startup voltage

[odieub]

well i think my starting problem may be do the battery voltage at start up when cold turn the key on drops to 11.2 with glow plugs on down to about 10.5 when cranking. just what does it need neither battery is bad but 1 is weaker that the other considerably. any ideas.

[vitalidle]

Yeah you have a weak battery dragging the good one down then. You need 10.5 volts for engine to fire.

[720Deere]

That sounds about right with glow plugs and AIH on the 7.3. My 6.0 drops to 11.2 and sometimes lower as long as the glow plugs are on. It is 12.8 usually with no draw. If one battery is weaker than the other that can cause problems. Make sure you replace then as a pair when the time comes.

[mschn99]

Originally Posted by odieub

well i think my starting problem may be do the battery voltage at start up when cold turn the key on drops to 11.2 with glow plugs on down to about 10.5 when cranking. just what does it need neither battery is bad but 1 is weaker that the other considerably. any ideas.

sounds to me like weak batteries.....with the glow plugs on..i would want battery voltage cranking to be at least 11V...