Snow!!!

I am really starting to get sick of this snow. It just keeps on coming!

The prototype controller is almost ready for serious testing! The snow has prevented me from going down the Radio Shack to purchase the final parts for the current limiting circuit and IGBT driver. The IGBT requires a dedicated driving circuit, whereas the MOSFETS were fine running of the 555 timer chip. I am building two seperate motor drive sections, the IGBT veriosn and MOSFET version. I am curious to see which one is more efficient. The MOSFETS are easier to control, but the IGBT is much more easy to place in a package.

This simple prototype is running at a mere 2KHz so it's quite audible, but I am figuring out how to increase this to 15kHz, but so far no luck. I hope to have a few PIC controllers, but I have no idea when or if the free samples will come in.

List of Parts

Ok, so here is a list of parts that I have in my possesion and/or have ordered up:

K99-4007 Motor
PB5 Throttle
Controller Parts- Pretty much all the guts are on the way
500 AMP Shunt
Probably some other things I can't think of.

I ordered up a PB5 throttle because I don't really have the time to make one out of the 5K Radio Shack potentiometer. I know how to do it, but getting the parts and machining them is a bit too much for me since I am building the controller.

I am also considering increasing my voltage to 96 volts since the new parts for my controller will take it, and my K99 would be happiest at that voltage. Calculations also show that at that voltage, the Wally World batteries would work fine getting my back and forth to school, with charging at school for maximum battery life.

Batteries

As I have been working on my controller, battery choices keep on popping into my head. Lead acid flooded, AGM, Lithium, NiCad, NiMH and more. So I have been putting together a spreadsheet of all sorts of batteries I find, punch them into the caclulator and see which will do what. I am still working on it, and trying to find the best prices. I did get a qoute from LionEV for a 78 Volt 120 Ah LiFePO4 for $5,000. It's $3500 for the batteries and then $1500 for the BMS system. I found that to be a very good price and it would give me decent range. I have not fixed the sheet yet, but when it comes down to capacity from lithium vs lead, a 50 Ah lithium pack is equal to a 100 Ah lead acid pack. I have not adjusted the graph appropriately, but the LionEV pack should give me about 70 real life miles. While I don't have that kind of money right now, I hope for the prices to come down and I will be keeping this in mind, possibly as a future pack. Or a day dream...

I have also been debating on what my first pack should be. Part of me is thinking I should just get a cheap pack from Wally World and beat the crap out of them while saving for a AGM system. Lead will probably be the way I go, and ideally I would like something sealed. US Battery UB121100 is one I am seriously considering since it is 110Ah, sealed AGM and I can place it anywhere. It does cost quite a bit, the lowest price I have found so far being $189. I am open to battery ideas and choices. As this is a budget conversion, I don't want to spend a lot on batteries, but I don't want junk either. Surplus UPS sealed batteries would be decent if they are sealed and not too abused. Maybe I will get lucky and a local company will be chucking some UPS batteries.

All Fired Up!

Well, I have put most of the MOSFET parts together, and did a very succesful test run. My test PWM is based of of a 555 timer, and I have a low frequency so there is a motor squeal, but that should change soon. I have ordered a few PIC controllers that have all the features I could want, and they were cheap. Actually, they were free samples and I ordered as many as it allowed me too. I also got a 1200Volt 300AMP IGBT for added fun.

Lets get to my picture. I have my K99-4007 on the table on the right my PWM circuit and MOSFETs on the table on the left, my 5K pot throttle on the wood stump and at the bottom, my ancient crappy 12 Volt Deep Cycle that has barely enough life leftto run this test. I only have 10 of my 20 MOSFETs hooked up since this is a basic test.

HHmm BB-Q...

Well, after many hours of soldering parts, more scrouging and mounting parts I was ready to do my test with 90% of this controller together, and I ended up blowing the single MOSFET I was using as my test unit. Well, I actually think I killed it when I went to resolder the wires on it and took way too long and burnt it. So when I went to test run, it worked for all of 1 sec, they popped and smelled like burning chips. The controller circuit itself is just fine, I just need to make my actual MOSFET system so it can the load. I also need some larger diodes for the final thing, but the ones I have now work up to 55 volts. I will have to take a pic of the whole setup before I delve into another week of creating the MOSFET heatsink system. That, and I still need to get the current limiting a little more sophisticated than a fuse.......