the purpose of this thread is to document the current state of an inverter i built and, to some extent, document my adventure with air conditioning which this inverter powers.
A quick history:
Once I realized that carrying around ice to try to keep cool in the hot AZ summers was pointless, I started to look into real air conditioning. my first attempt was inspired by a product I saw on ebay where a 5000 btu/hr compressor from a window unit was being sold. Turns out that unit was only 100 bucks at home depot, so I bought one, tore it apart, and built a small inverter to power it.
Here's some info on that at
DIYecar:
Bottom line, 5000 btu/hr is not enough. 10,000+ would be required to get a more acceptable vent temperature.
Scroll compressors for hvac units in this size range all require 220vac and I didn't want to go through the process of adapting another hvac unit to the a/c system or build another inverter (which I ended up doing anyway). Also, it wouldn't be a guarantee to be enough thermal power and I could imagine problems getting the oils/refrigerants to play well together.
Then came the decision to go with the original a/c parts - compressor, condensor and all. I wanted to drive the compressor with an accessory motor for a couple of reasons - mostly, I didn't have room on the tail shaft to mount the compressor, but I also like the idea of remote starting the a/c.
I also wanted to stick with DC motors since building a DC motor controller is fairly straightforward. I found a 120v 20A 3HP motor treadmill motor and thought it was worth a try. I built a small DC controller - 20A is easy to manage - but the motor wasn't powerful enough to power the compressor. It was already maxed out at 20A and could barely keep the compressor turning when it was 80F outside. There's no way it could handle 115+ temperatures.
Here's a picture of the undersized motor before i got everything set up.
So, I looked for a bigger motor. Turns out the only DC motors larger than the one I had were for small EVs and were expensive, low voltage (required a high amperage controller like the open revolt), or really large and heavy. That's when I settled on a 5hp 220vac induction motor by WEG. It was inexpensive on ebay and could be tested by powering it with house voltage before building an inverter. Looks like there's a similar motor by Leeson on there too.
So, swapped it in, tightened up the belt, powered it up and the a/c worked! So, now that the mechanical aspect of the system was functional, I began work on an inverter to power the motor from the vehicle battery.
I tried to find some pictures of the new motor installation, but all i have are recent ones with some plastic guard to try to prevent hot air from the condensor going through the motor. So, these aren't the best.
