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Venture MP with electrical problem draining battery when running

3K views 7 replies 2 participants last post by  darren_t_johnson 
#1 ·
Hey,
My sled is a 2008 Venture MP. It new to me so I don't know its history. Looking for some advice (maybe this has happened to someone before?) before I go blinding digging.

I took it out for a ride last weekend. Not very far, 10k. And the next morning the battery was too dead to start the sled. It was a new battery.

I've since charged it, and i'm pretty sure it is still good. If I let it sit for a week, it still reads 12.7v. I can start and stop the sled a few times, and it still reads 12.7v when the sled is off.

I've done some digging, and this is what I see so far. When the sled is running, the battery only reads 12.3. So something is drawing too much power or is shorted. And the sled is basically running off the battery. Which explains why it went dead.

If I disconnect the two headlights, everthing goes back to normal (i think). With the lights disconnected and the heated grips on high, the battery is reading over 14v. So the charging system appears to be working. And when I reconnect the lights, its right back to 12.3.

Someone mentioned offhand that a bad bulb could cause problems. Is that true? I dont see now the could. Unless the bulbs themselves could have a short to the ground/frame in them?

The wires that run from the main wiring harness to the lights don't appear to have any shorts... I measured them with a meter.

Old sleds are normally all grounded to the frame. Is that still true for this generation of sled? I'm asking, because the ground wire running back from the lights does have 0 resistance when measured against the frame. Would that mean there is a short? Or is that normal because the entire system is grounded to the frame?

Thanks
 
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#2 ·
I did a lot more reading (online and my schematics etc), and a lot more digging.
My stator resistance measures to spec. When running, the stator voltage output was with in the expected range (i forget the exact reading). I moved on to the regulator/rectifier... when running, it also read 14+v when my lights are disconnected. I checked all the fuses and relays and check many wires for any shorts. Check the high/low switch for any shorts.

Then... I read on some post some people warning other people to be careful when upgrading their bulbs as many "upgrades" may draw more power then their power system produces.

That led me to double check my bulb sizes. According to my owner manual and service manual, my sled calls for two 12v 60/55W bulbs, but someone has installed two 12v 100/80W bulbs on my bulbs.

To recap, with my sled running and no lights connected, my batter reads 14v, so its charging well. With one 100/80W bulb connected, it seems to hover around 13.3. And with two 100/80W bulbs connected, it drops immediately 12.6 and slowly drops over time as the battery is drained. I didn't let it run very long like this as I didn't want to run the battery down.

I've ordered some 60/55W buls, to see if that was my problem (100/80W bulbs are too large for my power system). I'll post the results when the bulbs come in.
 
#3 ·
Well, it was a long shot, but it didn't help. With properly sized bulbs, I still get the same results. I don't suppose anyone has any ideas?

If a stator is failing, i suppose it might not produce as much power as it should. But if the stator was failing, wouldn't the ohms reading be way off? The ohms reading was to spec. Or would something else failing in the stator cause it to produce less power?
Maybe that question doesn't make sense, I don't know much about how they work. But I do know it is produces high enough voltage that the rectifier/regulator can nock it down to 14v and run most of the electrical and charge the battery as long as the light are disconnected.
 
#4 ·
Another question/throught...
Could it still be a rectifier/regulator problem? It is possible that the rectifier/regulator doesn't "use" all thread legs from the stator, and that would mean less regulated/rectified DC power being sent to the rest of the system? And if so... is that easy to test?
 
#5 ·
Seems to me that you still have a large draw on the lighting system. This includes the tail lights and hand warmers. The Stator can only produce so much amperage. If someone added lights, etc, this can cause too much current draw. Make sure that all yellow power wires are not shorted to the chassis in any way. The grounds should all be shorted to chassis as indicated by near zero resistance to ground on your meter. You must disconnect all light bulbs and other draws from the power feed wires when measuring resistance to ground on power feed wires.

Meanwhile, you need to do a load test on the new battery. It may have froze when it went dead. If battery is bad, the stator demand could be too much when charging.
 
#6 ·
Thanks patrioticinnovations.
I'll work through that (disconnect everything I can to see if that identifies a large draw. I'll also re-check the grounds and power lines making sure i'm not getting any false readings to due to lights, etc.

I agree, it seems like there is still a large draw somewhere. i've also just been reading on how a regulator/rectifier with some blown diodes could also result in less DC power being produced. I've followed some test instructions for the diodes, and from one lead i read 445, 445, 445 and from the other lead I read 103, 103, 101 (i forget which reading was from the positive lead and which was from the negative lead of the rectifier). I don't know if that is bad or if all 6 readings should be in the 445'ish range. I have to read up on that a bit more to make sure i'm interpreting things correctly.
 
#7 ·
So turns out it was a bad stator. I did a running voltage test and it came up with 42v, 42v, 35v. And checked the lines out of the stator and I could measure a short to ground.
Opened it up and there is what I found. New stator is on order, and we'll see if thats the only problem. Thanks everyone!


 
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