aliveagain
Needs a life
Posts: 5033
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posted November 14, 2009 06:24 PM
minimum voltage
I was checking the starting system and noticed when cranking,the voltage is around 10.5dcv.I remember seeing or hearing about it,that the motor won't run below a certain voltage.Anyone know what it might be as I can't find it in the book?The battery reads 12.8dcv. after the first start,ignition off.Tomorrow,I want to check the rectifier and stator again because I only get 13.5 while running at the battery and it doesn't respond to rpm's.The manual said it should put out 13.8-14.2. I am just trying to eliminate any electrical problems.
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whitehendrix
Zone Head
fails!
Posts: 757
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posted November 14, 2009 06:46 PM
i wouldn't trust 10.5.
design voltage is 12.VDC.
max is 14.40VDC. average being 13.863VDC
10.5 is way low.. remember, you're losing exponentially on shit liek the spark power.
if you figure ( now, these aren't the correct voltages, but this is just to keep it simple) if you've got sparkplug coils with a primary voltage of 12VDC and a secondary voltage of 12Kv, your ratio is 1000:1
meaning, 1 volt in = 1000 volts out
now, remove 2 volts here.. see? ya just lost 2000 on the spark, and if you've got high compression or another factor that raises the resistivity of the air in the combustion chamber, that 2Kv might be all you needed between fire and no fire.
obviously, the ratio is higher if the secondary voltage is higher, and therefore, a voltage loss is more dramatic.
for your charing system, you battery itself won't respond to rpm and more power.. you may see an increase at he terminals, but be wary of how you word it, and as well, where you're actually testing. you'll get a difference sometimes just between testing from psoitive to the frame, + to the engine case, and + to the battery negative..
a shitty ground will cause that to happen.
if you're making 13.5, i almost wouldn't even worry about it unless theres something going on i don't know about. the cranking voltage is a hard thing to beat unless you've got a badass battery or a new one.
check the AC output of the stator with no load and varied revs if you really want a good idea of if you've got component failure on your hands.
i think everythings good tho.. not 100%.. i'm not the one working on it. .lol.. but as long as the battery recovers and comes back up quickly and the bike fires off, i think you're good.
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Duct tape is the handyman's secret
weapon. The black is for formal
occasions. - ZRXDean
ill never own a busa unless
someone gives me one.... and then
ill sell it -KZScott
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2000redrocket
Pro
Posts: 1662
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posted November 14, 2009 08:54 PM
typicaly i tell people if you around 10.0 or go below 10 it is time to think about replaceing the battery. how old is it?
13.5 running is to me bairley ok but ok. as it gets lower the ecu will start ritchening up the air fuel mixture when voltage at the fuel pump goes down. so it could start running different for you if it gets too low.maybe drive the bike as it is for a good ride then park it and check the batt voltage across the terminals then charge it till a charger says it is charged and let it sit again fir 24 hours and look at the voltage again. that should give you a idea if the batt is getting old or the charging system is not getting it all the way up.
it could be time for new stator. they do not last for ever i am finding. put a new one on a cb750 and what a difference. it was charging for him but not well enough to run the exrta running lights he added. now he can run them and then some.
unplug your lights and see if you can get the running voltage up to 14.0ish. i do not know what mine is at i may look at it and post it as a compair.
low cranking coil voltage trying to fire under compression at idle throttles closed probaly only has effective comp ratio of 7 to 1. no problem.
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aliveagain
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posted November 15, 2009 09:13 AM
The bike starts when cold with about the same cranking voltage.Unless it is so border line,I don't think this is my primary problem. I am seriously considering a speedcell battery in the spring but want to make sure all else is up to par electrically.
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I wondered why the baseball kept getting bigger. Then it hit me.
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted November 15, 2009 09:48 AM
You can have the battery load tested at an auto parts store. I would agree the signs point to the battery or a connection. Rather than chase your tail have the battery eliminated as a source problem.
A bad connection on the batery terminals or the starter system could cause problems.
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Randy
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aliveagain
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posted November 15, 2009 10:33 AM
I was just talking with my brother and mentioned about the speedcell and he suggested I take and wire the extra battery in parallel to see if extra cranking power would help.Over the phone,I let him hear how long it takes to fire up initially and the bike would not start ten minutes later for me to go for a ride.I want to see if the starter is bad also.
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I wondered why the baseball kept getting bigger. Then it hit me.
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2000redrocket
Pro
Posts: 1662
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posted November 15, 2009 03:06 PM
so how old is the battery in the bike now?? when you say it would not start the bike did it turn over but not fire or did the battery die while cranking it over and the battery is dead now?
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aliveagain
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Posts: 5033
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posted November 15, 2009 06:29 PM
The battery is a year old and turns the motor over.When cold it,turn over for about 5 sec and fire up.Once it warms up,I'll hear it sputtering like it wants to start but doesn't.After about 2 tries or ten seconds,the battery is drained enough where it will drop right off.
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I wondered why the baseball kept getting bigger. Then it hit me.
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2000redrocket
Pro
Posts: 1662
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posted November 15, 2009 06:48 PM
it sounds like a load test on the battery is needed but only after a full charge. if it is only 1 year old it makes you scratch your head with the sys voltage only at 13.5. that should be enough to have the battery full or dam full.you may want to charge it then put it in your bike and run it and after starting watch the system voltage. if it keeps getting lower then that may explane it starting the bike up cold then while running everything on the bike drains the battery to a point it has no capacity left to start it the second time.
it sure would be nice to see the cranking amp draw cold vs hot to rule out the starter.
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VincentHill
Needs a life
Posts: 6520
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posted November 16, 2009 08:00 AM
AA, it IS the Battery! My Friend Steve has a ZRX that was Very Tricky to start! More or less, it started when you let go of the starter Button and in some cases if you did not do it perfectly it would not start. He Battery read 12 .4 volts and turned over farily quickly. Then one day for Grins I put the Voltage meter on while he was turning the bike over and it read about 9.8 volts. We replaced the battery and NEVER a Problem again. The Battery was "Supposed" to be less than 2 years old!
BTW, when you are cranking the engine, that IS a Load Test.
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Made History @ Daytona and still one fast old man!!
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aliveagain
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posted November 16, 2009 09:28 AM
Tonite,I'm going to warm the bike up and shut it off for ten minutes.With the key on,I'm going to jump it with a car battery(jumper to ground and the other to starter motor) to see if there is a difference.
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I wondered why the baseball kept getting bigger. Then it hit me.
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted November 16, 2009 01:55 PM
Uh, that may not be the best approach. Jumpering from a stout DC source such as a car battery is a bad idea. You have an unfused DC source in your hand or attached to your bike. If positive touches negative or ground you will have a very large DC fire with nothing to break the circuit. The car battery could explode if shorted in this manner.
If you must do it this way jumper to the motorcycle battery. But be careful. If the battery has a dead or shorted cell the battery can fail internally with nasty results.
I deal with 130VDC systems on a daily basis. The chances of something going bad wrong are slim. The consequences of something going bad wrong are VERY large. Batteries contain a strong acid (sticky hard to wash off acid in a gel cell) and one hell of a lot of energy.
Even a ‘dead’ battery can produce a surprisingly large current when shorted.
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Randy
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2000redrocket
Pro
Posts: 1662
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posted November 16, 2009 02:26 PM
vince i guess i like using my carbon pile load tester and DC clamp on amp probe.
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aliveagain
Needs a life
Posts: 5033
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posted November 16, 2009 03:01 PM
Well it didn't work anyway.I thought I was getting somewhere when I revved it a few times to clean it out and it started right back up.I waited ten minutes and although it spun over good,it wouldn't fire.I guess I'll recharge and then unplug for 24 hours to see where she sits.I hear ya rtbain,I had a 6volt blow up in my face while trying to jump start an old 38 plymouth.
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I wondered why the baseball kept getting bigger. Then it hit me.
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