I am wanting to use an H4 bulb on my 66 Dream. What is the max wattage acceptable? I'm guess around 35 watts.
Thanks.
Yet another CA77 Headlight Bulb Topic
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? Did you go thru any old posts about headlights.I tried a higher watt H4, but it drained my battery while driving.I would not assume it is only 35w.Might want to verfy that.I bought a bulb on Ebay that was a 20/35w and used high temp RTV to hold it in one of the replacement headlights I got from Ebay also.
Yeah, read a bunch of old headlight topics. I may be more confused now than when I started! ;) I've looked but have yet to find a 20/35w H4 bulb.
Hey guys,
First & foremost: a glossary of terminology - Volts = electrical pressure, symbol V Amps = consumption of volts, symbol A Watts = dissipated power; also consumption (a more commonly used and understood term), symbol W (or I in theoretical calculations); W is a consumer's (device's) rating at its correct working voltage - A is the load within a circuit as a result of W A/h = Amperes per hour; rate of consumption - also refers to a battery's capacity, symbol A/h Ohms = circuit impedence (or resistance) - the lower the impedence figure, the more power that device will dissipate (use up) within a circuit (and the hotter is will get as a result), symbol R or Ω (Greek letter Omega); I include Ohms here because without it we cannot apply Ohm's Law (V=I/R, or Volts = Watts divided by Ohms, therefore A=W/V and W=VxA. Most H4 lamps are 60/55*; 60W being main (high) beam & 55W dipped beam. The rationale being that the extra wattage (power) on high beam will produce a greater light output for the required further projection. Back to the plot: 60/12v = 5 Amps. Ergo, 55/12v = 4.58; add that to the parking lights, both totalling another 10W (0.83A), and the power consumption of the ignition coil (plural for Type-1 motors, and which I know to be 2.3A, points closed, so, accounting for dwell let's say 2A) making riding safely, lights on, is going to consume a minimum of 7.41 Amps per hour; that's without applying the rear brake which will add another 21W for the duration of application (add another 1.75A). So, let's look at the realistic new battery usage (I say 'new' as the battery's capacity, in A/hrs, will reduce as the battery ages) with this H4 lamp: engine starting on the button will use, by my guestimate, 1A/h -- or 60 Amp/minutes -- of capacity, leaving those of you lucky enough to have the proper 9A/h battery, with 8A/hrs. Warm up for about 3mins, lights off** (see footnote), alternator producing circa 4A -- or 4 Amps per hour [1 Amp per 15 mins] -- then that 3-min warmup has replenished merely 0.2 of your 1A/h used up during starting. You now have, in the batt, 8.2A/h; switch on the lights and your usage rises another 5.41A/h. The alt steps up its output by 50%, from 4A(/h) to 6A(/h), by virtue of the light switch being in the 'Headlight' position. You are now debiting your battery account at the rate of the previously-calculated minimum of 7.41Amps per hour, but your alt is only paying back into the account at the rate of 6Amps per hour, leaving you with a minimum deficit of 1.41Amps per hour of riding. You started off with 8.2 in the account and lights-on riding is, realistically -- assuming rear brake usage etc --, going to debit the account by a further 2 per hour. So, 4 hours of this style of riding will mean your battery's account is more or less totally depleted! I know it's caused most of you reading this to glaze over by now, but when the problem gets broken down into actual figures, you can see why using a standard H4 lamp will result in quite quickly emptying your battery. I'm seriously looking into spending £100 on the HID alternative from www.hids4u.co.uk! See my post in 'Electrical - Wiring/Day riding light idea' for the link. *Excercise extreme caution when buying! I have used, in my past cars, H4s rated at 100/60, 100/90 & 135/90 from rally part manufacturers like PIAA, but only after modifying wiring and installing relays. These will, ultimately, damage your dimmer switch and, possibly, wiring harness if you don't have the prescribed 15A main fuse installed! Always read the label/engraved rating on the lamp; keep out of the reach of children; your investment can go down as well as up..... **Carrying out a warmup with the headlight switch on (c/w only) and the dimmer switch centred will increase the charge rate by about 1.2A/h -- the alt produces another 2A and the parking lights consume 0.8 of that (per hour). I'll post practical -- as opposed to theoretical -- figures once my CB's running again. Laters....
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