Need some help!! Voltage! Randon No Start

So I am having an issue that keeps us from trusting our slingshot. It runs great but randomly it will not start after the ride. Turning the key turns on the accessories as normal. I hear the fuel pump engage. When I press the starter button it will engage the starter and turn over the motor but just keeps trying to start and times itself out. The dash says 8 or 6 low volts while this is happening.

It has a brand new yellow top Optima battery. Ground, frame ground, checked all wires for loose connections, checked added aux fuse block connections, etc. I recently added the Tric LED Knight Rider Light, Upper and Lower LED Brows, and a voltage meter with usb's for phone charging.

After leaving it sit (((or backing it off the tow truck))) it fires right up like nothing is wrong and the battery and voltage is in the normal range. So after trying to start over and over it just suddenly works like nothing is wrong. It will perfectly again until it doesn't.

After these episodes, it leaves an engine code 65615-7 for the Electronic Throttle Control Actuation.

Is anyone able to give me some inside?

Here is a list of my mods and info to help.

All Recall up to date.

2016 SL

30k miles

Canadian Headlights with LED's

ECM Tune

DDM Air intake

1320 Headers

Thermal RD Rear Exit Exhaust

BOSS Head Unit-NEW

2-Sound Digital Amps running 4 6.5's and two cone tweeters

Underglow RGB's run by a XKGLOW hub and ON/OFF switch

FZ-1 Accory Fuze Block set to run without accessories on...

Air Horn

Upper and lower white LED "brows"

Tric LED Knight Rider Light

Yonhan Quick Charge 3.0 Duel USB Socket Charger with Volt Meter AMAZON

I did have the TriLED headlight on/off switch kit but removed after problems started and I did not like the installation on it. A little hookie for me...

I have included a clip of how it tries to start and the dash light.

It does only show that voltage when it’s not starting randomly. Voltage is normal all other times. It will show low when not starting but start the next minute or the next day for example with voltage reading normal.

Quote from BKL

My guess - If you're getting battery voltage readings as low as you posted but the battery can still start the engine most of the time , I'd suspect an intermittent short in the battery affecting several cells. Take it to a local auto parts store and they can hopefully test it for free. Can't hurt to give it a try. Like I said, this is my guess!

It did the same thing with the previous battery. It was an Optima yellow top as well and when I started to have the problems they replaced it under warranty and the battery is brand new. I will remove it and get it tested though. I was going to remove the alternator and have it tested too.

Quote from FunCycle

If I remember you have a volt meter installed. It should tell you what you need to know. That 5/6 volts is way to low to start the Sling.

Yes, I have a volt meter and it does read. When it's having the random starting issue the volts are 11.2-11.6, under load or trying to start they go to 10's. When it's working as should the volts are @ around 12v Starting and 13.2 when running. I would say this happens problem happens anywhere between 1 -10 starts.

Quote from DJohnson

That is a normal indication of a bad cell in the battery. Good voltage till a load is put on it. That cell may be shorting out at times. Get the battery tested. I deal with a lot of boat batteries and having a load tester comes in handy. Two boats 12 batteries.

It's a brand new battery but I will get it tested.

Quote from billythekidd

Since you stated it is a brand new battery, I would certainly take it out and have it checked at an auto parts store. Unlikely that it is the battery, as it is turning over the engine in your post. in my opinion but a intermittent ground in one of the mods you installed (if you did not have that issue before the install).

I would disconnect the new stuff that was installed and see if the problem goes away. Then one by one connect the mods to see which one is causing the problem. Just curious, the dash says 5 or 6 V what does the voltage meter that you installed say as far as voltage goes. Definitely start with the battery being tested and work back from there.

I have always used this as a rule of thumb for batteries:

If your battery is: Reading 0 volts, chances are the battery experienced a short circuit. Cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell. Fully charged (according to the battery charger) but the voltage is 12.4 or less, the battery is sulfated.

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It is a new battery that was replaced under warranty because the last one was in it when it started to act up so I figured that was it. When the problem happens the dash voltage says either 8v low or 6v low. My added voltage meter says 10-11's. It does charge to normal 12.2.

Quote from EjFord

Checking / replaceing battrery is about the cheepest thing that you can do. New batteries off the shelf can be bad.

Thank you, I will get the new battery checked too.

***UPDATE*** I wanted to post this follow maybe to help others figure this out. As many of you know from my posts, I had an electrical issue I could not figure out all summer. Hope this can help someone else going forward.

Symptoms:

-A couple of random engine misfires.

-Engine light code 656157 (656 15 7) Electronic Throttle Control (ETC) Actuation-Actuation Fault

- Completely random engine starts. Key would turn on, Fuel Pump would prime, engine would turn over and try to start but just time out

- Significant increase in battery draw and discharge

Fix:

Check Engine Fuse Box.

ECM 10A BRKR and Powertrain 20a BRKR were VERY loose in the box. When you place your finger on them you could hear an electrical arc noise as though they were making a connection under the fuse box. I removed the fuse box and checked the connection under, and they looked fine. I tried to spread the female spade connections at the top but there is not much room to do much, even with a fine pin. Again, they were very loose and hardly held the breakers in place. Every movement in the sling would cause them to work or not or send a current draw to the whole sling.

The final repair took 5 minutes. I cleaned and slightly twisted the breaker legs and added some dielectric grease to them before inserting them. After I added a small piece of foam to the top of the fuse box cover to create a little constant pressure on the relays, breakers, and fuses.

Worker perfectly since….

Hope this can help someone with this similar issue or at least rule it out.

Thank you again for all that gave me suggestions and help. I appreciate the Sling Community and how we help one another.