personally. Just merely pointing out that this simple issue is getting over complicated with EVERYONE's opinion. If you wanna keep it there and KNOW it will never fail, do it as state previously. Your results may vary from others due to unforeseen variables such as rust, broken welds and just plain asshatery. The fact of the matter is that these car were not designed to have the batteies in the trunk, so in order to compensate, by pass the cars body as part of the circuit.

 

[theevozero]

Also, sorry for ignoring your original concern. If you battery won't stay charge, your first obvious culprit would be the battery it's self. If that checks out, you obviously have a parasitic draw. This can be checked with a dvom and a fuse puller. But before you get too in depth, the first thing to do would be to check easy stuff and make sure all your lights are shutting off when the ignition is turned off. Some of the less obvious ones would be the trunk, glove box, sunvisor foot well lights. If you have an aftermarket alarm, I would also try to cut power off to that and see if the problem stops. It could be drawing too much amperage while the vehicle is static.

 

[JNR]

Being it's a unibody, it's not a bad idea to daisy chain (or run a full wire) the ground from rear to front.

I have a batt in the trunk on the VR-4 that "works" with the ground just on the strut brace (iirc), but ideally I want to continue the routing all the way up front. I don't want mystery issues down the road and being the car relies on the ECU so much, a 100% grounded system is essential. Comparing that to my chevelle that also has a batt in the trunk, it has a full frame so it's not as critical to run a wire all the way up, but I do need to pull points off the frame to the engine, body and so on to have things run smoothly and not have any potential headaches down the road. That car is carb'd and has no electronics other than the ignition (and stereo) so I can get away with a simpler approach...If I went to convert it to more modern setup, you can bet I would also ensure good grounds even more so.

No need to go over board, but think about the way electricity works and how thin the metal is on these cars and ask yourself does it really seem like a good idea to let that thin metal do the transmission of ground circuit?

 

[turbowop]

While you guys are at it, you should probably run a 2awg straight to the ECU ground location, for good measure. Even from the factory, all those electrons have to pass from the factory ground location on the front fenderwell, through all those weak little spot welds holding the unibody together, to the ECU ground at the A-pillar. I'm surprised the car even runs from the factory, or that the spot welds hold the unibody together.

This big metal unibody pictured below is probably just about ready to crumble from weak spot welds. And that thin metal...

Pic stolen from broke down's thread.

 

[EHmotorsports]

I agree with Turbowop. the Unibody is still made of mettle and will transfer power just great. thousands of tack welds/spot welds are throughout the car. if it wasn't a good conductor with all those spot welds the car would fall apart before it even hit the road. The problem i see 75% of the time is that the connections people use and how they wire are not quality. good soldering, good wire good connectors MUST be used for anything to operate the way it should for any amount of time.

for the OP
make sure all connections are contacting bare mettle and nothing is loose. have the charging system tested. have battery tested. any parts store will be able to test it for you for free. after all those items are tested and checked to be ok. you need to find the draw on the system. that will consist of but not limited to checking after market gauges,lights,fans,chafed wires, frayed wires,burnt wires, corrosion on connectors/terminals. focus on the wiring to any aftermarket components first and work your way out.

 

[Steve885]

Well I really stirred up things on this one. Thanks so much for all the fact and opinions..so far I moved the ground from the trunk latch and found that the bolt threads holding the latch were originally painted at factory..so I assume this wasn't much of a ground .. I ground off some paint around the shock mount bolt and attached it there . This was on Sunday eve every night after work since then I've gone out and have had no problem starting the car

 

[iceman69510]

I have done numerous battery relocations including race car set ups. On my oldest 510 I originally ran a cable all the way up to the front for the ground (to the trans), but years later borrowed it for the power installation on my GVR4 relocate. I have both grounded in the trunk are area now ( with 4 size). I have only ever had one issue, where I popped the fuse (120 A) in the GVR4 on a 0* morning when the current pull of the starter was great. I have since upped that to 150 A I believe.

One thing I have always done is use fine-strand welding cable for the long runs, as it has greater capacity. I believe I used zero.

 

[boostin4door]

Mine has been in the trunk since 03' with zero issues. 4ga all the way back, with breaker switch. Voltmeter gauge mounted on the box. Battery grounded in the trunk w/2 cables & @ 2 different spots [spare tire studs w/paint removed ofcourse]. Fuel pump housing grounded & 255 Rewired & grounded well. Apexi Voltage/Grounding box under the hood: starter has a extra gound strap, alternator,head , CAS,trans , intake manifold all grounded. And oh yeah my, ARC2 is/has it's ground cable all the way back to the neg battery post.

{Having extra grounds on a 20 yr old Import isn't a bad idea}