Two Batteries?

[AMcCormick]

I'm assuming that the two batteries are needed due to the high compression. Is this correct? Also if I were to need a jump start or jump start another truck would it matter which battery was used?



Thanks



Andy McCormick

New to me, 03 reg cab long bed, 4x4, 3. 73, Bully Dog torque dog

 

[B.G. Smith]

Yes the two are for the task of turning the engine for startup. OPretty good load especially when it is really cold. The batteries are connected in parallel and should not make any difference which one is used to jump strart another vehicle. When jumping another vehicle it is good to let the truck idle a few minutes after you hook up the cables to allow the battery in the vehicle being started to charge a little, also the jumped vehicle should not race the engine when started and still hooked up as it can put a high load on the alternator. bg

 

[AMcCormick]

Thanks just wanted to make sure I wasnt missing something

 

[Allnew2Me]

The starter is actually a gear-reduction starter that doesn't need two batteries to turn, but the grid heaters draw around 80 amps and that is the real reason we need two batteries. They cycle on and off when it is cold.

 

[DieselDoghouse]

I don't mean to horn in but—since I've seen posts about guys using one battery in the summer there may be more to the story. Yes our reduction starters do need juice—but I've started mine on one battery. HOWEVER, those intake heaters can draw 150—200 Amps during warmup (don't quote me-somebody correct that number if I'm wrong) and this persists for 3 minutes when cold or until the engine reaches 1800 rpm or 19 mph. Its the combination of the two that mandates 2 batteries.

 

[DieselDoghouse]

What allnew2me said and yeah - 150 - 200 sounded too high!!

 

[ekroman]

Not to confuse anyone, but First Generation trucks use only one battery (from the factory). When I got mine, it had a puny little car - like battery in it. I replaced it with a big truck battery from Batteries Plus, I want to say it's a group 31 battery.



Eddie

 

[JFaughn]

About jumping , 1st you need to run truck at high idle to get some charge into the dead batteries , alt does not do anything if the jumping truck has got fully charged batteries , regulator senses that batteries are charged & does not turn on alt till it sees a low charge or high load , the good batteries in the jumping truck will act like a buffer to regulator .
Next is after some minutes of charging , turn off running truck , when jumping truck starts it senses the low batteries & full field the alt , this sends a surge though anything that is connected , with the key turned off in the jumping truck its an open , so no suge , the surge can cause issues , alt , computer ect .
You could end up with 2 trucks with problems .

 

[Vaughn MacKenzie]

I've gotten away with 1 optima in each of my trucks. I found out that 0 degrees is about the crossover point between starting and not starting without plugging in the block heater. I had 15w40 dino oil in the sump.

 

[tgordon]

I belive the standarn issue for the second gen is two group 31's. I have seen where people have gone to a single larger battery to get away from the second under the hood, IMHO it is easier to find a spot for two small batteries than one large one. For charging I have been told one should put the + on one battery and - on the other so both take charge rather than only one taking the charge if both are hooked to the same battery, I do not personally worry about this.

 

[IanF]

I belive the standarn issue for the second gen is two group 31's.

According to all of the battery application guides I've found, the 2nd gen CTD trucks take two group 27's, which is a somewhat rare battery size. A bit larger than the common 24 and usually with a higher CCA rating. The only brand Pep Boys carrys in that size is Bosch and the only ones with the spec'd CCA Rating is the Bosch and the larger Optima Redtop. Of course, the Optima is about 2x the price of the Bosch...



My truck came with mis-matched brand/size batteries... a 24 and (I think) a 74... seems to start fine... although I eventually plan to replace them with the Bosch 27's.

 

[FLynes]

I just replaced my batteries with OE Mopars. I paid $110 for the both of them, which I consider a decent price, considering the price of one Optima. I've already toasted one Blue Top Optima in my RV this year... . #@$%!

 

[DieselDoghouse]

If you need to put one jumper cable to each battery then you have a wiring problem—the 2nd gen trucks (probably others too) have a large (#2) cable strapping the positives together—they are one battery electrically. The grounds are strapped together through the truck frame (I assume Dodge got THIS ground right). Anything you do at one battery replicates at the other. I have always attached my ground to hard metal rather than complete the circuit above a battery where there may be hydrogen gas, its from the old days before Optimas but I still do it!

 

[tony597fitter]

According to all of the battery application guides I've found, the 2nd gen CTD trucks take two group 27's, which is a somewhat rare battery size. A bit larger than the common 24 and usually with a higher CCA rating. The only brand Pep Boys carrys in that size is Bosch and the only ones with the spec'd CCA Rating is the Bosch and the larger Optima Redtop. Of course, the Optima is about 2x the price of the Bosch...



My truck came with mis-matched brand/size batteries... a 24 and (I think) a 74... seems to start fine... although I eventually plan to replace them with the Bosch 27's.

My buddy paid $100. 00 for EACH Bosch battery at Pepboys. I just picked up Optimas for $132. 00 each.

Not much more for a better battery.

 

[rbattelle]

The starter is actually a gear-reduction starter that doesn't need two batteries to turn,

Just to clarify, 2003-up trucks don't use a geared starter in the diesel. I don't know about pre-2003 trucks.

Service manual says warm-engine cranking amperage is 400-700. Cold conditions, new engine, or heavy oil (read: 15W-40) will require more current.

I've always figured that the diesels with 15w-40 conventional oil at temperatures below 32°F are drawing more than 1000 amp on startup (just a guess).

Each factory battery on a 3rd gen is rated to 750 CCA. Based on how mine sounds starting up below 20°F without block heat, I'd say it's drawing just about the whole 1500 amp from the batteries.

Vaughn's experience with starting on 1 battery at 0°F would seem to confirm the need for >700 amp at the starter during cold conditions with 15w-40.

Also, per the 2003 manual (again, I can't speak for pre-2003 trucks), each grid heater runs ~95 amp. So we're talking about something close to 200 amp to run both grid heaters simultaneously. (Of course, duty cycle reduces significantly after startup).

Ryan

 

[WKruger]

Huh what! Not calling you a liar, but they used gear reduction starters since Dodge used Cummins. Remember how much fun the direct drives were?

 

[fstfish66]

pepboys and auto zone in my area,are about the same price on group 27 batterys,79. 00 each,,walmart is 59. 00 on the MAXX brand 750 cca,, i run the MAXX brand in both my hot rods 1000 cca and one car sits in a trailer most of the year,,,great batteries,,i just hate walmart,,,

 

[AABEN]

I use 2 1000 cca in my 03 and 1 in my 89 all starts here in IN. at 20 to 30 below with out pluging in.

 

[fstfish66]

my batteries in my 20 are orignal, going on 6 years,,im now looking to replace the,,just to be safe,, the guy that said he paid 110. 00 for bot ha mopar. . wonder if he got them at a dealer,,,,or how ??

 

[FLynes]

fstfish66, I got them at the dealer... they had those rebate coupons on the counter too, which would have given me $10 off each, but I'm too darn lazy to fill that crap out and send it in.