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New Odyssey PC680 battery!

Lee, I went back and read that and see what you're saying. Raising the voltage won't solve the problem of overloading the alternator but will warm up the seat a bit if the alternator's not overloaded. Looking at the fuse panel, BMW was thinking about something less than 15A for "user stuff".
 
Power

The juice for all equipment needs to come from alternator amps, not battery charger volts.

POWER (watts) is Voltage X Current, V X I = Watts. An extra 0.4 volts X 40 to 50 amps is 16 to 20 watts. Not a huge increase over the stock VR but a somewhat better Alternator output and somewhat better peak battery storage. I may decide the VR cost and installation effort are not justified by the small gain.
 
POWER (watts) is Voltage X Current, V X I = Watts. An extra 0.4 volts X 40 to 50 amps is 16 to 20 watts. Not a huge increase over the stock VR but a somewhat better Alternator output and somewhat better peak battery storage. I may decide the VR cost and installation effort are not justified by the small gain.

You have a 50 amp alternator on a 2002 RT. With the loads you are adding there should be no need for additional alternator output to drive them. However, raising the VR setpoint will result in a higher state of charge on the AGM battery and it is worth doing for that reason alone. Being cheap, on my 2004 R1150 instead of changing the built-in VR in the alternator, I cut the ground between the VR ground and the alternator ground and inserted a 1N5402 diode to fool the voltage regulator into thinking that the voltage was 1/2 volt lower than it thought it was, which brought the system voltage up by that amount.
 
Lee, could you maybe post a picture of where and how to do that?

I sold the bike and didn't retain any photographs. If you remove the VR from the alternator, you can see where the negative lead from the VR wraps around to contact the grounded mounting post bolt. I cut that conductor and inserted the diode in the break. The cathode stripe on the diode is on the chassis ground side. You are not using the diode as a block, but are conducting through it and using the forward voltage drop of the diode to reduce the sensed voltage. This causes the VR to increase the rotor current and raise the system voltage.

EDITED TO ADD: I did Google around and find this write-up on the modification. It is not our specific hardware, but it is a Motorola VR and similar in construction...

http://www.hax.se/alternator/
 
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Thanks to both of you!

So there's no way to get at the regulator/brush assembly without taking the alternator out, and for that one really needs to remove all the stuff above (battery, ECU/Motronic, ABS unit)? My PC680 is now 8 years old, so I'm thinking of replacing it next spring. Maybe I'll switch back to a battery that will work with the standard regulator as is.
 
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Thanks to both of you!

So there's no way to get at the regulator/brush assembly without taking the alternator out, and for that one really needs to remove all the stuff above (battery, ECU/Motronic, ABS unit)? My PC680 is now 8 years old, so I'm thinking of replacing it next spring. Maybe I'll switch back to a battery that will work with the standard regulator as is.

Yes, it is a lot of work, but nuts and bolts really. If your PC680 lasted eight years so far, that is good service. Why do anything differently? You could let it spend some time on an AGM rated de-sulfating charger every now and then and call it a day.
 
Yes, it is a lot of work, but nuts and bolts really. If your PC680 lasted eight years so far, that is good service. Why do anything differently? You could let it spend some time on an AGM rated de-sulfating charger every now and then and call it a day.

I regularly (for several years now) run into starting trouble during the riding season. I got stranded two weeks ago after half an hour of stop-and-go traffic had emptied the battery to the point that it wouldn't start anymore. I now added a volt meter (which doesn't work right, so needs replacement), and a jump start post, and bought a lithium-ion jump start battery, but I'd rather deal with the root source of this trouble.
I do recondition/charge the battery (at the proper voltage) every winter, but I have no good way of attaching a charger during the riding season (bike is parked outside).
Otherwise the bike is very reliable, and runs smoother than ever.
 
Okay then... enjoy your hubbub. I'll apply the 9 plus years of real world experience with the battery and remain hubbub free....

Basically, what you are doing is ok-ish, but not the greatest for Odyssey capacity and longevity and not up to Odyssey specs. The battery tender jr may be getting close some of the time, but you'd need to measure voltage while charging to know that. I used to have a BT+ and sometimes it would charge to 14.2V; other times, 14.6V, or anything in between. The stock voltage regulator on the alternator is definitely under charging the battery. At the end of the day, the Odyssey batteries seem to be willing to take a fair bit of abuse, but you aren't getting all the power you could out of it and to some extent, you are shortening its life. How much being nicer to the battery is worth is up to you. In my case, I switched to an Optimate 7 select charger because I wanted a faster charger for car batteries anyway and I figured I'd get around to the voltage regulator the next time I had the ABS removed.
 
...parts that go into vehicles should be able to withstand the voltage spike produced by disconnecting the battery cable (>>20V) on a running engine. Sadly that isn’t always the case.

The Battery Tender SAE plug volt meter is another one where that isn't the case. At least they were nice enough to give me a free replacement. The same is true for their SAE - USB adapter; asked about that one rather than learning the hard way again.
 
Basically, what you are doing is ok-ish, but not the greatest for Odyssey capacity and longevity and not up to Odyssey specs.

I understand the technical aspect of what is being claimed but until I experience some real world deficiency in the performance of the battery I will not be modifying the charging system of my motorcycle. I'm already satisfied with it's longevity.... I'll report back when it finally dies.
 
I understand the technical aspect of what is being claimed but until I experience some real world deficiency in the performance of the battery I will not be modifying the charging system of my motorcycle. I'm already satisfied with it's longevity.... I'll report back when it finally dies.

+1

But since I experienced a measured, real world deficiency on two different Oilheads (slow starting and under charged batteries), I modified one alternator and got a recommended charger for the other.
 
+1

But since I experienced a measured, real world deficiency on two different Oilheads (slow starting and under charged batteries), I modified one alternator and got a recommended charger for the other.

Time to do spreadsheets can give you measurable results.

If it's working for you and you don't want to fix something that isn't broke yields immeasurable results.
 
I have Odyssey batteries in at least a couple of our bikes - I forget which because I treat them just as I do any other battery. Ride the bikes periodically. Use a smart charger when stored. Replace the battery as needed.

I am 100 percent sure I am not getting optimal life out of the battery but I don't care. They last longer than the cheap ones I have in other bikes. They don't suffer intra or inter cell connector failures (sudden death) like other AGMs I've had.

When run down - as in the GPS left on for a week or two or three - I charge them with at least a 6 amp charger as recommended by Odyssey.

And when a battery shoots craps I replace it.

Life is way to short for me to stress over battery perfection, especially with as much bad information as there is out there about batteries. It is at least as bad as a bad oil thread.
 
I was good with your reasoning (even the oil thread comment, lol) up to “battery perfection”. Why is using a product as described by its manufacturer seeking perfection? To me it’s like torquing a bolt. In 50 years of wrenching I never torqued a wheel bolt (or cylinder head bolt for that matter) until owning an Oilhead and never had a problem—never lost a wheel or damaged one. But now, when BMW has a torque spec I use it, why not?
 
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I might be slowly coming around on this issue. While I'm totally satisfied with the PC680 in my 1100S I also have a '04 RT, a '04 Rockster, a '04 1150R and a '00 LT. All with PC680s in them.

The RT does start much more slowly (annoyingly) than the others , I'll do some voltage measurements and will consider the mod depending on the results.
 
I was good with your reasoning (even the oil thread comment, lol) up to “battery perfection”. Why is using a product as described by its manufacturer seeking perfection? To me it’s like torquing a bolt. In 50 years of wrenching I never torqued a wheel bolt (or cylinder head bolt for that matter) until owning an Oilhead and never had a problem—never lost a wheel or damaged one. But now, when BMW has a torque spec I use it, why not?

I was being a little snarky with that "perfection" comment. I am just happy to ride the bike with the charging system BMW put in it, even though that might mean my Odyssey battery is about 95% charged at best. I do use chargers when bikes are "put away" or stored, but the three or four parked out front that we ride the most do not have chargers on them. When we leave home for the summer we have seven bikes put away with chargers attached. When we get home four months later they all start.
 
I have two Odyssey batteries; one in my '00 RT and one in my '81 G/S. The G/S has a simple electronic regulator that I adjusted to 14.5 but will be upping to 14.7 this coming season. The RT is way harder to modify so my interim solution there is to put it on the Opti Mate charger that has an Odyssey specific setting. Every time I put the RT on it even after a long trip to CA and back to BC it will bulk charge for only a few seconds, top up charge for well over half an hour and finally to to maintain mode indicating that even at the full charge the RT can provide it has more capacity I'm not using.

After a charge up it always starts faster and easier. Not by much but it is noticeable. I have not made any super accurate measurements but I have a lot of experience dealing with batteries having worked in that industry as a tech for over five years many moons ago. My "real world experience" tells me my Odyssey will perform a wee bit better with a FULL charge as specified in the technical documentation for the battery.

So I've traded off a bunch of work modifying it for an approved charger that maintains it whenever I'm home and leaves the bike compatible with lead acid batteries for now.
 
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