my assimilator light is staying on after startup. rather than pull the tank to get to it i figured i'd test the alternator. trying to rev the motor and hold the leads i got just upwards of 13 volts, need to get some alligators for the probes. then i got a 1 ohm resistor from radio shack, disconnected the alternator leads, put the resistor accross the leads, and was going to connect the meter when the resistor started smoking. disconnected everything. obviously the alternator is putting out power. another question; should this reading be taken w/ an ac meter as the current hasn't got to the rectifier yet? thanx, rick
alternator test gone bad
- Thread starter rgrigutis
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You are either very brave or very crazy.
I think you just need to stick the leads on the battery to see if the alternator is putting out.
Not sure what the resistor test was, unless you have pent up post-Fourth frustrations to get out.
I think you just need to stick the leads on the battery to see if the alternator is putting out.
Not sure what the resistor test was, unless you have pent up post-Fourth frustrations to get out.
The 1 ohm resistor across the alternator (to provide some loading) output is the accepted way of testing alternator output (meter set to ac) although I suspect the resistor you used wasn't of a high enough wattage. I usually just measure the voltage across the battery with headlight on and about 2000 revs, should get about 13 volts if it's charging ok. Only drawback to this method is that if it's not charging you won't know whether it's the alternator or the rectifier!
Dave.
Dave.
You should get about 9 volts across the 1 ohm resistor at 3000 revs.
This might help you,
http://rocbo.lautre.net/technique/norto ... p/136.html
This might help you,
http://rocbo.lautre.net/technique/norto ... p/136.html
jimc, my resistor looks exactly like yours. package says 1 ohm, 10 watt. nothing about wire wound. i just connected each lead to 1 of the alternator leads and the meter accross that. maybe there was some oil or mfg byproduct on the resistor causing the smoke. try again tommorrow.
swoosh,
i'm a little crazy and a little brave. served me well so far. i mostly work by myself neccessitating all sorts of awkward situations but few compromises.
thanx, rick
swoosh,
i'm a little crazy and a little brave. served me well so far. i mostly work by myself neccessitating all sorts of awkward situations but few compromises.
thanx, rick
JimC said:
AC on the meter for the alternator should give somewhere in the region of 17-19 just above 2000 as for voltage across the battery you want about 14.5 volts DC at @ 3000 there are other tests checking the current if you want more info let me know
maylar
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The workshop manual specifies 9 volts ac minimum across a 1 ohm resistor at 3000 rpm. I remember getting about 10 vrms when I did that on the stock single phase alternator and my Simpson 260 VOM (analog). The waveform is not pure sinusoidal, so different meters will read differently depending on how the ac volts function is implimented.
The resistor should be capable of at least 100 watts, or be cooled by water. Mine is three 3-ohm 100 watt units in parallel, which gives 1 ohm 300 watts. It gets warm. You can also tie both hi and low beams together (somewhere between 90 and 100 watts total) on an automotive headlamp and use that for a load across the alternator.
The resistor should be capable of at least 100 watts, or be cooled by water. Mine is three 3-ohm 100 watt units in parallel, which gives 1 ohm 300 watts. It gets warm. You can also tie both hi and low beams together (somewhere between 90 and 100 watts total) on an automotive headlamp and use that for a load across the alternator.
Hi,
You really don't need a resistor to check the alternator in fact 99% of all bikes out there (read Japanese) make no mention of using resistors when checking alternator output. Most manuals simply test for continuity between the stator leads (2 wires single phase or 3 wires three phase), and a check for continuity (shorting) to ground from any of the leads. AC output can be checked at any two leads with the engine running. Some manuals will specify an AC voltage amount ( for instance 80s Suzuki GS models called for 75 volts at 5000rpm), but, typically you can expect approximately 13 volts per 1000rpm.
The reason the use of a resistor is suggested is that it calls upon the principles of Ohm's law which states that 1 volt across 1 Ohm will cause 1 amp of current at 1 watt. By including the 1 Ohm resistor in the circuit your AC volt reading is also simultaneously an Amp reading, which makes the test a little more useful.
GB
You really don't need a resistor to check the alternator in fact 99% of all bikes out there (read Japanese) make no mention of using resistors when checking alternator output. Most manuals simply test for continuity between the stator leads (2 wires single phase or 3 wires three phase), and a check for continuity (shorting) to ground from any of the leads. AC output can be checked at any two leads with the engine running. Some manuals will specify an AC voltage amount ( for instance 80s Suzuki GS models called for 75 volts at 5000rpm), but, typically you can expect approximately 13 volts per 1000rpm.
The reason the use of a resistor is suggested is that it calls upon the principles of Ohm's law which states that 1 volt across 1 Ohm will cause 1 amp of current at 1 watt. By including the 1 Ohm resistor in the circuit your AC volt reading is also simultaneously an Amp reading, which makes the test a little more useful.
GB
maylar
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The most meaningful test of the complete system requires two meters: a DC voltmeter across the battery, and a DC ammeter in series with the rectifier output. Start the engine and turn on the headlight. At idle the battery supplies all power; voltage will be about 12v and rectifier output current will be zero. As you increase rpm the alternator begins supplying current and voltage on the battery will increase. At higher rpm the voltage stops increasing (that's your regulation point) and the alternator is supplying all the load.
This is a great test of the overall system, and also tells you what rpm you need to maintain with lights on without draining the battery. I found that with the stock charging system I needed 3200 rpm to maintain battery charge with my 65 watt halogen headlamp. With a 3 phase Sparx setup that dropped to 2500. Good info to have.
This is a great test of the overall system, and also tells you what rpm you need to maintain with lights on without draining the battery. I found that with the stock charging system I needed 3200 rpm to maintain battery charge with my 65 watt halogen headlamp. With a 3 phase Sparx setup that dropped to 2500. Good info to have.
maylar
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Cookie said:
Hondas don't have charging systems that allow the battery to run the motorcycle at idle. Their batteries are only used for starting, the alternator takes over once the engine is running just as on a car. Our old Brit Iron has a minimal system that's a bit more critical.
A new R1200 Beemer has an 840 watt alternator.. that's 60 amps at 14 volts. I wouldn't test one of those with a resistor either.
rgrigutis said:
14 Volts at battery 3000 sounds good so yes could be duff assimilator pretty expensive item for an "alternator is sort of working light" though I switched to a mini-voltmeter that shows the voltage across the battery at all times keeps me ahead of the game if I am riding at night with full beam , so I know i need to go faster :lol:
Cookie said:
You should try making a 1 ohm resistor from a long piece of wire as per the workshop manual "A suitable resistor can be made from 4 yards (Metres to you youngsters out there) of 18 S.W.G Nichrome wire and 2 flexible leads with crocodile clips" calibrate it I will not detail this LOL "wind the wire onto a 2" hollow asbestos former"....etc etc. :roll: I may have an old bike but a good Digital Multimeter with 20 A capacity suits me fine...
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