Okay so a couple of days ago I managed to kill the battery on my Lightning, but I jumped it and it ran fine now for the past two days until I tried to turn it on to leave work. It will crank over, but it cranks really slow and the guages keep cycling which it did alot when the battery died before. I still have the PATS and my tune is from Rick@amazon so I know its not in the tune. I checked on my diablosport predator to see what my battery voltage is, but all I could find was VPRW which I would assume is vehicle power? I assume that compares to battery voltage? My truck still has the OE battery and its an 01. The voltage was reading 9.5-9.9 and would vary . So do I need to be putting a new battery in this thing in the morning?

 

11 years on a battery????? The battery is way past its useful life. The reading on your predator may be skewed if there are any loose connections or corrosion on the connections. Get a voltmeter read the voltage at the battery terminals directly. If you are truly only getting "9.5-9.9 " volts then you have a dead cell and need to replace it. Automotive batteries have 6 cells that put out 2-2.5volts per cell. A good battery will read anywhere from 12.5-13.5volts with the engine off and 14-14.7volts with the engine running. If you are getting good readings at the battery, then take a good look at all of the battery connections (This includes where the cables connect to the engine and ground) and make sure that they are tight and not corroded, also make sure that the terminals on the cables themselves are good by giving them a good tug, if there is any movement at all replace them. Good luck!

 

Time for a new battery. That old and not holding a charge anymore.

 

Well, it looks like the battery was the problem. It would sit around 9.5 but after turning off the radio, auto headlights, and flipping the ignition on it would sit around 10.3-.5. I then got the truck to turn on and it cranked slowly as before, but then voltage shot up to 13.9-14.2 and would fluctuate +\- 1. As soon as I turned the truck off, however, it dropped right back to 9.5 progressively.

 

Definitely a bad battery if your voltage is 13.9-14.2 while running.

 

Sounds like a broken inter cell connector.
A problem like that, voltage readings are less reliable than a load test.
Can't draw large starter current through a high resistance.
The electrolyte may have even boiled away if you never check very often.
The lower it gets the more the alternator trys to replace a charge it can never accomplish and over heats the battery, over works the alternator as well, and boils the water out exposing the plates to air.
Good luck.

 

Wow, that's good info! I noticed some white residue on top of the battery about a week ago, and boiled out water would explain that. Got a new motocraft battery for 90 dollars with my dealer discount and we back on the road! Runs better than before, appreciate it guys