• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Electrical 1990 GT battery drain...

  • Thread starter Thread starter 2007_Crown_Vic
  • Start date Start date Apr 12, 2021
Prev
  • 1
  • 2
  • 3
First Prev 3 of 3

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
3,432
1,524
194
Maryland
Feb 16, 2022
#41
  • Feb 16, 2022
  • #41
The alternator is an upgraded 3G setup. I'll disconnect the alternator wiring and see if it has a measurable effect on the milliamp draw. Although I'm not sure if the 3G has the same potential to create these problems as the stock alternator.
 

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
3,432
1,524
194
Maryland
Feb 16, 2022
#42
  • Feb 16, 2022
  • #42
manicmechanic007 said:
50 to 85 milliamps is one spec for draw on a car like yours 200 is more like a new lincoln with 5 modules and a radio
Click to expand...

wait a sec, mine was drawing 20, not 200

That is after I removed all the interior bulbs so I could keep the hatch open while testing. It has a rear mount battery setup
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#43
  • Feb 17, 2022
  • #43
John,
Then your battery should hold for 10 to 14 days without a tender
And if it does not then the battery gets replaced even if it is a week old
 

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
3,432
1,524
194
Maryland
Feb 17, 2022
#44
  • Feb 17, 2022
  • #44
manicmechanic007 said:
John,
Then your battery should hold for 10 to 14 days without a tender
And if it does not then the battery gets replaced even if it is a week old
Click to expand...
Okay thanks. So, if I have the battery connected, and I begin with full battery 12.6v, after 14 days, what voltage reading would still be considered acceptable?
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#45
  • Feb 17, 2022
  • #45
Anything over 10.6 should crank slow but start the car
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,901
10,555
203
polk county florida
Feb 17, 2022
#46
  • Feb 17, 2022
  • #46
Keep in mind that a slow crank situation will cause wires, connections and starter overheating and damage stuff.
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#47
  • Feb 17, 2022
  • #47
I would really just like to see you drive it more
I have a van I do not drive much and it goes through batteries
Same with my Corvette. They just need driven and none of that bad stuff happens
Once they get down below about 10.5 it will start turning on lights like the abs and air ride
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Feb 17, 2022
#48
  • Feb 17, 2022
  • #48
2007_Crown_Vic said:
So after a day of sitting it was down to 12.61V. About 8-10 hours later it was down to 12.55V. About a day after that it is at 12.5V. I will check one more time tomorrow morning, but it looks like it has more or less settled in around 12.5V if it only lost 0.05V in a day of sitting. So while it may not be perfect, I think the battery is at least decent, certainly good enough for starting a car in warm weather at least.

So I will keep looking around, mainly at the immobilizer and keyless entry/alarm system to see what I can figure out. Those areas seem to be the most likely to be causing this drain I think.
Click to expand...
That the battery has not lost a lot of volts sitting there is not the same as a load test that helps see if it has any CCA or reserve power. At that low level of drain, I suspect you have two problems: 1. A weak battery 2. A small drain.

Please do the following:
Charge it up, hook it up, and get it to the FLAPS or Interstate battery dealer where the battery can be load tested and the charging system verified good.

The last battery I replaced in a car was charging up fine, but after sitting for 4 days would read good voltage, AND did not have enough amps to do more than make a horrible, repetitive clicking noise under the hood. It would charge up and run again. But it would do the same dying thing if parked. When “cranked” on a full charge with the tester, the load would pull the voltage down to 8.?v and it rebounded only partially. They warranted it and it’s great now.
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#49
  • Feb 17, 2022
  • #49
7991LXnSHO said:
That the battery has not lost a lot of volts sitting there is not the same as a load test that helps see if it has any CCA or reserve power. At that low level of drain, I suspect you have two problems: 1. A weak battery 2. A small drain.

Please do the following:
Charge it up, hook it up, and get it to the FLAPS or Interstate battery dealer where the battery can be load tested and the charging system verified good.

The last battery I replaced in a car was charging up fine, but after sitting for 4 days would read good voltage, AND did not have enough amps to do more than make a horrible, repetitive clicking noise under the hood. It would charge up and run again. But it would do the same dying thing if parked. When “cranked” on a full charge with the tester, the load would pull the voltage down to 8.?v and it rebounded only partially. They warranted it and it’s great now.
Click to expand...
Classic failure example +1 for Interstate
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,901
10,555
203
polk county florida
Feb 17, 2022
#50
  • Feb 17, 2022
  • #50
manicmechanic007 said:
Classic failure example +1 for Interstate
Click to expand...
Yeah, Interstate batteries are just horrible. That's why I have one in everything I own, well cept the toyota, that cheap ass battery is still working.
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#51
  • Feb 17, 2022
  • #51
It's kind of hard to find Interstate brand around here
Tunex and a few independents is all
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Feb 17, 2022
#52
  • Feb 17, 2022
  • #52
General karthief said:
Yeah, Interstate batteries are just horrible. That's why I have one in everything I own, well cept the toyota, that cheap ass battery is still working.
Click to expand...
I hope punctuation was missing and 007 was agreeing with me.
Interstate batteries are good. They still need a warranty as lead acid batteries have a high failure rate, especially for the price.
 

manicmechanic007

5 Year Member
Sep 26, 2017
2,531
713
143
Roy, Utah
Feb 17, 2022
#53
  • Feb 17, 2022
  • #53
Yes I agree
 
Reactions: 7991LXnSHO

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Feb 21, 2022
#54
  • Feb 21, 2022
  • #54
I found the privately owned FLAPS that sells Interstate batteries. I asked about a good battery for my Merc. For an Interstate battery, 850 CCA, three year flat warranty, $165. No more prorated extended warranties.
The local Napa store’s batteries are also flat rate warranties.
@Noobz347 and @General karthief etc. where are you getting the 7 year (84 month) warranty batteries now???
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,024
21,205
234
Box behind Walmart
Feb 21, 2022
#55
  • Feb 21, 2022
  • #55
7991LXnSHO said:
I found the privately owned FLAPS that sells Interstate batteries. I asked about a good battery for my Merc. For an Interstate battery, 850 CCA, three year flat warranty, $165. No more prorated extended warranties.
The local Napa store’s batteries are also flat rate warranties.
@Noobz347 and @General karthief etc. where are you getting the 7 year (84 month) warranty batteries now???
Click to expand...
Dealerships, I get mine from the GMC dealership down the street.
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,901
10,555
203
polk county florida
Feb 21, 2022
#56
  • Feb 21, 2022
  • #56
I haven't seen a 7 year battery for about 5-6 years now.
 
Reactions: 7991LXnSHO
F

Fri Guy

15 Year Member
May 10, 2007
435
259
83
Mar 11, 2022
#57
  • Mar 11, 2022
  • #57
I had a similar issue when my battery was moved to the rear. I had to add a good ground. Check your grounds.
 

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
3,432
1,524
194
Maryland
Mar 14, 2022
#58
  • Mar 14, 2022
  • #58
My grounds are good and are over engineered actually.

I just got three of these Foval float chargers from Amazon. They are cheap and work great as a true float device. Read the first review written by the engineer. I have verified they work just like he describes. I already mounted one under the hood on the wife’s 2013 Escape since she hardly drives it. I’ll be mounting one in the rear mount battery box in the 92 LX as well. I’ll just unplug the wire from the hatch latch so the interior lights won’t come on when the hatch is open. While it’s in the garage sitting, just pop the hatch and plug it in. I’m also gonna install a cig 12v power outlet in the battery box. I have one of those compact lithium jump starters and I’ll keep it plugged in to the outlet in the battery box. It will always be there, fully charged if needed.

Here’s the Foval

Amazon product ASIN B074Z2NFWWView: https://www.amazon.com/dp/B074Z2NFWW/ref=cm_sw_r_sms_api_glt_i_dl_JWPB1MNZDWBBZMDH72ME
 

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
3,432
1,524
194
Maryland
Mar 14, 2022
#59
  • Mar 14, 2022
  • #59
Here’s the Foval installed in the 2013 Escape. Believe it or not since new it’s had a defect in the sunroof motor which causes a parasitic draw of 200 milliamperes. I got tired of remote starting it every other day just to keep the battery up. So that, and the fact it doesn’t get driven enough is the reason for the float charger install.

On this install I have it wrapped in a ziplock baggy to provide some moisture protection. Don’t worry about it overheating because it’s only a 1 amp trickle max and hardly develops any heat.

The cord peeks out of the cowl for easy connection. The position of the charger even lets me monitor the status lights through the body seam when the hood is closed.

 
Reactions: General karthief and 7991LXnSHO
Prev
  • 1
  • 2
  • 3
First Prev 3 of 3
You must log in or register to reply here.

Similar threads

J
1990 fox starts on starting fluid only
  • Jfox
  • May 14, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
9
Views
189
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 15, 2026
AeroCoupe
Electrical Ron Francis Headlight / Alternator Harness
  • dan50
  • Apr 30, 2026
  • Fox 5.0 Mustang Tech
Replies
0
Views
208
Fox 5.0 Mustang Tech Apr 30, 2026
dan50
F
Alternator Not Charging
  • Fri Guy
  • Aug 29, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
410
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 31, 2025
AeroCoupe
S
All power lost at crank
  • saf_blu302
  • Mar 7, 2026
  • 1994 - 1995 Specific Tech
Replies
4
Views
230
1994 - 1995 Specific Tech Mar 12, 2026
General karthief
Alternator not charging
  • SchwarzStock
  • Jul 6, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
1
Views
45
1965 - 1973 Classic Mustangs -General/Talk- Sunday at 4:07 AM
apple99Mustangdude
A
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?