Parasitic Battery Drain

I've been having some kind of parasitic battery drain. It takes 3-4 days before I notice the voltage is slowly dropping. I started unhooking the battery when I don't plan to ride for a day or so and the problem stopped. I then discovered I had one blown tail light bulb (brake light filament still works)t . When I removed the bulb and left it out until I had time to get a new one the drain seems to have stopped. Can a blown bulb somehow slowly drain a battery?

BYW, this is happening on my 99 VFR.

 

Shouldn’t make a difference. You need to do a leak test to find out where your drain is.

Do you have any accessories fitted?

 

No accessories. I guess Ill get the meter out and do a test. Just seems strange that removing a half burn bulb would stop it. Unless, there was something shorting on one of the tail light wires. Still, the ignition would need to be on for that to be the case I would think.

 

Yes ignition would need to be on. However do you have the option to switch off lights?

 

It could be you just need a new battery. Load test your battery and see if it is weak.

 

possibly could be a bad r/r

 

Thanks for the input all. I put a new battery in and it and it started draining right away. It drained the battery down all the way a couple of times until that battery gave up and would not hold enough of a charge to start it. So, thinking I just got a bad battery I got another new one and the same thing is happening, although this time I did not let it drain all the way down. I don't think it's the R/R as I only ran the bike with the new battery for about a half an hour. My volt meter indicates proper charging while running (14-14.1v) and it charges the battery back up no problem after a good run. It starts to drain just sitting there until I took out the burnt taillight bulb when I found it. I've been watching and it's holding a charge just fine. I have 12.8v after sitting for over a week. I'm going to put the new bulb in and watch it.

I just can't figure out how this can happen without the ignition being on. Even if a bulb filament was somehow shorting out there should not be a drain unless the ignition/lights are on.

Oh well, so it goes for a VFR and all the electrical gremlins.

 

Does your ignition switch have a "park" position just counterclockwise from "off" ?

some Hondas have them to power a taillight while parking on narrow euro streets.

 

I have had my 83 since new, but never used the Park setting! Couldn’t figure out why my tailight was on ocasionally.

 

Ill repeat my post 2 comment. HAVE YOU DONE A LEAK TEST YET?

Before starting any of the tests ensure that the battery is fully charged (and reading between 12.8v and 13.2v across the terminals) and that all connectors are clean and tight. The only tools you need are those in your toolkit and a multimeter.

If you have found the battery discharged overnight there are two possible causes.
A voltage leak (something still drawing a current) or a knackered battery (sulphated or damaged cell)

LEAK TEST
Make sure the ignition is switched off and disconnect the earth/ negative (-) lead from the battery.
Connect the multimeter + probe to the earth lead and the – probe to the battery terminal. Make sure the meter is reading amps.

With the ignition off there should be no (0) reading unless you have an alarm fitted. The only non switched circuits are the cooling fan, clock and an alarm.

The max specified current leakage for carbed bikes is 1.2mA max.
For FS Injected its 2.0mA max.

If there is a leakage which exceeds the specified limits. A short circuit or an accessory on is most likely.
The best way to locate the short is to start by removing fuses one at a time will your leak stops then investigate that circuit by disconnecting connectors one by one until the culprit is found.


Hope it helps.

 

Low voltage/high current systems are very susceptable to high resistance connections due to corrosion, weak splices, poor grounds. These poor connections can pass voltage but not current. Voltage readings can fool your diagnosis. Follow Fink’s advise.

 

Yes, I've done a leak test. something is shorting. With the left rear taillight out I see no drain. However with the volt meter connected at the battery and I push a new bulb in I see a slight drop in voltage (key is off). Pull the bulb out and it goes back up. I think its obvious now there is a short somewhere. I just need to go through the the fuses now. It been so cold here lately i just have not got aroundto it. Thanks for the help.

 

There, no more excuses.

 

That's great I never heard of TUIT before. I'm going to use that one.
TUIT stands for Tashkent University of Information Technologies (formerly Tashkent Electro Technical Institute of Communication; Tashkent, Uzbekistan)
Which is where they designed the electrical system for the VFR.

 

LOL