What Fuse to use

[gold33]

Hi,

Trevor has mentioned putting a fuse on the out put side of my regulator.
What size should I use? my last use of the theory to calculate such things dates back to high school (and that was a couple of years ago).
By my calc' I was thinking 20amp but I'm just not sure whether I have allowed enough for surges.
I run a standard 6v system with 24-30w headlight, a tail light -brake light and a horn. after fixing a bad earth that stopped my low beam coming on I now have while light from the headlight so the wiring would appear to be in reasonable order.

[muskrat]

G'day Darren,
                  15-20 should be AMPle.
Cheers

[BSA_54A10]

I use Aust 20 amp blade fuses.
Now we Pommie derrativies use continious current so a 20A fuse will flow 20 A and blow around 25 to 30
US use a different system.
Some are more in tune with this that I but I think that a 20A UK is about a 35A USA.

I have been using "semi water proof " fuse holders for over 10 years with no problems.
Be careful what fuse holder you fit most are designed for power stations and come pre wired with 200A wire and getting a good "vibration proof" joint with such thick cable is a problem.


These are the fuse holders that I use.

.
They can be ganged together like this

On a  bike that I rewired around 7 years ago, we could not find any fuse holders so we "temporally" used a female blade terminal on both ends of the wire then a tiny cable tie to hold them together so that they did not pull apart.
It is still in the bike and running fine and the owner is one of the "if it ain't broke" types so he left it that way.

[gold33]

Thanks,

I have temporarily fitted a 20amp glass fuse with an appropriate fuse holder, and as you say Trevor it's wired for a power station not a 6v bike (just added substantially to the bikes weight).
I am going to order a repo original style headlight and will re-wire the bike when it gets here (currently have no park light at front, nor wiring to suit).

Where do you fit the blade fuse holders?
I would like the best of both worlds, easy access but hidden, my current battery fuse holder is in the same place as when it failed which is lying across the top of the battery (not nice to look at but you can hear it crackle just before it goes pop).

[BSA_54A10]

Yes, where do you put them.
That was the hard part, and took hours to figure out.
First I got the dremmel tool out and cut a sort of 3 tooth comb so that the fuse holders slotted onto the comb which was bolted to the battery holder, but not only did it get in the way but looked most obvious.
Final solution was to gang them together cut down a bit of flat iron ( same stuff I used for the comb) to fit in the gang slot so that they sat on the end like a toffee apply then dropped this "stick" down the open frame tube under the single saddle.
So what I have is a wire attatched to each of the battery terminals.
These go to a "T" shaped spade plug ( I do this on all BSA rewires ).
The other side of the plug goes to 2 fuses under the seat and from there to the common earth (seat spring mount) or ampmeter.
The amp meter wire is split near the fuse ( double bullet ) with the extra wire running down to the stop lamp switch.
The power wire from the regulator goes to the third fuse and then to the ampmeter.
Thus every thing on the bike is fused.
The other non standard item is the dip switch.
The bike has the headlamp switch for hi/lo which is a PIA to get at so I rewired the terminals thus;-
Off, tail lamp , pilot + tail , head + tail.
This way if the battery is slowly running down I can shut down to only the tail lamp so drivers approaching me from behind ( where you can not see them) can in theory see me. I fitted a halogen pilot lamp which while not providing mush of a beam to see by dose light up the headlamp more than good enough for on coming traffic can see it.