I thought the ferroresonant transformer in a Lester charger was for
power factor correction, if I raise the AC input voltage by 10v RMS will the
DC output voltage not raise accordingly?----- Original Message ----- From: "Joe Smalley" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, October 12, 2002 10:49 PM Subject: Re: Battery Charger > Comments inserted... > > > ----- Original Message ----- > From: "Richard Furniss" <[EMAIL PROTECTED]> > To: "EV List" <[EMAIL PROTECTED]> > Sent: Saturday, October 12, 2002 8:18 PM > Subject: Battery Charger > > > > Hi All; > > > > I have been helping my co-worker with the fleet of golf carts we have, > > about 20 of them. The education process has been going slow, I just keep > > nudging him in the right direction (in my opinion) on the care and feeding > > of the batteries, it's the only thing there having a problem with. When > the > > cart would no longer last all day on a charge he would just put in a new > set > > of batteries, what I have found is that it's only one or two stinkers > > causing the problem so we built up a surplus of, good, used batteries to > > replace the stinkers with instead of replacing the whole pack. > > > > The problem that I'm finding now is an imbalance in the battery pack, > > most of the chargers are Lester chargers and they taper to about one amp > and > > stay there until unplugged or timed out, my plan now is to do a > equalization > > charge as part of the regulator maintenance on the carts. > > > > Please correct me if the above strategies is incorrect or needs to be > > changed. > > Your intention is good. > > > The charge and equalization charge needs to happen in six hours or > less > > during the regular maintenance, my first thought was a variac with a > > isolation transformer, > > You can do much better than this. The current tapers off quickly with > increasing battery voltage. What you want is a constant current source, not > a taper charger. > > > then there was a bench top power supply it all ready > > has isolation, > > Good choice if it has a constant current mode. > > > then there was putting the variac in front of the Lester > > charger. > > Bad idea. Many Lester chargers have a ferroresonant transformer that tries > to keep the voltage constant on the output. Turning down the input voltage > has a very limited effect on the output. It is not linear and makes a > terrible equalization source. > > > I like the idea of the bench power supply, that way I can dial in the > > amps and set the voltage high and it will do the 36v and 48v carts, I have > > looked but haven't found anything that fits, yet, I'm thinking 70v and 10 > > amps. What do you guys think. > > You don't need 10 amps. 6 should do it. The excess current capacity of the > 10 amp unit won't hurt anything if you keep it turned down to about 6 amps. > 48 volts of golf cart battery should not go over 60 volts under charge. Some > may so you might need 64 volts out of the power supply. > > You should add a voltage recorder. A DMM with an RS232 port and data logging > software is available for under $100 on sale from Radio Shack. Dataq > (www.dataq.com) had a free starter kit a while back would do the job. The > starter kit has changed and they now supply a four channel module for $24.95 > (http://www.dataq.com/194.htm). You need this view to see when equalization > is over (when the voltage stops rising) to shut it down. If six hours has > passed and the voltage is still rising, then the battery is not done > equalizing and needs more time. > > Joe Smalley > Rural Kitsap County WA > Fiesta 48 volts > NEDRA 48 volt street conversion record holder > [EMAIL PROTECTED] > www.lasvegasev.com Richard Furniss Las Vegas, NV 1986 Mazda EX-7 192v 1981 Lectra Centauri 108v 3 Wheel Trail Master 12v Board Member, www.lveva.org Las Vegas Electric Vehicle Association
