Hello everyone,
my project will use a battery from 2.2 amph to 5 amph 12V, it will contains 19 3mm leds, an arduino nano, 2 shift registers, a current sensor, 4 rotary switches, 6 push buttons, 3 potentiometers, NRF24L01 long range tranceiver, video receiver FPV and screen. So my question is, do I have to use fuse for this and when should a fuse be used ?
Yes, you need to use a fuse to protect against a short circuit causing a fire.
It will not protect electronics from damage. 
Paul__B:
Yes, you need to use a fuse to protect against a short circuit causing a fire.It will not protect electronics from damage.
ok i see, so what usually should be done to protect also electronics ? a diode maybe ? any circuit that can be used for that ?
firashelou:
ok i see, so what usually should be done to protect also electronics ? a diode maybe ? any circuit that can be used for that ?
protection methods vary from circuit to circuit.It also depends on the total current consumption, environment type etc etc.
Protect against what exactly? Short circuit, over current, over voltage, battery over discharge, battery over charge, connected with wrong polarity - just to name a few things you may want to protect against.
There are also electronic short circuit (over current) protection circuits that can protect from shorts without burning a fuse, and react faster even.
firashelou:
...NRF24L01 long range transceiver...
Long range?
In ideal conditions.... maybe...
raschemmel:
NRF24L01 LONG RANGE
Consider yourself lucky, if you get 100m in an urban environment.
Consider yourself lucky, if you get 100m in an urban environment.
That goes without saying.
VHF is probably line of sight too.
raschemmel:
That goes without saying.VHF is probably line of sight too.
With LoRa 866Mhz you get 10Km at a breeze...
In urban environment ?
If that battery is a SLA type (sealed lead acid), you always need a fuse as they are capable of large currents that will set wiring on fire. (True for lithium battery types too, and large batteries of any type).
Current limited power supplies don't normally need a fuse on the output if you use thick enough wire for their max current - for instance USB 5V supplies are limited to 0.5A or 2A, not an issue for most wiring.
Fuses are there to stop wiring catching fire or being destroyed, sometimes they protect components too (for instance transformers and motors, which can also catch fire in a fault situation, and here the fuse will limit damage to the battery itself). The usual fault situation is a short-circuit.
Fuses often take far too long to fail to protect semiconductors, semiconductors protect the fuse(!)
With LoRa 866Mhz you get 10Km at a breeze...
Line of sight, yes, through dense wet vegetation, not a chance.
MarkT:
Line of sight, yes, through dense wet vegetation, not a chance.
LoRa performs 40Km in line of sight.
10Km urban is doable. Above all when it uses a frequency 866MHz that is not so crowded as 2,4GHz or 433 MHz.
And LoRaWan performs worldwide in metropolitan environments, since it uses relays and Ethernet gateways,...
Can you post a vendor link for a standalone module
that doesn't require you to have an Xbee socket?
raschemmel:
Can you post a vendor link for a standalone module
that doesn't require you to have an Xbee socket?
You can find the Seedstudio Dragino-LoRa-Shield modules locally for ~50% more$ but you will get them much faster...
Use the 868MHz or 915 MHz versions depending on your country legals, but avoid the 430MHz variant in metropolitan environments.
MarkT:
If that battery is a SLA type (sealed lead acid), you always need a fuse as they are capable of large currents that will set wiring on fire. (True for lithium battery types too, and large batteries of any type).Current limited power supplies don't normally need a fuse on the output if you use thick enough wire for their max current - for instance USB 5V supplies are limited to 0.5A or 2A, not an issue for most wiring.
The best solution is to use a 1$ step-down buck converter and feed the arduino directly at Vcc.
It will mainly be more efficient and provide current limitation as well.