Engine/Transmission (1998.5 - 2002) Batteries, IOD, or what?

[Ramtuf1]

Batteries were new last February but I have had problems with low battery voltage after cycling heaters once so truck starter wouldn't spin fast enough to start. Now I have read almost all the posts on batteries but I have two Car Quest installed (series 27, 820 CCA @32 deg F/670 CCA @0 deg F). Supposidly made by Exide



If I let it sit two days or on a few occasions, over night, I can't start the truck. Now we have had our run on cold weather and if I leave it plugged in, will most likely start but not with a lot of ooomph. I have reviewed the service manual in the battery section (8F-16) and it indicates that if the "IOD" (Ignition-Off Draw) is over 35 milliamperes, the problem must be found. But, if you look at their chart and total up the current draw of each of the modules, it is in excess of 100 milliamps. I also waited over an hour monitoring the draw to see if it drops off in the case of the modules going into a sleep mode.



I am seeing 120 milliampere draw even after an hour. I don't see where the "IOD" drops down to less than 35 milliampers. Is this a problem? The chart shows N/A for all the modules indicating that none of them use a sleep mode. I had a diesel mechanic tell me that it will go into a sleep mode after about 15 minutes. More confusion.



In most all of the forums on batteries and charging, I haven't seen any mention of the "IOD". Can any one help me. I am not sure if I need to scrap these one year old batteries and get the red topped Optima's or what.



I have never had any problems with starting since I have owned the truck new. If it doesn't start, it only takes a half hour on a small charger to get the job done and get her fired up. It is good for the rest of the day then.



Help!!!

 

[WestTN]

An eigth of an amp draw isn't going to be significant over night, or a month for that matter. You may have batteries with inadequate storage capacity, a charging problem, inadequate run time or some other draw that is depleting the batteries. My batteries are size DT34's bought at Sam's Club. I'm not familiar with the size you listed.

 

[AKAMAC]

Try pulling the neg. terms. off after driving it around for a while, check voltage of each then let sit overnight. Check the voltage of both units in the AM. The voltage should be VERY close to what you had the night before. I'll bet you have a bad cell in one of the batteries.

 

[Bob4x4]

An eigth of an amp draw isn't going to be significant over night, or a month for that matter. You may have batteries with inadequate storage capacity, a charging problem, inadequate run time or some other draw that is depleting the batteries. My batteries are size DT34's bought at Sam's Club. I'm not familiar with the size you listed.

Group 27 is standard on 2nd gens



Bob

 

[Ramtuf1]

I agree that an eighth of an amp when you are looking at two batteries of that size in parallel is nothing. That is what I thought but I just wanted to see if for some reason it was getting pulled down over night or over two days especially in this cold. As for one of the other comments, I did remove the negative terminals and let them set over night and then checked them in the morning and the outside temperatures were in the teens. It was 12. 6 volts on each and they only dropped a few millivolts while sitting disconnected. I reconnected them and they did start the truck but again not with much to spare after cycling the heaters.



Yes, the Series 27 is what DC calls for in the 2nd generation truck. I just might have to bite the bullet and get some new ones. It seems that when the heaters cycle on, the voltage really drops until they turn off. The charging system doesn't appear to be a problem 14. 5 VDC or so while running around as measured with a DVM in the auxiliary DC plug inside.



We are again talking batteries and I really was curious if anyone had every checked and measured the IOD on a second generation to see what it does over an hour or so. You have to make sure that nothing is on even the under hood lamp. Thanks for the replies though.

 

[Ramtuf1]

Follow up to my original post:



First of all, the "Car Quest" batteries which were a year old were Group 27 but were only 675 CCA. The Dodge truck specs are for Group 27's with 750 CCA so after a year, the batteries didn't have much reserve to fire the intake heaters and then crank the starter as fast as required in cold weather. I replaced them with Interstate Group 27-750 CCA (per specs).



Secondly: Back several years ago there was either a post or a quick article in the TDR magazine of a gentleman who changed the power window fuse arrangement so he could run the windows up and down without having to insert the key and select the "On" position. I made the mod and had good luck for years and it was a great convenience. Here is the kicker.



The IOD is supposed to be between 5 and 35 miliamps according to the manual. I was seeing about 120 miliamps. One responder indicated that that wasn't much. I agree but with my battery situation as originally faced, an overnight sitting in cold weather with just that increase of IOD took the marginal batteries to a point where I couldn't fire the truck.



I removed all the fuses in the JB and when I removed the last one (window fuse) my IOD dropped to within specs. The controlling module couldn't go into the sleep mode keeping the windows with available power. I changed back to stock and the IOD is now within specs. Temperatures are in the low 20's and the truck fires up just as when it was new.



Anyone remembering that article or post and having made the change might remember this information if they ever have any problems with drain on the batteries. The additional 100 miliamp load or so isn't a lot but is DOES make a difference when getting down to it.