Peltier/Seebeck chips to supplement a tiny alternator

[larkout]

I have a bike built around a 186 type single cylinder with a (rated) 35 watt alternator (or generator I can't remember which). All of my lights are LED's including the headlight, which is supposed to be about 16 watts on low, and 32 on high, I thought that I would be able to run on low beam cruising down the highway all day and the battery would stay topped off. This isn't the case. As it is, I can turn off the headlight completely (not my favorite option...) and I have no power issues, but if I ride for a few hours in the evening with the light on low then the battery will be too low to start cold the next morning.
So, I get to wondering about how to generate more power. My friend has some Peltier chips laying around, and I've been thinking about how well it would (or wouldn't) work to rig these up to the exhaust? I think that if I had another 5-10 watts consistently going to the battery then everything would just be hunky dory. It appears, after briefly looking around, that you might be able to get 1-3 watts from each of these 40mmx40mm chips in reality... so maybe a strip of 4 or 5 of these under the muffler would do the trick?

I see people talking about how you can get power from exhaust like this, but I don't see any examples of folks actually doing it, or how efficient these are in real world conditions??

Charging from 2 different power sources seems like it might be a challenge that is beyond my abilities, so then I wonder if it is realistic to have two batteries that are on basically separate circuits but they can be linked for starting... one would be in line with the main generator and lights, and the other would be always topped off by the peltier chips and could charge the other while stopped, or at night... I don't really understand what goes on in a charging system so this is loose speculation.

The simple option for my troubles is to just order a kickstart lever...

Anybody else put thought into a scheme like this? or seen it work out well anywhere?

[Eddy Wane]

Using Peltier devices is an interesting option but I would be tempted initially to either add an extra LED to the headlight as a running light or find a lower wattage main bulb or even fit a LED control device to strobe the headlamp unit this will act as a dimmer and can be set to an acceptable light output for daytime use.
Eddy.

[boutje]

You could better rewind the coil of the altenator.(more windings each coil)
The problem with the 186 engines is that the coil of the altenator only deliver enough power on high rpm.(must run faster than 2000 rpm)

[sideshow]

I have a little bit of experience with thermoelectric generation (or rather I have colleagues that do). It sounds like they really wouldn't be robust enough to use on an exhaust - the temperatures involved vary too much, and would most likely end up damaging the unit.

[alexanderfoti]

Agreed, plus you must keep the cold side cold, otherwise they wont generate any power. With the whole thing in close proximity to the exhaust, it may pose a problem.