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Re: (ET) Converter losses



1. The controller I purchased is also available as a 36V part, 36V golf cart controllers are the standard these days, although 48V golf carts using 8V batteries are the top of the line models.

2. The power loss on the modern controllers is pretty negligible compared to tractor drive power. The silky smooth speed control is very noticeable compared to contactor switching resistors.

3. Curtis PMC in the US is a large manufacturer of golf cart controllers. Some of their models are available from vendors offering electric car parts (like Wilde Evolution www.wilde-evolutions.com). My controller is from a British company 4QD, their website is www.4QD.com and they have a US distributor). You will need at least a 200 amp controller at 36 volts, new ones are $300 and up.

4. AC motors would be impractical in the tractor - the standard 120VAC motors require peak to peak voltages above 300 volts! The electric cars using AC motors have 336volt battery packs and very (more than $10000) expensive controllers.

Monty McGraw

From: Allan <allanhv worldnet att net>
I have been considering rebuilding the controls on an E20, which, at the
very least, needs several relays replaced and the charger repaired.  I
have been thinking about updating the controls and/or charger with newer
technology, and have some questions:

1. Has anyone attempted this with a 36V system?  I'd rather not convert
my tractor to 24 or 48 if I don't have to.

2. How much power loss is there in using a converter for motor control?
It seems to me that replacing the mechanical contactors with a
solid-state equivalent (transistors of some kind) would result in a
voltage drop across the solid-state devices.  Is the loss significant?
I would guess something like 2V * 50A * 2 devices = 200 Watts?

3. Who makes appropriate controllers and how expensive are they?

4. Has anyone considered using an AC drive motor with an appropriate
converter?



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