Battery doesn't charge when fan runs?

[MaParkerColo]

Hey guys, so the bike has stranded me twice now and it jus pisses me off! '93 FZR600 with the Honda VR upgrade (after the OEM fried and cooked my headlights, taillights and turn signal relay.) After doing the VR upgrade and replacing the lights it ran great. Until a couple of weeks ago. I rode the bike 40-45 miles to work, parked it and it started right up for the ride home. It was hot and there was a lot of stop and go traffic the last 10 miles...about 5 miles from home it started trying to die on me and wouldn't stay running even at full throttle. I pull over and can't start it b/c the battery is too low.

I did the VR troubleshooting flow chart and everything look good. I was charging within parameters with the headlight fuse pulled so no suspected issues with stator or the new VR. Since that looked good I assumed the battery had just died on it and replaced it with a newer battery from my other bike. I rode it several times with no problems but never that far, the longest ride was probably 30 or 40 miles.

Jump ahead to yesterday. I ride to work no problem, start it to ride home no problem. Hit major stop and go traffic close to home and it is brutally hot. Get about a mile past where it died last time and same thing happens

After having it repeat I realized that it had been really hot and that the fan had been running alot on both these rides. Has anyone every run into a case where the bike wouldn't charge b/c the fan pulled too much juice? Anyone have suggestions on how to trouble shoot that? Any suggestions of a fix that doesn't involve disabling the fan?

Any help or suggestions would be really apprciated...if I call my wife to pick me up again b/c it strands me I may as well put a For Sale sign on the bike!

Thanks,
Mark

[MaParkerColo]

Nobody has any thoughts? Is there any way to have the fan run while testing the output volts to determine if the fan is pulling too much? Any suggestions on why the fan might start pulling too much current?

I'd appreciate any suggestions....

[kilika2]

I'm definitely not an electrical genius by any means. So let me start with that. Haha. But two things I would look for are a short or break in the line that is only a problem when the circuit closes when the fan is on. And the other thing I would check is exactly what you probably don't want to hear. Start the bike in your garage (with a box fan) and get it to temp where the fan kicks on. Check voltage before and then after it kicks on. Then after you have the second reading disconnect the fan and see if the voltage comes back up. It would at least eliminate the fan if it isn't the problem.

Chris.

[MaParkerColo]

Thanks for the reply Chris. I do need to find out if it is the actual fan or if something else is going on and the heat is just coincidental.

[kilika2]

I should be able to ride tomorrow. I will check my voltage with and with out fan on but I can't imagine any way that that could be causing it unless there is a short in the line or possibly the fuse that runs the fan is blown from your old vr. And when it overloads that "fuse" it's dumping all the excess voltage to ground. Again I'm shooting from the hip here.

Chris.

[MaParkerColo]

I took a chance yesterday and rode it to work again, but I took the precaution of packing another charged battery in my saddlebags! I also decided that I would not brave the stop and go traffic and spend the 5 bucks for the toll road. No problem, without the stop and go I rode all the way home and the battery had plenty of juice to spin the starter just like normal?!

I went ahead and tested voltages with the headlight fuse pulled and then with the headlights on and the fan running. I got voltages around 13.4 and 12.2, BUT today when I went to measure DC voltage on the legs of the stator my multitester appears to be DOA. It shows not voltage across the battery terminals (even the though battery starts the bike!) If you try a continuity test it beeps a short even if there are no leads plugged into it! So now I am not confident in those numbers... Argh!

Help me with my logic here, it looks like with the fan running I am only keeping the bike going at 3000rpm, at idle the battery would probably be draining since the stator is actually putting out less voltage than the bike needs to be happy, right? So if I idle around with the fan running I am running the battery down just keeping the bike running. This does not seem right does it? I am thinking that I need to take a look at my fan, maybe it is pulling more current than it should? Maybe cleaning it and the contacts in its circuit would help lessen drain?

Appreciate anyones thoughts or advice,
Mark

[kilika2]

Anytime the bike is running the stator is "charging" the battery. I have the quotes because it would be more like keeping the battery at a constant. And the reason I say that is because some race bikes run without a battery all together. Or maybe it's no stator. Total loss. Someone correct me. Haha Either way I'm not 100% sure in your case too. Also I didn't get to ride like I wanted. So I didn't get to check my voltage.

Chris.

[MaParkerColo]

Thanks for following up Chirs. If you do get your voltages I'd love to hear what they are. I finally got a new multitester last night but won't be able to run tests for a couple more days. I am hoping that the stator is OK and that I can resolve it by cleaning terminals ,making sure the fan spins freely, etc.

Best,
Mark

[DonTZ125]

You don't measure DC across the stator legs, but rather AC. The resistance across the stator coils should be a mere 0.31-0.37 ohms at 20C - pretty hard for cheaper meters to read, and you may simply get a 'Continuity' signal.

With the VRR plugged in, measure the DC voltage across the battery terminals at 5k rpm; you should see 13.5-14.5vdc (numbers different from the manual, but based on discussions with experienced forum members - some of them crusty and cranky). Unplug the VRR, and measure across each pair of stator wires: 1-2, 1-3, and 2-3; you should see 30-60vac across each set. If you have dropped a leg, then you won't have sufficient power to keep the system running with the fan. By the same token, if the stator winding is good but the diode for that leg in the VRR has fried, you still won't get the power from that circuit to the battery.

[MaParkerColo]

Don,

Thanks for the reply, I didn't see it until today. I haven't sorted everything out fully, but it looks like what was happening is that the coolant level was low and the system had to work overtime to try and cool the bike. I topped off the coolant and everything has been fine so far. The problem is that the extreme heat that we had been getting ended so that I have not been able to duplicate the temps that I was seeing before. So no more dead batteries, but also no over-heating so I don't know if I really fixed the problem or have simply managed to avoid it. I do still need to test the stator though since I did fry a RR and replaced with an upgrade. I might have killed a leg of the stator, but I don't think so.

Thanks for the advice though!

[HybridSport600]

Hi man, new to this site, but over 20yrs exp with cycle mechanics. i would start with a draw test to determin if anything is pulling unwanted juice from the system. heres how to do just that. remove the neg batt cable and attach a standard test light in between the neg cable (one end on the cable and the other on the batt term) with the ignition off look to see if the light is on. if its off good. if its on you have a draw problem. with the light still on procede to pull fuses one by one till the light goes out, when it goes out look at the circuit of the last fuse you pulled to make it go out. this is the problem circuit. do this and let me know...