I have a '64 Chevy with a battery in the trunk, NHRA Kill Switch, and 2 power distibution points (trunk and engine bay). The primary wire gauges in use are 00 or 4g. I have enclosed a basic depiction of the way I have it configured.

Batt to Kill switch is 00 (about 3 feet)
Kill switch to Starter is 00 (about 12 feet)
Alt to Batt is 4G (about 12 feet)
Kill switch to Distribution point 1 is 4G (about 5 feet)
Distribution Point 1 to Distribution point 2 is 4G (about 12 feet)


When the car is running I get

14.5 at the battery and front side Kill switch
14.3 at the back side of the Kill switch
13.9 at distribution point 1 (powering the fuel pump, aeromotive A1000)
13.4 at distribution point 2 (powering 2 cooling fans)

I see 13.4 on the scanner.

Should I expect this type of drop or do I have the wrong wire gauge/grounds?

 

Using different ground points with each measure? If so, try grounding the voltage meter at the battery every time.

 

Yep I was using different points. I’ll run a wire back to the batt, check again, and report back.

Does this variance in voltage indicate my grounds are bad or inadequate?

 

Okay re-tested with the car running at idle... MUCH better when grounding back to the battery but still a small drop.

14.3 at BATT
14.3 front side Kill SW
14.2 Load side of Kill
14.1 Distribution point 1
14.0 Distribution point 2

Also the scanner shows between 13.8-14.0 for the control module voltage.

Also tested the car not running before I tested at idle and got the following using different ground points for the distribution points.
13.2 at BATT
13.2 front side Kill SW
13.2 Load side of Kill
13.2 Distribution point 1
13.2 Distribution point 2


FYI:
I believe I'm chasing a charging problem which drains the battery and prevents me from starting the car as I get the noid click when I try to start her AND I notice the dash volt gauge drops from 13 ish to 9 ish.... It's a new optima yellow top battery

I have run a paracitic draw test and see 5mV key off.
- NOTE HPT Cable pulls anywhere from 60-75mV when I plug it in, so that no longer stays plugged in.

Previously I intalled a diode between the Alt and what I thought was the "exciter wire" to prevent the alternator from backfeeding the engine after the kill switch was hit.. I took that out and now I'm seeing the alternator put out more while under load so I think it's going to charge better. Probably not going to make the NHRA guys happy but I'll research and fix that problem after I get the basic's covered.

I also can't rule out the ignition wiring... this is a new direct fit American Autowire harness that I modded to run the car. The trigger wire off the ignition switch runs to the remote starter noid, I then use another relay which is triggered from the remote starter to trigger the original starter noid. Originally I had a jumper wire at the starter to noid but thats no good as the starter hangs up a smidge I assume/read due to current generated by these starters...

Any help, questions, or comments welcome!

 

Engine rubber mounted ?
you did not mention a negative lead from battery to engine.
I'd start with an engine ground.
Also, possible battery is defective, they occasionally let a bad one get through QC..

 

Standard rubber engine mounts.

Engine grounded to frame
Alt grounded to frame
Batt grounded to frame
Frame grounded to body at a few places.
Subframe connectors welded in as well.

So are these types of drops consistant with a bad ground or are these drops okay?
Sorry for the basic questions but again this isn't something I truely understand how it works.

 

I think the results are good in post 4, low variance. I’m sure someone more knowledgeable ( Andrew) will chime in shortly.

 

The reason all the voltages are the same when the car is off is because there is no current flowing through the various resistances. So you expect all the voltages to be the same. Current is what causes voltage drops across resistances. Each of your conductors, including, kill switch, ground straps and the chassis itself are resistors. Some are a lower value than others (lower is better).

From what I see by your 2 measurements, the voltage drop across your copper wires and kill switch is 3 times less than the voltage drop across your ground straps and chassis. This will even be worse when the starter is running. The voltage drops will also vary based on load, especially if the fans and fuel pump are running at max power, etc. Chances are since your battery was drained, there is also a high current going through the grounds to recharge it.

The losses from your copper is tolerable in my opinion. I would try to improve the ground side of your setup.

I also have a remote battery and kill switch. I double ground the battery connection to the frame as well as the engine block to the frame. I use heavy sized ground lugs, large ground straps and protect the frame to lug connection with an anti oxidation coating.

BTW, from what I see, the kill switch will not shut down your engine.

 

LS Swap,

Thanks for that info, greatly appreciated. I think what I'm gonna do is rebuild/replace my ground straps and give everything a good cleaning and see how she responds.

I do have a few Q's

Do you run from the batt to the engine from the trunk? I understand why that would be best (starter has to be the largest draw) but dam I really want to avoid stringing another 00 the length of the car!

This is probably hard to answer but what should I see for a drop assuming I have the car at idle 2 fans and a pump going? Right now it's just over 1V (14.5 to 13.4) with the config I have, should I be aiming for 1/2 that or better?

Is a 4 gauge ground sufficient from Alt to Frame? It's a short run, no more than 3'. I figure if you used a 4G supply a 4G ground would be good but again what do I know. Also that "supply to ground gauge" model is what I follow, so all my 00 supply's have 00 grounds

I think the rest of the guages are okay but here it is anyway...
- Batt to Frame gets 00
- Engine to frame gets 00
- Frame to body is 4g (2 points, front/rear)


Last Q, the Kill SW problem... I'm hoping your gonna say the alternator will backfeed the fusebox.... Also hoping you might have a solution that works better than my previous idea.
- - I took a diode out of the Alternator harness because I believe It was messing with the alternator knowing when to step up the charging. Pretty sure I was right because I was reading 12.5 or less when both cooling fans kicked on, now I see 13.8 with both fans on.

 

In my NHRA car, I used a kill switch with an extra set of low current contacts that would kill the power to the ignition relay and dual grounds at the battery and engine. ECM and misc stuff grounded to common point on engine.

 

and there it is....

You'd think being this old would make me smarter. Had car wired this way with my SBC.... You'd have thought when I swapped it I'd have thought about this a bit better/harder/at all....

Thanks, I'll add this to the list.

 

What LSswap said: " I would try to improve the ground side of your setup".
We do a lot of wiring and never use the frame for a main ground source.
Body to frame.
Batt to engine and frame.
Your comment on drop at start is a good clue. "AND I notice the dash volt gauge drops from 13 ish to 9 ish".

 

Well, I’ve tested just about everything else and I have the wire so I might as well run the BATT GRD up to the engine and see if that helps.

 

So I found the problem I was chasing...

I had thought the battery was being drained from improper charging which resulted in the ignition to starter noid not having the juice needed which got me the annoying CLICK when trying to start the car. This is how I bumped into voltage drops and wondered why I wasn't seeing 14+v while running... Turns out charging was a problem but it wasn't the real problem.

After a fair bit of testing it appears the STARTER, specifically I believe the Starter Noid went bad...

And here is the thing, I think I caused the problem.

Originally I had a jumper wire from the Starter BATT to the Starter noid, I did this cause I had a remote starter noid which triggered the Starter BATT. I noticed the Starter would hang a bit after the engine started so I removed the jumper and used a relay that tapped off the Remote Starter Noid. I'm gonna say my problem (intermitant) started just before I remover the jumper and tossed in a relay.

I don't know why a jumper would create that kind of problem but I'm not gonna do that again.

 

Are you using a permanent magnet starter? I've got a Powermaster PMG starter on both my WS6 TA and my LS3 swapped Fox coupe. The Powermaster instructions say that the starter will hang if a jumper wire is used.

Do you think that your starter solenoid is now bad and its causing a voltage drop?

 

Danny, thanks for sharing that reply.

Somewhere a while ago I remember reading something like that but never applied it to ACDelco starters and honestly I couldn’t remember the PMG term until just now…

Google says a ton of ACDelco starters are perm mag starters and since I heard it hang up I’m gonna go out on a limb and say a stock 2002 Caddy Escalade ACDelco starter is indeed a perm mag unit.

I’ll stay on the limb and say not only will the starter hang if you use a jumper wire, it may also smoke your starter noid and cause intermittent start issues.

AND if your like me your gonna swear it isn’t your new starter and take an extended troubleshooting and “while I’m here I might as well fix <name dumb thing here>” tour around your car until you arrive at the last place you thought to look…

sometimes it’s hard to love this hobby but here I am. What’s weird is part of me wants to order a starter noise rebuild kit just so I can have a look at wtf happened.

 

You got this right! Sometimes I think this hobby is a curse. Other times, I absolutely love it!