This post is to replace the one in the tech folder that has a broken link.

Sometimes it is not obvious that you have a battery problem. Because of this, I own a load tester. It is a GREAT tool to have. If you do not have one, the auto parts stores will be glad to test your batteries.

Once you have identified that you have even one bad battery, it is advisable to replace both batteries unless the one good battery is relatively new. Since the batteries are connected in parallel, if one battery has been bad for awhile it most likely has resulted in the other battery carrying a bigger load and shortening its life. If you only replace one battery at a time, you MIGHT get into a vicious cycle of frequently replacing a battery and may even get stranded. I know some people disagree with this, but this is just my experience and opinion.


Replacing batteries:

• Connect and tighten the terminals just enough so the battery does not move. Over tightening could crack the battery case.

REMEMBER:

Procedure (from the manual) for un-hooking dual batteries (both at the same time) is:
1) Disconnect the black, ground cable at Secondary Battery (LH).
2) Disconnect the black, ground cable at Primary Battery (RH).
3 Disconnect the red, positive cable at Primary Battery (RH) – then wrap insulation material around it.
4) Disconnect the red, positive cable at Secondary Battery (LH).
5) Remove old batteries and replace with new ones.
6) Reverse this procedure for hook up.

Procedure (from the manual) for un-hooking dual batteries (one at a time) is:
1) Disconnect the black, ground cable at Battery.
2) Disconnect the red, positive cable at Battery – then wrap insulation material around it.
4) Remove old battery and replace with new one/
5) Reverse this procedure for hook up.

Also (from what I have read):
If you ever have something happen that drains batteries like leaving lights on, keeping key on listening to radio for more than 4 hours, or having a failed alternator, you MUST charge them with a charger to get them back to full charge .... and restore their potential for full lifespan. The "I'm gonna drive to the store to charge up the battery" deal DOES NOT WORK!!! Alternators do not keep voltage high enough to bring back a weakened battery. Alternators can not have increased voltage level without also having increased amperage. High voltage and high amperage would dry out the electrolyte and cause failures for that reason. A battery charger on a lower level for 24 hours or more will do a great job of restoring battery as it has the higher voltage needed for restoration but with limited amperage.
Do this AND clean your terminals twice per year as a PM practice and you'll spend a lot less on batteries.

 

Good instructions and tips.

I just had to replace my batteries. I bought the Die Hard Platinum AGM batteries. Each is 930 CCA, full replacement for 4 years, prorated after that for another 5 years. They are Mil Spec but on the expensive side.

 

Great info on disconnect and hook up. I am trying to find info on proper maintenance charging for my 04 6 liter with dual battery's. I have Battery Tenders on my Bayliner, Yamaha ATV, Harley, and Kubota. I bought a dual port Battery Tender and thought I might as well put on the truck, but dont know enough about how they are wired, or which one to hook up to. Are there any previous post on the subject or wiring diagrams so I can see how the battery's are tied together? The batterys are good, I just am not using the truck much this time of year. Thank in advance for any help.

 

Batteries are wired parallel (+to+ and -to-) with no type of isolator. This keeps the system at 12v and combines the amperage of both batteries. You can wire the battery tender to either battery and it will service both of them. If the Dual port tender is designed to charge two batteries at the same time be sure to read the manual and see if it's ok for the two outputs to be connected to each other (I'm thinking it's not ok) They will "see" each other through the battery cables.

 

You're gonna love those. After a couple of years, mine still sling the motor around when the temps are below zero. My injectors aren't always so happy about the cold though.

 

My batteries died and I unhooked them to charge, when reconnecting the dual batteries I read it said LH or RH is that from the drivers seat view or standing in front of the truck view? And would someone tell me what order to hook up I am confused and a little paranoid as this is the first time I have done this.

One more question on batter charging if I charge the batteries on a charger does the charger know when to shut off? I mean if I leave it on for a day or two will they over charge or do most chargers stopp charging when full? I think mine the green light blinks on and off that means its done? what if it does that at like 2am at night do I need to run out there and unhook it or is it says to leave untill the morning?

 

Left hand side of truck is the drivers side and you can hook up either side first.
The type of charger you have will determine if it can be left on indefinitely or not. Read the charger manual.

 

I just replaced my two Costco batteries in less then 2 years. I had bench charged them several times without much improvement. Both Motorcraft and Costco's Kirkland brand are mfg'd by Johnson Controls and weigh about the same for lead content.

I too, pulled only one out at a time to maintain a constant 12v's to the system. I'm only charging at 13.8v and would hope to see up to 14.2 or so. Maybe my next step is to replace or rebuild the alternator.

More testing first.

Costco was very good at returning. No questions asked with a 3 yr free replacement.

 

The appropiate charging voltage will vary with tempuature.

 

So my batteries died on me a few months ago. I replaced both batteries because I assumed they were bad because they were very old. After a couple months my battery light came back on and my batteries ended up dying. I then replaced the alternator with a TYC 110 amp alternator. I have a single alternator system. I had the batteries recharged and after a couple months again my battery light came on. It was strange, when I accelerated past 2000 RPM the battery light would go away. Almost as if the alternator would produce enough power to charge the system when I was accelerating past 2000 RPM. As soon as the RPM drop below 2000 the battery light would come back on. Then a couple days went by and the batteries died again. AAA came and jump the batteries and said my batteries werent getting any juice from the alt at idle. Do you think I received a faulty alternator or is there something else that could be causing this like bad cables.

There is no corrosion on the battery connectors and no visible worn wires. The truck only has 80,000 miles. obviously everything is very old. Any info helps thanks!

 

Dude, you are posting all over the place; it gets annoying.

 

Sorry Im new I didnt know which forums were active.

 

Different forums are not bad, but when you start to post in multiple threads in one forum .......

Most of us look at new threads; if you are going to get a response, you will.

 

I understand. I apologize.

 

No apology necessary. Newbie mistake.