I would like to chime in and share my experience with tuning various cars... with my Alarm, GPS and a few other gadgets battery in my car is ran down quickly. On a cold-start, cool (50F) morning after 2 days of sitting I am already at 11.3V with a mediocre lead acid battery. I've seen resting voltage in the 11.8-12.2 range with stock S2Ks with them just sitting overnight.

Once cranking is initiated with AEM infinity it will crank for 1.2sec until AEM infinity syncs. Add another .6-.8sec for it to catch and finally start. During this whole time the battery is steady at 9.1Volts.

I can confirm that with ultra-large injectors on OEM ECU and Emanage and now AEM Infinity it's the same. I've gone through 4-6 batteries since I bought the car in 2006.

I am sharing this experience so others know that below 10Volts does not seem to be indicative of a bad battery from my experience. Maybe an abused one like mine that I run down so badly all the time. Also that AEM Infinity (in my case with my own tune) will fire just fine even with 9.1V at crank.

P.S. Just in case I carry a lithium jump starter and only once had I needed to use it with AEM Infinity and that was because I left the lights on for 24+ hrs.

P.S. 2.0: In case folks wonder how long before car can't start, especially with AEM Infinity, it's roughly 3.5-4 weeks from my experience. That's with my tracking gadgets slowly draining the battery.

PS 3.0: If, after a hot restart, you are cranking for that long and battery V drops to the above mentioned voltage, then I am with the rest of the S2KI crew that something is off.

 

If not your battery or grounds it sounds like a starter to me btw.