Yet another CA77 Headlight Bulb Topic

[joeweir1]

I used an H4 for alittle while, but it did wipe my battery out so I used it sparingly until I found a lower watt bulb on fleabay.Joe

[Dogsbd]

I used an H4 for alittle while, but it did wipe my battery out so I used it sparingly until I found a lower watt bulb on fleabay.Joe

What wattage worked? Was it too an H4, just lower wattage?

[e3steve]

Wow, thanks for the electrical lesson. I for one can use it. How would use of an updated rectifier effect the above equation, if any? It is my understanding that modern rectifiers make the charging system more efficient.

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!

[e3steve]

Mmmmm...

OK I am a total novice at electrical so bear with me. It is my understanding that the CA77 charging system only generates at its highest rate when the headlight is on high beam. Is this correct?

If so am I also correct in assuming that an H4 bulb that is listed as 35 watt on low as well as 35 watt on high (and I don't understand that either) would pull too much current on low beam but be OK on high beam?

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!

[e3steve]

Guys, 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

[Wilf]

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

[e3steve]

Hey Wilf, how's summer in Canananadia?

My rec is a Schottky diode type; typical forward attenuation is 0.3V. But you're right, of course; only two of the four diodes afford attenuation. My apologies.