Electrical hitch??

[Eveready1100]

My '79 Special has recently been giving trouble with the battery discharging when left for a time. After getting it started (boost or bump), it can be ridden around all day and it starts fine, even if it's only been running a few minutes. But if left overnight, the battery is flat as a fart in the morning. I assumed the battery was dying but after a bit of a look around under the seat and covers checking the wiring connections, I noticed that the fuse block mounting plate has a positive .2 volt reading. I pulled out the fuse block itself to make sure it wasn't shorting at the back and checked again and it still read .2volts. All the connections are tight in the area and there's no sign of any chafed wiring. Can anyone point me in the right direction if they have experienced a similar thing?
Regards,
Errol

[randy]

First of all, if you're using a digital meter, it's probably too sensitive for a job like this. I think if you stick two fingers on the meter lead it'll read a voltage. Mine does. Try this with a good old analog meter:

The way to locate a drain is to remove the main postive lead from the battery and place the meter leads between the battery post and the main lead. With the key off, you should not see a reading. If you do have a reading, remove one fuse at a time to find the troubled circuit. Once you find the circuit, replace the fuse and start removing components one by one to locate the bad component. If pulling components doesn't solve your problem, worst case, you have a short somewhere inside the harness.

[Ivan]

On non computerized vehicles, I use a 12v test light rather than a meter. Easier to see when you are pulling out components in the trunk (or other side of the bike). Otherwise the process is the same.

[randy]

The test light will work ONLY if the draw is large enough to light the bulb. YMMV

[Ivan]

If the draw is enough to drain a battery over night, it should light a test light.

Also, if it drains with the ignition off, you can usually eliminate the circuits that are dead with the key off. Which also makes me think of one other thing, If you are locking the steering, there are two positions, lock and turning it even further is "park" which leaves the running lights on. If you are turning it too far, that may be the answer. On my bike, it is hard to tell where the detent is, so I always look at the tail light, just to be sure.

[boyat68]

I personally think that you have a battery cell going. The trouble you indicated is a symptom of a shorting cell. You could charge the battery up fully and check each cell to see if all are within a few tenths of a volt of each other, then let the battery sit for about an hour and check again.

[Ivan]

I personally think that you have a battery cell going. The trouble you indicated is a symptom of a shorting cell. You could charge the battery up fully and check each cell to see if all are within a few tenths of a volt of each other, then let the battery sit for about an hour and check again.

That is another good idea. Especially if you let it sit in the cold too long.

[randy]

I don't know how you would go about checking the VOLTAGE of individual cells. You could, however, check the SPECIFIC GRAVITY of each cell with a hydrometer.

[red bandit]

An easy check is charge the battery and disconect one of the leads to the batt. Leave it sit overnight. If it's dead in the morining it's the batt. if not you have something draining it.

[Larrym]

When checking for a “drain” on the battery which is coming from the bike’s wiring I agree with Randy except I would have the multimeter set to measure DC Amperes. There will always be a small milliampere reading due to the leakage of the diodes in the charging system rectifier but any real “drain” from the bike’s wiring would show up as half an amp or even more.


To check out the voltage of a battery’s individuals cells the meter is set to read Voltage and the multimeter’s leads are placed directly into the electrolyte. This IMO is a very risky procedure that can go horribly wrong if your meter doesn’t have the right Ohms/Volt rating or let’s say the meter is set to read Amps and the leads are connected to the Amps terminals. This could lead to a small spark and FLABOOOSH! You can end up looking like “Fire Marshall Bill”.

A dead cell in a battery equals a worthless battery. A safe practice is to remove the battery from the bike and charge it with the proper charger (less than 2 amp charger..) overnight. Then let the battery sit for another 12 hours. After the battery has “settled” you can check the battery with a digital meter and if it’s less that 12.5 Volts you know something is not right. Doesn’t matter what is wrong: bad cell, reversed cell. high internal resistance, contaminated electrolyte, diluted electrolyte, etc. The battery is a candidate for the landfill. But if the battery passes this test, the problem will likely be the wiring of the bike.

The charging system of the XS is designed to keep a good battery from discharging when the lights, ignition system are trying to drain it. This same charging system is not really up to the task of keeping the lights powered up AND trying to charge a discharged battery/bad battery. (Bad JOO Joo)

[rpgoerlich]

I don't know how you would go about checking the VOLTAGE of individual cells. You could, however, check the SPECIFIC GRAVITY of each cell with a hydrometer.

If you open the cell caps and insert your meter lead into a cell(has to contact acid) with other lead on a post, you will see the voltage of that cell and the cells between that cell and the post. So if you check each one as you go from one end, you can subtract their voltages from the total to give you a single cells voltage. Just be sure and clean you meter lead good .