1 battery or 2, 12V

[gnicholson]

2 guage has an amperage capacity of about 150 amps at 10 feet with a voltage drop of 2 percent. a typical gear reduction starter will draw 150 amps 250 to 300 for a direct drive unit. remember this is for a fully charged battery. as the battery discharges amperage goes up.

[1320racer]

You don't need 16v but without question you should change out the cable to 1/0. If it's still hard to start, the next culprit is your starter. Whose starter and model are you currently using?

That said, I run two 12v batteries in my dragster and my door and always have because they were built for 2 batteries.

[1legjerry]

Battery cables should also be changed out every 5-10 years also. It is getting hard to find good wire and it will go bad. You should also check the terminals on the cables too make sure they are tight. I would suggest doing a voltage drop test on your starter/battery circuits a couple of times a year. It should also be the first thing you do when you are having a starting issue.

[FED 387]

If you use 2 12 volt batteries you can wire the car so that the starter gets hit with 24 volts and the rest of the electrical system is ONLY 12 volts------Ever listen to Greg Andersons Pro car when he hits the starter ??? Cranks probably at 500 RPM(LOL)- It starts RIGHT NOW !!!!Most pick up truck diesels use 24 Volts to start while the rest of the electrical system remains 12 volts ---- You don't need the weight of 2 big 16 volt batteries or even 2 "large" 12 volt batteries to accomplish this if you do it this way---FED 387

[DailyDriverSst]

The battery cables are about 3 years old. The connectors are copper plated and the wire is 100% copper. The connections were crimped first, then soldered.

The issue isn't that the engine spins over slow (at least, at first). It's that it takes about 30 seconds of spinning before it starts to cough and start firing. About that time is when the starter slows down and it gets into a low voltage situation where the fuel injectors won't fire with the starter spinning. If I'm lucky, i can keep it spinning fast enough that when i release the starter, the injectors will start to fire while it's spinning down and it will start running on it's own. Usually that isn't the case. (Also, the whole starter/injector conflict is common on all the 97-05 dodge trucks. The low voltage cutout for fuel is somewhere around 11.25, spark cuts out around 10.5).

Even though it's on pump gas, it's starting ability is up there with a low compression N/A alcohol engine. It just doesn't like being cold.

I'm considering adding a 120VAC block heater over winter to help get the engine warmed up a bit, but I'm also considering adding the second battery so that I can keep spinning it over until it catches at full speed. With a group 75 battery one would think there would be enough reserve to last longer than that, but it's also a 4 year old battery.

[1320racer]

whose starter?

[Tom Goldman]

Your issue is not uncommon amongst EFI cars .
I have a lot of EFI stockers come thru the shop and it is something I've seen happen on several older built cars .
I am defiantly a proponent of dual batteries , the reserve they offer comes in handy when going rounds with minimal time to charge the batteries . ... . Running an alternator is a must with any EFI car to keep the voltage above 12.5 v.
Two areas that are overlooked are grounding and master disconnect switch .
I see many cars with no ground wire between the frame and engine or battery grounds bolted to the sheetmetal floor.
I have seen 2 cars this year with problems due to disconnect switches with high resistance /voltage drop issues. ….look at the amp rating of the most common disconnect switches with 3/8" studs ,most are only rated for 125-150 amps intermittent {starting} current . while the heavy duty ones from Moroso or Flaming river are rated for 1000 amps or higher intermittent current.
One last thought regards the wiring of the ECU itself . Holley in particular is adamant about having the ECU connected directly to the battery with no interruptions.