Battery/charging system voltages question...

[Shuriken]

I suspect I have a battery problem. Before I replace it (was considering a Panasonic-type SLA), I would like to get some input from you guys.

First, the bike has run fine for years on this same battery, but this season, the bike has killed a time or two and would not restart due to low battery voltage.

I have observed that the battery DCv does not increase with RPM (I have seen this issue before and thought there was a charging system fault but it turned out to be a battery that would not recharge). So I charged this battery with an external charger until battery idle volts measured 12.5. Then I reconnected to the bike and it started the bike. However, charging voltage at engine idle is around 13.5v and if I rev the engine, voltage decreases to 13v.

I haven't tested the stock voltage regulator or stator resistance/voltage output in awhile but before I do, I thought I might simply connect the vmax battery terminals to a known good car battery and test the charging system again. With a good battery, I suspect I would see more than 13v when I rev the engine.

If I check the stator I'll make sure the connector is clean.

Anything else you guys would recommend?

 

[sdt354]

It sounds like a R/R problem, but I'd still check the stator a/c output, and load test the battery. All connections being clean and tight.
Steve

 

[SpecOps13]

Near or over 14 volts when charging. My 89 actually charges higher at Idle than when being revved. Normal batteries last a couple years reliably. Both my 89 and my 94 have Odyssey's and they will stay charged to 12.90-12.95 volts with normal use. One of them is 5 years old and still going very strong. Let us know your opinion of what you buy. Always looking at new things...

 

[Miles Long]

I suspect I have a battery problem. Before I replace it (was considering a Panasonic-type SLA), I would like to get some input from you guys.

First, the bike has run fine for years on this same battery, but this season, the bike has killed a time or two and would not restart due to low battery voltage.

I have observed that the battery DCv does not increase with RPM (I have seen this issue before and thought there was a charging system fault but it turned out to be a battery that would not recharge). So I charged this battery with an external charger until battery idle volts measured 12.5. Then I reconnected to the bike and it started the bike. However, charging voltage at engine idle is around 13.5v and if I rev the engine, voltage decreases to 13v.

I haven't tested the stock voltage regulator or stator resistance/voltage output in awhile but before I do, I thought I might simply connect the vmax battery terminals to a known good car battery and test the charging system again. With a good battery, I suspect I would see more than 13v when I rev the engine.

If I check the stator I'll make sure the connector is clean.

Anything else you guys would recommend?

As suggested, you should first remove your battery and have it load-tested. Most auto suppliers will do this for free.
For kicks, you can load-test the battery yourself, by observing the voltage while cranking the bike over on the starter. Voltage should not drop below 10.
However, in my particular case, even this self test did not indicate a problem with my 6 yr. old Odyssey battery. It showed about 10 volts when cranking, but in the end, turned out to be on it's "last legs" This may be a characteristic of AGM batteries, because they fail at a slower rate than lead-acid ones. A new Odyssey solved what I thought were charging issues. - the new battery reads a whopping 13.1 volts, after the bike has been given a workout, and allowed to cool down for a few hours.
Another indication which pointed towards a "tired"battery was the voltage after using a battery charger. It would eventually show 13 volts or so, but after sitting overnight, the voltage would be 12.4 - 12.5 . According the the Odyssey website info, these numbers indicate a battery of only 50% charge!
New, out of the box Odysseys read 12.8 volts, which is 100% charged.
If you haven't already, read the Electrosport fault-finding chart. You will notice the first instruction is to ensure that you are dealing with a good battery.
Cheers!

 

[Shuriken]

I ordered a battery which is similar to / generic of the Panasonic battery listed in the Electrical Section under battery replacement.

When I removed the old one I was surprised to find a wal mart brand SLA. Probably the reason it lasted longer than I thought it should was because it was SLA. Anyway, when trying to disconnect the various harness connectors, the connector that disconnects the 3 white stator wires sort of stuck and the wires pulled out. I ended up just cutting out the connector and soldering the wires directly.

I tested the new battery and it was at 12.8v. I then installed the battery and took a ride on the bike for a half-hour and then tested it when I turned off the engine afterwards and it was around 13.5v. Everything is working fine and the generic SLA I'm using really cranks the engine over well.