Made 4 passes then realized the car wouldnt shift (electric shifter). Voltage on Gauge says 16 (16 volt battery) but when you hit the start switch the battery acts as if its dead, starter solenoid clicks and all lights, electronics etc.. flicker click and act as if battery is dead. Once you let off the start button everything comes back on and volts show 16v. Now I swapped batteries because I thought it was bad. Once changed car seemed fine for one pass. Then the same thing with that battery.
16v Battery, Alternator and Mega panel wiring board, checked all grounds and connections and all seems tight and good.

Master cutoff switch maybe?

Gonna try and check that today. That’s something my tunnel vision forgot.

Check all of your grounds.

I will go over all the grounds again today. We did it already but may have missed one. Here is a little update. Car sat over night, turn ignition on and it spins over 8 times, then we spin it over 8 more times, 8 more and 8 more THEN bam it acts like battery is dead but gauge says 16v.

Wouldn't be surprised if your battery(s) is toast. 16 volt batteries don't seem to give any warning when they fail. Had one first week out that was about 3 years old and it worked fine for first few passes then hoped in car to make another pass and it was acting as you describe. Hope this helps! Kevin

The issue I have with it being the battery is that we changed it with another 16v that was fine and had same issue after a pass.

Use a voltmeter and start checking voltage drops through all connections including cable ends. Google voltage drop test is you're not sure how, it's not just checking voltage at certain points.

All grounds checked, master switch checked. Only voltage drop on the car is when you turn the fan on it will drop about half a volt.
Now I did notice my XS Intellicharge 16v charger acting funny and making a small thumping (very light) noise, fan inside the charger working normal. When I moved the charger I noticed the noise was gone and display amps were going up and down and acting funny. Put my other charger on it and let it charge for about 2 hours. Now I cannot get it to repeat the issue. I think my issue was a faulty charger that went unnoticed on a hot summer night and going some rounds.

If it checked 16v it wasn’t charged.

Yes thats what I figured, just had tunnel vision when looking at gauge. I am leaning to faulty charger here.

Here's what doing a voltage drop test is, not just looking at your voltage gauge.https://www.hagerty.com/media/maintenance-and-tech/measuring-voltage-drop/

Problem has been found and it is the result of a faulty battery charger. XS Intelli Charger doesn't seem to be charging on 16 volts. Works fine on 12 volts though.

IF he needs to buy a new charger, the best 12/16 volt charger is Interactor's Road and Track Series, this is the Moroso and Rock charger

http://interacter.com/products...ack-series-overview/

I think there is a place where you can get replacement parts to fix the Intelli chargers. maybe someone here knows where.