Voltage drop on the cluster gauge

Voltage drop on the cluster gauge

Postby Olivier02 [OP] » November 26th 2020, 3:23am

Hi

I noticed a voltage drop when i put the front climate power at full blast and the rear defroster on (at idle ). When i accelerate it comes normal again. Does it have a link with my battery, alternator or wires ? Thanks a lot
Original Poster [OP]
Olivier02
Fueling (3/8 tank)
Fueling (3/8 tank)
Posts: 48
Topics: 14
Joined: June 2020
Gender: Male
Alias (AKA): Olivier
Van Model Year: 2005
Van Make/Model: GMC Safari
Extra Info: SLT AWD 4.3L

  • Similar topics
    Replies
    Views
    Author
  • 1995 Astro Replaced Starter Now Running Low Voltage
    by Melvin-_-_-Marvelous » February 2nd 2021, 1:18pm in Electrical
    1 Replies
    99 Views
    Last post by AstroWill View the latest post
    February 2nd 2021, 6:48pm
  • Drop in Alternator
    by Psyckosama » March 30th 2021, 6:22pm in Electrical
    15 Replies
    462 Views
    Last post by Psyckosama View the latest post
    April 4th 2021, 5:03am
  •  
    9
    93
    Last post by AstroSafari.com View the latest post
    April 13th 2021, 12:12pm

Re: Voltage drop on the cluster gauge

Postby Rod's Trucks » November 28th 2020, 1:19am

Quick answer: Yes, it is definitely linked! :banghead:

Explanation:
You are putting a large load on the electrical system, and the alternator is not supplying as much as needed to keep up when at Idle, so the system voltage drops some. You might even notice headlights get a bit dim under those conditions. On many systems. the charging voltage is 14 to 14.5 volts, but at idle that probably drops to close to the battery voltage when no charging ( 12-12.5 volts) . The dashboard 'voltmeter' is usually grossly inaccurate, for anything but general trends. I know mine reads nearly 2 volts high, if I go be the numbers on the gauge. Until I realized that, I was concerned about boiling my battery on long trips, but then I found the problem was only a high gauge reading.
That, roughly 2 volt difference, makes a noticeable difference in fan speeds and lamp brightness.
I would say to some extent, this is normal, but having an actual voltmeter connected to 'measure' the voltage present would give you better information.
Known problem areas are in the heater blower circuitry and particularly the dropping resistor assembly for the fan ( but that is bypassed in the HI position so it should not be part of your possible issue),
For short term situations, this condition should not be a problem, as the battery ( if it is a good one) has the capacity to fill in for the deficiency. Adding the WS wipers to the mix aggravates the situation a bit more.
Check all the electrical connections at the battery, and the grounds too. Also, you might want to look up the 'BIG 3" mod for wiring, That mod improves the main power circuitry to and from the alternator, battery and vehicle frame.
A voltmeter should measure close to the same voltage on the blower motor leads as it does at the battery, under the same conditions ( there will be slightly lower voltage at the blower motor due to normal losses in the wiring) I would suggest anything more than 1/2 volt might be cause for further investigation, but I have not actual experience with actual measurements on that circuit.
If you take some actual measurement s and have questions, come back with more details, and you will get more help.
Rod J
Issaquah, WA
Rod's Trucks
Firing on 6 Cylinders (L1)
Firing on 6 Cylinders (L1)
Years of Membership: Rod's Trucks has been a member for 1 full year
Posts: 632
Topics: 35
Images: 57
Joined: January 2020
Location: Issaquah, WA
Gender: Male
Alias (AKA): Rod and/or WE7X
Van Model Year: 1998
Van Make/Model: Chevrolet Astro
Extra Info: Forest Green LS AWD

Re: Voltage drop on the cluster gauge

Postby Olivier02 [OP] » November 29th 2020, 3:14am

thanks a lot Rod ! i will look up for the big 3 mod. Do you know where i can buy it ?
Original Poster [OP]
Olivier02
Fueling (3/8 tank)
Fueling (3/8 tank)
Posts: 48
Topics: 14
Joined: June 2020
Gender: Male
Alias (AKA): Olivier
Van Model Year: 2005
Van Make/Model: GMC Safari
Extra Info: SLT AWD 4.3L

Re: Voltage drop on the cluster gauge

Postby MmusicmanMmusicman is online! » November 29th 2020, 3:32am

Olivier02 wrote:When i accelerate it comes normal again.

This tells me your stock alternator isn't producing enough output at idle (when heavily loaded)
This is pretty much normal.

I had same problem running dual a/c on full, PLUS electric fan, plus headlights & auxiliary lights AT IDLE. Stock alternator was extremely inadequate. I installed a larger AD-244 case 145A alternator, which completely solved my troubles. I now have amazing output at idle. It dropped right in for me (but some have had to go one size larger belt).

See my story: https://www.astrosafari.com/viewtopic.php?f=76&t=143944

AD244 vs Stock
Image
Image
2000 Astro LS 4x4 | NP233 | 31" LT265/70R17 Tires | 8" LIFT | 10" TOTAL
92 Chevy Astro Cargo Shorty | V8-350
http://www.CruisinSouthFlorida.com
User avatar
MmusicmanMmusicman is online!
V8 Swap Achievement
V8 Swap Achievement
Firing on 8 Cylinders (L5)
Firing on 8 Cylinders (L5)
Years of Membership: Mmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full yearsMmusicman has been a member for 7 full years
Posts: 4949
Topics: 73
Images: 59
Joined: June 2013
Location: Ft. Lauderdale, Florida
Gender: Male
Alias (AKA): Scott
Van Model Year: 2000
Van Make/Model: Chevrolet Astro
Extra Info: 2000 4x4 - 92 V8-350

Re: Voltage drop on the cluster gauge

Postby MechBob » November 29th 2020, 4:12am

Yes,no and maybe. Lots of misinformation,here.Automobiles are generally built to minimum standards.For the lights to get dim,heater to slow down,wipers to slow down,has been standard since the 1940's,when all vehicles had generators. Over the years,only higher priced vehicles,that came with alternators/batteries systems so this did not happen, did not have this problem.There is nothing wrong with your van,"as built". But you can upgrade it. And,I am sick and tired of people thinking this is an issue,usually comes from people that live in warm climates.How old are you people,13?
User avatar
MechBob
Firing on 2 Cylinders (L2)
Firing on 2 Cylinders (L2)
Years of Membership: MechBob has been a member for 2 full yearsMechBob has been a member for 2 full years
Posts: 1277
Topics: 11
Images: 12
Joined: August 2018
Gender: Male
Alias (AKA): Bob
Van Model Year: 1994
Van Make/Model: Chevrolet Astro
Extra Info: 4x4

Re: Voltage drop on the cluster gauge

Postby Rod's Trucks » November 29th 2020, 7:57am

Olivier02
The Big 3 upgrade is not something you buy as a kit.
It is a process whereby you upgrade to some heavier wiring.
Go into the search box and put in big 3 upgrade; or go to the electrical section and look for it. It is one of the top three or four articles.
You buy the wire and the necessary terminals, and then you get to do the work to install it.
As others have indicated, what you are observing is pretty common. But as I said, a real voltmeter will give you enough information to figure out if is is cause for concern.
Rod J
.
Rod's Trucks
Firing on 6 Cylinders (L1)
Firing on 6 Cylinders (L1)
Years of Membership: Rod's Trucks has been a member for 1 full year
Posts: 632
Topics: 35
Images: 57
Joined: January 2020
Location: Issaquah, WA
Gender: Male
Alias (AKA): Rod and/or WE7X
Van Model Year: 1998
Van Make/Model: Chevrolet Astro
Extra Info: Forest Green LS AWD


 
  • Related topics
    Replies
    Views
    Last post

Return to Electrical

It is currently April 13th 2021, 12:12pm

Electrical Forum
ElectricalDiscussion specific to electric components of vans. Category for alternators or batteries, starters and ignition parts, anything 12v and electrical issue like fuses, circuitry, wire, terminals, switches, connectors, bulbs, relays, and wiring. Voltage and amperage diagnosis.
To create a new topic in Electrical, click this button:
Previous topic Next topic
Recent Image Attachments
Attached by:
Attached by: GaryMacGuyver
GaryMacGuyver
in Electrical
Views: 53
Comments: 2
Date: Apr 10 '21
Time: 11:29am
» Read last comment
Attached by:
Attached by: stent
stent
in Electrical
Views: 1844
Comments: 36
Date: Apr 06 '21
Time: 11:08pm
» Read last comment
Attached by:
Attached by: stent
stent
in Electrical
Views: 1844
Comments: 36
Date: Apr 06 '21
Time: 9:58pm
» Read last comment
Attached by:
Ken2.7
in Electrical
Views: 1030
Comments: 33
Date: Apr 04 '21
Time: 2:38am
» Read last comment
Attached by:
LumaWJ
in Electrical
Views: 247
Comments: 4
Date: Apr 01 '21
Time: 8:38am
» Read last comment
Sponsors

Who is online

Users browsing this forum: No registered users and 15 guests