Topic: not getting past 12 volts on tender/charger

[000jeremy]

I have a fairly new sealed battery that I drained a bit while testing some electrical issues.  I put it on my battery tender jr, but the light goes straight to green , or tending mode, as opposed to red, charging mode.   Im getting only 11.88 volts so it seems like the tender should be still charging till it gets up past 12.  Any idea why this isnt working?

Thanks in advance,
Jeremy

[Whaleman]

No, Nobody will know. I would take my car and turn off the engine and leave the headlights on for 15 minutes.  We should all agree that the the battery should be down a bit . Put the battery tender on and see if it charges. If not then the battery charger is defective. Dan 

[Bob Wessner]

i'm inclind to agree. If I turn on the ignition and then one of the blinkrs for just 2 blinks, the tender goes into charge mode.

[TwoTired]

Stick a load on the battery and monitor the batt voltage.  Use something like a 5 amp headlight.

Watch and time how fast the voltage drops to say 9V.  Report results here.

While the load is still hooked up, connect your battery tender.  Since the tender cannot supply power to both the headlight and battery for recharge, the charger should never switch and should try to raise the battery voltage (If it does switch over, your charger is bad).  Now remove the load, and time how fast the voltage rises, and to what peak reading, before the charger switches to low (tending).

The battery may have gone high impedance, allowing the charger to reach its trip point without actually charging the battery (cause it can't accept a full charge).

Or, the charger may have gone bad and modified its own trip points.  (Which would be strange, but it could happen.)

Cheers,

[000jeremy]

under load the voltage dropped from the 11.88v that I was getting to around 9v in about a second...pretty quickly.

I then hooked up the tender and again it immediately went to green...

When I removed the load the voltage rose a bit slower than it had dropped and the tender still stayed green.


So I can conclude that the charger is bad?

[Kong]

If the battery is reading eleven point nothing volts its dead as a doornail already, and your charger can't cope.  However all is not lost, neither your battery or your charger is definitely toast.  Here's what you do, get a second battery and connect it to your dead one with jumper cables and then put your charger on the second battery and leave it there for two days.   I'd be willing to bet that not only will your charger mystically begin to work again but you'll also have two good batteries two days from now.

[TwoTired]

under load the voltage dropped from the 11.88v that I was getting to around 9v in about a second...pretty quickly.

That could be from an undercharged battery, or a bad battery.)

I then hooked up the tender and again it immediately went to green...

When I removed the load the voltage rose a bit slower than it had dropped and the tender still stayed green.


So I can conclude that the charger is bad?

Seems like it.  But, you were supposed to report at what voltage the charger went to green.

However, if you are saying that the charger went to green (indicating battery full) while the battery was still under load and reading 9V, then the charger is probably faulty.  (The uncertainty comes from not knowing the charger internal design specifics.)  It's not supposed to switch to "tending" mode until the Voltage reaches 14.5V (or nearly so, The V-trip depends on charge rates).
Maybe your battery is bad, too.  But you can't really tell that, until you know that a full charge cycle has been applied to the battery.

Why can't you use the bike to learn if the battery will accept a charge?

Cheers,

[000jeremy]

the problem is that the tender is always showing green (tending mode), no matter what ...

I can still kick start and ride around, so Ill try doing that for a couple days to see if the charge comes up.

Thanks again,
Jeremy

[TwoTired]

The bike's (SOHC4) charging system is really only a battery maintainer.  It only charges the battery at a 1-2 amp rate when the RPMS are above 3000.  To fully charge a flat but good battery you have to run the bike above that RPM for 10-12 hours.

In order to prove that your charger is screwed (and not your battery), you need a test bench or a substitution device.  If you can determine that the battery voltage is capable of getting higher V with another charging device, such as your bike, then you can rest easy diagnosing your charger as the guilty culprit without a test bench.

Make sense?

Cheers,

P.S. You could also measure the battery voltage and note the Voltage change trend when you rev the bike.  Just remember it will take time to for it to reach peak.  But, you should be able to tell in a few minutes that the voltage is slowly rising, the charger is doing it's job, and the battery is capable, even if undernourished.

[Deltarider]

Curious...
Your charger's 6V/12V switch isn't accidentally in the 6V mode, is it?

[camelman]

Curious...
Your charger's 6V/12V switch isn't accidentally in the 6V mode, is it?

Good point DeltaRider.

Also, even a new battery could be bad.  I just went through that a while back with a friend's bike.  Took the battery back for a warranty return, and it has run flawlessly since.

Camelman