Lately when I start my truck it seems sluggish when it turns over, the battery doesn't seem strong enough anymore. Both batteries are almost 7 years old and I think I need to replace one or both but I'm not sure what each battery is for. I can only guess one is to run the electrical system and start the vehicle and the other is for the glow plugs. Can anyone give me a rundown as to what systems each battery supplies? Do I have to replace them both?

Thanks

Tim

 

[sm=welcomesign.gif]The life expectancy for a battery is about 5 years so i would replace both.[hr]As for the 2 battery's on what they run I am realy not shure.

 

Up in the North the battery life is longer then us in the South because the North charge the batteries. Each cell in the battery is basicly a battery. When one of the cells go bad it off-sets the rest of the cells per that battery. The truck still demands the same power from both batteries, long term problem, bad for starter, this is why starters go bad after new batteries are installed, or the starter will kill a cell in the new battery(short out.) South batteries are about 3yrs compared to the North at about 5-7yrs.Hope I helped

 

Thanks for the replys. This morning it wouldn't turn over and it's the batteries with out a doubt. I found out that it requires 2 batteries due to a higher compression ratio.

My next question is, does anyone have a preference on a type of battery? I'm looking at autolite and interstate, both have a 7 year warrenty and interstate is more expensive. I'm not apposed to price, just would like to know what other people think would be good and what to consider in a deisel battery.

Thanks again.

Tim

 

The important part of a 'set' of good batteries, is that the 7.3 needs to meet a specific RPM minimum during cranking.. If the PCM doesn't see it through the CMP (cam position sensor) it won't fire the injectors via the Injector Driver Module.. Sometimes the batteries will 'seem' OK, but if cranking a little slow (under 100 RPM min) it won't light off.. AT ALL.. Alot of batteries are made by the same company like Exide ect, and may bare a different name as to who is selling them.. The higher AMP rating or cranking AMP usually determines the higher cost and expected life.. Most will come with 18 month or better free replacement, and pro rated after that should one or both need service.. When buying batteries for the 7.3, I tell people its like buying a 'pace maker'... Go cheap, and you just never know Which ever brand you buy, or which vendor, just get the highest cranking AMP, as this will determine battery life in most cases... Group size is 65..

 

In response to your first post..


The trucks batteries are hooked in 'parallel'.. Basically meaning they are cable as one unit for a larger reserve.. But, the battery on the right (passenger side) is considered the primary, and the left (Drivers side) secondary.. You may hear that a 'text book' jump start on a 7.3 should be done off the primary side, but really isn't 'all' that critical.. Especially if your cables, or the position of the truck won't allow a primary connection, and the batteries aren’t stone dead.. The reason for it is that cranking/system draw, is pulled off the primary, (as well as system charge), and being their 'linked' in parallel, the current is being pulled from primary and secondary as reserve.. The draw is technically off both, but should one battery start to loose charge or reserve, the other battery may/will drain or be drawn down to a more 'equaled' out available voltage/amperage.. .
The batteries could be uncabled and charged individually, and load tested individually as well ,to see their specific state of charge, but if the batteries are that old, chances are their on the way out.. Or if only one was changed, it may shorten the life or available volts/amps at some point on the new one when really needed..

 

I thought they might be in parallel but I wasn't sure. The batteries are original when I bought the truck new in December 1999 and spent 4 years at Minot AFB, so I'm glad they've lasted as long as they have. Neither one has been replaced...untill today.

Thanks for the info on how the battery system works, this is they type of stuff I need/want to know. Where can I go to get this type of info on other or all systems of my truck? I'm used to doing most/all maintenance on my F-150 but I've never owned a diesel until this vehicle and havn't had anything go wrong with it until now.

Well I'm off to get a set of batteries with the hightest cranking amp from a diesel place, I figure this place has a better knowledge level and can help me out better than any auto parts store down the road. Maybe I can pick their brains and get more knowledge too...

I'll post back and tell ya how it goes.

Thanks

Tim

 

I bought 2 Group 65 750 cold cranking amp batteries (same thing I took out), installed them, and started her up with no problems. Thanks again to everyone, I've even learned how the batteries work in my truck, my wife will be happy (since she drives it all the time). Just one more question: Where can I go to get this type of info on other or all systems of my truck?

Tim

 

I would buy a repair book at the auto part's store,[hr]Or book store.[hr]Either Chilton's manual or Haye's are good.

 

I had one of those manuals for my F-150 (can't remember which) and it was great. Is there anything better?

Tim