David's 2001 Civic EV (80-100 mile range; 65+ MPH; 8 second 0-60)

[Daox]

Where are you going to get this 36V from? A dc/dc converter?

I think 36V is still much too low. If your motor is rated for 1.5hp continuous at 95V, you have roughly 1/3rd that hp available at 36V, so only .5hp. I'd guess you need around 1hp at least to run the A/C. Therefore, I'd run it at at least ~63V (95*.66), and get a pulley to make your rpms at the compressor to what they would have been at idle or slightly above with the OEM engine. You can fairly accurately estimate the rpms by looking at the stock volts per rpm specs. At 95V you get 6750 rpm, or 71rpm/V. So, at 63V you would get 4475 rpm. I did these same calculations when I put the PM motor in my riding lawn tractor and it worked out great.

[TheSGC]

Originally Posted by Daox

Where are you going to get this 36V from? A dc/dc converter?

I think 36V is still much too low. If your motor is rated for 1.5hp continuous at 95V, you have roughly 1/3rd that hp available at 36V, so only .5hp. I'd guess you need around 1hp at least to run the A/C. Therefore, I'd run it at at least ~63V (95*.66), and get a pulley to make your rpms at the compressor to what they would have been at idle or slightly above with the OEM engine. You can fairly accurately estimate the rpms by looking at the stock volts per rpm specs. At 95V you get 6750 rpm, or 71rpm/V. So, at 63V you would get 4475 rpm. I did these same calculations when I put the PM motor in my riding lawn tractor and it worked out great.

It's about the RPMs of the motor and what these little guys can really handle before the brushes spark. I tried 48v and 36 volts with the 3" pulley and 36 volts ran much nicer on the pulley and the A/C compressor was operating, blowing cold air into the hot car.

I am building a small 50 AMP motor controller that will take pack voltage (144v), I'll be making the compact PCB this week.

[NeilBlanchard]

The folks at Illuminati Motor Works would tell you not use a clutch. They (probably) would have won the X-Prize if they had not used a clutch. They just use the car in either 3rd gear (better acceleration) or 4th gear (about 2% better efficiency).

[Daox]

Originally Posted by TheSGC

It's about the RPMs of the motor and what these little guys can really handle before the brushes spark. I tried 48v and 36 volts with the 3" pulley and 36 volts ran much nicer on the pulley and the A/C compressor was operating, blowing cold air into the hot car.

I am building a small 50 AMP motor controller that will take pack voltage (144v), I'll be making the compact PCB this week.

If you're building a controller why even worry about what voltage to run it at? Just tweak the duty cycle and you're set.

[Daox]

There isn't anything wrong with using a clutch. It just has to be rated for the torque output of your motor. So, you just have to be aware that motors can put out a NICE amount of torque. There should be amp/torque charts for the ADC motor he is using and he should be able to size his clutch accordingly.

[HyperMileQC]

A Manual EV? Subscribing now!

[mechman600]

Originally Posted by NeilBlanchard

The folks at Illuminati Motor Works would tell you not use a clutch. They (probably) would have won the X-Prize if they had not used a clutch. They just use the car in either 3rd gear (better acceleration) or 4th gear (about 2% better efficiency).

The clutch/no clutch debate is hotly contested on DIY EV forums. The arguments never seem to mention efficiency, because clutches are pretty well 100% efficient (when fully engaged). The only inefficiency may be the added inertia of the flywheel and clutch assembly that may hinder acceleration a tiny bit, but since this isn't the X-Prize, it is probably irrelevant.

The "pro-clutch" people seem to like clutches not because of shifting (although it is a nice bonus to be able to shift normally), but because of the added safety measure - being able to disconnect in the event of a runaway. (The event that will change your pants from green to brown in about 2 seconds).

If you have the skills to incorporate a clutch, then I advise taking that route. If not, then the no-clutch route is simpler and easier and nearly as good, just as long as you make sure your HV system has plenty of safety redundency in case of the dreaded runaway.

[TheSGC]

It was easier for me to play with the treadmill motor using the batteries I have before I make a controller.

As for the clutch debate, it was simple: the adapter I made for my previous AutoTranny EV mimics the engine hub, so it was as simple as bolting the flywheel, clutch and pressure plate to my existing adapter. No machining, no designing, just mount and go. I also need to shift due to the gear ratios of my manual transmission.

Yesterday we started building the control tray and test fitted a few parts:



The weather is quite awful now so I have no clue what will get done in the next few days. I am going to try and finish bolting the control tray mounts then hookup the heater when the rain stops. The end of this week looks better for the weather so hopefully I will be wiring this weekend!

[Daox]

Have you figured out what you're going to do for balancing the pack?

[TheSGC]

Originally Posted by Daox

Have you figured out what you're going to do for balancing the pack?

I have my eye on the MiniBMS at the moment. I am thinking about getting the MiniBMS and then letting my Elcon 2000w charge them up and measure each cell, I am only aiming for 3.55v/cell charging, but I can bump it up if I want too.