Fuse values......

71basketcase · Apr 27, 2008

Greetings

Please accept my humble apologies for yet another electronics thread: it should be pretty simple and quick. I did a search and couldn't find the answer to this one.

What is the correct amp value for the main fuse between battery and ignition switch? The search revealed 35 amps but many people reccommend going to 20 amps. Is that accurate?

I'm considering a fuse on the headlight, turn signals, and brake light and found a small blade type 4 fuse block on line.......what would be the correct amperege for each of these circuits?

thanks so much for your time and expertise.

Karl

L.A.B. · Apr 27, 2008

71basketcase said:
What is the correct amp value for the main fuse between battery and ignition switch? The search revealed 35 amps but many people reccommend going to 20 amps. Is that accurate?

There's a certain amount of confusion about fuses because the 'old' British system marked fuses and referred to them by their blow rating! The blow rating being double the continuous rating as used elsewhere in the world and a standard that has now been generally adopted in the UK automotive industry for some while.

If the fuse is a British 1-1/4" glass type, then the 35A marking will refer to the blow rating (some of these fuses are marked with both ratings now)

So if a spade fuse, Japanese 25mm glass fuse or European ceramic fuse or other type is substituted, then the fuse value needs to be halved (approx.) as the continuous rating of the '35A' British glass fuses is 17.5A
The nearest equivalent to that normally being 20A.

L.A.B. · Apr 27, 2008

71basketcase said:
I'm considering a fuse on the headlight, turn signals, and brake light and found a small blade type 4 fuse block on line.......what would be the correct amperege for each of these circuits?

Watts = Volts x Amps

Amps = Watts / Volts

Volts = Watts / Amps

So add up the total amount of Watts for the particular circuit, and then divide that amount by the Volts, which will give the Amps.

For example:

60 Watt bulb /12V system

60W/12V = 5A.

71basketcase · Apr 27, 2008

Watts = Volts x Amps

Amps = Watts / Volts

Volts = Watts / Amps

So add up the total amount of Watts for the particular circuit, and then divide that amount by the Volts, which will give the Amps.

For example:

60 Watt bulb /12V system

60W/12V = 5A.

That is the most succinct and clearest definitiion I've seen regarding the relationship between watts/volts/amps....... exactly what I needed: Thanks very much and enjoy your week.

Karl

hewhoistoolazytologin · Apr 27, 2008

Thanks LAB...Straight to the point and...now don't take this wrong...uh...understandable. I printed it out and slipped it in my Haynes Manual.

71basketcase · May 1, 2008

let me add another bit of puzzlement: when I use the kick start to spin the motor, if I hold the alternator wires against the engine case, I get a good healthy spark from one wire but nothing from the other side...... is this because it's alternating current being produced, so at any given time one wire is + and one wire is -?

that's my theory and it's a new alternator (old rotor) but it wasw an e-bay purchase so I want to make sure it's good before buttoning up the cases ....

like grandPaul, I'm waiting on (*&*(&%(*&^( wheels! (and another $$ windfall so Ican buy some of the remaining bits I need to get it started....)

but I can see a narrow beam of light at the end of the tunnel!!!!!! 8)

thanks in advance......

Karl

hewhoistoolazytologin · May 1, 2008

Karl,
Greetings to the Cape...haven't been there in a number of years, although I did live there once.

Couldn't resist asking...how can you hold those wires against the engine cases and bent over like that, still kick that stinker over? Sounds like contortionist tendencies to me.

Come to think of it...didn't some circus usta winter out there on the cape? Might explain something. (Joke...joke...)

Now we wait to see if your theory is correct...might be. :wink:

L.A.B. · May 1, 2008

hewhoistoolazytologin said:
Couldn't resist asking...how can you hold those wires against the engine cases and bent over like that, still kick that stinker over? Sounds like contortionist tendencies to me.

I'm sure you'd think to take the plugs out first, Hewho......wouldn't you?

71basketcase · May 1, 2008

Couldn't resist asking...how can you hold those wires against the engine cases and bent over like that, still kick that stinker over? Sounds like contortionist tendencies to me.

Come to think of it...didn't some circus usta winter out there on the cape? Might explain something. (Joke...joke...)

yup, plugs are out.......

and yes, there is a village in hyannis near the airport that was the winter home for a variety of little people who were in the circus. The houses are all about 3/4 scale. I don't know if they're still living there or not but that is correct.

I thought for sure you'd know if my theory is correct, LAB........

any other thoughts, folks?

thanks in advance

Karl

L.A.B. · May 1, 2008

71basketcase said:
I thought for sure you'd know if my theory is correct, LAB........

I had to try it for myself, as I hadn't really got a clue about it, and I saw sparks occur at both wire ends. Whether they were actually alternating between the two wires and the case or not would be difficult to say for sure? If you connect a meter between the stator wire terminals then you should see an AC pulse.

My T140V was actually used for the experiment, but I don't see that it would make any difference to the result (same RM21 stator).

71basketcase · May 1, 2008

Thanks, L.A.B.

I teach woodworking and guitar building at a local high school.... I keep meaning to bring my multimeter home and keep forgetting. they're so cheap (and I'm getting ready to start wiring the ol basketcase) I might as well get one for home AND work!

thanks again:

Karl

Jeandr · May 2, 2008

71basketcase said:
let me add another bit of puzzlement: when I use the kick start to spin the motor, if I hold the alternator wires against the engine case, I get a good healthy spark from one wire but nothing from the other side...... is this because it's alternating current being produced, so at any given time one wire is + and one wire is -?

that's my theory and it's a new alternator (old rotor) but it wasw an e-bay purchase so I want to make sure it's good before buttoning up the cases ....

Karl

The alternator wires "should" be insulated from any frame part, this means touching one wire or the other should not make any spark to the frame when it is spinning. Use an ohmmeter and measure between the two wires, the resistance should be very low (few ohms), then measure between any wire and the alternator frame, the resistance shold be infinite (open), if any of these conditions are not met, it's defective.

Jean

L.A.B. · May 2, 2008

Jeandr said:
The alternator wires "should" be insulated from any frame part, this means touching one wire or the other should not make any spark to the frame when it is spinning. Use an ohmmeter and measure between the two wires, the resistance should be very low (few ohms), then measure between any wire and the alternator frame, the resistance shold be infinite (open), if any of these conditions are not met, it's defective.

However, as I understood it, what Karl described he was doing was touching both wires to the engine casing simultaneously? So the 'frame' acted as a conductor between the two wires.

Perhaps Karl could give a more detailed description of exactly what he did?

71basketcase · May 2, 2008

I held the two alternator wires about 1-2 mm from the engine case (I figured the engine and alternator would both share the same ground) and rotated the enngine via kick starter. I could see a visible spark coming off one wire but I didn't ever see one coming off the other (only a couple of turns.... even with the plugs out, it takes some arm strength to use the kick starter!!!)

I threw the multi tester in the car and will check the readings as you suggest, Jean.

BUT.... I demand that you all have a great weekend!

Karl

L.A.B. · May 2, 2008

71basketcase said:
I held the two alternator wires about 1-2 mm from the engine case (I figured the engine and alternator would both share the same ground) and rotated the enngine via kick starter. I could see a visible spark coming off one wire but I didn't ever see one coming off the other (only a couple of turns.... even with the plugs out, it takes some arm strength to use the kick starter!!!)

If you can be certain that the other wire wasn't actually touching the case when you saw the sparks, then you could have a problem?
There should not be a circuit through only one stator wire to ground. The encapsulated stator windings being isolated from ground, the only time there would be a circuit was if both wires touched or were nearly touching ground, thus giving off sparks? You could try a more thorough test to confirm what you saw, only keep one of the wires well away from the case while testing the other. I'm not entirely sure how conclusive a test this is, as far as testing the alternator is concerned?

71basketcase · May 7, 2008

update:

I finally remembered to bring the ohmmeter home: the stator reads 3 ohms across the leads and (much to my dismay) the old stator that I thought was bad also read 3 ohms.......

no continuity between any wire and the frame. so I guess I'm good to go.....

Thanks for your help, all..............

kfh

Fuse values......

71basketcase

L.A.B.

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hewhoistoolazytologin

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