resistance on power/ground

[blakflash 1]

how much resistance is too much on a grounding point? Ive already read that under 1ohm is optimal but after doing some checks i'm just not going to get that in the rear in comparison to the front. my lowest reading in the back was between 1.8-2.1 Is that good enough?

My next question is on the power wire. I'm using the rear battery as a distro for my amps. measuring from front to rear then from amp to the the end of the wire is normal. but when i connect all to the battery the rear battery and measure I'm getting 30+ ohms on all connections in the rear even on the wire that is coming from the front battery. also this occurs on both ground and power wires. the battery is an kinetick hc800 I'm assuming this isn't supposed to happen. my biggest question is why it happening.

[blakflash 1]

anyone??

[slim2fattycake 85]

Did you check the resistance of your probes?

[blakflash 1]

yes they barely register .01 with the cable i used to test the cross car resistance is at .02.

[j-roadtatts 1,129]

Why are you worried about the resistence of the power/ground wires?

What you are showing is the resistence of the wire and battery. Anything that conducts electricity has a little resistence.

[blakflash 1]

i'm concerned because I want the most out of what I have. And my biggest concern is with the resistance I'm getting when hooking up the rear battery and why its like that. 30.0+ ohms not .30 incase thats what some thought. isn't that odd. My second concern was if the resistance on the amp grounds was high enough to cause damage or not with it sitting at about 2ohms

And no I did measurements from alternator to battery, alternator to chasis at multiple points, alternator to engine, battery to chasis at multiple points, battery to engine and then went from battery ground to amp grounds, then battery ground to other points i could ground at. then battery power to the rear with and without the rear battery attached.

[blakflash 1]

was doing research while looking up good power wires and the effects of resistive connections i happened to come by was this

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Replacing Battery Terminals

the part that shocked me was the box in the middle

[NB50 206]

Are you taking measurements with the battery hooked up?

[blakflash 1]

I did both. the one with the high resistance is with it hooked up but it's only at that one point onward. when i say battery i mean the terminal that connects to he battery.

with the exception of the high reading on the rear battery when connected the only thing i wonder about is that amp ground and if that is sufficient enough

[j-roadtatts 1,129]

If YOUR wire is the right Gauge and you don't have any ground whine coming from the signal then don't worry about it. If you have a poor ground you will know it.

[NB50 206]

Just for future reference, you can not measure resistance with power applied to the circuit. This means you must disconnect batteries, capacitors, amplifiers, turn car off, etc. They will give you a false reading as you've seen. All you should be measureing is the wire run, nothing attached to it.

[blakflash 1]

noise free so far except on the 2ch amp but its not noticeable unless the volume is turned pretty much all the way down. I assume thats the amp since the noise isn't being amplified. the only electrical issue I have is the lights dimming only on bass hits but not on bass tones/notes when I turn it up. I should have sufficient alt power and I would have thought the rear battery would keep that from happening but it's not? any input on that? I also read that insufficient grounding can cause amps to overheat which mine does shut off for a second or two at high volumes and I do have it wired to .7 ohms (its 1 ohm stable) but i wouldn't have thought that enough to push it to its limits because I'm sure the impendence rises to an acceptable level while in use. those two things are what originally got me checking resistances

[KU40 173]

This is why you can't depend on impedance rise in daily systems. I really wish everybody would stop recommending that.

It would also help us immensely if you told us what equipment you were running.

[blakflash 1]

two idmax 21d2 v3 sealed in seperate chambers audiopipe ap1500

the 2ch is some spl amp i found in a closet. not sure who left it there says 360 on it so i'd assume about i can do 180 watts at 2 ohms been a pita finding info on it

[95Honda 486]

When you measure the resistance of your power and ground paths, you should read almost nothing more than the resistance of the thin test leads that came with your meter.

If you do, you are either measuring wrong or something is seriously wrong with your install.

Even 4 gauge power cable (which is pretty much considered a bare minimum for anything) in a 20 foot run has almost no DC resistance when it is cold...... At least less than almost 99% of the multimeters and test leads people are using....

Additionally, you should see zero mesurable resistance across any of your connections with all but the most advanced test equipment.

Again, if you see anything even approaching 1/4 ohm or so, you have a bad install....

[klee7013 10]

agreed with people above- to read ohms you cant have power hooked up- also if you have your wire ran through your amp you may need to unhook that wire and see because you could be reading back through your amp doubt it but i have seen some crazy things in my line of ducy(resident air condtioning)

also shouldnt be over 1 ohm if is you got a bad ground connection or split in the wire where it is connected but not well - maybe loose to where you bolted up

[bassahaulic 155]

Man where are you at in LA? I"m sure we could meet up and I could help you with whatever troubles you have.

[altoncustomtech 773]

I'm not sure what kind of terminals your rear battery has, but I have seen on SEVERAL occasions when someone used the standard top posts on a battery where the posts had some oxidation on them that they didn't clean before putting the terminals on which caused the connections to have problems within a day or two of the installation. Took the terminals off, cleaned the posts and terminals with a dremel brush and put them back on. Two guys I've helped with this I know are still bumping the same stuff today, one after about a year, the other has been running strong 3 years now.

[blakflash 1]

the front battery is new as well as the terminals but I think I'll gp back and solder the front connectors down. the ground from what I've read I may have to run it from the front to rear due to gms wonderful handywork. I even checked the grounding locations for the factory keyless entry and antenna motor and they sit at around 1.2 as well when compared to the front.

any suggestions on fixing the light dimming problem? It only happens for a split second but still its annoying when on certain songs. I'll modify the ground tommorrow right now I have them on a seat belt bolt the threads are in/under the floor i should say which Is why i thought it'd work because first contact was actually to the floor.. Oh and I have a 220 amp alternator the original was a 105 or was suppposed to have been it had been replaced with bosch alternator before I got the car.

[blakflash 1]

was running some numbers and other random things after rewiring my subs in series with vcs parallel... and came to realization about something. i've been running that audiopipe at .35 ohms for the last 4 months thing it was at .7. makes me wonder how i never managed to break anything. I know i have good listening habits but damn...

That realization raised another question tried searching for it but couldnt find a good explanation. Do overload protection circuits limit the output power or shut the unit down?

[KU40 173]

Shut it down basically. It won't power off, it just sorta trips a circuit breaker in there.