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Battery

pglaves

#13338
I had an interesting experience with a battery yesterday / today that is worth describing. The bike happened to be an F650 Dakar but that wasn't critical or even very important to the story. Yesterday I rode the bike 53 miles into Alpine, made 4 stops in town, and then rode home, dropped some meat off in the freezer and proceeded 25 miles down to Terlingua and delivered some stuff we had picked up in Alpine.

And then - the bike wouldn't start. The dash lights would barely light. After some milling around we used booster cables to start the bike but as soon as we disconnected the cables it quit running. Get trailer. Tow home.

Today we went hiking with relatives/visitors in Big Bend National Park and while we were gone I left the battery on a charger. Then when we got home the charger's volt meter and dash lights said fully (100%) charged. No start. Dim lights.

I pulled the battery out of the bike. Hooked jumper cables from my car to the bike and started it. The voltmeter I had on the car battery (car engine off) said the bike charging system was charging the battery. OK.

So sitting on the workbench the battery showed 12.7 volts. I hooked up a little 12 volt pump I have and the battery wouldn't power it. Huh?

So I hooked up my volt meter. Still 12.7 or 12.8 volts. So with the volt meter still hooked up I hooked up a little test light I have comprised of a little tail light bulb. The battery voltage immediately dropped to 4.8 volts. Some big load test!

My diagnosis is that the battery failed, suddenly and totally. Yet it still showed a standing no load voltage of 12.7 volts. But it had virtually no capacity to power anything. It wouldn't power a tail light bulb, let alone a starter.

The lesson is that you certainly need to test more than the no-load voltage if you think you have a battery problem.
 
Good morning Paul:


Is the battery an Exide by any chance?

Over on the R1200R group, many of us have experienced the "Sudden Battery Death Syndrome" and it is specific to those batteries. Most of us have changed to anything but. The the common thread among all of us is the magic 2 year old battery point. For some reason, at or about that point they just do not want to play anymore.

Many of us have changed to the Odyssey batteries:

http://www.odysseyfactory.com/powersports.html

The particular one I adapted to fit is the PC535. It involves shaving some of the plastic fins down to allow it to fit into the recess on the RR, as it is a larger battery physically.
 
Good morning Paul:


Is the battery an Exide by any chance?

Over on the R1200R group, many of us have experienced the "Sudden Battery Death Syndrome" and it is specific to those batteries. Most of us have changed to anything but. The the common thread among all of us is the magic 2 year old battery point. For some reason, at or about that point they just do not want to play anymore.

Many of us have changed to the Odyssey batteries:

http://www.odysseyfactory.com/powersports.html

The particular one I adapted to fit is the PC535. It involves shaving some of the plastic fins down to allow it to fit into the recess on the RR, as it is a larger battery physically.

Doug,

When you say Exide, that means Yuasa. Has anyone in your group/forum had any response from Yuasa on this issue? It seems like a big problem.

Jon
 
I've seen this many times Paul. I don't know if I can explain it scientifically or not. As a reference on a piece of wire the voltage is carried on the outside of the wire and the amperage on the cross section of the wire-example a glass fuse. In the case of the battery there can be a plate separation yet the voltage carried by the electrolyte. If the batteries have fill caps or the pop on after fill strip in the case of Yausa batteries it can be checked with a volt meter. Battery voltage and charge voltage looking good but no start is frustrating. One easy field check is key on and watch lights, hit start button and all the lights go out and nothing but solenoid click from starter. HTH Gary
 
There are several ways a battery can fail.
One of the cells can fail hard ( 1 of 6 in 12v bat) and then the voltage will read less than 12 v. easy call

More often the cells (a varing rates) sulfate. this means the plates loose effective area and can not hold a full charge(electrons/amps not volts).

the best way to test this is a load test. The head light mentioned in an earlier post is a simple way. Old technology battery testers put real 50 or 100amp loads on car batteries and measure how the voltage dropped.

How best to test. The problem is different batteries have different load capacities..ie a motor cycle battery is not capable of loads a bigger car battery can handle so a 100 am load that would be ok for a car battery would fail a motorcycle battery....so one would have to know the amphr capicaty of the battery and adjust the load....too complex for most shops

so the modern battery tester measure voltage and put a light load, somethinglike 5amp and see how much that voltage drop is and then estimates if the battery is weak. Unfortunately this is an unreliable test..some batters that are in fact partially sulfated still pass...but will not hold a charge...especially in case where there is small but continious draw on the battery when the car /motorcycleis turned off. (alarm systems, other electonics).

If I have an 3 or 4 year old lead acid battery and the engine cranks slower than normal i start thinking new battery.

The new technologies each work and fail differently....o joy.
 
Followup comments: The battery was branded Scorpion, model YT12CL, sealed AGM type. So it probably wasn't part of the Yuasa problem series. I had a Yuasa in my Funduro years ago that failed instantly with something broken inside which lost continuity through the battery - zero volts at the posts.

The failure didn't really surprise me, once I figured it out. I bought the bike in November and battery age is unknown.

I certainly didn't need a load tester or even a headlight for a load test. One little tail light bulb was enough load to show what was happening voltage wise.

What did surprise me was the huge voltage decrease with the very little load. I've seen headlights and starters drop voltage considerably but hadn't seen such a drop from hooking up just a test lamp bulb pulling about .5 amps.

I posted the original post to illustrate the need to do more than just a standing voltage no-load test when pondering whether or not you have a battery problem. I knew this before - thus the hook up of the pump as a load - but this case gave me good numbers as an illustration where a half-amp load dropped the voltage from 12.7 to 4.8 instantly, and then the voltage showed 12.7 again as soon as I disconnected the bulb.
 
As a reference on a piece of wire the voltage is carried on the outside of the wire and the amperage on the cross section of the wire-example a glass fuse.

This is called skin-effect and it only happens at RF frequencies.
 
Just for grins let me tell you what else this cute little bad battery is doing.

As noted, standing voltage 12.7 to 12.8. Hook up my .5 amp load testing tail light bulb and it drops to 4 something volts, and the light glows dimly. But, if I leave it hooked up the voltage goes slowly UP to somewhere between 7 and 8 volts with the light glow getting brighter, until - snap - it jumps to 12.7 volts and the bulb pops on to full brightness.

Disconnect - repeat - and it does the same thing.

So other than knowing that the battery is junk I am still baffled as to what is exactly going on inside that evil little black plastic box of metal and acid.
 
So other than knowing that the battery is junk I am still baffled as to what is exactly going on inside that evil little black plastic box of metal and acid.
In a lead acid situation, I would suspect the battery is trying to do what a battery can't help but do-generate an electrical charge. This small charge would try to create a "whisker" connection between a plate separation. My guess is that if the load was increased to 2 bulbs it would drop back to almost nothing-the "whisker" almost acting like a fuse. Gary
 
The battery has developed a high internal resistance.

When you measure it with a meter, the voltage appears OK. This is because the meter has a very high input impedance and it doesn't draw but an infinitesimal amount of current from the battery. If we plugged it into Ohm's law, the voltage drop would be minimal, because the current through the (failed) battery's internal resistance is so tiny.

Next, a load, like a lamp or a starter motor draws a lot of current. That's because the starter or lamp has a low resistance. When this is connected across the battery, the bad internal resistance drops voltage in accordance with Ohm's law. (that Ohm guy really can't be beat).

Some people call it a "surface charge" or some such. But really, between the 6 cells connected in series inside a 12v lead-acid battery, something has gotten a bad connection or one of the electrodes in a cell has been contaminated or physically failed in a manner that it has substantial resistance.

Not much you can do about it, except change the battery.
 
I suspect that sudden failures like this are an internal fracture in the battery. A conductor is cracked and barley making contact. At very low current, it will not be noticeable, but will quickly drop voltage under any load. This would also explain the the sudden failure. Sulfation is a long slow processes. It is all speculation, because when our batteries die, we seldom find out way.
 
Had a similar sudden failure of a Westco (Panasonic) battery in my 94 RS, just after an 800 mile weekend up in remote upper Michigan no less! Two days later, at home, I went to start the bike, nothing! Put the charger on it till I was getting 13 volts, but no cranking power, barely a crank over.

That Westco battery was just three months into its second season in the bike (the original Mareg lasted eight seasons, and still working). I called Westco about it, they said, "Yup, that happens."
 
What he said:

The battery has developed a high internal resistance.

When you measure it with a meter, the voltage appears OK. This is because the meter has a very high input impedance and it doesn't draw but an infinitesimal amount of current from the battery. If we plugged it into Ohm's law, the voltage drop would be minimal, because the current through the (failed) battery's internal resistance is so tiny.

Next, a load, like a lamp or a starter motor draws a lot of current. That's because the starter or lamp has a low resistance. When this is connected across the battery, the bad internal resistance drops voltage in accordance with Ohm's law. (that Ohm guy really can't be beat).

Some people call it a "surface charge" or some such. But really, between the 6 cells connected in series inside a 12v lead-acid battery, something has gotten a bad connection or one of the electrodes in a cell has been contaminated or physically failed in a manner that it has substantial resistance.

Not much you can do about it, except change the battery.

My compliments, Paul. You have observed Ohm's Law, albeit a few hundred years too late for much recognition. :brow

These are the kind of actions which make batteries mysterious. When actions are mysterious, mere mortals try way too hard to invent superstitions that attempt to explain them. One result is the Odyssey vs. all other batteries war of warm air.

Although it has no moving parts you can see, what goes on inside a battery is complex, with many options for odd behavior. In line with the 'internal resistance' theory above, there are several things which can cause that condition. Some are metallurgical, like natural oxides and sulfites on the electrode surfaces, contamination of the gel or liquids inside by breakdown or dissolution of the electrodes, actual corrosion of cell connecting surfaces, and so on into the night.

To add to the mixture, these causations can happen singularly or in combination. The cause might be an odd batch of metallurgy on an internal material. Also, it could be an incorrect or contaminated formulation of the gel or liquid during manufacture.

The single connecting cause of any or all these complex issues is economics. When you are buying a battery, you are buying a near commodity. At its price per pound, it's hard to afford extreme quality control.

But what is not superstition about batteries, among other things, is internal resistance. Every electrical device, when maintained above superconducting temps (minus 254 C. - Brrrr), has an internal resistance. That is an equivalent resistance, resulting from just as many factors - and more - than above.

You are correct to test battery voltage under some load. The choice of a light bulb is about the worst, as it can have coefficients of resistivity vs. filament temp. A better choice might be a small coil of NI-Cr wire, wound in a helix, and having a measured resistance of, say 2 to 6 Ohms. Industrial and aviation battery testers us something similar, usually encased in a ventilated enclosure, and fused. Separately, the resistor is called a load bank. Collectively, it's usually called a battery tester (not a voltmeter or ammeter). It registers battery voltage with and without a load.

Until you cobble one up, or purchase one, your light bulb isn't such a terrible idea. Me? I'd go for something that consumes higher current, like a sealed beam headlight lamp. :idea

 
I use one of these

Battery-Load-Tester-1DGV7_AS01.JPG


http://www.grainger.com/Grainger/OTC-Battery-Load-Tester-1DGV7?Pid=search

Not the greatest in the world, but it works well enough for my purposes.
 
I tried the pump first. Bigger load. It wouldn't do anything. Then tried the light bulb because it was in fact so puny. I also tried a 2.5 amp MR16 bulb which when attached dropped the measured voltage to less than one volt. An H4 high beam at about 4.3 amps pulled it down to something approximating .1 volt.

Lacking a real load tester these different loads were sufficient to tell me in certain terms that the battery was headed to the recycler. But I just found it weird that the difference between the standing no load voltage and the .5 amp load voltage was so striking. I have had broken connectors or similar inside batteries before where the thing actually went open between the two posts - ie - I got no voltage reading whatsoever. This I understand. But the 12.7 down to 4 with minimal load is what I wanted to understand.
 


Until you cobble one up, or purchase one, your light bulb isn't such a terrible idea. Me? I'd go for something that consumes higher current, like a sealed beam headlight lamp. :idea


I use one out of the pile of headlights in my garage that were changed due rock chips and BB-pit-holes in the glass over the years.

The filaments are not as themistor-like as people imagine.
 
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