T-Max cheapo regulator rectifier

So, it happened again...

My nose identified the smell of burning insulation and electrolyte, and I noted some smoke emerging from "down there".

I quickly pulled off the road (smoke being spread by the fan) shut off the ignition, pulled the tool kit and disconnected the battery.

This left me on the side of the road, so I pushed it down a lane a little ways (to keep it from attracting the wrong kind of attention), hitch hiked home (I was on the way home), got my truck and came back with a new part and tools.

It requires a bit of jiggery to organise me getting back both vehicles.

Readers of my blog will know of my previous issue (documented here) and my conjecture of would it survive the hottest days ... I'm pretty sure I know the answer now ;-)

As I wrote back then when I fitted the fan unit:

I was riding around and thinking about how close that graph got to 50C and thought that since the air temperature right now is like 20C (middle of the day) and that in summer its going to be nearly 50C (coming directly off the road) that will drive that temperature up closer to limits again. So I decided to look for power and attach a small case fan to assist cooling.

So as I suspected on at +34C day it didn't get sufficient cooling.

I decided that I needed to do new testing (because it was still bloody hot) and so I thought test it with

• cover on (fan cooled only)
• cover off (fan still there)

To test I embedded a sensor between fins to avoid air cooling of the sensor (and get the temperature of the heatsink) like this:

*(Note: the new cheapo part is no longer black, which is stupid)

The "cover off  ride looks like this

with good exposure to air for the cooling. The temperature plot (which included a length of highway at 100km/h)

which is quite reasonable. You'll note that temperature rose as soon as I returned into 60km/h town region and stopped recording when I pulled into my yard.

I then slipped the cover on 

note the breather which is a vent (see the earlier post) that leads to the center of the fan (and hopefully blows fresh road air in).

and went back out, getting this reading

you'll note that it got to 60 pretty soon and flattened (I was keeping an eye on the meter readout) and rose briefly when I was back in town (presumably due to lower air flows.

This temperature is very close to thermal runaway temperatures and IMO far too warm for a cheap piece of shit like this. This site on that subject makes that clear.

Semiconductor parts are most often specified for use in the “commercial” 0 to 70°C and, to a lesser extent, in the “industrial” -40 to 85°C operating temperature range. These operating temperature ratings generally satisfy the demands of the dominant semiconductor customers in the computer, telecommunications, and consumer electronic industries.

So I've ordered a Yamaha part to test. I want to know if the part that costs $300 is worth its money. Perhaps it may run cooler?

I'll post more when it comes to hand. For now its not being ridden.

Addendum

So, as promised, I took the T-Max into Warwick (37km) on a warm (but not scorching) 29 ~ 30C day (just a few days after this was first written). The results were very interesting. First the full trip

We start off with the surface of the heatsink being 25C, and I let it sit for a little while before starting off. I did the same when I got back. I rode into town, parked at a hardware shop at about 9:40. The temperature of the heat sink started to rise after the air flow stopped (I presume as the hotter parts inside the unit transferred their heat out and it was radiated away).

I then rode to another shop (quite close) which resulted in a quick air cooling and then a smaller rise. I was there until about 10:15, where I started up and rode home.

Lastly, after getting home I let it sit for a bit before shutting off the data recorder.

The trip in. Please note that in this graph I removed temperatures below 20 which does tend to change the actual scale of the graph, it also makes it a bit easier to see. I topped it out at 60C because I feel that's the danger zone.

The trip home.

Again we see that as soon as it is generating heat (by rectifying the AC from the alternator into DC and regulating that and dumping what the battery doesn't require as heat) its also moving, and when its moving slower things heat up faster. You can see when I come into town, slowing down and getting less air cooling.

So next I'd need to test this in traffic ...

I'll keep you posted