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Bike is electric ignition with dfi.

So the past couple days it has been raining in Socal and I don't have a bike cover. Yesterday, I took my bike out over lunch (in the rain) and it started having problems.

After about 3 minutes of riding, I noticed the battery light came on. Within about 15 seconds, the gauges all shut off and and the engine just died. All day from that point, the bike was totally unresponsive, although it made some small signs of life when trying to bump start it. Later in the day, I started debugging it and found the main fuse (30A!) blown. Swapped the fuse and then there was life.

Now normally, by battery would sit around 12.5-12.6 VDC with the bike off for a while. After sitting all day without running, I noticed it was at 12.1 (which wasn't too worrisome) but it started up alright. I let it run for about 30 seconds and the battery light came back on. I immediately shut it off and decided to disconnect all my auxiliary circuits and see what was going on.

I connected my DVM straight to the battery and started it up. It was at 11.9 VDC just before starting and struggled a bit. Once running it was at 11.59 and I just let it keep running and watched as the voltage slowly went down to 11.41.

I decided to take it a couple blocks and it died on the way back. I haven't done any further diagnosis yet.

Now I assume that since the main was blown that there must be something drawing crazy levels, but I don't really know where to start looking.

The other thought was something wrong with the charging system since it slowly decayed (although I guess 1 volt in about 2 minutes isn't that slow).

Anyway, my question is, what would be a likely culprit to check next?

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  • Is there a fuse box on this bike?
    – Zaid
    Commented Dec 9, 2018 at 6:32
  • Yeah. On first incident I checked each fuse there and they all passed the eye test. Haven't done anything else with them yet.
    – kyle_engineer
    Commented Dec 10, 2018 at 16:21

1 Answer 1

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An easy way to narrow down the source(s) of parasitic draw on the battery is to measure the voltage drop across each of the fuses in the fuse box using a multimeter.

This is done by bringing the probe tips into contact with the terminals on the face of the fuse. A non-zero voltage reading indicates that there is current passing through the fuse, indicating that the system it is part of is actively draining the battery.

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  • I'll check this out and update.
    – kyle_engineer
    Commented Dec 11, 2018 at 16:03

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