--- In [email protected], "Radu Babau" <[EMAIL PROTECTED]> wrote: > > I am wondering about this 12-16 weeks brushes life time. Some of us have > cars which we mostly ride in the city, 90% of their life time, on which the > normal motor speed is something from 1000-3000 rpm's. Usually there is > something like 1.5 ratio between the alternator and motor shaft. Other > people are mostly using their cars to run on highways, which means 2000-5000 > rpm motor speed. In both cases the life time of a alternator (including > brushes) is at least 5 years, even more. It is that kind of equipment that > you only change once during a normal car lifetime. > > Am I wrong ? Am I right ? > > > Radu >
In service in a car, the alternator rarely puts out full load. If you have a good battery and the car starts rapidly, the amount of juice drawn from the battery is made up in 10-15 minutes of running, and then the alternator supports only the running load. In a toyota during the day, this could be a small as 10 amps. How long do you drive the car each day ? Most people drive less than 4 hours, and that is often broken down into multiple trips. the car is off more than it is on and things have a chance to cool down. So, alternators often last 5 or more years. If you take that same alternator and put into use as a hydro generator, the thing is spinning at speed 24/7. And you are running it almost fully loaded the whole time. So, you have maximum friction at max speed, and maximum excitation current (heating). It never has a chance to cool down. This means maximum wear. So, expect to change the brushes 4 times a year, or more. If you get by with less, count yourself lucky. Oso ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
