In rec.autos.makers.honda sharx333 <emil.santos@gmail.com> wrote:
> Is the "light bulb" test (putting a 12v bulb in series with the battery
> circuit) an accurate test for a parasitic drain? My ammeter only goes
> up to 0.25A, and I don't want to risk overloading the meter.


I had a light bulb that was a parasitic drain, once.
I thought I just had a dying battery. It was a little sluggish starting
sometimes, and dead if I didn't drive it every day.
I bought a new battery, and that made things much better, and then it was
dead again after it sat for a few days.
I charged it up, got in, and noticed a strange glow on the floor. At first
I thought it was a street light, then I realized that the glove box light
was on. The switch had gotten knocked out of it's mounting. I didn't see
the dim light under daytime conditions, and only happened to notice it at
night.

> How bright should the bulb light up, if it should at all, for a
> "normal" drain? (clock, ECU, radio memory)

I would say that a dual filament 1157 bulb should glow dimly. If it is at
all bright, that is a pretty good load. At full brightness:

bright filament: 12.8V, 26.9W, 2.10A (R=V/I=12.8/2.1=6.1 ohms)
dim filament: 14.0V, 8.3W, 0.59A (R=24 ohms)

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Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5