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vtluu
07-13-2005, 09:49 AM
I'm bored and tapped for cash so I'm going to do an inexpensive mod: move my Odyssey battery to the trunk. Could use a couple tips though:
- Is 4-gauge wire thick enough or should I use 2? Power draw would be basically same as for a stock Evo (plus the Pioneer AVIC-N1 nav system);
- What capacity fuse? And it should be located near the battery, right?

smack
07-13-2005, 12:38 PM
4 gauge shoud be fine. i used to use that in some of the big amp systems way back when
and that was drawing way more amperage than the car does. the zenons probably have
the biggest constant draw(you might want to check the fuse for the headlights just to be safe)
and the starter having the biggest short spike. i would run the same fuse values that are
under the plastic terminal cap on the stock part and yes you NEED to run the fuse right next to the battery.

if the wire grounds out and there is no fuse to cut power the cable gets red hot,
will melt off the insulation and you can burn the car down(i've seen it happen to a whole interior)

also make sure the thing is mounted in a real box or tray. there is a lot of weight getting
thrown around once you get to the track and you don't want that thing coming loose on you.

vtluu
07-13-2005, 12:49 PM
Thanks Sean; more ponderings:
- 15' of 2-gauge copper wiring weighs a bit over 3 lbs
- 15' of 1-gauge aluminum wiring weights about 1 lb

(Aluminum is a poorer conductor so you need to go 1 gauge thicker.) So it seems that since the amount of weight savings is interesting (well it's a bit silly but if I have the choice, why not)... But if this was such a bright idea I figure it would be done more often, so why is it people don't use aluminum wiring (in cars anyway; Al wiring in houses is fairly common)?

I'm getting one of these to secure the battery to the trunk:

http://www.odysseybatteries.com/images/billet/680stand_m.jpg

Still trying to decide if it will go in the extreme left rear (above the evap equipment) or right rear (above where the muffler is), and how to run the wire up to the engine bay and through the firewall (there's the bung I use for the boost gauge and oil temp wire, or should I just drill a new hole?).

smack
07-13-2005, 03:26 PM
i've never used aluminum wire so i can't tell you much about it. but it sounds like a good thing
weight wise. yeah i always thought that the weight of the 4gauge would counter most of the
benefits of moving the battery to the trunk.

i think just going to a smaller one up front is pretty good but if you can mount yours sideways
you might think about mounting it under the pass. seat. it will counter driver weight a bit
(nothing personal :lol:) and you keep the weight as low in the car as possible.

just a thought.

oh btw, on running the cable, i ran mine along with the main loom that goes in through the driver's side just in front of the door.
i goes in front of the battery, into the area between the fender and liner, and back to the door jam.
then you can run it down the length of the car along with the other loom thats there under the scuff plates(or whatever those things are called)

oh yeah, nice mounting box

SouthernCrane
07-13-2005, 04:06 PM
Thanks Sean; more ponderings:
- 15' of 2-gauge copper wiring weighs a bit over 3 lbs
- 15' of 1-gauge aluminum wiring weights about 1 lb



what is the price difference?

vtluu
07-13-2005, 04:11 PM
what is the price difference?
I don't know... I'm not even sure where to buy aluminum wiring. Hopefully a trip to "Orchard Supply Racing" tonight will prove fruitful. 8)

Compared to just mounting a small battery up front, relocating it back won't provide any advantage in net weight. But one might argue it improves weight distribution since it makes the car less nose-heavy.

More importantly, it should improve the reliability and life of the battery because batteries--especially SLA (sealed lead-acid) units like the PC680--don't fare very well when exposed to heat, and there's basically no hotter place to put the battery than in the engine bay.

smack
07-13-2005, 06:03 PM
yeah i agree that it's not just about weight. but i was mainly refering to people who
move a full size battery to the back plus the wire as opposed to going to a lighter battery under the hood.
i think most people aren't at your level of car prep either, so there are
places where others could better spend their $ in the quest for better handling. a decent
allignnment or some camber plates come to mind.

i do agree that it's nice to get the weight off the nose though.

Evo442
07-13-2005, 06:26 PM
Thanks Sean; more ponderings:
- 15' of 2-gauge copper wiring weighs a bit over 3 lbs
- 15' of 1-gauge aluminum wiring weights about 1 lb

(Aluminum is a poorer conductor so you need to go 1 gauge thicker.) So it seems that since the amount of weight savings is interesting (well it's a bit silly but if I have the choice, why not)... But if this was such a bright idea I figure it would be done more often, so why is it people don't use aluminum wiring (in cars anyway; Al wiring in houses is fairly common)?

I'm getting one of these to secure the battery to the trunk:

http://www.odysseybatteries.com/images/billet/680stand_m.jpg

Still trying to decide if it will go in the extreme left rear (above the evap equipment) or right rear (above where the muffler is), and how to run the wire up to the engine bay and through the firewall (there's the bung I use for the boost gauge and oil temp wire, or should I just drill a new hole?).

Nice battery box... i'll have to check that out. I've wondered about putting a mini battery in the trunk. Will there be a problem sticking a mini-battery so far from the starter, in terms of cold weather starts ?

I vaguely remember someone telling me that if I relocate my battery to the trunk to stick with a full sized one.

vtluu
07-13-2005, 06:53 PM
Cold weather starts, here? :lol: j/k

Is cold weather + relocated battery an issue because the battery is no longer in the engine bay (and therefore maybe colder), or because of the voltage drop associated with the longer wire (which you can mitigate by using a thicker wire)? Or is a smaller battery more subject to cold weather (because of its smaller mass it will get cold faster)?

Evo442
07-13-2005, 06:55 PM
Cold weather starts, here? :lol: j/k

Is cold weather + relocated battery an issue because the battery is no longer in the engine bay (and therefore maybe colder), or because of the voltage drop associated with the longer wire (which you can mitigate by using a thicker wire)?

I think it had to do with the voltage drop assoc with the longer wire....

Probably not an issue in Sacto, but would suck getting stuck in Tahoe! :lol:

vtluu
08-02-2005, 09:22 PM
Hey, where'd my battery go?

http://www.norcalevo.net/gallery/albums/album292/batt2.jpg

Ah, there it is:

http://www.norcalevo.net/gallery/albums/album292/batt1.jpg

I bought the battery hold-down I mentioned and cut some of it out to save a bit more weight (about 0.1 lbs :lol:). Instead of a fuse, I'm using a 100-amp circuit breaker from Monster Cable (JB-welded to the battery hold-down, with some rubber strips placed to prevent accidental short-circuits). The circuit breaker is nice because not only do you not have to have a replacement fuse, you can use the switch on it to cut off battery power if you need to work on electrical bits of the car, reset the ECU, etc.

Weight? Well, I used just over 16' of 4-gage welding cable--weight, 3 lbs. The hold-down weighs well under 1 lb. So figure that with all the hardware and circuit breaker, maybe 5 lbs. But:

http://www.norcalevo.net/gallery/albums/album292/batt3.jpg

The battery hardware I took out--tray, fasteners, old battery terminals, etc.--weighs about 2.3 lbs. So in fact the net weight gain is under 3 lbs. And now it's in the back of the car, on the right side (which was lighter), and the battery is away from the heat of the engine compartment so it'll last longer.

wilson1
08-02-2005, 09:56 PM
looks good!
Now come and do mines. :D

Evo442
08-02-2005, 09:56 PM
Sweet!

gOt BoOsT
08-02-2005, 10:54 PM
NICE... i'm LAZY so i just bought the neisi mini batt. kit...it opened up lots of space & saved probably 10 lbs...