The battery on my 93 GS/PD will sit on the tender for more than 24 hours and still not be charged. It will eventually. The battery in the R90 charges in a few hours. It's a poor test, but does that mean the GS battery is on its way out?
I assume it also won't be taking a charge very easily underway.
thoughts?
thanks
Yup, battery.
The battery on my 93 GS/PD will sit on the tender for more than 24 hours and still not be charged. It will eventually.
- Not sure what you mean by this. "Charged" meaning the bike will crank ? Or, that the measured voltage is up to a certain level ? Please explain.
- What type of "battery tender" ? What is the charger's output voltage and current ?
- Is the battery still in the bike when you do this ?
- What type, size, brand of battery ?
- And what constitutes "eventually" ?
- Have you had the bearings in either or both starter motors re-packed ?
1. I'm not denying that it may simply be time for a new battery, but batteries are expensive and quality levels vary widely because most generic batteries are made off-shore. AGM type batteries do have a better track record for longevity... but only WHEN your bike's charging system is properly set up for them.
2. The 2 biggest parts of "charging system setup" are A. a modern solid state Voltage Regulator which matches the battery and B. use of an LED headlamp bulb.
3. Charging is ALWAYS better done by the motorcycle. Period. The quality and performance of 'chargers' vary even more than batteries !! So it's important to understand your charger's voltage and current output.
4. But since the motorcycle should be the main battery caretaker, where you ride (open road vs. intown 'stop & go'), and thus the length of time spent above 3000 RPM become important factors in battery life.
Considering all the above, if you are an occasional rider you may actually be better served by buying 1 really nice battery, and then moving it back and forth between the bikes... totally eliminating the interim "maintenance charging".
Just my 2 cents.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
A typical tender charges at 1 to 2 amps. So it can take 24 hrs to charge a flat battery. Maybe the voltage regulator on your R90 is set to a higher voltage an or has an aftermarket alternator with a higher wattage. Maybe the charging system on the R90 is in better shape. I am assuming it is the same or at least the same model battery tender on both bikes? Is it the same model/type battery in both bikes?
Batteries typically (but there are other failure modes) by sulfation which decreases battery capacity. It actually charges faster. There are smart chargers that have a desulfation mode. They work pretty well with some forms of sulfation, but not others. I mentor a high school robotics team. The robots use roughly the same size AGM battery as an Airhead. We have roughly 20 batteries. Typical characteristic of a bad battery is very short charge time.
So a rather long winded answer to no. I would not take the charge time on a battery tender to an indication of battery condition.
A typical tender charges at 1 to 2 amps.
This is true. We call the 2A ones "car chargers" because a motorcycle battery shouldn't be continuously charged at more than 1/10th their AH rating. It's OK to place a motorcycle battery on a 2 or 3A charger as long as you limit the time. Heat buildup is the reason. Batteries don't like to be cold, but neither do they like to be hot. And that's what happens with indiscriminate, long-term charging. The internal temps that are bound to build, end up "cooking" the battery.
Maybe the charging system on the R90 is in better shape. I am assuming it is the same or at least the same model battery tender on both bikes? Is it the same model/type battery in both bikes?
And this is why I keep touting electronic voltage regulators. Everyone here has had a motorcycle with points, and they replaced and adjusted those ignition points to keep the bike running great. But what does everyone do with the same "points" inside the OEM voltage regulator? Nothing! If you replace ignition points every 3-5 years, then what should be done with voltage regulator points that are 40 years old?
Electronic regulators use a completely different system, which has no springs, points or point gaps. It's all done with electronic circuitry which is completely immune to wear, vibration, water, heat, poor adjustment, etc, etc.
Batteries typically [die] (but there are other failure modes) by sulfation, which decreases battery capacity. It actually charges faster.
This is true, and in the older translucent case batteries sometimes you could actually see the white sulfate on the plates. But no matter how, it's important to know that batteries are dying from their first day. The longevity depends heavily upon the maintenance and temperature environment they go to live in.
Sulfation or not, the main way to determine relative battery health is a Load Test. This is done a couple of ways, but the main one you'll see is a huge resistor that sucks off all the 'surface charge' and then measures the remaining voltage. And while we call them "12V batteries", in actuality when they reach 12.0V they are only good as boat anchors. Really new batteries are up around 12.8V, and they take a long slow slide toward 12.3V when they are about used up.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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