BMW K bikes (Bricks)

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1Back to top Go down    1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 18:10

lefthander

lefthander
active member
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I have a 1992 k75 with from what I've read here it has a 32 amp alternator. I am going to add the Symtec heated grips per Ducks instructions using an OEM grip switch. My question is if I am wearing an electric jacket liner plugged into the BMW outlet with a GPS plugged into the cigarette lighter plug would I be over stressing my system? Electrical is a big weakness of mine and I don't want to fry anything. Thanks in advance for any insite. ;BMW; ;BMW;

    

2Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 18:17

duck

duck
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You should be OK I think. (Don't worry about the GPS - very small electrical load.)

Try it out with both the heated grips and jacket on full. The alternator light in the cluster may glow a little but if it starts getting brighter then turn the jacket off. If you "overtax" the system it won't hurt anything it just doesn't charge the battery. Turning the jacket off will get the battery charging again.

Do you have a manual for the jacket? How many watts does it use on full?


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

3Back to top Go down    alternator capacity on Mon 21 Jan 2019, 18:39

lefthander

lefthander
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Hey Duck, It's from Aerostich. I'll look it up tomorrow and post it. Thanks for the quick reply.

    

4Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 18:47

duck

duck
Life time member
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I looked it up - 75 Watts. I think that might be just a tad too much but trying it out won't hurt.

Note that if you have a heated jacket liner and insulated gloves that heated grips aren't as necessary because the heated jacket liner keeps your body core and arms warmed up so you're pumping warmer blood to your hands.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

5Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 19:23

Point-Seven-five

Point-Seven-five
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I would estimate your approximate current draw as follows:

6-9 amps- Jacket and grips
7-10 amps- Headlight, tail light, brake light and turn signals
5-8 amps- engine operation(fuel pump, injectors, ECU)
3-4 amps- instrument cluster, GPS

If you add halogen running lights, you will probably be overloading the alternator. If you have running lights, it would be better if they were LED. Don't worry about your GPS, they typically draw less than 1/4 amp.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

6Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 19:28

Two Wheels Better

Two Wheels Better
Moderator
Moderator
ETK say they're 33Amps which x 12Volts equals about 400Watts (396W to be exact). My '87 RS has the same alternator and I can roll down the motorway at legal speeds or less powering two heated jacket liners (a Gerbing @ 77Watts & a Powerlet Atomic Skin a bit less) at full blast on a frigid day. I don't have heated grips on that OZ-based bike. My AGM battery has never even hinted that it struggles to start during a trip like that, and the alternator light isn't glowing.

Same deal on my '77 Airhead with a Motorad Elektrik 400 Watt upgraded alternator. Heated grips switched to high and a Gerbings full heated liner and we're off. It does have a 28Ah battery so perhaps a bit on reserve over the 19Ah K100RS, but never a problem. Caveat: the bike isn't fuel injected with its bigger draw than a set of carbies (zero draw) and basic wiring loom stuff, H4 headlamp, taillight, indicators, etc., but does now have electronic ignition...

Back in "the day" the original dodgy 280Watt alternator on my Airhead still managed to power my ancient (forget the brand name, now defunct) heated vest with nary a drama. I just couldn't idle it round town too long, but out on the road above 3,000RPM it was all warm and fuzzy.

I reckon you're good to go.


__________________________________________________

1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

7Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 20:02

duck

duck
Life time member
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My power guess is based on a 93 K1100LT when it had the old alternator. Before I upgraded it to a 50A alternator the battery would drain if I ran the OEM heated grips and a pair of 35W aux lights. So my rough math tells me 100W+ was too much.

It may be that the 4V bikes suck more power for the basic power stuff though so a 2V may have more "spare" watts from the smaller alternator.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

8Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 20:06

Two Wheels Better

Two Wheels Better
Moderator
Moderator
At the end of the day it's no harm to run heated grips and a jacket liner or vest, just watch the charge rate by keeping an eye on the alternator light, and know that at night when home you just whack the battery tender on before you go night night.

For yucks, attach your multimetre to the battery, run the engine through a rev range typical of where you'll ride while switching your accessories on maximum. 12.6 to 14+Volts or so and as we say Down Undah, 'you'll be laughing.' Another option: attach a slim LED voltmetre directly to the battery. They make 'em tiny and stick on nowadays. Keep an eye on it while riding. For sure, nothing's gunna blow up.


__________________________________________________

1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

9Back to top Go down    Re: 1992 k75 32 amp alternator ability on Mon 21 Jan 2019, 20:15

duck

duck
Life time member
Life time member
Good point. My battery ran down when running errands in the city so the alternator wasn't putting out 14V the whole time.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

10Back to top Go down    Re: 1992 k75 32 amp alternator ability on Tue 22 Jan 2019, 01:16

nino

avatar
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I had similar problem with 32 amp alternator on K 100, but since I changed voltage regulator problem dissapeared. As I understood old voltage regulator was 14,4 volts, but new one 14,5 volts. It charging a battery in city traffic very well even with two fog lights. You can try maybe.
Regards.

    

11Back to top Go down    Re: 1992 k75 32 amp alternator ability on Tue 22 Jan 2019, 03:55

Dai

Dai
Life time member
Life time member
Just a general FYI: when calculating electrical loads, the indicators, horn, brake lights and any warning lights are classified as 'intermittant supported by the battery' and are ignored for the purposes of figuring out the total steady load supported by the alternator.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

12Back to top Go down    Re: 92 k75 alternator amps on Tue 22 Jan 2019, 15:03

lefthander

lefthander
active member
active member
Thank you to all for the info. I'm very much getting attached to the bike. And to all the help here when trying to sort things out, it's much appreciated. The bike just turned over to 40,000 miles as I pulled into my garage last night. I feel confident I can keep it going a long time as it seems to run really well. For a bike that's aprx. 27 years old I'm impressed by how good it runs. Even after sitting for about 5-6 years in my sons garage.
Peace

    

13Back to top Go down    Re: 1992 k75 32 amp alternator ability on Tue 22 Jan 2019, 15:23

duck

duck
Life time member
Life time member
40K? Just getting broken in.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

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