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Old 01-25-2013, 09:29 PM   #1
Desert2202 OP
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Watts Amps ??

Hi All, does anyone know how many Amps the 720w alternator puts out on a 2011 R1200GS ??

Thanks in advance.

Geoff
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Old 01-25-2013, 09:32 PM   #2
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Old 01-26-2013, 01:28 AM   #3
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actually it's E=IxR...

"E" is the concept of electromotive potential, which is measured in Volts.

"I" is the concept of the intensity of the current which is measured in Amps (6.241 1018 per second)

"R" is the concept of resistance, measured in ohms.

and one measure of power.... "watts" (named after James Watt)... is: P= IxE


so it's 720/system voltage (12ish).... but the engine speed plays a part too.... max electrical power is delivered at higher engine RPm... you get the picture?
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Old 01-26-2013, 01:50 AM   #4
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Approx. 60 at mid to high rpm(watts/volts=amps). I'd design at 40 and you'd still have a good margin for error.
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Old 01-26-2013, 02:14 AM   #5
MsLizVt
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Just trying to be helpful ...

Geoff, hi!

Your bike should be putting out 60 amps at 12 volts, which gives you 720 watts (60x12=720).

Max's BMW fiche shows a 60 amp alternator.

But here's the confusing part. Generally an alternator is producing 14 volts, or just under that. Many manufacturers and aftermarket suppliers will quote their alternators as putting out 700 watts (50amps x 14volts = 700watts) and 840 watts (60amps x 14volts = 840 watts). Then others will do the wattage calculations based on 12 volts, which people can relate to because they have a 12V battery. It's the same battery, obviously.

In your case, the fiche confirms 60amps.

Is this helpful?



Liz







#Part Number DescriptionlbQtyEach
01 12 31 7 712 825 GENERATOR - 60A DENSO7.16 1 $808.71
ONLY IN CONJUNCTION WITH :
-- 61 12 7 691 725 ADAPTER CABLE FOR ALTERNATOR - DENSO0.02 1 $32.56
-- 12 31 7 680 683 OVERVOLTAGE PROTECTION0.04 1 $68.22
02 07 12 9 903 925 ASA-BOLT - M8X250.02 3 $1.84
03 07 12 9 905 542 HEX NUT - AM6-8-ZNNIV SI
1 $0.79
04 46 62 1 453 668 CAP - M6
1 $0.60
05 12 31 7 680 683 OVERVOLTAGE PROTECTION0.04 1 $68.22
06 12 31 7 690 571 RIBBED V-BELT - 4PK5820.09 1 $28.67


12317690571 was superseded by 12318528385.
07 12 31 7 694 069 PULLEY0.73 1 $50.38
08 07 11 9 904 701 WASHER
1 NA
09 07 11 9 901 102 HEX NUT - M22X1,50.11 1 NA
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Old 01-26-2013, 03:20 AM   #6
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The only thing you need to know is that if things get a bit dim, turn the gerbings and a few lights off
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Old 01-26-2013, 04:40 AM   #7
Desert2202 OP
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Thanks Liz, very helpful indeed, I appreciate your help.

Geoff

Quote:
Originally Posted by MsLizVt View Post
Geoff, hi!

Your bike should be putting out 60 amps at 12 volts, which gives you 720 watts (60x12=720).

Max's BMW fiche shows a 60 amp alternator.

But here's the confusing part. Generally an alternator is producing 14 volts, or just under that. Many manufacturers and aftermarket suppliers will quote their alternators as putting out 700 watts (50amps x 14volts = 700watts) and 840 watts (60amps x 14volts = 840 watts). Then others will do the wattage calculations based on 12 volts, which people can relate to because they have a 12V battery. It's the same battery, obviously.

In your case, the fiche confirms 60amps.

Is this helpful?



Liz







#Part Number DescriptionlbQtyEach
01 12 31 7 712 825 GENERATOR - 60A DENSO7.16 1 $808.71
ONLY IN CONJUNCTION WITH :
-- 61 12 7 691 725 ADAPTER CABLE FOR ALTERNATOR - DENSO0.02 1 $32.56
-- 12 31 7 680 683 OVERVOLTAGE PROTECTION0.04 1 $68.22
02 07 12 9 903 925 ASA-BOLT - M8X250.02 3 $1.84
03 07 12 9 905 542 HEX NUT - AM6-8-ZNNIV SI
1 $0.79
04 46 62 1 453 668 CAP - M6
1 $0.60
05 12 31 7 680 683 OVERVOLTAGE PROTECTION0.04 1 $68.22
06 12 31 7 690 571 RIBBED V-BELT - 4PK5820.09 1 $28.67


12317690571 was superseded by 12318528385.
07 12 31 7 694 069 PULLEY0.73 1 $50.38
08 07 11 9 904 701 WASHER
1 NA
09 07 11 9 901 102 HEX NUT - M22X1,50.11 1 NA
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Old 01-26-2013, 09:15 AM   #8
MsLizVt
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Quote:
Originally Posted by DesertKLR View Post
Thanks Liz, very helpful indeed, I appreciate your help.

Geoff

Geoff, hi!

You're very welcome!



Liz
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Old 01-26-2013, 10:26 AM   #9
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Liz did a terrific job clearing up the confusion - it's just simply volts x amps = watts, with the caveats due to marketing (basing claims on 12V versus 14V outputs).

(With due respect to other posters, being an anal engineer myself, I could not resist. Your replies are a bit out of topic: electromotive potential does not exist; electromotive force is an obsolete term used in early days of tinkering with electricity; voltage is a difference of electric potentials. But I digress...)

Here is what the OP should really know: the alternator on your GS is powerful enough for most of accessories while you are at speed. Don't sweat it. I've been running fog lights, driving lights, heated grips and heated vest at the same time, without any issues. However, at low RPM's, you may not be getting enough juice - especially if you are powering a lot of lights and heated gear.

The proper way to watch that is with a voltmeter: once your system voltage starts dropping below 13.5V, it's time to shed loads. There are many solutions available; what I am using is a $25 themometer/clock/voltmeter from Cycle Chrome (? - search the Web) - my installation is shown below.
The meter is not waterproof, but with the little metal shield around it I never had any trouble.

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Old 01-26-2013, 12:03 PM   #10
freyke
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Approximately 55 DCA is about the maxim sustainable load that should be applied.

Based on throughput via a 13.1VDC 6 cell battery (2.1VDC per cell).

freyke screwed with this post 01-26-2013 at 12:11 PM
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Old 01-26-2013, 01:35 PM   #11
Dan-M
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Quote:
Originally Posted by freyke View Post
Approximately 55 DCA is about the maxim sustainable load that should be applied.

Based on throughput via a 13.1VDC 6 cell battery (2.1VDC per cell).

60 amps is the rating and in the real world it will probably do even more but running constant at 90% of it's rating is a good way to shorten its life.
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Old 01-26-2013, 02:00 PM   #12
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ha ha... ya, when I went to school some of the instructors were pretty adamant about confusing the concept with the measurement... it's a hangover, sorry if it confused the issue.

anyway, the 60A is a nominal rating. I've tested countless generators that make more than rated... at least until they heat up, then maybe not. in any case, they are RPM dependent... putting around at low speed will not give you full output. best real world advise is as above, watch the voltage & if it drops too low for any extended time shed some load. whats too low? I would be OK with 13V... maybe even 12.7 as long as the battery was in good shape and didn't need a charge. thats me... YMMV. I have V-meters on my 2 ADV bikes
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Old 01-26-2013, 03:23 PM   #13
Desert2202 OP
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Thanks for your help too. I have just fitted 2 Aurora LED spot lights that draw 5 amps each so I have plenty in storage, maybe I'll buy another two, that way I can watch out for all the bloody Kangaroo's that keep trying to knock me off the bike at night .

No chance of using heated grips or heated suits where I live, it's damn hot in summer and winter drops to 20 Celsius. Hardly ever rains either, we can ride 340 days a year.

Thanks again

Geoff.

Quote:
Originally Posted by rdwalker View Post
Liz did a terrific job clearing up the confusion - it's just simply volts x amps = watts, with the caveats due to marketing (basing claims on 12V versus 14V outputs).

(With due respect to other posters, being an anal engineer myself, I could not resist. Your replies are a bit out of topic: electromotive potential does not exist; electromotive force is an obsolete term used in early days of tinkering with electricity; voltage is a difference of electric potentials. But I digress...)

Here is what the OP should really know: the alternator on your GS is powerful enough for most of accessories while you are at speed. Don't sweat it. I've been running fog lights, driving lights, heated grips and heated vest at the same time, without any issues. However, at low RPM's, you may not be getting enough juice - especially if you are powering a lot of lights and heated gear.

The proper way to watch that is with a voltmeter: once your system voltage starts dropping below 13.5V, it's time to shed loads. There are many solutions available; what I am using is a $25 themometer/clock/voltmeter from Cycle Chrome (? - search the Web) - my installation is shown below.
The meter is not waterproof, but with the little metal shield around it I never had any trouble.

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Old 01-26-2013, 04:18 PM   #14
rdwalker
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Quote:
Originally Posted by DesertKLR View Post
Thanks for your help too. I have just fitted 2 Aurora LED spot lights that draw 5 amps each so I have plenty in storage, maybe I'll buy another two, that way I can watch out for all the bloody Kangaroo's that keep trying to knock me off the bike at night .

No chance of using heated grips or heated suits where I live, it's damn hot in summer and winter drops to 20 Celsius. Hardly ever rains either, we can ride 340 days a year.

Thanks again

Geoff.
Wow, your weather sounds AWFUL! And I actually mean it: I'd rather deal with (reasonable) cold; I hate heat. My motto is that I can always add clothing, heated or not, but there is only so much I can take off.

More power to you!

Back to your discussion: the power-output numbers for the alternator are meaningless, because no one knows the baseline: power consumed by bike's computers and fuel injection. This adds to the original lighting and then to anything else you install.

In reality, you will need to rely on anecdotal evidence provided by us in the forums. For my part, as I mentioned, I have been running two 35W HID fog lamps, two 50W halogen driving lights, heated grips (about 40W total, I believe) and 50W heated vest without any issues.

I had problems in traffic jams: low output from the alternator at idle (plus added load of brake light and ABS brake pump) would cause the battery voltage to dip. Never had a problem, because I'd start turning things off (voltmeter helps), but I have observed the battery going below 13V after 10 minutes of stop-and-go with all loads on. Something to remember.

Robert.
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Old 01-26-2013, 07:40 PM   #15
MsLizVt
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more just trying to be helpful ...

Quote:
Originally Posted by rdwalker View Post

Back to your discussion: the power-output numbers for the alternator are meaningless, because no one knows the baseline: power consumed by bike's computers and fuel injection. This adds to the original lighting and then to anything else you install.

In reality, you will need to rely on anecdotal evidence provided by us in the forums. For my part, as I mentioned, I have been running two 35W HID fog lamps, two 50W halogen driving lights, heated grips (about 40W total, I believe) and 50W heated vest without any issues.

Robert.
Robert, hi!

Please know I'm just trying to be helpful.

As you may or may not know, my bike has a 'few' lights on it. When making the decision to put them on the bike, there was a lot of research done. Somewhere, and it would take me a while to go back and find it, but somewhere I came across the point that an R1100GS's system, with a 55W headlight on draws 200 watts. That wouldn't be when running the starter.

That's what I used as a baseline for my light and gerbing set up. I'll post a photo below, with the explanation that the entire set up was free. The light bar is a leg off an old steel desk (still have three backups), the lights came off one of my old rally cars, from the days when Hella sponsored me, and the wiring harness was from Hella as well.

Now the base wattage used for other bikes, like KLR's, 1200GS's, KTM's etc, I have no idea.

You're right though, a lot of what we know is dependent on the hive knowledge of 200,000 of us ADV inmates. Some of that knowledge is scientifically backed, some is just "... this is what i think it is ... ", but all that is what's cool about ADV and how reading these threads stimulate our minds, don't you think?

Enjoy,



Liz




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