Hi Team, Just need to confirm I have a dodgy R/R. Bike is a VT250F and it has one of those SSB Dry Cell batteries ( http://www.slipstreamperformance.co...-VT250F-1982-1988-SSB-V-Spec-AGM-battery.aspx). Anyhoot, it runs fine for a little while (5mins) and then dies. No probs if sitting and idling, but riding with revs means certain death. Suspected R/R so tested it and it passed the basic static test. Wired a Volt Meter onto the battery and went for a ride...results follow. Engine off = 12.6V Idling = 14ish Idling + headlight on = 13ish Riding...starts climbing & gets to 15v pretty quickly (at this point I pull in the clutch and let the bike return to idle so Volts drop back to 12.5ish and then engines starts to die (I assume from low voltage). I think the R/R is the problem as battery seems to hold charge. Any words of wisdom? Thanks
How old is your battery? The reg/rec only converts AC to DC voltage to charge the battery. It does not control the bike performance in terms of supplying spark or current to the other electrics. If the reg/rec is your problem the battery won't charge - the bike should still run fine for a while until the battery eventually runs out of charge and the bike dies. In your circumstances it sounds like your battery has dropped a cell, given how quickly the bike dies under load it doesn't sound like it's supplying enough current. When you charge the battery you can get a "superficial" reading when it's first charged that makes it seem like it is holding but under load if all isn't well it will die out pretty quickly. This sounds like what is happening to you. Another reason I believe this is because if you are losing 1V when you turn the headlight on, that's a pretty massive voltage drop under these sorts of circumstances. Voltage, in essence, is "potential current" ie until it has a circuit it really is an idle measurement. When you are pulling current your potential to supply current is dropping at a pretty high rate which means something isn't keeping up with the demand (if that makes sense) hence I think it is whatever is supplying your current (ie the battery). Batteries that are dropping cells can lose the potential to hold voltage in the range of 0.1-0.5V so it's a small relative drop. It could also be something like a short somewhere... but I'd be betting on the battery as the first point of call especially given those voltage readings seem borderline to me.
Thanks Joker, Battery is 6 months old, but I will throw in another one next week and see how that goes. Just to clear something up...I thought one of the issues with a faulty R/R is that it can supply too much DC to the battery and that then makes the stored voltage rise sharply. With a normal liquid-cell battery, this causes a sulfur-like smell to be emitted warning the rider that there is a problem. I'm guessing sealed batteries can't do this so the voltage just continues to rise until something gives. Does anyone have any experience with this scenario? I'm wondering if my R/R has damaged the battery. Thanks
It doesn't seem possible because the RR just converts DC to AC , it would have to be something else that would do it
The rectifier converts AC to DC and the regulator controls the voltage https://www.quora.com/What-is-a-motorcycle-rectifier-and-what-does-it-do
The regulator part (as hinted at by Grey) is supposed to maintain some sort of consistency in the current to charge the battery (when compared to AC, not load) so if something is seriously wrong I guess it has the potential to fry a battery cell. I'd be testing both, the symptoms you have described sound to me like the battery but that may or may not be the root cause. Have you actually tested it? You may have seen this:
Haven't pulled the battery out yet, but I'm guessing it's stuffed. I have a spare MB9U laying around, so will plug that in to see what happens.
I tested the R/R and it came through correctly... 3 nothings and 3 readings and repeat. I wired a voltmeter to the battery and went for a ride. The battery voltage rose as I was revving the engine. when it got to 15V I stopped revving it as I believe 15V is the "do not cross" line for batteries. This all happened in 200 meters of riding. Once I stopped revving the bike, the voltage dropped straight back to 12.something and then the engine started to stall, so I'm guessing battery is toast. Will test next week.
I think the RR converts AC to DC and the battery stores it for use by the bike's electrics. You don't need a stator or a RR for a bike to run, but eventually the battery will drain to a point where the bike will stall. I only know this because at one stage my drag bike was set up this way (to save weight).
Okay...back to the VT with the dud battery...or is it? I swapped the old (6-month old) battery for a brand new Motobatt MB9U and guess what? exactly the same thing is happening. took pictures this time... This is the bike turned off (12.6V) This is bike idling (14.5V) and this is it running with the headlight turned on (12.6V) And I stuck a multimeter on it just to make sure the Voltmeter was accurate ... and it was. I will now swap the RR to see what that does. Are we taking bets?
Okay, time to put a period on this thread. Thanks to Admins for moving it to a separate thread. Replaced RR with another from a working bike and it's all good. Bike Off: 12.6V Idling/revving: 12.5-13.1V Lights on: 12.5V It would appear that these early VT250F's might have a problem with their RR's. I went to take 2 off parts bikes and this is what they looked like (below). Strangely, both of these RR passed the static RR test, so maybe I'll just try and find new plugs for them and see how they go. All-in-all, a good experience for me and now I'll put the original battery back in and see if she's damaged or not. Thanks to all for your input and ideas.
Could be the position of the RR .... like in the ZXRc where it just doesnt get enough air to cool under the tank and cooks the plug/wiring .... and I guess possibly toasts the RR as well Good bit of trial and error there mate
You're probably on the right track Grey. On the 1983 VT250F the RR is hidden behind a plate (that the connectors rest in) and it's wedged between the shock absorber, puke tank for the radiator and the rear cylinder! Almost designed to fail. I'm surprised this hasn't happened on any of my other VT250F bikes. @Murdo is the design the same on your later model? Also Murdo, I thought you mentioned an online place that sells plugs for motorbikes in another thread. Was that you? and can you remind me of the place please Sir? Thanks
The thread on the plugs was on vtr.org. Have checked mine today and is the same place but plugs all look good.
