Starter Amp's and battery size question

[Theamania]

Howdy!
the bike in question is a GS 550M (katana) 1982
Ill jump straight into the questions:
How much does the starter use right in the starting moment?
Ive read somewhere around 50-80A but that doesn't sound too much..

Regarding the issue of overheating R/R unit, would there be a disadvantage to use a Smaller battery? Since the battery will be fully charged quicker, and the RR will have to send of the "leftover" power by heat?
Correct me if im wrong, i've read the statorpapers on cliffs site and measured so everything seems fine..

Got a 12V 4.8A battery (with a 160A staring 'power') which "should" be theoretically enough to get the bike running.

(and once again, I apologize if some words doesnt make sense, english aint my main language, but i figured swedish wont make sense to the main population on this forum

cheers!

[tom203]

Howdy!
the bike in question is a GS 550M (katana) 1982
Ill jump straight into the questions:
How much does the starter use right in the starting moment?
Ive read somewhere around 50-80A but that doesn't sound too much..

Regarding the issue of overheating R/R unit, would there be a disadvantage to use a Smaller battery? Since the battery will be fully charged quicker, and the RR will have to send of the "leftover" power by heat?
Correct me if im wrong, i've read the statorpapers on cliffs site and measured so everything seems fine..

Got a 12V 4.8A battery (with a 160A staring 'power') which "should" be theoretically enough to get the bike running.

I say the starter would draw about 80 amps under normal circumstances.Your 4.8 amphour battery doesn't have much reserve capacity if something goes wrong, but it shouldn't harm the R/R unit. Some of these new batteries have large starting power despite their small size.

[posplayr]

I say the starter would draw about 80 amps under normal circumstances.Your 4.8 amphour battery doesn't have much reserve capacity if something goes wrong, but it shouldn't harm the R/R unit. Some of these new batteries have large starting power despite their small size.

The manual lists 3-4 ohms for an 1100E starter. That would be about 4-3 amps.

Max power would be P=13^2/3=56 watts=> 0.075 Hp

[Theamania]

The manual lists 3-4 ohms for an 1100E starter. That would be about 4-3 amps.

Max power would be P=13^2/3=56 watts=> 0.075 Hp

Dont we all love a little math on a friday night?
But isnt 3-4 ohms just the resistance of the starter when its not engaged?

seems a bit low for it to use about as much power as my 50w headlight :P

As for the battery, (latenight theory here, feel free to correct me)
If the starter uses 80A for 5 sec it would only use up 0.11Ah??
(80*(5/3600))

Hmm.. getting too late for this :P

[Steve]

The manual lists 3-4 ohms for an 1100E starter. That would be about 4-3 amps.

Max power would be P=13^2/3=56 watts=> 0.075 Hp

Something is DEFINITELY wrong here.

Pos, I happened to use my 'new' clamp-on amp meter on my 850 before I left home.
The current fluctuates, so it's hard to get a good reading, but it's definitely in the 70-80 amp range.
I have it with me, I can try in on any of the bikes on the Catskills ride this weekend.

If it were in the 3-4 amp range, like you suggest, why would the starter run the battery down so much quicker than a headlight, which draws about 5 amps?

.

[fishfarm]

This is a screenshot from my GS1100G manual:

[posplayr]

This is a screenshot from my GS1100G manual:

80 amps @ 13V is P=80*13=1040 watts or 1.4 Hp That seems pretty high.

A 1 hp motor is going to be at least twice the size of the GS starter.

http://www.nextag.com/motor-1-hp/stores-html

I agree that 3 amps seems small, I would think it is closer to 1/4 hp ==> 15 amps at 13V.


80 amps is probably a peak current before the motor starts to move.


EDIT: OH Crap, I just looked again the 3-4 ohms was the STARTER SOLENOID RESISTANCE.

The way I calculated power from quoted resistance is only valid at stall and not steady state.

When you first apply voltage to a motor and it is not moving (or it is stalled), the current will be the terminal voltage divided by the resistance (as i calculated it). But as the motor starts to move, depending upon the load/speed the current drops off to a steady state value depending on the load/speed.

50-80 amps still sounds like a peak value.

[posplayr]

OK I dug out a starter, that I think is for a GS750. It is labled 0.5 Kwatts that would be 2/3 hp (750 watts/hp)

750/2=375Watts
375/13=29 amps

Of course the current will depend on the speed that it cranks. I guess when I get around to testing my dummy load, I can also measure the current draw (if I remember)

I forget , what is the point of the question?

[Graham]

You can’t compare continuous run motors to starter motors. Continuous run motors like used in pumps are as the name implies made to run for long periods of time. Starter motors are designed to run full load for short periods of time and if used for long time periods even with no load will overheat. 50 to 80 amps would be peak current but then again a starter motor runs at nearly peak current under load.

A 4.8 amp 160cca (160A starting) battery is what we use in little Chinese 110cc ATVs and their starters only draw 29 amps. I would never trust a 4.8 amp battery to start my GS1100 on a cold day. A GS550 may be easier to push start so give it a try.

[Theamania]

Thanks everyone for helping out with manuals, measurements and just plain theory :P
Tried the 4.8Ah battery and it started up just fine, fiddled around with the voltmeter and everything seems just great. Gonna get a new battery when i order some stuff tho (clutchwire, gas wire, breakpads, oilfilter and all that "boring" stuff :P )

Will also start a new thread regarding a strange effect i noticed today...
i like to call it the "neighbours looing down the street with a slightly annoyed look when I fire up the bike"-Effect. Yepp... stock exhaust & mufflers

[Steve]

Will also start a new thread regarding a strange effect i noticed today...
i like to call it the "neighbours looing down the street with a slightly annoyed look when I fire up the bike"-Effect. Yepp... stock exhaust & mufflers

That's OK, they are just JEALOUS.

.