first mod

[edyle]

I read that thread and i have a question on calculating watts to figure out what fuse i need with my batteries. I looked up how to calculate watts and it google said to multiply amps and volts to get watts. so my question is would i multiply watts by continous amprage or pulse amprage? Pulse right? Because thats youre batteries peak and a fuse should blow when you're pushing the batterie beyond its peak. Thanks guys all of you helping me out have been very helpful and knowledgeable.

You don't need watts to figure out which fuse, you need amps to decide the fuse.

Use the continuouse amp rating for fuse purposes.

 

[dmrg1961]

Okay so its that simple hahaha? I just need a 40 amp fuse then. I figured out my watts then. 168 watts

 

[Stosh]

Okay so its that simple hahaha? I just need a 40 amp fuse then. I figured out my watts then. 168 watts

That would be pushing the batteries to their maximum. You could fuse it at 30 amps and light up most any coils possible.

Like your batteries, wired in parallel to double the amps, if you wire your fuses in parallel
you can us two 15 amp fuses. (may be easier to find and a good bit smaller.

 

[dmrg1961]

Whats the best way to post pics here? Id like post pics along the build

 

[dmrg1961]

So if i used 2 15 amp fuses it would automaticly change the amps to 30 instead of 40?

 

[edyle]

So if i used 2 15 amp fuses it would automaticly change the amps to 30 instead of 40?

If you put a 15 amp fuse on each battery, then if 1 fuse blow2, all the load falls on the other battery;
I'd use 1 fuse on the combined output.

You should use 30 amp batteries;

If you use a 20 amp fuse, that would mean you're well within the capability of the combined battery and if something goes wrong with one battery, you're still within capability of the remaining battery.

With 4.2 volts at 20 amps, that's a wattage rating of 80 watts.

Corresponding ohms would be 0.21 ohms.
If you aim for 0.3 ohm and above you're in able territory.

 

[dmrg1961]

I already bought the mnke 20 amps. so could i put a single 30 amp fuse for both batteries what would you guys recomend?

 

[edyle]

I already bought the mnke 20 amps. so could i put a single 30 amp fuse for both batteries what would you guys recomend?

I'd get 10, 15, 20, 25, 30, 40 amp fuses.

While putting the thing together I'd use the lower amp fuses.

When the work is just about done and it's time to put things through some paces, I'd put the higher amp fuses.

In production usage, I'd want to use an appropriate fuse for the build.

If you were going to a cloud contest or something, then you might make lower ohm coil and use the higher amp fuse;
but chances are, you regular usage will be somewhere in between.

 

[Stosh]

If you fuse it lower than the batteries are capiable of producing, if something goes wrong, you replace a cheap fuse and save the expensive batteries from damaging themselves or stressing themselves...

Murphy's Law of Electronics - The $100 component will burn out to protect the 0.15 cent fuse.....
Avoid Murphy's Law of Electronics......

 

[dmrg1961]

After plugging some numbers into the ohms law calculator stosh posted, thanks man. i think i am going to start with a 25 amp fuse. Just bought the fuse and the fuse insulator.

 

[dmrg1961]

Could i have a series of fuses inside the mod and use a button to switch to different fuses to control wattage??

 

[edyle]

Could i have a series of fuses inside the mod and use a button to switch to different fuses to control wattage??

1:
Doesn't sound very practical/worthwhile

2:
The part about "to control wattage" sounds like you don't understand the function of the fuse.

If you put a 0.5 ohm coil on your mod,
4 = I x 0.5
I = 8 amps.
So you put in a 10 amp fuse

If you're going to build a 0.2 ohm coil, you replace the fuse with a 25 amp fuse;

what you can do is design for the fuse to be accessible on the outside of the box.
Maybe even use plugin type fuses like what is used in cars.

 

[dmrg1961]

Okay gotcha. Duhhh. You cant build coils with lower resistance than the fuse can handle.. thankyou. You would put a fuse in it to suit youre mod and youre coils.

 

[dmrg1961]

picture of the box i just finished tonight

 

[dmrg1961]

 

[rhelton]

What you have in the box? It looks good so far, ive never seen a honeywell box.

 

[dmrg1961]

As in money i have absolutely nothing but a little work. I found the honeywell cover in my basement and thought it would make a perfect box for what im doing. And i had a roll of aluminum sheet so i took the shield and just made the rest of the panels with some sheers and riveted them together exept the back panel it has allen head sheet metal screws. But nothing so far as in electrical components. Still waiting on shipping...