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Ken O
Joined: 05 Mar 2014
Posts: 112
City/Region: West Yellowstone
State or Province: MT
C-Dory Year: 1990
C-Dory Model: 22 Cruiser
Vessel Name: Ravens' Roost
Photos: Ravens’ Roost
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 Posted: Fri May 19, 2023 5:22 pm Post subject: Fuses at both ends charging cables? |
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I'm upgrading my solar power and adding a DC-DC chargers. The chargers can't fit in the starboard lazarette/battery compartment, so they will go in the cabinet under the stove. This means that I will have 2 hefty cables with batteries at one end and chargers at the other. Current source could be at either end. Would there be any harm in putting fuses at both ends of a cable? We are usually told to put the fuse near the battery, but in this case, I could have 20 amps going the other way, and I don't think a short in the middle would care if there was a fuse at the battery end. Thoughts? Thanks.
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"If it were easy, everyone would be doing it." --Circumnavigator and author Larry Pardey. |
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WCF
Joined: 21 Feb 2023
Posts: 80
City/Region: Central
State or Province: WA
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
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| Posted: Fri May 19, 2023 7:46 pm Post subject: |
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I just went through this with the same sized DC-DC; I also put it in the galley cabinet. It sounds like you are building almost the same system I put together; I had a similar question 
The manual for my DC-DC charger specified that ANL fuses were required at each end. I used one ATO at the start battery (Bluesea battery terminal fuse block type) and one ANL and it has been working great. My charger recommended 30 amp fuses at each end, which is acceptable for most ATO type fuse blocks.
You mentioned heavy wire. Double check the wire size you need for a 20 amp charger; the manual for my DC-DC charger, and confirmed by Bluesea's chart put me at 10 gauge, which is a lot easier to work with.
http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg |
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T.R. Bauer
Joined: 17 Nov 2007
Posts: 1789
City/Region: Wasilla
State or Province: AK
C-Dory Year: 1993
C-Dory Model: 22 Cruiser
Vessel Name: C-Whisperer
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| Posted: Fri May 19, 2023 11:50 pm Post subject: |
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| There are systems that require fuses on the ground side too...Not making that up! Anyway, more the merrier I suppose. |
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smckean (Tosca)
Joined: 18 Jan 2014
Posts: 975
City/Region: Guemes Island (Anacortes)
State or Province: WA
C-Dory Year: 2005
C-Dory Model: 25 Cruiser
Vessel Name: Tosca
Photos: Tosca
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| Posted: Sun May 21, 2023 1:53 pm Post subject: |
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| Quote: | | I don't think a short in the middle would care if there was a fuse at the battery end. |
Exactly! A fuse protects the wire downstream of the fuse. A short before the fuse (i.e., between the source and the fuse) could fry the wire (fire?) between the source and the short since the over current would not need to flow thru the fuse.
I think you're smart to put fuses at both ends to keep wire between source (any source) and the fuse as short as possible.
P.S. WCF is correct. Wire size mostly depends on max amps flow. Those huge cables you see on batteries are for the circuits that will carry 50, 100, or even more amps (volts don't matter except in terms of voltage drop for longer runs).....such things as engine start cables or inverters or battery to major distribution buss.
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Purchased Tosca in 2014
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