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Small Cabin Forum / Off-Grid Living / Fuse Problem
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ArtifactJack
Member
# Posted: 24 Nov 2019 05:13pm
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I had a problem with my new solar system when I plugged in a small 3A vacum cleaner. It blew the 30A fuse between the battery, and the converter. My son who helped me design the system told me to remove the fuse, which fixed the problem. I have one 12v battery with a 30 amp CC, 1000w converter, and 300w of solar panels. Is it OK to not use a fuse between the battery and converter, or is something else wrong with my wiring design? Also the battery was fully charged when I plugged in the vacum.

ICC
Member
# Posted: 24 Nov 2019 05:49pm - Edited by: ICC
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1. That is an INVERTER, not a converter. There are such things and they are different. Converter take DC and make it into a higher or lower voltage. Some also take AC power and convert it to DC power. Inverters take DC and make AC.

2. There should always be a fuse between the battery and the inverter. Always. And as close to the battery as possible. The fuse is to prevent damage (meltdown, fire...) to the wiring in case of a malfunction of some sort. The fuse did its job, BUT...

A 30 amp fuse on a 12 VDC circuit is not large enough to serve a 1000 watt inverter. Probably need more like at least a 100 amp fuse in that DC line.


3. Can you post a diagram so we could have a look? I made some assumptions above, so a diagram and complete equipment list, make, model, will help.

4. I assume the vac in question is a 120 VAC unit? What else was running when the fuse blew?

ArtifactJack
Member
# Posted: 24 Nov 2019 08:17pm - Edited by: ArtifactJack
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Its a inverter alright. I don't have a diagram of my system, its basic. Lights and a challenge. Its off right now. A 100 amp fuse would probably be the wire size from the battery. What is that, a dc/ac fuse........

ArtifactJack
Member
# Posted: 24 Nov 2019 08:36pm
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Its a inverter alright. I don't have a diagram of my system, its basic. Lights first, its on pilot right now. A 100 amp fuse would probably be the wire size from the battery. What is that, a ac/dc fuse........? I have no idea how to size anything going to AC from DC.

ICC
Member
# Posted: 24 Nov 2019 09:32pm - Edited by: ICC
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A fuse holder something like this would work. I would verify the size needed by referencing the user manual info for the inverter you have.

A very useful equation when working with electricity is
Volts x Amps = Watts

Possibly useful site

Fuses are made for DC or AC, usually never the same fuse for both but there can be exceptions.


What wire gauge are you using for the line from battery to inverter?

Fanman
Member
# Posted: 25 Nov 2019 07:00am
Reply 


If your vacuum is pulling 3A at 120V, that's 360W. 360W at 12V is 30A, so hardly surprising the fuse blew, especially as the starting current is likely higher than 3A.

1000W from 12V is 83A, so a 100A fuse sounds reasonable, but the right thing to do is use the fuse size the inverter manufacturer recommends. The wiring must also be sized for that current... at least 4AWG for anything over 80A.

ArtifactJack
Member
# Posted: 25 Nov 2019 08:39am - Edited by: ArtifactJack
Reply 


Thanks for explaining what is going on guys. I will buy a 150 amp fuse to fix the problem. A #4 wire also as I believe its a size 10 braided wire right now.. You people rock. Thanks again.......

ArtifactJack
Member
# Posted: 5 Jan 2020 04:57pm - Edited by: ArtifactJack
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Oh well....

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