2009/3/26 Tobias Gogolin : > Hi happens that I find the piclist to be the community of the fittest > electronic engineers that I know on the web, that's why I ask here and not > on some of grid living list... > > I may have mentioned before that I use 10 pc. 12V car batteries at my of > grid ranch, and that I charge those using a simple rectifier, either Bridge > from 120V AC or 2 diodes using half of each of the 2 120V outlets around the > center of my generators 240 V AC output (I do that to reduce the chance of > any one of the automatic breakers of the 2 120V circuits from tripping). > > This seems to work quite good, but I just read that it is not advisable to > charge Car batteries on pulse current, and since they would be charged only > when the generators output voltage reaches above their current charge > voltage, it definitely is pulse... > > So I have been toying with the idea to try a different circuit, and I would > like some comments and hints on dimensioning the circuit! > === here it goes === > > If I use a circuit like they use on computer power supplies that double the > voltage using 2 diodes and 2 Capacitors, but hooked it up to the battery > bank, the capacitors would have to discharge completely every cycle (maybe > even reverse polarity, which I could prevent with another diode per cap), > but since last half waves capacitor starts out with minimally the voltage of > the bank, the new half wave charging the next capacitor would push up that > voltage and therefore start discharging the Cap to the Battery starting from > 0... > > I know it may be difficult to describe in words, but its a simple enough > drawing! > I wonder though would kind of capacitors would stand this type of abuse and > how I would estimate the current that would be required? > I figure there must be a possibility to develop a formula using the Coulombs > at max voltage, and then average out this number of electrons over the cycle > to get an estimate for the produced, now less 'uncontiniously' pulsing! > > Thanks for any hints or help to express this better so more responses are > possible! > > > > > -- > Tobias Gogolin > skype: moontogo > messenger: usertogo@hotmail.com > > You develop Sustainable Ranch Technology at > http://tech.groups.yahoo.com/group/SURA-TECH > an Open Source Electric Motor/Alternator at > http://groups.yahoo.com/group/Performance_Axial_Flux > and an Open Source Motor Controller at http://groups.yahoo.com/group/GoBox > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > Hi Tobias. We manufacture "68V" power supplies /chargers for telephone exchanges. We do not manufacture 120V 'rectifiers' although they are available from other manufacturers. Typically these power supplies work by boosting the voltage to a DC level above the peak of the mains voltage and then performing a DC-DC conversion to the final battery voltage - about 53V for "48" volt systems. A 2 stage conversion that provudes power factor correction, low THD and excellent output voltage control - temperature compensated for best battery life.. Anyway, you really do need to minimise the ripple on the charge current. The easiest way would be to try and get a couple of old Telecom supplies and run them in series. Or a UPS charger. Adding a heavy series inductor would help a lot also - but it would need to be big to be useful at 100 or 120 Hz. I can't remember the maximum current that you are running at but a capacitor based voltage doubler won't provide much current - for reasonable values of C. If you just want to increase the voltage you are better off with a transformer. But with just a diode rectifier the peak current will be high, along with the THD and the power factor will be low. Basically, you will not be getting the best bang for your buck from your generator. Richard P -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist