12V Battery In-line Fuse keeps blowing every few days... 10 Fuses blown and melting

[sharpharp]

Hi,

I have a one 180Ah 12V Varta LFD180 Battery, connected to a Victron Solar Controller (also tried a Triron Solar Controller) connected to 2x 240W Semi Flexible Solar Panels.
The Load is switched on at Dusk till Dawn powering a Raspberry Pi and 2x USB Crypto Miners (total load is only around 14W at 1.1A)

I have an In-line fuse between the solar controller and the Battery, but every few days it is blowing (i.e. the plastic melts on fuse) and I have to replace it.
I have tried 5A, 10A, 15A, 20A, 30A and 40A fuses, but they all keep blowing/melting after a few days.

Can anyone else me diagnose the issue. The setup is super simple and the load is small and only used overnight, during the day the panels charge the battery, so i can't figure why the inline fuse is blowing.

Any ideas?

[SunEagle]

Try using a DC clamp-on ammeter to see how many amps it is drawing.. The way you describe the issue sounds like high amps for a long period which creates heat. There may also be a loose connection which can create heat build up.

Also if the controller is rated for X amps then you should use wire and fuse ratings to cover that amount.

[sharpharp]

Try using a DC clamp-on ammeter to see how many amps it is drawing.. The way you describe the issue sounds like high amps for a long period which creates heat. There may also be a loose connection which can create heat build up.

Also if the controller is rated for X amps then you should use wire and fuse ratings to cover that amount.

It's only drawing 1.1A max. Connections are solid and the cables are rated to much higher loads.

[SunEagle]

It's only drawing 1.1A max. Connections are solid and the cables are rated to much higher loads.

Well something is making that fuse see a lot of amps causing it to blow and melt.

So I think you will have to perform more tests and measurements to see why.

[Bala]

A fuse that has just blown with no melting is from overcurrent.

A fuse that has melted is from poor connection at the fuse.

There may only be 1.1 amp draw on the battery but assuming that fuse is in the cable that is supplying current from the panels via controller to battery as you have 480w of panels so theoretical 40a.

[littleharbor2]

What type fuse are you using? Might need to get a more appropriate fuse. If it's getting hot there's a, high resistance, poorly fitting connection, simple as that. Change your fuse style or correct the ill fitting, or oxidized contact surfaces.