Parasitic draw clarification

[chuckycheese]

I've got a dead battery again and have been trying to figure out why. I read past posts about parasitic draw (which I suspect) but find it confusing. Here's why:

I read a couple of posts that said to leave the positive battery cable connected...then disconnect the negative cable...then check for voltage by touching the positive multimeter lead to the negative post and the negative lead to the disconnected negative ground wire. I did this, thinking it would show no voltage; instead it shows 11.6 volts! So, what's going on? Thanks!

 

[saddlewarmer]

unless i am reading it wrong, you are trying to determine if there is any current draw with the key off. the connection of the probes you described would be to check current draw, not voltage. your meter needs to be in the amperage or current reading position. this will show any current being drawn with the key off. otherwords, to measure voltage we go across the circuit (parallel), to measure current we go in series with the circuit. hope this helps.

 

[omaharj]

What I did was disconnect the pos wire and test from the pos terminal of the battery to the wire you disconnected. I got a reading of 1 volt and was able to trace it back to the key ignition. Good Luck!:-D RJ

 

[Boondocks]

Parasitic loss is measured in milliamps (MA), not volts. To check for a faulty circuit causing a battery drain, the meter should be set to measure amps in series with the circuit as saddlewarmer has stated. The reading should be the same whether the positive or negative battery terminal is disconnected and tested in series between the terminal and cable. Set the range to the highest MA setting and work downward to lower settings. If a current drain is detected, you will have to isolate which circuit is causing the problem. You can do this by removing fuses, which may indicate which circuit is involved. After the circuit is identified, you can then trace it for shorts, bad switches, etc..

 

[chuckycheese]

Thanks

Thanks

Thank you all, VERY MUCH!! I think I understood what each of you meant and I'll give your suggestions a try to see what I come with. If I can't come up with an answer, I'll seek your advice again!:-D :-D :-D

 

[chuckycheese]

Drain

Drain

OK, I did as you suggested. I found a current drain of 0.01...is that significant? (I'm just guessing, but I doubt it.) Thanks, as always.:-D

If it's not, maybe my one year old battery is pooooopy!:-s

 

[saddlewarmer]

.01 what is the question. Milliamps or amps. .01 amps is 10 milliamps. what scale were you using on meter. 10 milliamps i would not consider bad at all. thats approx 120 milliwatts of power being used. try to find which circuit is drawing it and see if theres room for improvement tho.

 

[nabrams]

Maybe your dead battery has nothing to do with current draw happening while the bike is not running.
Maybe the bike's charging sytem is faulty while the bike is running, leading to a dead battery.
Have you verified voltage at the battery terminals is 14.x volts DC while revving at 5000 RPM? If it's anything less than 13.x then your charging system is at fault.

 

[chuckycheese]

Charging

Charging

The charging system is working just fine. I recently put in a new stator and R/R and it checked out great according to the Stator Papers. Thanks, again, for the help and suggestions!:-D

 

[hungryman]

Ok, some misconceptions going on here. By disconnecting the negative lead and measuring the voltage from pos to the frame you are checking for current leaks without using a current meter. If there was no path to ground, the voltage reading would be (depending on your meter) close to zero.

Now, if you want to make a current measurement, there is no need to disconnect the battery ground lead as Boondocks stated.

Last, a 10 milliamp current draw is about a 1200 ohm load. I would do some investigation and find out what circuit is guilty.

 

[Boondocks]

Ok, some misconceptions going on here. By disconnecting the negative lead and measuring the voltage from pos to the frame you are checking for current leaks without using a current meter. If there was no path to ground, the voltage reading would be (depending on your meter) close to zero.

There is no misconception. Whether parasitic loss is serious depends on the volume of current loss measured in milliamps. A voltage reading may indicate a potential problem, but it doesn't measure the extent of the problem. A voltage reading may be shown for a current draw so small that it is negligible.

Now, if you want to make a current measurement, there is no need to disconnect the battery ground lead as Boondocks stated.

I stated that either battery terminal (negative is better because it prevents sparks) could be disconnected and the current measurement made between the terminal and the disconnected cable. This is a common troubleshooting starting point to identify the extent of the the current draw and determine whether further tests to isolate problems are necessary. This is obviously not the only way to make a current measurement, but is the first step in parasitic loss troubleshooting.

chuckycheese hasn't told us what range the meter was on to get a 0.01 reading. If it was the 10A range, a 0.01 reading would be 100MA (milliamps). This would be a serious loss and would drain the battery in a few days, 10 times faster than a 10MA loss. A 100MA drain is 1.3 watts, and would be like leaving an instrument panel light bulb turned on all the time.

Under ideal conditions, there should be no current loss unless something like an "always on" aftermarket gauge has been connected.

 

[BadBillyB]

A voltage reading may indicate a potential problem, but it doesn't measure the extent of the problem. A voltage reading may be shown for a current draw so small that it is negligible.





Under ideal conditions, there should be no current loss unless something like an "always on" aftermarket gauge has been connected.

These statements are both right. A voltage reading just means there is some continuity. It does not tell you the extent of the current draw. A reading close to battery voltage would make me suspicious. I am an old school mechanic and only use an unpowered test light to measure current draw. This does not give you a particular figure, but it tells you if you have a draw large enough to cause a problem. I have been using this method on cars for 25 years and it has not failed me yet, even on modern cars with many capacitors in the system.....I do not even own an ampmeter.....Just put a plain tail lamp bulb in series with the disconnected negative battery terminal and the negative battery post. If there is any significant current draw it will light the filament (high draw) or make it glow dimly (low current draw). If you have a dim glow of the filament, this is enough of a draw to be an issue. You can then leave the bulb connected while you pull fuses or connectors to find the affected circuit......Simple, effective and cost efficient for anyone.......BadBillyB

 

[dcpower]

battery drain

battery drain

to test cars we use an ampmeter that is digital and set on 10amp scale.
the meters usually read 2 or three digits below the amp range ex 2.541
if you have a draw of .01 on a bike battery that will kill it probably in one night
we use .025 as a limit on a car size battery so if you take a bike battery at about 20% the size of a car battery .01 amps or 100mill amps you have way to much draw and the battery will end up dead.
have alt and starter shop and we run into this alot

 

[hungryman]

There is no misconception. Whether parasitic loss is serious depends on the volume of current loss measured in milliamps. A voltage reading may indicate a potential problem, but it doesn't measure the extent of the problem. A voltage reading may be shown for a current draw so small that it is negligible.

Yes, but it doesn't void the statement that you are essentially checking to see if there is a current leak. It doesn't address magnitude, but it is a valid way to check for a current leak. This is a go, no-go check.

 

[hungryman]

I stated that either battery terminal (negative is better because it prevents sparks) could be disconnected and the current measurement made between the terminal and the disconnected cable.

I was agreeing with you, although after reading it again it was a bit vague.

 

[saddlewarmer]

now that i am confused!!! (i had to deal with a 2 solar powered radio sites all day with Battery and charging issues). 10 milliamps of current can be significant on a bike, i was thinking car on my statement(oops). current draw is what is going to drain the battery, not any kind of voltage draw. if current draw is excessive , the battery will die, but what is excessive in this case? narrowing the offending circuit down is the first step, and then narrow it to the offending item. could even be corrosion between a hot point and ground! might take some work, might not. resistance measurements at different points in the offending circuit (to ground) can narrow it down to a specific area, maybe even a specific item. the lower the resistance, the closer you are to the shorting item ( measured to ground). the light bulb trick is an old but good one, had not thought about that in ages. hope i have not confused anyone anymore than i am. any questions ask!

 

[Boondocks]

The consequence of a parasitic current drain can be estimated by comparing the current leak in MA to the ampere hour rating of the battery. A new fully charged battery of the type commonly used in larger GS bikes may be rated at 14 AH (10 hour rating). This means that the battery should be able to deliver 1.4A for 10 hours before its charge is depleted. A smaller current will usually allow more total power to be delivered over a longer time period.

In the case of a 100MA drain, it would take 140 hours to transfer 14A from a new fully charged battery. At 70 hours, about 3 days, the effect of losing about half the battery's charge would be so apparent that it might seem like battery failure. If the battery is not new and in perfect condition, the performance loss would be even more rapid and severe.