HT 6v Charging System w/- ground

[sofasurfer]

I'll be darned!
You could pass for an electronics teacher.
I now know more about electronics than I ever did before.

 

[Tinker1980]

It is great to hear that you got a working system put together. The 10w resistor is fine, just a little bulkier than needed. That is what I used since that is all they had. I almost picked out that same battery but decided on a lower capacity one in order to save on weight and size. The 2.5ah spotlight battery will allow you to use your headlight for longer continuous periods of time. Are you using the spotlight as your headlight? That might be a good idea. It could be your headlight and hold the battery. You just need a good way to mount it. The selection of electronic components at Radio Shack is pretty slim these days. You won't find a suitable zener diode there. Did you find a 6.8v, 5w zener diode at the other store? Or something close? Since our town's last real electronics store closed a couple of years ago, I've had to order many of the parts that I need. I too soldered my final system before installing, but the terminal strip is nice for testing and actually works well. It makes it easy to swap components. Keep me posted on the longer term results.

I used to have the spotlight mounted to the handlebars on the bike, it had a LED and a halogen light, you could use one or the other. The LED was pitiful, could hardly see past the front tire, the halogen was really bright, but would only stay on for 15 minutes or so. I have considered using a 6v bicycle headlight or even a 6v flashlight with this setup, either would be bright enough for my needs. The spotlight bulb is 6v and 35 watts, so to run it longer I would just need a bigger battery. I don't know that a bigger battery would get a very good charge from the little magneto.

I did find a 6.8v 5w zener diode at my new favorite electronics store. (Affiliated electronics) I'm now looking around the house to see if there is a small enclosure I can use to hold the battery and the charging circuit, I may end up using a small piece of PVC for it all.

-Mark

 

[Scotchmo]

I used to have the spotlight mounted to the handlebars on the bike, it had a LED and a halogen light, you could use one or the other. The LED was pitiful, could hardly see past the front tire, the halogen was really bright, but would only stay on for 15 minutes or so. I have considered using a 6v bicycle headlight or even a 6v flashlight with this setup, either would be bright enough for my needs. The spotlight bulb is 6v and 35 watts, so to run it longer I would just need a bigger battery. I don't know that a bigger battery would get a very good charge from the little magneto.

That 35w bulb might be optimum for lighting up the road. But I too am going to look for a better compromise. My 6v generator headlight is just adequate so I still want to try an LED bulb of similar wattage. From reading other posts, the maximum wattage available from the white wire is about 5w. In my tests, I got considerably less. Even at the optimistic 5w maximum, the 35w light would require 7 hours of daylight driving for every hour of night driving. And you would need at least a 6ah battery to run the light for 1 hour continuously. The system could charge almost any size 6v lead acid battery but I think 6 to 8ah is about the practical limit.

 

[Tinker1980]

That 35w bulb might be optimum for lighting up the road. But I too am going to look for a better compromise. My 6v generator headlight is just adequate so I still want to try an LED bulb of similar wattage. From reading other posts, the maximum wattage available from the white wire is about 5w. In my tests, I got considerably less. Even at the optimistic 5w maximum, the 35w light would require 7 hours of daylight driving for every hour of night driving. And you would need at least a 6ah battery to run the light for 1 hour continuously. The system could charge almost any size 6v lead acid battery but I think 6 to 8ah is about the practical limit.

For my commute home after work (at 3 am) I need about 20-30 minutes of really bright light, the other 15 minutes or so are along well lit streets. Nice thing is, from what I've seen, a 6ah 6v battery is much cheaper than a 6ah 12v battery. And just to sweeten the pot, I come to find out that the 6v light bulb is exactly the same shape and size as the 12v light bulb I have in another light... I put the 6v bulb in the 12v light (it came from a forklift) and now it's even *brighter* than the spotlight since it's shining through the Fresnel lens that's part of the forklift headlight. And of course, the light already has a bracket for mounting, and will take far more punishment than a motorized bike on bad roads can deal out.

-Mark

 

[Scotchmo]

For my commute home after work (at 3 am) I need about 20-30 minutes of really bright light, the other 15 minutes or so are along well lit streets. Nice thing is, from what I've seen, a 6ah 6v battery is much cheaper than a 6ah 12v battery. And just to sweeten the pot, I come to find out that the 6v light bulb is exactly the same shape and size as the 12v light bulb I have in another light... I put the 6v bulb in the 12v light (it came from a forklift) and now it's even *brighter* than the spotlight since it's shining through the Fresnel lens that's part of the forklift headlight. And of course, the light already has a bracket for mounting, and will take far more punishment than a motorized bike on bad roads can deal out.

-Mark

The 6ah 6v battery should be cheaper and about half the weight. If you want to match the capacity of the 6ah 12v battery, you will need to get a 12ah 6v battery.

volts x amp-hours=kwh/1000

12v x 6ah = .072 kwh
6v x 6ah = .036 kwh
6v x 12ah = .072 kwh

 

[loquin]

The pneumatic/hydraulic equivalent of a zener diode is a pressure relief valve. When pressure gets too high, the pressure relief valve opens, allowing the excess pressure to bleed off. A spring loaded valve will close when the pressure drops a bit.

With the zener diode, when the voltage (pressure) gets too high, the zener diode (relief valve) resistance drops to a lower value, allowing the excess current to bypass through the resistor. The circuit isn't very efficient though, as all the excess is wasted as heat in the resistor. It's a simple, easy to build circuit, though.

 

[Scotchmo]

The pneumatic/hydraulic equivalent of a zener diode is a pressure relief valve. When pressure gets too high, the pressure relief valve opens, allowing the excess pressure to bleed off. A spring loaded valve will close when the pressure drops a bit.

With the zener diode, when the voltage (pressure) gets too high, the zener diode (relief valve) drops to a lower value, allowing the excess current to bypass through the resistor. The circuit isn't very efficient though, as all the excess is wasted as heat in the resistor. It's a simple, easy to build circuit, though.

I like your pneumatic/hydraulic analogies as applied to electronic components. They are more intuitive than electron behavior.

The zener regulator does indeed waste all excess charging energy but overall, it ends up being only a small amount. It is a small price to pay for having a fully charged battery ready to go. Even when the battery is full, no power is wasted until the white wire voltage rises above 6.8v. And even at that point the opposing emf of the battery allows only the peak of the wave that is over 6.8v to be wasted.

These HT motors are all about simplicity. The excess charge is so small that many implementations may not even need the regulator. Some users may even find the rectifier diode/battery/fuse system is more complex than they want or need. They just run the white wire directly to a light. It has it’s drawbacks, but it works for them. The simplified battery system and zener regulated system described here are both compromises but still allow implementation of a full electrical system without being overly complex.

The simplified system is similar to early 1960s Honda motorcycles. Silicone diodes of that time were either inadequate or unavailable so they used selenium rectifiers. The 1960's British motorcycles used a zener regulated system. And they were burning off relatively large amounts of power through the zener diodes. So I believe that we are using the appropriate solutions, with more modern components.

 

[sofasurfer]

Got all my parts today. Hope to get the battery this weekend.

 

[Scotchmo]

Got all my parts today. Hope to get the battery this weekend.

Before you assemble your charging system, try this test. At idle, hook one end of the rectifier diode up to the white wire and short the other end of the diode to the motor. If the motor dies, reverse the diode and try it again. The motor should continue to run even with the shorted diode. That is the correct polarity to use. If the diode stripe (cathode) is toward the white wire, then you will need to configure for a positive ground system, otherwise, use the negative ground system.

I have heard that other HT motors are better suited to positive ground but I have yet to find one. This simple test will determine how to set yours up. Please report back with the results.

 

[Scotchmo]

I'm going to have only occasional internet access for the next 4 weeks. I'll be touring the northwest on my other bike (Goldwing). I'll check back in on this thread when I get back.