Required

Well, it does require two batteries to start any diesel due to the high compression ratio. It burns fuel with the compression stroke of the engine instead of Sparkplugs. You could turn a diesel over with one battery but it would wear out in no time. They are connected in parallel to do the job of starting. So around 1450 amps to start Reliably for years to come.
Steve

 

good to know

 

On my old LB7, I had a very loose battery connection that was causing only one battery to truely do the starting. It did it, but only if it was above 40*F outside! It would crank slowly and longer before I found the problem (dealer f'd up when they put injectors in it I guess). With two batteries back on, the thing spun and started like it was supposed to.

 

ok, great info - thanks!

I was thinking that even high compression engines use a different starter but single battery... but my head was stuck in gasoline engines!!! I just looked up the CR and this puppy was *reduced* to 16.8:1 <WOW>.

Thanks once more for the info!

Now... about installing an isolator so that if there's a short you can limp on one battery...???

 

16.8 is the lowest of all the D-max engines I believe

 

I read that oo. Was a tick over 17:1 IIRC. BTW, are those dyno numbers on a stock LMM at the rear wheels?

 

battery question

The Do_G_ out side needs 480 amps to turn the motor over and 220 amps to keep it rotating. Probably at 60*F so make it colder and older and add in thick oil. The air intake heaters draw about the 220 amps as well that is why the lights dim and cycle when it is warming up. IF you are interested multiply that by 12 Volts and see where the watts come to? amps x volts = watts , 746 Watts = 1 hp I don't know what the electrical particulars are for the 09 5500 outside.

 

ok, so that's a draw of 480 + 220 + 220... just 920. I've had 1000CCA batteries in my cars before, so it sure sounds like you could just do it with one battery. The CCA is just a quick burst and not anything sustained, but I'm guessing they found better reliability with two batts than one... thinking about it some, what are the CCA and Amp/hr ratings on the stock batts? I'll have to look in the morning.

 

You can not forget about the glow plugs, them thing draw a little juice too..

 

I know guys with twins in their trucks have to remove the passenger battery. I dont know if they relocate the second battery or just run with one. You can ask IdahoRob about that since he came out with a twin set-up. In the cold I would think it is required to have 2 batteries to start the truck.

 

def sounds like we're drawing a little juice!!!

 

Hey wsup, newbie here whats the letters for when you all describe your trucks...LMM, LTZ. What is mine? I have a 08 GMC 2500HD 6.6 Duramax Ally. crewcab 6.5 bed

 

you have an lmm