why did my fuse blow between car battery and dc to dc charge controller?

[tsunami3775]

Hi guys.

Here’s my setup Starting from the car battery
Car battery with 40amp fuse to
30amp renogy dc to dc with 50amp fuse to
12v 100amp lithiumbattery to
1000 watt renogy inverter.”no fuse between”

System worked fine.
I plugged in my laptop to inverter which can pull max 14amps “see pic”
It’s been charging for about 8 hours. So yah i must’ve drained the battery. This is unverified since I don’t have my multimeter on me.

I started my car hoping to charge the system through the alternator and the fuse blew between car battery and dc to dc charge controller. Did it do this because my secondary battery was dead? It’s never done this before.

 

[tsunami3775]

Also my inverter was still set to “on”. So maybe that’s the reason?

 

[tsunami3775]

After reading this I’m thinking the laptop charger only pulls 4 amps.?

 

[time2roll]

Yes the secondary battery was extra low. Need to swap the 50 and 40 amp fuses assuming the wire is good for it.

 

[Pierre]

Seems like a combination of a discharged battery inrush and the inverter inrush current. Does the DC/DC not have current limiting ?

 

[tsunami3775]

Yes the secondary battery was extra low. Need to swap the 50 and 40 amp fuses assuming the wire is good for it.

Copy that. Thanks! Do you like these fuse types? I’m considering of using them so I don’t have to keep buying fuses. And the 50amp fuse is not blown.

 

[chrisski]

Copy that. Thanks! Do you like these fuse types? I’m considering of using them so I don’t have to keep buying fuses. And the 50amp fuse is not blown.

That looks like a fuse used in an audio system, and they are not reliable. Normally see them in stereo systems.

If it is a reliable manufacturer like busman, may work.

 

[tsunami3775]

That looks like a fuse used in an audio system, and they are not reliable. Normally see them in stereo systems.

If it is a reliable manufacturer like busman, may work.

Ok thanks

 

[time2roll]

Copy that. Thanks! Do you like these fuse types? I’m considering of using them so I don’t have to keep buying fuses. And the 50amp fuse is not blown.

Looks like a breaker. Get a quality item and they are great. Consider Bussmann Hi-Amp (amazon)
What size wire? I recommend #6 minimum to feed the DC-DC and a 60 or 70 amp fuse/breaker.
Fuse/breaker should be mounted near the power source and the DC-DC should be mounted near the battery that is being charged.

 

[tsunami3775]

Looks like a breaker. Get a quality item and they are great. Consider Bussmann Hi-Amp (amazon)
What size wire? I recommend #6 minimum to feed the DC-DC and a 60 or 70 amp fuse/breaker.
Fuse/breaker should be mounted near the power source and the DC-DC should be mounted near the battery that is being charged.

I saw the high amp but i only saw one for 48v. I didn’t see any for 12v

 

[chrisski]

I saw the high amp but i only saw one for 48v. I didn’t see any for 12v

The 48 volt is max rating

 

[RV10flyer]

I use a lot of these….various sizes, take your pick.

LENKRAD A-Series Red Toggle Circuit Breaker - Single Pole 40A https://a.co/d/igVDt3I

 

[mikefitz]

Renogy recomend an ANL link fuse rated at 45 amps at the starter battery end of the cable to the unit. I suggest a 50 amp fuse. There are many poor quality fuses on Amazon and eBay, this maybe why the 40A fuse failed, as the Input current to the Renogy unit could approach 40 amps.

 

[Levo]

I have 60A fuses either side of my Renogy 40A DC-DC per their recommendation, makes sense according to my own reading of articles, no problems to date.
Now installing Victron 12/12/30 DC-DC with a friend. Victron manual says 60A fuses, even for 30A unit (seems too big!) Sure that will ensure no nuisance trips, but is protection adequate?
This is all I have found so far:

Orion Smart 12/12/30 Fusing - Victron Community

community.victronenergy.com

Thanks for any input.

 

[time2roll]

I have 60A fuses either side of my Renogy 40A DC-DC per their recommendation, makes sense according to my own reading of articles, no problems to date.
Now installing Victron 12/12/30 DC-DC for a friend. Victron manual says 60A fuses, even for 30A unit (seems too big!) Sure that will ensure no nuisance trips, but is protection adequate?
This is all I have found so far:

Orion Smart 12/12/30 Fusing - Victron Community

community.victronenergy.com

Thanks for any input.

60 amp fuse is not too large. Only the wire might be too small. I recommend #6 minimum to feed the charger.

 

[Levo]

60 amp fuse is not too large. Only the wire might be too small. I recommend #6 minimum to feed the charger.

6AWG already in the plan, and I have 60A fuses on hand, so good to go. Many thanks for the simple answer, PDQ too!