Lights go dim when braking or rolling windows up/down after battery relocation

[onosqv]

Ok, Batteries have been relocated to the trunk. Before, never had a problem, now seems like I'm drawing too much power .

At night w/ lights on & electric fan (altima fan) on, voltage reading off battery is about 13.2v or so.

If I roll both windows up or down at the same time, the lights will dim & reading goes to 12.2v or so.

Similar thing happens when braking.

Current wiring setup:

Battery w/ 0 gauge wire from trunk to engine bay -> distribution block -> * 4 gauge wire -> battery isolator terminal w/ 4 gauge as the alternator input-> - one side starter wire for battery 1 - one side the other wire that is suppose to be connected to the battery attached to the fuse block for battery 2. * 12 gauge wire connected to electric fan power source

Please keep in mind that this is "revision 1" of battery relocation, I had a fuse in the line, but it blew everytime I started my car... so currently running fuse-less (yikes) & wire sizes were determined mostly by what I had available.

Any suggestions on what/how I should be running this to alleviate my problem will be great, I'm just glad to have a running car right now .

89 240sx.

Thanks!

**EDIT: o yea, the rest of the setup:

From alternator 4 gauge wire -> circuit breaker -> 0 gauge wire from engine to trunk -> battery isolator distribution block or whatnot connected to alternator terminal & each battery on the other ones (main battery is battery 1).

Original ground is now grounded to metal area between coolant & washer reservoir (best I could do at the moment). All ground areas where sanded/wire wheeled to bare metal before attachment.

New battery grounds are connected to the center of the spare wheel well where the wheel hold down once was (no more spare tire).

I know pix would help a lot more, but it's late, i'm tired, and the car is not very "pretty" right now, haha.

Battery 1 is Optima Red TopBattery 2 is Fusion Deep Cycle (competition battery)
Modified by brokeAs240sx at 1:09 AM 7/25/2005

[PoorManQ45]

What's happening actually sounds normal.

Try turning on the AC compressor and turn the fan to high once. You'll notice that the voltage meter drops damn near to 12volts.

The window motors draw a high amperage which causes the overall voltage to drop due to the limited output capability of the alternator.

To rectify the problem you'd need a HO alternator. Although this isn't actually a problem sinse the electrical system is fine most of the time

[xekushnr]

i can damn near stall my '04 neon by locking the wheel with the radio blasting and all the lights on while idling. its normal. the cars electrical system is only meant to handle a couple systems at once without dropping voltage. once you increase the resistances of course the voltage is going to drop.

the reason why you're noticing it now is most likely because there is more wire for the power to traverse through. voltage will drop over distances, despite what size wire you use.

[PoorManQ45]

Yep, I suspect that you didn't use a large enough wire from the alternator to the battery. Normally a 1awg of 0/1awg wire is used.

[onosqv]

Ok, thanks for the reply guys, I'll do some rewiring.

I alleviated "some" of my problems.

Basically, since I reallly needed a part to get my car connected in front & I didn't want to do a "bolt & washer" style connector, I bought a battery isolator. Found out the other day that the battery isolator loses about .4-.7 volts or so... considering I already had one from the alt->batteries (needed since I have 2 batteries, bla bla bla), this wasn't too ideal.

Soooo, I took the wires from fuse box that were connected to battery 2 spot on the isolator, moved it directly to the battery wire in the alternator position, and for now left the starter on the battery 1 position just for safety. Much less dimming, still not ideal, but livable for a week or two until I can get my set of circuit breakers, distributors, etc.

As for the starter -> battery wire, I have 0 gauge most of the way, but have the first 5 feet or so 4 gauge becuase that's what I had (goes from starter around engine bay to driver side, where it hooks up to the circuit breaker -> 0 gauge -> battery term -> 4 gauge wire to each of the batteries. I had thought 4 gauge would be enough since that's what was used when my batteries were in front... I just reused a 0 gauge that was being used for something else already wired up, haha.

Yea, lots of unnecessary wiring in my car... I'll post up pictures/diagrams of how my car is laid out w/ more specific details once I get to "stage 2" of wiring.

I'll try to replace all w/ 0 gauge wire if I can get my sponsor to send me another set .

p.s. Anyone need a battery isolator?

[PoorManQ45]

The battery isolator is only supposed to be on one of the batteries to prevent it from increasing the demand on the alternator. THe isolator keeps it seperated until it reachs a certain voltage, most likely close to 11volts, and then conects it to the rest of the electrical system to charge. Once it reachs ~12.5v it disconnects.

Also, I suggest that you go through the engine bay and reroute some of the wires. I bet you could shed close to 10~15lbs just in wasted wiring

[Jookmasta]

i have the same issue. i thought about upgrading my alternator but who knows. i was also thinking about a grounding kit but that is also up in the air. so should i just get a 0 gauge wire and use that to ground my alternator to the chassis?

[PoorManQ45]

That's a little large, but sure you could do that

[audtatious]

I agree with PMQ concerning the battery isolator (did I really say that? ). When working with battery locations, make sure you fully sand down all grounds as well. It sounds like the battery system is currently running together which is presenting a greater load to the alternator, thus causing the dimming problems.

[Jookmasta]

well since 0 gauge would be overkill, 4 gauge or 8 gauge? which would u use?

[PoorManQ45]

depends on ht elength of the run. If it's under two feet then 8 would be fine. Longer then that and you should use 4

[Jookmasta]

also, there wouldnt be any point to leavin the factory ground wire and using the new 4 gauge wire in conjunction with it right? or just use the new 4 gauge wire? also i forgot to mention that altho i have the same issues, i am only using the factory battery to power the system along with the car. i tested the battery BTW and pepboys said it was good so hopefully its not the alternator going on me. thanks in advance for the suggestion. u then wouldnt happen to know somewhere generic where i could get 4 gauge wire for cheap?

[audtatious]

Multiple grounds never hurt.