Battery wire gauge

[Katfish]

What size wire are you using from trunk to PDU/starter?

Having an issue with hot starts.
Car won't start after driving 30min and trying to immediately do a restart.
It acts like the battery is dead, won't even turn over.
Wait 20-30 min and it spins fast and starts right up.
Thought it might be a heat issue, I bought a starter thermal wrap and it didn't help.

Now I'm wondering if the battery doesn't have enough CCAs?
Does the motor/starter require more current when hot?

This battery is 3yr old with 585 CCA
2016 3G cars specs call for a 800CCA battery.

2 things:
- Thought the first C in CCA is for cold, and when most current is needed?
- I'm thinking the higher number for the later cars is for all the "other" electronics?

[anlauto]

This is the kit I bought 2 AWG no issues whatsoever 
https://www.summitracing.com/parts/QCR-57-011

[MoparLeo]

Heat = resistance. The hotter the wire the more it is restricting current flow. That is why computers have fans inside, to cool off the ecu.
The battery you have is about 25% smaller than the factory recommended size.
https://alternatorparts.com/wire-size-chart.html#:~:text=Contact%20Us-,Battery%20Wire%20Size%20per%20Voltage%2C%20Amperage%20Load%20and%20Length,0%20AWG,-Site%20Map

[Katfish]

Alan,

What brand starter do you use?
I'm surprised that 2AWG isn't an issue.
I'm using 1/0, I might have a bad starter, I can't believe the wire is getting hot.

I'll try and take a voltage measurement for cold and hot start.

[anlauto]

I'm using the starter from Chrysler #56029274AA 

[dodj]

I use 1/0 motor lead wire. But what you describe sounds like a starter issue, not wiring.

[Dmod1974]

Agreed...  That's a classic starter hot soaking issue.  A hot engine should spin over easier, and consequently put less load on the starter which will then pull less current.  It'd be worse after a complete cold soak if it were battery or voltage drop related.

[Katfish]

Not sure where to go from here, it's a brand new starter, hate to buy another if not needed.
Any other way to test it?
The thermal wrap I put on it covers it well, and the headers aren't really that close.
I'll measure the voltage drop at the PDU hot and cold to see if that indicates anything.
I have 16' of 1/0 AWG from trunk to firewall, then 4' of 2 AWG to starter.
And I'm surprised it only takes 20 minutes of driving to cause the issue, these motors run hot (~210), but that's not crazy hot.

[Dmod1974]

Just how close is it?  What starter are you using?  Start with basic electrical troubleshooting....  When it acts up, measure voltage drop through the heavy starter cable.  My guess is you'll see no drop because the starter solenoid isn't closing the circuit and thus the starter motor isn't drawing any current.

[Katfish]

I'd say the closest distance between the header and starter is at least 1"
The starter shield material was long enough to wrap it around twice.  So there can't be much radiated heat getting to the starter.
Pretty sure the solenoid is working/closing, it acts like a classic dead battery, tries to turn over, but just too slow to start the motor.
I can measure the drop from trunk to PDU, no way to access the starter terminal while this is happening.
Picked up starter on Amazon

DB Electrical 410-48238 New Starter Compatible with/Replacement for Dodge 5.7L
5.7 Ram Pickup Truck 05 06 07 08 2005 2006 2007 2008 Manual Transmission 56029274AA 17932 M0T21271ZC M0T21271 2-2725-MI

https://www.amazon.com/gp/product/B007XUIP6Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Dmod1974]

If you have an inductive ammeter (amp clamp) that'd tell you a lot too.  Make a jumper to get to the starter terminal if needed.  I run that same style starter and you can get to the terminals, but I wouldn't want to be anywhere near that when hot.  Those 2 measurements should tell you what's wrong.

[MoparLeo]

So now we are getting more details. Battery in trunk... Is there room to put a battery back in front for testing ?
Get a load tester. They start out pretty low in price. Get one that will test battery load, starter cranking amps, resistance, etc.. This way you can test in real time.
Do all the tests with everything cold to get a baseline first.
If everything tests ok cold, then you can go for a drive to heat things up and then come home or wherever your are doing your testing at and test it all again.
Whenever you are using modified wiring it is usually a connection problem, Never assume everything is ok. Clean and check all electrical connections both power and grounds to all components. Number one item though to test anything electrical on an automobile is have the proper sized battery and that it is fully charged (like 13. volts or more at rest), before any testing.

[crackedback]

Where the main cable on positive side gets the most heat, you've placed the smallest cable in the circuit.   

What do you have for ground cables for the vehicle?  How is the battery grounded to the chassis?

I build quite a few 1/0 battery cables for mopar folks.  Not a single report of what you have occurring.

Do this test.  Grab a set of jumper cables, go from battery negative to wherever the starter is bolt too.  Does it start or crank over easier?  You likely have your answer.

[Katfish]

I have a 2awg cable from engine to inner fender, freshly ground off paint.
The negative cable to the battery is 4' long 1/0 awg bolted to floor pan under back seat, freshly ground bare metal too.

This is all the same wiring used with my 340 for 6 months before I did this 3G engine swap.
The only wiring  difference is the extra 4' section of 2awg from PDU to starter.

I'll see if I can take some pics once the storm passes.

Still wondering why this only happens when hot?
I wouldn't think the ground connections change over temp.

I can't emphasize how easy it turns over and starts when cold.

[dodj]

Still wondering why this only happens when hot?

Well, the starter is the only thing getting hot besides the engine..so....if it were me I'd be looking at replacement starters. Actually I'd do the below test first.

While it may be too difficult (hot) the only way to definitively determine wires/connection or starter is to put a meter lead on the positive terminal of the starter when it happens.