Search found 265 matches

by EVguru
Tue Aug 19, 2008 11:49 am
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

Out of curiosity what is considered high voltage? Well, my definition for an EV starts at about 144 volt. An awful lof of cars have been converted in the US and experience has shown that 96volt is the minimum to get adequate performance (with series wound motors) from something of VW Rabbit (MK1 Go...
by EVguru
Tue Aug 19, 2008 11:25 am
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

what would be a typical motor kw output to vehicle all up weight, to permit one-speed transmission ? It's not really the power, that just determines the top speed. It's the speed/torque range of the motor. Acceleration = force / mass, so the weight of the vehicle determines the torque you need at t...
by EVguru
Tue Aug 19, 2008 11:06 am
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

Care to tell us what this vehicle is? I noted the s in Vehicles which implies more than one and I can think of a fair few myself for a start Milk Floats, Luggage tractors, Segways, Golf carts......... goes on and on really oh The Gwiz ........... What's more, they run at high voltage too Which elim...
by EVguru
Tue Aug 19, 2008 10:00 am
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

There are now well over a million vehicles driving around the highways of the world, with no clutch and a directly coupled electric motor to final drive.


Care to tell us what this vehicle is?
by EVguru
Tue Aug 19, 2008 9:17 am
Forum: General
Topic: Lithium vs lead batteries
Replies: 19
Views: 23658

A warmed up 42Ah Hawker Genesis will hold 10 volt with a 1000 amp load, some 700W/Kg. The JCI Inspira batteries produced for the proposed 42 (really 36) volt automotive systems were a great deal more powerful, a 7Ah battery supporting over 1000 amp at peak power (50% voltage sag). Whilst these were ...
by EVguru
Mon Aug 18, 2008 10:13 pm
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

You can't do pulse by pulse current limiting or desat detect if you're barely reaching saturation. EMC and turn off spikes are a real consideration. People that design controllers for a living have found frequency shifting or pulse skipping to be necessary. A shift to a resonant technology would hel...
by EVguru
Mon Aug 18, 2008 8:33 pm
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

A fast, low Rdson, 180A max, 75A average, 100V FET, like the IRFB4110 Giving the specs for a 100 volt FET kind of misses the point about high voltage systems. Turn on times are usually limited by the reverse recovery current of the rectifiers (unless running synchronous rectification) and turn off ...
by EVguru
Mon Aug 18, 2008 6:30 pm
Forum: Conversions
Topic: Clutch - leave in or not?
Replies: 39
Views: 19695

The difficulty with high voltage systems (above 144 volt) is of getting a suficciently PWM short pulses whilst making sure you turn the power device fully on to minimise heat generation. You start having to do other tricks like a lower switching frequency (Curtis 1221/31 - C) or random pulse skippin...
by EVguru
Mon Aug 18, 2008 6:16 pm
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 42406

I know you mean well, Paul, but there are quite a few of us around who possess enough knowledge and experience to weigh up the hazards and make our own decisions as to the degree of risk we are prepared to accept. I agree, but I want other people reading a thread to appreciate the difference betwee...
by EVguru
Mon Aug 18, 2008 5:48 pm
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 42406

I built my variac/ bridge rectifier charger based on the discription and diagram in Bob Brants book. Bob's book was one of very few reasonable sources of EV information when it was published. It is however is some places a very flawed book. In particular in the section where the conversion of a pic...

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