There is something to the effect on the pred that it will charge the battery up to keep it running, but will not charge it up until it is completely charged(like a car would)........I don't think the pred has a generator on it......so this is why your battery dies every so often.........

 

I've also heard of alot of dead battery problems with aftermarket CDI boxes. They seam to drain the battery as they sit not running. Also they make the Pred harder to start due to no timing retard on cranking like the OEM unit. Try the stock CDI to see if you battery drain goes away.
Another thing to check is the frame ground at the coil. I dont have a Pred but I hear there is a ground wire in this area that may not have a good connection due to paint that needs to be removed.

 

I have the stock CDI, so i dont have a problem there. But i am positive it is the battery, charged the new one yesterday and it works fine now.

 

I ran into the same problem with my wife's Trailblazer. After sitting for a few weeks, the battery was very low. If I started by the recoil and she ran it for a while, the engine would charge up the battery so the starter would work. So it was not a charging problem. I took a VOM and measured the current draw with the quad off. It was only drawing 1 milliamp. At this rate, the battery would easily last 10,000 hours before it discharged. So it clearly wasn't some device on the quad discharging the battery. It appears that the battery is just self discharging. I currently have the battery (fully charged) sitting on my work bench to verify that it is in fact self discharging (need to wait two weeks). Since this battery is only a year old, it clearly is a Yuasa manufacturing defect, IMO. I have Jetskis and snowmobiles that get bounced around as much as these quads and I don't have batteries failing in them after one year. It seems I have read about a few people having problems with these Yuasa batteries on new quads. So I tend to agree with cr125predator that this is a battery problem.
Bryce

 

Well it definitely was a battery problem. The battery has been sitting on my work bench since last saturday with nothing connected to it. Last night the battery measured 13 volts. Tonight the battery measured 10 volts. The battery has an internal short and is self discharging after only a week!! Guess I'll pick up a new battery.
Bryce