Voltage Drop

[Coyote]

My acid fill battery lives on a tender. The tender keeps it at a constant 13.4 volts. Shortly after removing the battery from the tender, the voltage drops into the mid 12's. Turning on the ignition (no lights), the voltage drops to 11.74. Leaving the ignition on, the voltage continues to drop about .01 every 30 seconds or so. Is this normal? I haven't started the bike yet so the charging circuit is still a question mark.
I read all the time that a fully charged battery should be about 13.4 volts. It stays at that voltage while on the tender. It's easy to see he tender work by hooking up a voltmeter while the battery is 'tending'. The voltage is at 13.4. the tender shuts off internally. The voltage drops to 13.1in pretty short order. The tender switches back on at that point and pushes the voltage back to 13.4 and the cycle begins again. On at 13.1 - off at 13.4. This cycle happens 4 or 5 time a minute. But when you take the battery off the tender. it drops to the mid 12's in about 10 minutes.
Seems like my last 550 (RedZone) acted pretty much the same way.. Once started, the voltage would stabilize in the mid 12's at idle. revving the motor raised it to about 14 volts.so the battery was always hot.. Always in the mid 12's when off. NEVER 13.4 WHY? (yes, my multimeter is accurate)

[ConnerVT]

I suspect your battery is less than good. Try this:

Remove the battery from the bike.
Put on battery tender until the tender indicates that it is charged, plus a few hours.
Remove from tender.
Record voltage.
Record voltage after 1 hour.
Record voltage after 12 hours.
Post your results here.

[Craig380]

I'm running total-loss electrics on my 380 (rotor wiring is shorted) so I've got a fairly new 9Ah lead-acid battery. I use an old-style trickle charger which puts out less than 1 amp and doesn't adjust voltage / amperage.

After a ride, the battery needs charging for about 8 hours, at which point the voltage across the terminals is around 15.5V, then I disconnect the charger. After 12 hours or so, the resting voltage across the terminals is around 12.9 - 13V.

It sounds to me like your battery isn't in good shape. A fully charged lead-acid battery should show at least 12.6V.

A quick question - do you fully charge the brand-new battery before fitting it to the bike?

[Coyote]

OK Conner. I did the test. Here are the results thus far:

On tender. 13.10. I don't know what's up with that. It used to take it to 13.4

Immediately off tender. 13.00

After 1 hour. 12.81

After 6 hours. 12.52

After 14 hours. 12.48 --- sorry. I was sleeping at 12 hours

After 24 hours. Haven't got there yet

Battery will be 4 years old this August. Has been on the tender for most of the time. I have never used it. I had to add distilled water once about 3 months ago. The tender has 4 modes, indicated by an LED.
Flashing Red = the battery is bad or not hooked up correctly
Solid Red = charging
Flashing Green = 80% charged
Solid Green = fully charged and the tender is keeping it that way.

Here is the sequence of why the battery has not been used. A few years ago in the dead of winter, I bought a Parts Unlimited battery from Amazon. The battery lasted exactly 2 weeks before frying itself internally. Would not charge. I took the battery to my local bike shop. They messed with it a couple of days and declared it bad. He said he could get me a new one on warrenty - even though I bought it from Amazon. This was in January. I waited a couple of weeks and then was told the battery was back ordered till June. Well, I couldn't live without a battery so I bought another and put it in RedZone. The back ordered battery finally came in in August. The bike shop did me a favor (NOT!) by filling it and charging it before calling me and telling me they had it. So here I was with a perfectly good battery already installed in RedZone and another hot battery with no home. Of course my plan was to shelve the new battery and fill it when I needed it. That didn't happen. So the (this) battery just sat. My tender was busy on my GS so I bought a new tender about 6 months later and this battery has been on it ever since.

[ConnerVT]

Well, not the best of numbers. You are correct, on the tender (believe you have the same branded "Battery Tender" as I) you should be seeing close to 13.4V. Right off the tender it will drop to 13 and some volts, and hold near that for about an hour. If it lost 1.3V - 1.5V quickly, would usually indicate a bad/shorted cell.

In this case, (assuming that the battery is filled to the correct level, and the meter is accurate), the battery is just worn. Sitting on the tender, without there ever being a load on it, floating for a few years, probably isn't the best way to store a wet lead acid battery. A friend who works in building facilities used to come home with the large starting batteries for the hospital's emergency generators. They basically sat on a float charger for year(s), and they would swap them out as preventative maintenance.

It will probably work for awhile on your bike. It just won't live as long as a brand new battery. Myself, I'd probably run it, and watch for any electrical issues that make me suspect it is time to replace it.

[Coyote]

I had to put the battery back in the bike for electrical testing. Ran the lights, turn signals and brake light. Used the electric starter to check spark.It's been 24 hours now and the battery checks 12.5. actually up .02 from this morning.