Bigg Boy Posted August 31, 2008 Report Posted August 31, 2008 Ok well I cant seem to figure this out.... I took my meter and test the impedance of my ground from my ground to my batt, and it was like 4.2 ohms !!!! WTF!!!!! (grounded with 2 runs of 2/0) I tested the impedance of my ground to another grounding spot got like .1 ohms (not to bad??) I then tested my wires and they had .25 ohms across them so when there combined I get about .13 So why would my ground have a impedance of 4+ ohms when its all connected? Its straight to the bare metal.... Please Help..... Dodge Magnum with custom 300c front end, laid out on air bags *4) 12" Cadence Daytona walled *1) AudioQue 20k *270a DC Power Alt (Dual coming soon)
roscoe1129 Posted August 31, 2008 Report Posted August 31, 2008 All wire and connections is going to have resistance and 4.2 ohms is lowwwwwwwww Some people need a sympathetic pat... on the head...with my hammer Scientia est Vox "In Nomine Patris et Filii et Spiritus Sancti" DONT BE AFRAID TO USE THE SEARCH BUTTON!!! SMD SUPER BUYER/SELLER
Bigg Boy Posted August 31, 2008 Author Report Posted August 31, 2008 4.2 is low??? I allmost allways have them less then 1 ohm..... Dodge Magnum with custom 300c front end, laid out on air bags *4) 12" Cadence Daytona walled *1) AudioQue 20k *270a DC Power Alt (Dual coming soon)
roscoe1129 Posted August 31, 2008 Report Posted August 31, 2008 wow your good... Some people need a sympathetic pat... on the head...with my hammer Scientia est Vox "In Nomine Patris et Filii et Spiritus Sancti" DONT BE AFRAID TO USE THE SEARCH BUTTON!!! SMD SUPER BUYER/SELLER
Krice420 Posted August 31, 2008 Report Posted August 31, 2008 x2 haha 2 18'' fi btls fully loaded 2 sundown saz 3000d 1 iraggi 200 amp alt 3 powermaster 3100d series batts 11.75 cuft wall after displacement tuned to 31.08 hz
Bigg Boy Posted August 31, 2008 Author Report Posted August 31, 2008 I could be wrong, but I always remember my grounds being real low.... Dodge Magnum with custom 300c front end, laid out on air bags *4) 12" Cadence Daytona walled *1) AudioQue 20k *270a DC Power Alt (Dual coming soon)
missinglink Posted August 31, 2008 Report Posted August 31, 2008 I could be wrong, but I always remember my grounds being real low.... It can have a lot to do with how you are measuring things, and the meter you are using. Measuring low resistances in large cables is an art, and the average DMM can give you readings that are very wrong. If you actually have a 4 ohm drop across the ground, you are pissing away about 50 watts of power. This would be completely unacceptable in the power distribution business. In a switching station, a 1/0 cable would be expected to have loss measured in micro ohms. The best way to measure extremely low resistances would be a six wire bridge arrangement, but for car audio a 4 wire arrangement will work just fine. You can build yourself a simple adaptor to make this kind of measurement with a standard DMM: Low Ohm Adaptor Link Digital meters are great for testing sensitive components, but they fall short on things that need a larger test current like 1/0 wires, and .001 ohm resistances. I send my meters out for calibration on a regular basis, and still keep an old Simpson 260 around for checking things like grounds... 'Link missinglinkaudio The United States Marine Corps. When it absolutely, positively has to be destroyed overnight - even if "it" belongs to the base commander...
newls1 Posted September 1, 2008 Report Posted September 1, 2008 I just bought a VERY CHEAP DMM to read ohm's, and for other stupid crap around the house, but was wondering if you can tell me what/how to read the OHM load on my grounds? thanks I love my staffie So anti FACEBOOK it isn't even funny
Bigg Boy Posted September 2, 2008 Author Report Posted September 2, 2008 put it to dv voltage, make sure there is no voltage across the wire.... and set it to ohms..... and place the test leads on each side where you want to test... Dodge Magnum with custom 300c front end, laid out on air bags *4) 12" Cadence Daytona walled *1) AudioQue 20k *270a DC Power Alt (Dual coming soon)
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