What would cause your battery to die off of one try at the starter?
The history:
One of my headlight bulbs burnt out. Like a responsible motorist I purchased a new one (60/55W - instead of stock 45/45W)
Installed the new bulb, fired up the bike, rode to my gf's. All was well.
The next day - battery is dead. No lights, nothing.
Took out the battery, charged it fully.
Installed the fully charged battery (correctly. At this point I was double checking everything). Turn the key - lights are on (horray), hit the starter - dead. Lights went away. When I turn the ignition on there's no headlights, only the instrument cluster is lit but very very dim!
What the heck could this be?
Any help would be appreciated. I really don't want to have to tow my bike to the shop.
^ Agreed - battery for sure. A dead battery can take a bunch of stuff with it - the bulb was probably due to the battery. Change it before it kills anything else.
I charged up the battery. This time I took out my voltmeter and tested the voltage - 13.5 after full charge.
I put the battery in and turned the ignition on and the voltage dropped to 11.5.
Then I thought - why not unplug the new bulb. After unplugging the 55W bulb the voltage went back up to about 12.8
I started the bike and it fired up after a few tries (it had been sitting outside in 0 C weather for the past two weeks)
Went to Honda and bought the OEM replacement of 45/45W for the ridiculous price of $50 for a freaking bulb, installed it, bike runs fine. Voltage is fine.
So - now my question is - was it really the extra wattage from the 55W bulb that was causing the issue? Perhaps my battery was a bit low before and it just needed an extra boost?
Still could be a weak battery. It's not likely that the additional draw from a headlight bulb change could affect the voltage that much. A battery can hold a 13+ volt charge, but not be able to supply adequate amperage to turn turn the starter. Think of it like a garden hose that's turned on at a trickle. You can place your thumb over the end of the hose and let the pressure (voltage) build up. Then a little bit can be released (amperage) while maintaining the pressure. Let too much water out (high amperage) and the pressure (voltage) drops precipitously. Turn the water up and you can spray more water volume at the same pressure (supply higher amps at the same voltage). A load test measure's the battery's ability to supply voltage at a high enough amperage to turn the starter. An at-home way to load test the battery is to measure voltage across the battery while the starter is cranking. It should be able to hold 10 to 10.5v or so. If the battery is fine, look for high resistance in the headlight circuit - grounds are often culprits. High resistance in a circuit will eat up voltage as it tries to overcome the resistance.
Bad battery.........you can get voltage stored, but little current capacity. You use your scant number of amp-hours (prolly milliamp-hours now) in a few seconds. Power to start the bike is volts x amps, so 13.5 x 2-3 (guessing) is 25-40 watts, just enough to light a bulb, but DOA for turning it over to start. I have chased this one down before, too. It's amazing how a battery can fritz from one day to the next.
only 10W (.83 amps as 12V) shouldn't be enough to lower the cranking power but since it sounds like the battery is/was on it's last life it could be all it took. Of course the light should be off when the starter is working so just changing the bulb should have no effect...
Always check your grounds, most common issue when it seems the starter is drawing more power than you would expect.
End of thread · 11 posts recoveredWayback Machine snapshot 21 Jun 2015