Motorcycle alternator/battery relationship? Dead battery after running for a while!?

Question

I just bought a used 2001 Suzuki Intruder VS800 with less than 3,000 miles on it. It definitely needs a tune-up and idle adjust because it stalls very easily when in neutral. Last night it stalled after it had been running fine for about an hour, and when I tried to restart, the battery was dead. I jumped it with my car, let it run for a few minutes, and it stalled again and needed another jump. This time I made sure to give it extra throttle so it wouldn't stall again, so I was able to ride it home without a problem.

Why would the battery die after it had been running fine for an hour? especially since when I had turned it on the first time, it started right up with no problems? Does this mean that there is a problem with the recharge circuit? When a motorcycle motor is on, do the lights, etc, run off the battery or the alternator/stator? If it's like a car and they run off the alternator, I don't understand how the battery could discharge enough to die after the bike had been running for so long.

Thanks!

Answer 1

Was that running fine for an hour bit done at idle?

Motorcycle alternators generally have low output at idle. Often low enough to let the battery discharge with all the lights on. An hour is enough to drain the battery.

Fully charge the battery with a charger. If it runs flat again, you will need to start doing some checks. First thing is making sure all the connections are clean and tight.

Answer 2

My guess is that this bike has been sitting for a long time prior to you buying it. Replace the battery, check your connections, and then make sure that you are getting juice from your pick-up assembly. Chances are you are just dealing with an old, bad, dead battery.

Answer 3

Here is the test procedure for determining battery or alternator problem after requiring a jump start. Note, requires a voltmeter [$3.50 at Harbor Freight]

1] Check battery voltage on non-start vehicle. Will probably be under 12V. Verify good clean connections, look for cracked corroded or loose terminals.

2] Jump start. Note, always have the jumper vehicle running when performing a jump start, sounds basic but I actually had a friend who argued it should not, meaning he would be jumping with less voltage & could strand both vehicles.

3] With jumper cables removed, engine running, check voltage at battery. It should be 12.8V to 13.7V. If below 12.8V the alternator or voltage regulator are suspect. If in the range, the battery is either dead, low on water or in need of a full charge. If over 14.7V the voltage regulator is not functioning properly.

Most likely it needs a battery, motorcycle batteries have notoriously short lives.

Answer 4

Sounds like it's not charging.

Probably either the alternator or voltage regulator.

Answer 5

Look in the battery, I garuntee you its all sulfated,

Answer 6

It's not charging up or it might have bad connections. Could be the starter is acting up as well. Don't get so emotional about it!