Which mAh fuse to protect a metal detector?

[Turboair]

Hello,
I have just modified my 5900 DI PRO SL with no. 2 18650 (3000mah) unprotected cells and a battery holder with pcb.
It erogates 7,4V, and I used a Hobbywing BEC 5A converter, input 8V-42V to output voltage of 5/6V. I measured outing voltage and it reads 5,7V.
Now, this is the question. To protect my detector I inserted a 200 Mah fuse, but it fuses, so I replaced it with a 315 mah.
Now it works well, but I would like to know if it is normal that a 200 mah cannot do the work. Is it normal?
There is a risk that the 315 mah fuse will leave me while I am out detecting?
You will forgive me if this could be a dummy question...
Any help will be very appreciated

Thank You.

Turbo

[Davor]

It is not. The overseen part is that during a power up, almost every rig draws excessive current to fill the electrolytic capacitors, calm the rush in currents and stuff. For that particular reason fuses are made as slow or fast, and that responds to different ways they blow. In any case, an integral of i^2*t is responsible for heating up their wires and making them blow. You may try some of the surge protectors such as ICP-N15 as a permanent replacement for a fuse. Funny thing is that these devices are also cheaper than the traditional fuses too
See a product chart ...

[Turboair]

Thank You for reply. I did not know about that component, and I think it should be too hard for me to find one.
What about the 315 ma fuse actually in use. It looks is doing its job well. I left the machine on for more than 3h and no problems at all...
maybe it is strong enough to absorb the starting kick off.

[Davor]

Could be, but if 200mA blown, and 315mA did not, better use 400mA or 500mA not to spoil your fun too soon. In case of a real short a 500mA will blow for sure.