voltage regulation from a 186

[larkout]

Hey folks,

Electricity is dark magic to me, so please pardon if this is simple.
I'm trying to understand some electrical gremlins which basically cause me to have a flat battery after riding with the headlight on for more than a couple of hours. The bike is based around a Launtop 186fa with its stock regulator. The sum electrical load with lights is about 20 watts, which shouldn't drain the battery the way it does... Also I find that on a low battery a whole day of riding with the lights off doesn't bring the battery back up to charge. The battery does take a charge from a wall charger and will maintain enough juice to start the bike a dozen times day after day if I keep the lights off.
So at this point I assume something is loose in the charging system or the battery is on its way out, but cheapskate that I am I don't want to experiment by just replacing parts which might still be fine.
I got a little led voltmeter I can watch while riding. The result is that the battery resting voltage is 12.7v, and while riding the system voltage is about 12.8v, dropping to 12.6v when all lights are switched on. This points to a problem- I know the battery wants 14v to charge fully and I assume that the regulator should be putting out around 14.5v?
Is there any reason that this lower running system voltage would be due to a malfunctioning battery? My experience with regulator/rectifiers in the past is that they work or they don't, is there an obvious reason why the regulator would be maintaining a much lower voltage than what it was designed for? It is very possible that the wiring was just hooked up incorrectly to begin with, the schematic didn't really correlate with the real wiring and so we had to put on our Sherlock hats and do a little deduction. Could we have done something which caused just a slight drop in the voltage?
Any and all ideas are appreciated!
Cheers

[sbrumby]

Are your lights LED lights Because a normal bulb is about 50 Watts, back 10 Watts, brake light 20 Watts. I presume your engine is about 10hp. These engines are stationary engines so if they have electric start as in a small generator they are meant to start the engine and run for some time to allow the battery to top up what it has just used on start, and nothing else. There are a few questions you need to answer. What is the wattage of the alternator? What amps does the starter eat. And if you have regular bulbs can you replace with LEDs.

[boutje]

I had the same isseu with the 186.
The problem is the coil.
The output voltage of the coil is too low.(only good on full rpm)

I solved this by rewinding the coil with more windings.
The result was that the system even charge at ilde.

[bf109v7]

Did ypu take pictures of this coil? In my engine there is a Ring with several coils on it.
Alex

[boutje]

This is the rewind coil.

[bf109v7]

Thank you, I should do this also. My flyweel is very tight on the crank, I hope I can get it off again. When I remenber correct, on my coil not all legs have wires on.
Alex

[larkout]

sbrumby- generator output is supposed to be about 30 watts, all of my electricals are LED except the bulb behind the speedo, which I've actually measured and its draw is miniscule. The headlamp pulls 18 watts while on. If the head light is off then the only draw is that speedo bulb and the taillight at half power, if the voltage in the system was high enough there should theoretically be plenty of current to recharge the battery.
I suspect its a voltage issue, so rewinding the coil is something I will try.

bf109v7- Can you give me more details about how you rewound this different than stock? Same guage wire? Just more windings per post? How many?

[bf109v7]

I did not rewind mine yet, the picture is from Boutje. Boutje, maybr you can give us some more information.
Alex

[boutje]

I have rewinding it with 1 mm wire.(that is what i have in the workshop)
But original it was 0,8 mm.

What i did was the following:

I disconnect the regulator.
Started the engine with the original coil.
Measure the output ac voltage of the coil when the motor is running on idle.

I measured 10,2 volt ac
Then i took the coil apart and counted the windings.

That was 315 windings.

10,2 volt / 315 windings = 0,032 volt per winding

I wanted a minimum of 14,5 volt ac out of the coil on idle.

So 14,5 volt / 0,032 = 453,13 windings

I have 9 coils .

453,13 windings / 9 coils = 50,34 windings per coil

50,34 is an impossible number so i make it 51 windings per coil.

Thats roughly 45 % more windings per coil

[bf109v7]

Thank myou very much. The rewinding is not the bigigest problem, the Problem is getting the flyweel of. And with your information I have to do it only once.
Alex

[Diesel Dave]

Make sure you copy the winding direction on each bobbin.....