Yet another CA77 Headlight Bulb Topic
Hi db, From my post http://www.honda305.com/forums/viewtopic.php?t=1838 "Selenium diodes have a forward volt-drop of about 1.5V whereas silicon diodes drop by 0.7V; you gain, in theory, 3.2V -- not 2.8 as I miscalculated in that post -- (as there ar 4 diodes in a bridge rec). If you really want to supercharge, seek out a Schottky-diode rec; these devices nominally drop by a mere 0.2V each, but that may result in overcharging or 'boiling' of the battery, so therefore I can't recommend it without further experimentation." Hope this helps and doesn't bore you all.... Sorry bro', to answer your Q: in theory an additional 3.2v will provide your battery with a 44% increase in charge (equation: 13.8 [nominal charging voltage] / 100 x 3.2 [gain of silicon diode rec over the original selenium diode type]= 0.441 = 44%). This gain can be directly converted into the same figure in amps, therefore: light switch OFF, 4A + 44% = 5.76A, and light switch ON, 6A + 44% = 8.64A. A substantial increase, although only theoretical as it depends on the quality of the materials used in the battery. A high-quality battery will serve to cap the terminal voltage at its required ceiling of 13.8 - 14V, whereas a lesser-quality product will allow that voltage to climb. This means that, initially, the charge will seem greater -- lights brighter, horn sharper -- because the voltage is higher, but that voltage will not necessarily be converted into Amps in a battery that can't accept it. Therefore the voltage, and subsequently the ability to hold that charge (remember: capacity = A/h) will quickly decay. E&OE - I'm only human!
The lighting switch increases the alt / dyn o/p (output) by 50% with the light switch fully c/w, irresepective of which lamp's filament is lit. Moving up to a silicon diode rec will replace most of the additional burden that would be placed upon the charging system when fitting a 60/55W H4. The gain using a silicon rec is approx 2.6A: Whichever light you select, remember the parking lights always tax the system by 0.83A Original tungsten filament lamp 35/35 = 2.9A, high or low beam + .83 = 3.73A Generic automotive H4 tungsten halogen lamp 60/55 = 5A high and 4.58A low, each + 0.83, leaving you with a gain of c0.9A when using low beam and c0.85A on high. Looking at these figures, it should, in theory, work OK. Talk about striking a balance!
LightingGuys, take a look here (thanks to Phil-UK for providing Paul Goff's name); a very informative lighting site:
http://www.norbsa02.freeuk.com/goffybulbs.htm Steve,
I think the voltage gained by replacing the selenium rectifier with a silicon bridge will only be 1.6 V. The difference in voltage drop across each diode is indeed .8 V, but because only 2 of the four diodes in the bridge are conducting at any given time, the gain will be 1.6 V, not 3.2 V. Wilf
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