Help With Battery Drain

[Mandel]

I've been using Yuasa batteries but they always fail in less than a year. I installed a new, fully charged batter in October 2012, had it on a tender periodically, but it ran out of juice this morning moments after I disconnected it from the tender, even though the tender showed a solid green light indicating the battery was 100% charged.

It seems like something is draining the battery when the bike is turned off. While it's also possible that the battery is not getting charged when the bike is running, it seems pretty strong after I ride for a while, make a stop and start up again.

The only things that I have attached to the battery are: (1) a powerlet socket that has nothing plugged into it, and (2) an SAE connector for a slime pump which is disconnected unless I need to use the pump.

I added LED turn signal lights in the mirror housing but they're powered off the turn signal wires when the bike is running and get no power when the ignition is off. I also added an LED running light/turn signal bar on the rear of the bike, pulling the power from the tail light and turn signal wires, which don't illuminate when the ignition is off.

I have a stack of 7 drained batteries in my garage, all bought new and fully charged. I'm going to add another one: This morning I was stranded when the battery I replaced in Oct. 2012 died.

Any ideas?

Mandel

 

[okmurdog]

Find an ammeter to measure the amount of current that is being drawn from the battery while the bike is off - IIRC, the drain is ~ 2.5 mA.

Also, check the charging voltage when the bike is running - measure directly on the terminals of the battery. It's possible there is a bad connection somewhere in the charging circuit that is dropping voltage and not charging your battery fully.

 

[dwalby]

if you don't have an ammeter, get a cheap multimeter from Harbor Freight or Frys. Put meter between positive terminal and positive battery cable. If you see high drain, start pulling fuses and try to narrow down the location from there. I think you can also use a cheap continuity light from an auto parts store, but I think the meter will put less of a voltage burden on the load, so if you have a very small current leak it might be more measurable with the meter than with the light.

 

[Mandel]

Thanks dwalby.

I have a multimeter but I'm not sure how to use it to run this test. Should I set it to read the voltage between the positive battery terminal the positive Cable? Should the bike be running when I take the reading? (If it's running, then some farkles will be drawing power.)

I'm guessing that I need to measure the output of the battery first and then compare it to the measurement I get when I put the meter between the terminal and the cable to determine whether there is current drain, correct?

Sorry for the questions but I obviously don't know what I'm doing!

 

[T_C]

Should I set it to read the voltage between the positive battery terminal the positive Cable?

No.. don't do that. It'll be a meter killer.

Without knowing the specific model of meter (and maybe seeing a picture of the face would hgelp) it;'s hard to give you advice on how to use it. Generally when you put a meter on to read amperage you have to move where the positive lead plugs in.

Not all multi-meters can read amperage. Look on the switch face and see if there is an A symbol somewhere. Hopefully it has a straight line above it and not just a squiggle. If it's just a squiggle, then you can only read AC amperage.

But take a picture of the meter front and post up here.

 

[st1300r]

Since a new battery is going in take the time to check clean and reconnect both end of the battery cables after you charge it with the tender.

Then turn the bike key to light the headlights for maybe 10 seconds, then turn it off.
Now measure the battery voltage. Hopefully somewhere around 12.8 volts.

Leave the leads connected, start the bike.
Check the voltage at idle. 12.8 or so?
Now look at the meter while rev to maybe 5000k and hold it there.
Is your voltage climbing as rpms increase to around 13.8 and less than say 14.8?

Your looking at voltage to see if the charging system is working properly.


Then

You're looking to measure the current with the bike off to see if something is killing it while the bike is sitting.
A picture of your actual meter would help.

If the probes plug into ports on the meter there's probably 3 or 4 ports for the 2 leads.
One common (black lead) ground.
The red lead plugs into
-one for volts, ohms, frequency or whatever your meter does.
or
-another one for low current amps in mA of thousandths of an amp
and maybe also
-a third one to measure high current in amps. Max maybe something like 2, 5 or 10 amps depending on the meter.

 

[schlep1967]

My first question is what battery tender are you using? Especially if you have used the same one for all these batteries. Could be overcharging or not charging at the proper current.

 

[sofawizard]

id consider doing without the battery tender as it maybe the fault a day or 2 without it connected will show if the bikes at fault

 

[st1300r]

That's a good point a trickle charger over time could cook a battery.
If the new battery is over 12.4volt as recieved you could put it in as is and check the voltage vs. rpm to check the charging system.
Or put the voltmeter on the battery as the charger is doing it's thing as verify it's not overcharging.

The battery tender (brand) has different modes as it is charging the battery.
Somewhere on here I posted aprox voltages where it switched modes while charging a battery at room temp with a starting point of 12.4.
iirc 14.4v was about the most the battery was subjected to.

 

[Mandel]

Thanks guys.

I'll take some measurements this weekend and probably have more information -- and questions -- to post.

 

[Optimus]

Mandel the only way to check for a draw is using the amp scale on your meter. Usually even the cheap meters have a 10amp DC setting . Set your meter & probes for this position. Then disconnect your negative cable from your battery put the red wire from your meter on this cable & the black lead from your meter to the battery neg post KEY IN THE OFF POSITION do not turn on the key during this test.Now you should have pretty much a zero reading. Typically in my trade 0.03A is ok but if your reading is much higher you have a draw. Start disconnecting fuses to locate the problem circuit

 

[dwalby]

Thanks dwalby.

I have a multimeter but I'm not sure how to use it to run this test. Should I set it to read the voltage between the positive battery terminal the positive Cable? Should the bike be running when I take the reading? (If it's running, then some farkles will be drawing power.)

I'm guessing that I need to measure the output of the battery first and then compare it to the measurement I get when I put the meter between the terminal and the cable to determine whether there is current drain, correct?

Sorry for the questions but I obviously don't know what I'm doing!

You will need to have one lead inserted into the meter port that says something like "10A", and the other lead inserted into a port that says "COM" or common. Which port you put the red wire into isn't really important, the only difference is you'll get a negative current reading instead of a positive one, but all you care about is how much current draw you see. On the meter mode dial you should see options like A, mA, and either a tilde (~) above the A/mA, which means AC, or a straight horizontal line, which means DC. Select the DC (A) setting, not the mA setting.

Then disconnect one of the battery cables and connect the meter between the cable and the battery post that it was attached to. Again, polarity isn't important, either lead can be attached to either point. Either positive or negative battery terminal will work equally well, anywhere you break the circuit is fine because the current is flowing in a loop between the positive and negative terminals of the battery. For these types of jobs I like to use a set of leads that have alligator clips on the ends instead of the usual circuit probes. Otherwise, you'll have to drop the leads to pull the next fuse, then attach them again, etc. Also, for small amounts of current you need to make sure you have a very solid connection to both the battery post and the battery cable you removed from the post. Having strong alligator clips helps in that regard too.

Once you see how much current is flowing using the 10A setting, if its small (less than 0.2A for example) then you can switch the meter lead into a different port that will say something like "300mA" if you want better resolution. And you'll likely need to move the mode switch to the DC mA position as well. The risk with that setting is if the current spikes up above 300mA for some reason, you'll blow the fuse in your meter, so if you can get a decent reading in the 10A mode use that mode exclusively.

Also, don't turn on the ignition switch while making these measurements, and let us know what you find.

 

[superdiver]

two very nice write ups on checking fro draws... I have an '72 honda 90 i need to do this with...

 

[st1300r]

For the US spec 1300 bike off current should be 2.5ma or 0.0025 amps.