After 45 years of driving Chevy, Ford and Toyota, I just bought my first Diesel. 2003 Dodge Ram 2500 HO. I thought I had read up, at least a little about diesels, but there's so much I don't know and understand.

Boy, I love this tryck!

Just curious...Why does my truck have two batteries?

 

Big Motor, high compression, relatively thick oil, variable operating climates = 2 batteries.

All diesels - Chevy, Ford, Dodge have 2 batteries (unless they have that monster battery I seen somewhere on the net - sorry no link).

 

Everything that he said...you need a really big starter to turn these babies over...check the price on them sometime. :-

 

The grid heaters take a lot of amp's. That the reason, I think it is like 95 or so amp's drawing on the batteries for 5 to 30 second's If you just had one battery i think you would kill it in a very short time.

 

[quote author=DodgeRamCO42 link=board=17;threadid=20174;start=0#msg189543 date=1064549977].................Just curious...Why does my truck have two batteries?
[/quote]

I see you live in CO., and maybe being unfamiliar with diesel operation, I'm going to be a little lengthy. You'll be using the preheaters a lot during the winter. Below 50[sup]o[/sup], the "Wait to Start" light will glow for a few seconds. As the temps get colder, that period will increase in duration. As an example, at 0[sup]o[/sup], without a block heater, the light may stay on for over 30 seconds. During this period, a toaster like element heats the the intake air, so when you crank the engine, that hot charge is drawn into the cylinder aiding initial combustion. The batteries need to provide all of the current necessary for preheat, as well as the starter. As the posters before have said, it's a substantial amount. When temps fall below freezing or so, you can help things along by using the block heater for a few hours prior to starting. This will greatly conserve the battery drain and make starting much easier. But it's nice to know the Cummins engine will start in -0 [sup]o[/sup] temps without the block heater with a couple of preheat cycles before actually cranking the engine. Brace yourself for below 0 starts. Even that quiet 03 engine won't sound too good when it fires up. There's nothing wrong, it just sounds like heck!

 

Good Day!
The starting motor is 24V. You have two 12V lead/acid batteries -- in series (when starting) they provide the greater voltage needed.
If you were to have a 12V motor, the starting amperage would be prohibitively high -- too hard on one[glow=red,2,300]big[/glow] 12V battery.
You have two 12V for this 24V starting system so that you can otherwise run 12V stuff, e.g., the radio, etc.

 

[quote author=Pickle link=board=17;threadid=20174;start=0#msg189837 date=1064620047]
Good Day!
The starting motor is 24V. You have two 12V lead/acid batteries -- in series (when starting) they provide the greater voltage needed.
If you were to have a 12V motor, the starting amperage would be prohibitively high -- too hard on one[glow=red,2,300]big[/glow] 12V battery.
You have two 12V for this 24V starting system so that you can otherwise run 12V stuff, e.g., the radio, etc.

[/quote]

Wow if this is so the Cummins is different from the Fords. I thought the batteries were in series?? ???

 

The starting system is 12 volt, not 24. That, and the toaster grid in the intake, (as Commatoze pointed out) is why there are two batteries. Gotta have a lot of amps to crank the high compression diesel, and you've just been wasting them running the toaster. My work truck has a bigger engine with an intake heater grid like the Cummins, and it uses 3 batteries in parallel to get cranking.

 

That's an important point "wanna". They're in parallel, not series, so you get 12Volts with a mondo current supply.

Pickle, slide underneath and check out the size of the starter. It's a monster.

 

Wow! got my truck on Thursday & my eyes were so drawn to that nice looking engine under the hood that I didn't notice the second battery on mine ;D

Once I read it here I had to go look and there it is!

Z....