3000iphones Posted March 17, 2021 Report Share Posted March 17, 2021 hello, back with more electrical issues/questions. i'll try to make this simple. my front battery "NAPA Power no.65" 70 Ah, cca: 675 A, ca: 830 A, sits around 14.1-.6 at the front battery terminals while idling, and from the few times i've checked, my d3400 starts around ~13.1 and creeps up to ~13.5 while idling. i charged my d3400 last night with hf1215 and it sat at 12.9 before putting it in. 2 runs of 1/0: front battery -> dual fuse -> rear fuse holder -> rear battery, though the connection from front to rear battery is unfused in the trunk. i just realized, maybe i should fuse it. i have the smd fuse holder that works as a bus on one side and you fuse across to amps/whatever else. i have three battery wires connected to the bus in total, so they should all be connected well. my amps see the same voltage my front battery sees, but my d3400 tends to rise from ~13.1 to ~13.5 at idle. d3400 is resting at 12.5 while connected to the system with engine off, stock battery is ~12.3 while connected to the system with engine off. d3400 does see minimal voltage drop when bass hits hard directly at terminals. (it went 13.6 to ~12.6 playing lows) if none of this information is enough, i can provide more numbers after the batteries sit overnight. to conclude.. is this normal, or is something wrong? Link to comment Share on other sites More sharing options...
Dafaseles Posted March 17, 2021 Report Share Posted March 17, 2021 How much power are you pulling from the batteries and how well are both batteries grounded? 2011 Chevy Silverado under construction My build log here. Check it out! Link to comment Share on other sites More sharing options...
3000iphones Posted March 18, 2021 Author Report Share Posted March 18, 2021 4 hours ago, Dafaseles said: How much power are you pulling from the batteries and how well are both batteries grounded? my rear battery is grounded twice to the frame with 2/0. front battery is grounded to the frame and alt with 1/0. i revised both grounds multiple times to make sure they're sound. im running two smart 3's maxed out. if that isn't scientific enough, i can probably look into how much power is actually being used. Link to comment Share on other sites More sharing options...
Dafaseles Posted March 18, 2021 Report Share Posted March 18, 2021 41 minutes ago, 3000iphones said: my rear battery is grounded twice to the frame with 2/0. front battery is grounded to the frame and alt with 1/0. i revised both grounds multiple times to make sure they're sound. im running two smart 3's maxed out. if that isn't scientific enough, i can probably look into how much power is actually being used. How many amps is your alternator putting out and what brand is it? Have you done the big 3 upgrade? 2011 Chevy Silverado under construction My build log here. Check it out! Link to comment Share on other sites More sharing options...
3000iphones Posted March 18, 2021 Author Report Share Posted March 18, 2021 1 minute ago, Dafaseles said: How many amps is your alternator putting out and what brand is it? Have you done the big 3 upgrade? i have a 290a singer. (idle: 240+A, 315 peak). two 1/0 power coming off alt to front battery plus factory power. two front battery grounds: one to frame, one to alt. Link to comment Share on other sites More sharing options...
Dafaseles Posted March 18, 2021 Report Share Posted March 18, 2021 I fear that your alternator can't keep up with the power draw needed for 2 smart 3's. So if I can just make sure I'm 100% correct, with the car off, the batteries testing voltage is the same, but with the car running, they differ quite a bit with the rear battery being low. It sounds like your rear battery might not be grounded well enough. You have enough ground runs, maybe they're not connected to good grounding points? But the frame usually is good. Are they excessively long runs? Do the batteries differ with the system off as well? If you have a buddy bring the RPM's up, does the rear battery charge better? Are you using good OFC cable? I would think 2 runs from the front to the back would be sufficient, but maybe go 3 to make the power distribution more fluid? I've never heard of it making a difference, but maybe split the 2 runs from the alternator to the 2 batteries instead of just the one? And both batteries are AGM, so you're not mixing chemistries.... Just kind of brainstorming things out loud.... The XS battery isn't old is it? 2011 Chevy Silverado under construction My build log here. Check it out! Link to comment Share on other sites More sharing options...
3000iphones Posted March 19, 2021 Author Report Share Posted March 19, 2021 6 hours ago, Dafaseles said: I fear that your alternator can't keep up with the power draw needed for 2 smart 3's. So if I can just make sure I'm 100% correct, with the car off, the batteries testing voltage is the same, but with the car running, they differ quite a bit with the rear battery being low. It sounds like your rear battery might not be grounded well enough. You have enough ground runs, maybe they're not connected to good grounding points? But the frame usually is good. Are they excessively long runs? Do the batteries differ with the system off as well? If you have a buddy bring the RPM's up, does the rear battery charge better? Are you using good OFC cable? I would think 2 runs from the front to the back would be sufficient, but maybe go 3 to make the power distribution more fluid? I've never heard of it making a difference, but maybe split the 2 runs from the alternator to the 2 batteries instead of just the one? And both batteries are AGM, so you're not mixing chemistries.... Just kind of brainstorming things out loud.... The XS battery isn't old is it? the battery voltages are very similar after sitting with the engine not running. you're correct, the rear battery's voltage is lower while idling. my rear battery is grounded twice to the frame with short runs of 2/0. the battery is located damn near directly above the frame grounds, so the wires are being pulled pretty tight. the only thing i can do is check them over again, but i clean the metal and tighten the shit out of them every time. my car, a mercury grand marquis, for whatever reason, regulates voltage in a way that any RPM i sit at gives the same amount of voltage at idle. driving is a different story, though. my voltage is super strong when the wheels are moving. (just reread, i'll check how the rear battery charges at different RPMS soon.) as far as the electrical system not keeping up, my electrical/amps love lows, so i can run them all day at idle with the volume cranked. any frequency above maybe 35 isn't very friendly. if you're thinking my setup is strange, just know i do too. im gonna go a different route on my next car. i just want to figure out why this is happening and if it's a problem. the battery is about a year old, not sitting while being disconnected from anything for long periods. Link to comment Share on other sites More sharing options...
Dafaseles Posted March 19, 2021 Report Share Posted March 19, 2021 16 minutes ago, 3000iphones said: the battery voltages are very similar after sitting with the engine not running. you're correct, the rear battery's voltage is lower while idling. my rear battery is grounded twice to the frame with short runs of 2/0. the battery is located damn near directly above the frame grounds, so the wires are being pulled pretty tight. the only thing i can do is check them over again, but i clean the metal and tighten the shit out of them every time. my car, a mercury grand marquis, for whatever reason, regulates voltage in a way that any RPM i sit at gives the same amount of voltage at idle. driving is a different story, though. my voltage is super strong when the wheels are moving. (just reread, i'll check how the rear battery charges at different RPMS soon.) as far as the electrical system not keeping up, my electrical/amps love lows, so i can run them all day at idle with the volume cranked. any frequency above maybe 35 isn't very friendly. if you're thinking my setup is strange, just know i do too. im gonna go a different route on my next car. i just want to figure out why this is happening and if it's a problem. the battery is about a year old, not sitting while being disconnected from anything for long periods. I don't think your setup is weird. Those smart 3's are bad ass! I just want to figure this little issue. If you aren't falling below 12 at all, I don't think you're going to damage anything though. It's just a little strange that with the vehicle running, the batteries are about a whole volt apart 2011 Chevy Silverado under construction My build log here. Check it out! Link to comment Share on other sites More sharing options...
3000iphones Posted March 19, 2021 Author Report Share Posted March 19, 2021 2 minutes ago, Dafaseles said: I don't think your setup is weird. Those smart 3's are bad ass! I just want to figure this little issue. If you aren't falling below 12 at all, I don't think you're going to damage anything though. It's just a little strange that with the vehicle running, the batteries are about a whole volt apart it's OFC wire by the way, a mixture of GP, rockford, and sky high. Link to comment Share on other sites More sharing options...
3000iphones Posted April 7, 2021 Author Report Share Posted April 7, 2021 the electrical in this car has been so damn confusing/annoying. my voltage is substantially lower/very inconsistent while idling in drive than park (between 13.0-14.0). only my rear deck speakers whine/buzz when i press the gas petal (even in acc, car off) or when the engine revs. the HU ground has been revised, and i've also bought ground loop isolators, ran with and without grounding. crescendo s4 4 channel amp (4 ga) ground has been changed multiple times, though i haven't tried grounding the amp itself directly to the alt, rear battery, or to the frame. my rear battery sat at 13.1 at idle after a long drive without any bass today. my voltage at the smart 3s reach 14.6 on cold days at idle, but lower to ~13.6-~14.4 i don't know if the factory voltage regulator may be at fault, or if i should install something like a brand x regulator. i can say that i never checked the fuse box, if anyone thinks a fuse might be causing any issues. all factory wires are intact, except factory front battery grounds, which can be reattached, i just need a lug. i have two 1/0 grounds to the front battery to alt and frame. sorry for this paragraph. i also want to state that, though i've had these voltage issues, my batteries have never failed to start my car, so the vehicle is still functional. i just don't understand why my voltage is all over the place. i'm not even sure if these problems can be diagnosed over a forum, so i understand if no one has any ideas. i almost want to part my trunk out and get to work on my 89 caprice edit: car is a 2001 grand marquis Link to comment Share on other sites More sharing options...
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