Paul & Sabrina's cheap DIY 144v motor controller

[zsnemeth]

Paul, I have a very serious question, which isn't came up until now, interestingly.
I'd need the +5V pin of the serial port. Can I just tap the C8's leg? Would it mess up something? I'd like to use a built in serial bluetooth adapter, instead of serial cable...

[adamj12b]

Originally Posted by zsnemeth

Paul, I have a very serious question, which isn't came up until now, interestingly.
I'd need the +5V pin of the serial port. Can I just tap the C8's leg? Would it mess up something? I'd like to use a built in serial bluetooth adapter, instead of serial cable...

You do not want to tap onto C8 for power. This is a bootstrap cap for the max232. You will want to tap onto C12 or U4 pin 15(gnd) and pin 16(+5V) directly.

-Adam

[electricstorm]

Got to hook the controller up to the o'scope in class today. Works like a charm! The pulse width would start to rise as the throttle pot was moved to simulate driving off. The Pulse width signal would eventually max out and cause a fault due to never seeing any current at the current sensor. There were some spikes in the PWM signal waveform at pin 7 of U7 (or at D6), is this normal?

We tried to simulate current draw by wrapping several loops of wire through the LEM, connected to a 25 watt, 1K resistor and hooked this up to a DC power supply, but it didn't work. The most we could push was 7 amps (looping the wire multiplies the current somehow according the the industrial text book). 7 amps didn't even register in RTD Explorer.

The instructor asked what the minimum amperage the controller would detect, but I didn't know. Don't recall seeing that information in the posts here. Does anyone know what the minimum is?

Well, time to assemble the power board now!

Jim

[Anaerin]

Originally Posted by electricstorm

We tried to simulate current draw by wrapping several loops of wire through the LEM, connected to a 25 watt, 1K resistor and hooked this up to a DC power supply, but it didn't work. The most we could push was 7 amps (looping the wire multiplies the current somehow according the the industrial text book). 7 amps didn't even register in RTD Explorer.

The instructor asked what the minimum amperage the controller would detect, but I didn't know. Don't recall seeing that information in the posts here. Does anyone know what the minimum is?

Given that the controller is meant for 500-1000A, 7 amps is less than 1% of it's range. If you can get up to 100A you should definitely notice something - Try connecting a few (incandescent) light bulbs in parallel and driving those. That should give you a fair load. Or a large (the bigger the better) coil in a rubbermaid container of water would do too.

[electricstorm]

I will be mating the control board and the power board either today or tomorrow. I hope to take it back to class and demonstrate it to fellow students per my instructor's request. We will be using a 12 volt lead-acid battery and a starter motor.

My question is:

For this test, do I need a pre-charge resistor before applying full power? If not, at what voltage would I need to add one and what value and wattage do you recommend? I am sure the answer is in this thread somewhere, but for the moment, it eludes me!

When a pre-charge resistor is needed, again, what value seems to work and how long do you set the pre-charge time on the controller for? I am planning to run it on a 120v DC battery pack when I install it into the vehicle.

Jim.

[adamj12b]

You should always use a pre-charge resistor with any voltage. 100 ohms is a Perry good value for any voltage pack. You will want already a 10 watt one but 20 would be better.
Here its a good site to use too calculate pre-charge time.
scriptasylum.com/rc_speed/nospark.html
-Adam

[MPaulHolmes]

Only 3 more weeks of horror, and then I can have a life again and can hopefully finish that dang blasted 1000amp controller. Never again will I sign up to teach so many classes.

[pamcmills]

Originally Posted by Georgia Tech

I have a motor simmilar to this as well. So you say yours ahs been working really well? I plan to drive mine with the 1000 amp controller when it is done.

Been a while since I've been here. Took the S-10 apart to put an automatic transmission in it. Did an inspection of the motor and it still looks great. Have seen no signs of abnormal wear or problems.

[MPaulHolmes]

School's out! Grading done for all 250 students or so! I have some time to work now!! ya! Step one will be to stare forward and do nothing. That sounds nice right now.

[ChedMpls]

a question and a big boo-boo to report.
first, did the post #'s change? my notes say post#3365 should start a pre-charge resistor conversation and it doesn't seem to be there. same with other post#'s. ???
second, i hate to admit it but i shorted the controller across b+ and b- connections. the caps were charged and i touched them with a wrench i was holding. it literally sounded like a gunshot and i thought i fried my cougar. it really sounded like something blew up but there was only a small scorch mark on the b- , the controller had no visible damage and it has since been operating normally. i think i might have blown a finger off if i had touched shorted these with my hand. i think i might have croaked if i had shorted these with 1 hand on each of these (through my body).
EVERYBODY BE CAREFUL WITH THE CAPACITORS! I plan on adding a 115v bulb across here so the caps will drain after my contactor opens. I'm looking for the posts where someone describes their precharge setup using a 115v bulb.