My 74 Nova being Reborn - Page 77 - Chevy Nova Forum
Visit our sponsor, National Nostalgic Nova
 
Steve's Nova Site is an automotive enthusiast website dedicated to the 1962 - 1979 Chevrolet Nova, Chevy II and Acadian automobiles. We work together to preserve, restore, drive, show, race and provide fellowship for these classic cars. This is one of the best places to find information about parts, rebuilding, restoration and racing. This website is not affiliated with GM, General Motors or Chevrolet in any capacity.

Go Back   Chevy Nova Forum > Non-Technical > 3rd Generation Chevy II/Nova's


StevesNovaSite.com is the premier Chevrolet Nova Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
Old 20th-April-2017, 11:21 PM   #1141
Tarantula
(OP)
 
Tarantula's Avatar

Title: Nova Guru
iTrader: (0)
Status: Offline
Join Date: Dec 2008
Location: California
Nova(s): 1974 "454" Nova Custom
Posts: 1,729
Quote:
Originally Posted by romancommander View Post
My question regarding the alternator wire size, has to do with recharging and overall system voltage.

Stock, Gm connected the battery and alternator through a 10ga wire going to the starter. While easy for manufacturing, it is not the best for a fuel injected electrical system. Compounding the problem is the fact that your battery is 20 feet away from it. I asked because if you are running the stock 10 ga wire (hell or even 4 ga) you'll have 15% or more voltage drop from the alternator to the battery. The alternator may output 14 volts, but your battery may only ever charge to 12V, and remember dropping system voltage is your main problem here. It is all related. The bigger the wire from the alternator to the battery, the less voltage drop.

.
I definitely am not using stock wiring. All was renewed. The wire size is 2 Gauge. When car is on, The highest I have seen is 14.5v (when cold). Average is 14.1v. When electric fan is on its 13.8v

Quote:
Originally Posted by romancommander View Post
With the car off, what is your voltage reading at the battery?.
I have not used the car in almost a week and I do have an alarm light that stays on all the time when the car alarm is active. I just checked and its currently 12.85V at the battery. At the front posts its 12.8V.


Quote:
Originally Posted by EdyJun View Post
I have 2 questions, isn't the ECU supposed to be connected to the battery directly? (where are you installing the ECU?)
Yes. The ECU is connected directly to the battery posts in front. There are two connections.

Quote:
Originally Posted by EdyJun View Post
And instead of spending the money on the cap, would it make sense to upgrade the wires from the batt in the trunk to the front instead? (that would fix a lot of the issues)
Not practical. And though I would like to have 12V to the ECU while cranking, Its not a big enough reason to justify redoing the wiring from 1/0 to 2/0.

Quote:
Originally Posted by EdyJun View Post
BTW isn't the vol 13.0-13.2V for YELLOWTOPs
Correct. When I placed battery in the car it was at 13.1 Volts. The Redtops fully charged are at 12.8v
__________________
Steve

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by Tarantula; 20th-April-2017 at 11:24 PM.
  Reply With Quote
Sponsored Links
Advertisement
 
Old 20th-April-2017, 11:35 PM   #1142
romancommander
 
romancommander's Avatar

Title: Nova Guru
iTrader: (2)
Status: Offline
Join Date: Oct 2013
Location: Roseville, Ca
Nova(s): 1973 2dr
Posts: 3,163
When the car is running, you are reading alternator voltage at the point where your gauge is hooked in, which your numbers point to a healthy alternator. Voltage drop increases as current demand increases (which is what you are seeing when your voltage dips below 12v).
__________________
Jeremy

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
  Reply With Quote
Old 20th-April-2017, 11:47 PM   #1143
romancommander
 
romancommander's Avatar

Title: Nova Guru
iTrader: (2)
Status: Offline
Join Date: Oct 2013
Location: Roseville, Ca
Nova(s): 1973 2dr
Posts: 3,163
Since the Ecu draws so little, you maybe money ahead with a separate small 12v Agm. Something from a power wheels would work, like an 8 amp hour. Then just connect it with a small "run hot" not "start hot" lead to charge it. I don't think you'd even need a battery isolator as it would be separate from the starting circuit. I buy these type of batteries from my local Batteries Plus.

https://www.walmart.com/ip/Universal...&wl13=&veh=sem
__________________
Jeremy

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
  Reply With Quote
 
Old 21st-April-2017, 10:58 AM   #1144
Tarantula
(OP)
 
Tarantula's Avatar

Title: Nova Guru
iTrader: (0)
Status: Offline
Join Date: Dec 2008
Location: California
Nova(s): 1974 "454" Nova Custom
Posts: 1,729
From my understanding of capacitors, they lose voltage (discharge) over time. There are times when I have the car sitting for a couple days and if the cap is a temporary source of power, then that would be bad.
So I asked about it...

Quote:
Originally Posted by romancommander
So there are two factors that cause a capacitor to discharge. 1. Internal leakage (known as desulfating in a battery)
2. External Current draw, (memory wires, alarm, etc)

If you buy a good cap, then it should have minimal internal leakage and stay charged a long time, but it will also be connected to the battery so it would at minimum maintain the batteries level of charge. I would not try to use a cap that wasn't connect directly to the battery, I don't think it would work.
.
So I came up with this Concept.



The Capacitor would receive power from the battery always when the car is off via a NC relay. This would keep the capacitor charged at all times. When I turn on the car, the NC relay would open and cut power from the battery to the capacitor. This would prevent the capacitor from discharging by starting the car. The Capacitor would then slowly power up the ECU giving it 12v.
When car starts and Alternator starts to charge (over 13v), the capacitor would once again receive battery power via the battery combiner/isolator.

Starting the car would take seconds so it is my understanding that the capacitor would be able to power the ECU for a little while (while the car is cranking) before being completely drained because it would only be consuming less than 10 amps. I chose a 2 Farad Capacitor which in my understanding would be equivalent to 166 amps of storage power.
There are 2 connections for the ECU. One in which is specifically for the ECU to turn on. The other for all the sensors of the ECU to get power. This connection would be connected to the battery. The ECU connection goes to the Capacitor.
__________________
Steve

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
  Reply With Quote
Old 21st-April-2017, 12:18 PM   #1145
romancommander
 
romancommander's Avatar

Title: Nova Guru
iTrader: (2)
Status: Offline
Join Date: Oct 2013
Location: Roseville, Ca
Nova(s): 1973 2dr
Posts: 3,163
Quote:
Originally Posted by Tarantula View Post
From my understanding of capacitors, they lose voltage (discharge) over time. There are times when I have the car sitting for a couple days and if the cap is a temporary source of power, then that would be bad.
So I asked about it...



So I came up with this Concept.



The Capacitor would receive power from the battery always when the car is off via a NC relay. This would keep the capacitor charged at all times. When I turn on the car, the NC relay would open and cut power from the battery to the capacitor. This would prevent the capacitor from discharging by starting the car. The Capacitor would then slowly power up the ECU giving it 12v.
When car starts and Alternator starts to charge (over 13v), the capacitor would once again receive battery power via the battery combiner/isolator.

Starting the car would take seconds so it is my understanding that the capacitor would be able to power the ECU for a little while (while the car is cranking) before being completely drained because it would only be consuming less than 10 amps. I chose a 2 Farad Capacitor which in my understanding would be equivalent to 166 amps of storage power.
There are 2 connections for the ECU. One in which is specifically for the ECU to turn on. The other for all the sensors of the ECU to get power. This connection would be connected to the battery. The ECU connection goes to the Capacitor.

A couple things.

1. I originally suggested a cap to attenuate your voltage drop when installed in the engine bay and help your starting, to alleviate having to change out your 1/0. I still think this the best idea because it fixes a systemic problem, but I understand the engine compartment lack of space problem, and the fact that its only an issue during cranking. It was merely a thought I had, there are tons of wasy to skin this cat.

2. The scenario you are outlining would probably work, but is a little expensive and a little complicated, and technically not the best use of a cap.

Since the ECU draws so little, a simpler system would be to go with what you originally intended, involve a small 8ah-ish battery mounted in the trunk, relatively large wires going to the ecu to negate voltage drop (12ga? 10ga?) and instead of battery combiners or isolators a simple charging relay/trickle charger that only energized when in the "run" position. It would be a completely separate system, cheap, easy, small.
__________________
Jeremy

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by romancommander; 21st-April-2017 at 12:20 PM.
  Reply With Quote
Old 11th-May-2017, 10:09 PM   #1146
blu_iiz4

Title: Nova Newbie
iTrader: (0)
Status: Offline
Join Date: May 2017
Location: St. Louis
Nova(s): 1974 Custom Hatchback
Posts: 3
LOVE this thread!

Quote:
Originally Posted by Tarantula View Post
Man, this thread is more like I'm talking to myself lol...
I bought a '74 Custom Hatchback last year and am finally get it completed this month. I am so excited to see your work & can't wait to finish reading your posts to see the outcome!
  Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Site best viewed set to 1024 x 768.

All times are GMT -4. The time now is 01:38 AM.

Custom Designed for Steve's Nova Site by: vBSkinworks

 
Powered by vBulletin® Copyright ©2000 - 2017, Jelsoft Enterprises Lt
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.