Thanks, LynnEdwards, I'll check that out when I am up next.

 

LynnEdwards, I tried measuring the Eton Vector 250's voltage when the engine was running, and at first I got up to 14.5 or so, but then later I only got a max of 13.39, and the machine was running rough at that point. As well, both the battery and a 300 amp booster battery that I hooked up in parallel went down to 12.5 volts or less. The ATV battery I can explain as a bad battery that won't tolerate a load (even though I can charge it up to 13 volts). However, I did not expect the booster's voltage to drop like that. (It is a rechargeable booster which I had charged up to 13 volts prior to this little test.)

So now it appears that there is an intermittent problem where the stator sends out 14.5 volts sometimes and only 13.4 volts at other times. How is this possible? As well, even with the booster attached, the system will sometimes go dead and then come alive again when you turn the key off and then back on. And how can an ATV that is running and putting out 13.4 volts then run down a 300 amp car booster, down to the low 12's?

Aaaargh!

 

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Hey, thanks again, LynnEdwards - you have given me a ton of ideas, and in fact maybe also provided a potential explanation for why we have also had problems with my daughter's Arctic Cat 150 battery (namely, the booster). Will try using an ordinary car battery like you suggested, and see what happens.

One additional worry has to do with the "cutting out" that I mentioned previously. What happened this weekend was that, while I was trying various things, I would intermittently get the whole system on the Eton Vector shutting off as if there were no battery at all. (No electronic display, nothing.) The I would try turning the key off and on, and wait a bit each time, and then eventually the display would light up again and sometimes there would even be enough power to crank and start the engine. Or, I might get the electronic display lighting up, but only get a clicking/buzzing sound when I tried cranking the engine. (Thus I suspect something might be loose or have a bad connection.) But of course I will have to try it again with a car battery as you suggested, which will not run down right away like the little quad battery did.

May go up again this weekend to try this out. Will keep you posted.

Thanks again - you have been a great help!

 

BTW LynnEdwards, the instructions for a new (9AH) battery I just bought for my daughter's Arctic Cat 150 say that the battery should read 13 volts when fully charged, and that 12.8 is only 75% charged, and I believe that 12.5 or 12.6 is only 50% charged, so perhaps the 12.6 volts that you suggested in your last post varies as a function of the manufacturer and/or size of the battery? (The Eton Vector battery I believe is a 12AH battery.)

Also, the weird part is that none of the Vector problems were happening until after the ATV had been running for a while (a good 15 minutes or so), and even then if I could coax it to run after the problems started I could usually keep it going if I was driving around at speed. It would then just die and give me grief if I stopped and/or let the engine slow down to anywhere near idle speed.

 

It doesn't make sense to me. A lead acid battery produces 2.1 volts per cell. A 12 volt battery uses six cells stacked up together to make 12.6 volts. The voltage is also not a function of the size of the battery. A 200 amp-hour bulldozer battery should be the same voltage when fully charged as your car battery, and also your quad battery. There are a lot of things I don't know (I'm learning every day), but I've never heard of a 13 volt lead acid battery that is 50% discharged at 12.6 volts.

I just downloaded the vector 250cc wiring diagram today. Like most published diagrams it mostly unreadable, but I do see that your ignition system is powered off the 12 volt power bus (unlike many quads). If your charging system isn't working and your battery goes dead after 15 minutes of operation, the quad will quit running too as the spark gets weaker at low RPMs. If this were the case the battery would be so dead after the quad dies that the starter motor wouldn't have enough power to crank the starter again. Another thing to try: When the engine starts to falter at low RPM's, turn on the headlights. If that kills the engine dead then there you go... But if the headlights light up bright and the engine runs the same then you have other problems.

 

Thanks again, LynnEdwards - will try it when I am up next. Sure hope it's just a crappy battery!

 

LynnEdwards, it turns out that the existing the battery will no longer hold a charge (I just got a buzzing sound even though it was charged up to over 12.5 volts, but then it immediately dropped down to 11.5 or so), so I substituted a 20 AH battery from another ATV, which worked fine and did not die when the ATV lights were turned on. I drove the ATV around for quite a bit, until the old problem started again, and then I measured the 20 AH battery while running - just over 14 volts (even at idle), so the stator seems fine. However, I still got the same old problem, where it starts to stutter, but only after driving it for a while (but not after letting it sit idling, even if it is for a long time.) As well, if I shut it off and let it rest for even 5 minutes, the problem goes away until after I drive it again for a bit.

I also tried using the booster as a battery, and that worked, but I did get some buzzing like I get with a bad battery when trying to start it sometimes, but if I try again and again the starter will eventually catch. (Also, when I got the buzzing sound with the booster I measured the voltage right away and it was still up to 12.6 or so, suggesting that the problem might be with the circuitry, and intermittently so.)

I am bringing the ATV down to Toronto with me tomorrow to play with it some more, but in the meantime I am stumped, and at this point I am afraid it might be some intermittent electrical problem that will be very difficult to diagnose.

 

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Actually, when the problem occurs the ATV will still run fine at full throttle, IF I can get past that initial jerkiness by feathering the throttle off the line. And when I say jerkiness, I don't mean bogging (although that will occur if I push the throttle too far off the line). What happens is a very violent jerking, as if it was going in and out of gear - so violent that I become afraid something will break. (I will have a look at the fuel filter, though.)

I spoke to an Arctic Cat dealer who had a Can-Am 250 trade-in with a similar problem (no surprise, since Eton apparently makes the 250 for Can-Am), and he said it was likely either the spark plug (easy to check), the coil (relatively cheap to replace), or the CDI (more expensive). He also said there is gearing electronics downstream of the (mechanical) gearbox which could be at fault, but I didn't catch exactly what it was. As well, he thought that the fact it only occurred after riding a while was diagnostic, since a lot of electronic failures occur only with heat.

Anyway, I have it with me here in Toronto now, and I will get a new spark plug and have a look at the old one. I also emailed the Eton Canada Dealer in Alberta, and will call Switzer Motors here in Toronto (where I bought the ATV) again, to tell him it is NOT an old gas problem, and see if he has had any problems with other Vector 250s.

Also, I will see if I can get a timing light and rig it up as you suggested, but that may take some time.