Hmm. Well, that didn't work out any better. Guess it simply can't provide enough surge current. I dont' think I can put big enough caps on it to do so either, without the surge current into them at power-on damaging the DC-DC.
I'll live with the blinking tail, I guess. Attracts more attention anyway.
No time to work on anything else today, since the bad luck I had with the window A/C unit got worse. The below is really only related to this thread in that it has macguyvering and ebike parts in it, and involves motors and troubleshooting:
Woke up about two hours after I finally fell asleep to 90F temps. In my bedroom. The AC unit failed (the same way) again, and because it didn't pump correctly it just ADDED heat to the room instead of taking it out.
I was far too tired to fix it then, and had to get sleep so I could go to work about four hours later, so I had to shut all the dogs out of the room so they wouldn't come lay against me and heat me up even worse, then set the box fan on high across me and fitfully slept a little.
Got home from work around 730pm, started working on the AC unit by 8pm and determined I cannot fix it by 830pm. not only is it impossible to get it to stay connected on that corroded-off terminal, I can actually see tiny little bubbles flowing from the glass seal--I guess it's not sealed anymore either, and the R22 and lubricants in the compressor are very very slowly leaking out. That may well be what caused the corrosion in the first place, rather than water, perhaps. I don't know if that stuff is reactive like that when combined with air and moisture, in high temperatures.
Time to pull out the "backup" unit, which is an old one with it's own issues, given to me by someone a few years ago and not used a lot since then, except for a few months by my younger sister till she decided the noises it makes were too much for her. Since it is a slightly different size, it took about two hours to get it installed, and then it worked about 10 minutes before the air circulation fan in it died, spinning slower and slower and slower and finally stopping. Compressor still works nice, but no good if the fan doesn't move the air thru the coils (external ones to remove the heat from the unit, and internal ones to remove the heat from the room).
I messed with it for another hour or so, but I can't figure out why the motor is acting like this. It did not recover after cooling off, either. Freely spins by hand. I dunno. It's a sealed motor and I can't open it up. I pondered a few ways of driving the shaft by a belt to another motor, a friction drive to the squirrel-cage fan inside, and other things, but I just don't have the time to do any of them since again I have to get to sleep so I can get up for work in the morning.
I ended up disconnecting the internal motor entirely, but physically leaving it in place since I don't have time to take it all out of the window a third time. So now I have lashed a big box fan to the outside, running it's extension cord thru the window alongside the AC unit, and that pulls air thru the external coils to cool them off. That works really well, so well that with no air flowing thru the internal coils, they actually freeze moisture out of the air in about a minute.
Since it doesn't do any good to just freeze the air right at the coils, I had to find a fan small enough to fit over them but powerful enough to move some serious air thru them. I somewhere around here have some nice big muffin fans that run on wall power just like the box fan, but of course I can't find them. So I had to use a 48VDC version of that kind of fan, which will actually run on quite a bit lower voltage, fortunately. But not low enough to run on any simple wall-wart I had laying around. Had to use the other ebike battery pack, the 36V 9Ah NiMH pack I used to use on DayGlo Avenger. I charged it up (was already almost full) and it is now running the fan, and hopefully will last thru my sleeping, assuming I get to do so.
It's REALLY REALLLY loud, like a vacuum cleaner a foot from your head.
I routinely use fans for white noise to help me sleep, but this is not the same kind of noise, and is really annoying. I have a lot of trouble with annoying noises, they actually make me angry and I have to work at it to get past that and try to ignore them (usually not possible, but I try really hard).
Since the room got up to about 100F during the day while I was gone, it's going to take a long time to cool down. It's finally down to 84F now, so at least I'm not sweating to death or anything. But the bed (waterbed) and walls and stuff are all still a lot warmer than 84F, probably mid-90s, and it's going to be a while for them to cool enough to let the air really cool down enough so that the AC unit can shut off periodically. It's been running constantly for not quite an hour, I guess. Might be more; I lost track fo time a while ago, since my brain is melted from heat and lack of sleep.
And I am still tired and will need to calm down before I can actually sleep. Hopefully posting this will be cathartic and I'll stop having it go round in my head constantly.
Tomorrow after I get off work, I guess I will be figuring out a way to hack the fan motor out of the dead-compressor unit into this one. They're similar but not identical, and they don't even have the same number of wires. I can figure it out, but it is going to take a while, and I will have to have the units both apart (and no AC running, of course) while I do it.
If I had the money I would just go buy a new unit. I am that miserable and tired of all this that I am ready to buy something new instead of recycling and repurposing old stuff for it.