Notices
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Checked batteries and have an issue.

Thread Tools
 
Search this Thread
 
Old May 23, 2011 | 01:46 PM
  #1  
glovemeister's Avatar
glovemeister
Thread Starter
|
Cargo Master
15 Year Member
Photogenic
Joined: Nov 2010
Posts: 3,244
Likes: 40
Checked batteries and have an issue.

84 Ford F250 with a 460. The batteries are of unknown age came with the truck and don't look all that bad. I'd figure no more than 5 years old. I had them both tested (have a dealer added camper splitter/isolator package) and it appeared that one is bad. Would it be feasible that the one bad battery would drain the other battery (the good one)?

Also I can charge it up and then shut down both batteries at the splitter and then go out a few days later and it will slowly turn over. I was under the impression that the camper setup totally shutdown the electrical flow. Even though said one battery tested out good could this be the isolator wearing out?

I guess the most likely scenario is that the bad battery is killing the other good one (although they are both the same type, age, brand etc. so I suspect the other one should be replaced also. ) The thing that gets me is whether or not the isolator could be causing this issue.
 
Reply
Old May 23, 2011 | 10:22 PM
  #2  
84-6.9L's Avatar
84-6.9L
Posting Guru
Joined: Feb 2011
Posts: 2,216
Likes: 0
From: Princeton MN
One battery will drain another one since they are hooked up in parallel, the vltage will equalize. One m 6.9 i had a cell short out in one battery and it pull the other one down to 8 volts
 
Reply
Old May 24, 2011 | 01:18 AM
  #3  
glovemeister's Avatar
glovemeister
Thread Starter
|
Cargo Master
15 Year Member
Photogenic
Joined: Nov 2010
Posts: 3,244
Likes: 40
Sweet good to know. One sexy truck you have btw! Since I am going to be running about 10 kc lights, would it be prudent to get one huge battery and a good amp alternator 200+ amp, or the alternator and two batteries so I can isolate one and have one fresh one?
 
Reply
Old May 24, 2011 | 01:26 AM
  #4  
84-6.9L's Avatar
84-6.9L
Posting Guru
Joined: Feb 2011
Posts: 2,216
Likes: 0
From: Princeton MN
Why thankyou sir!2 batteries will have much more reserve and cranking amps then 1.Thats why a lot of old 24v systems used 4 6volt instead of 2 12volt. The one big battery would also be alot of weight on one plastic inner fender and the 10KC lights tells me this ain't for loading groceries! its for off roading
 
Reply
Old May 24, 2011 | 01:52 AM
  #5  
ford390gashog's Avatar
ford390gashog
Fleet Owner
20 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Club FTE Gold Member
Also make sure both batteries are of the same group size or else one will kill the other off. For a high output upgrade consider a 3g style 200a alternator.
 
Reply
Old May 24, 2011 | 02:00 AM
  #6  
muscletruck7379's Avatar
muscletruck7379
Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
Club FTE Silver Member

hang on a second, if you have an isolator it is supposed to keep one battery from draining down while using accessories (such as when the truck isn't running) so that you will always have one battery to start the engine with (and will pull juice from both to start with). non isolators just hooked the batteries up in parralell (no isolator box, both batteries connected via cables. such as a factory diesel)

however, if you go to start it and it has the load from both the starter and the dead battery pulling from the one good battery, it could cause a no-start issue. I'm gonna need to do some research into isolators, as i am only relaying what i have read in catalogs and packages in the parts store, and intend on running one in my bronco. if i find something i will return.
 
Reply
Old May 24, 2011 | 02:12 AM
  #7  
muscletruck7379's Avatar
muscletruck7379
Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
Club FTE Silver Member

from wikipedia:

"A battery isolator helps to ensure that the starting battery has sufficient power to start the engine and recharge the batteries if, for example, loads on the auxiliary battery (e.g., refrigerator or navigation lights) cause it to be drained, or if an auxiliary battery fails."

a typical isolator system,


i would say that if your setup is hooked up correctly, your isolator may have a bad diode.
 
Reply
Old May 24, 2011 | 07:26 AM
  #8  
Grubbworm's Avatar
Grubbworm
Cargo Master
Joined: Apr 2010
Posts: 2,936
Likes: 9
From: Acworth, GA
Originally Posted by muscletruck7379

i would say that if your setup is hooked up correctly, your isolator may have a bad diode.

 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

10 Ways Ford is LOSING to the Competition

 Joe Kucinski
story-1

Top 6 Best Deals Available on New Fords & Lincolns Right Now

 Brett Foote
story-2

This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level

 Verdad Gallardo
story-3

Top 10 Fords at 2026 Carlisle Ford Nationals

 Joe Kucinski
story-4

3 Best / 3 Worst Parts of Modern Ford Ownership

 Brett Foote
story-5

10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

 Pouria Savadkouei
story-6

Every 2026 Ford Engine Explained

 Brett Foote
story-7

10 Ugly Ford Trucks That We Still Kinda Love

 Joe Kucinski
story-8

10 Things Every Truck Owner NEEDS (2026 Edition)

 Michael S. Palmer
story-9

Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
Old May 24, 2011 | 09:22 AM
  #9  
Skoiv's Avatar
Skoiv
Senior User
Joined: Oct 2004
Posts: 481
Likes: 3
From: Tualatin, OR
You are right muscletruck. I bet the previous owner just wired them up into parallel. That is what I did on my camper special since I don't have a camper. Lots of battery power coming from my two Optimas. And yes... a bad battery will drain the good battery. Always replace both at the same time.
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
bc4x4f250
1968-Present E-Series Van/Cutaway/Chassis
7
Apr 29, 2013 05:18 PM
Raider949
1987 - 1996 F150 & Larger F-Series Trucks
13
Dec 22, 2012 07:31 AM
bigred66
1999 - 2016 Super Duty
4
May 23, 2010 05:30 PM
cobrpassport
1968-Present E-Series Van/Cutaway/Chassis
15
Oct 25, 2006 11:52 PM
kenh123
Electrical Systems/Wiring
1
Aug 2, 2004 07:26 AM




All times are GMT -5. The time now is 03:30 AM.

story-0
10 Ways Ford is LOSING to the Competition

Slideshow: 10 ways Ford is losing to the competition

By Joe Kucinski | 2026-06-15 09:52:01


VIEW MORE
story-1
Top 6 Best Deals Available on New Fords & Lincolns Right Now

Some great targets in today's expensive world.

By Brett Foote | 2026-06-15 09:35:19


VIEW MORE
story-2
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level

Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.

By Verdad Gallardo | 2026-06-12 11:01:55


VIEW MORE
story-3
Top 10 Fords at 2026 Carlisle Ford Nationals

Slideshow: Top 10 Fords at 2026 Ford Nationals

By Joe Kucinski | 2026-06-09 11:10:08


VIEW MORE
story-4
3 Best / 3 Worst Parts of Modern Ford Ownership

Based on years of owning multiple modern Ford products.

By Brett Foote | 2026-06-09 10:53:36


VIEW MORE
story-5
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

SPONSORED: From muddy boots to rain-soaked cargo, these upgrades address some of the most common frustrations Ford truck owners face every day.

By Pouria Savadkouei | 2026-06-08 18:50:34


VIEW MORE
story-6
Every 2026 Ford Engine Explained

Here's everything you need to know about every Ford engine available for the 2026 model year.

By Brett Foote | 2026-06-05 12:58:01


VIEW MORE
story-7
10 Ugly Ford Trucks That We Still Kinda Love

Slideshow: 10 ugly Ford trucks that we still kinda love.

By Joe Kucinski | 2026-06-03 09:51:16


VIEW MORE
story-8
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-03 15:43:58


VIEW MORE
story-9
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-06-03 11:38:36


VIEW MORE