Converting 12v house to 'golf cart' 6v s..

May 20, 2016
3,015
Catalina 36 MK1 94 Everett, WA
Shouldn’t the be a fuse on the cable running from the battery to the charger at the battery end?? The way it’s drawn you can be draining all the battery capacity thru a #2 or smaller wire

Mahalo
 
Jan 11, 2014
13,998
Sabre 362 113 Fair Haven, NY
Les,
The fuse should be at the power source, in the case of a charger the source is at the charger.
 
Feb 26, 2004
23,330
Catalina 34 224 Maple Bay, BC, Canada
Dave, regardless of where you may think the power comes from, in your case the charger, consider when it is off. Then you have this battery that is the SOURCE for large currents in the event of a short, usually in the wire. Les is right, fuse at the battery end. Most chargers have fuses inside them, too.
 

Bob J.

.
Apr 14, 2009
775
Sabre 28 NH
Not all "golf cart" batteries are 6 volt. I am very happy with my Trojan T-1275 12 volt 'golf cart' batteries. They have the same footprint but are taller. 150a/h each.
I got 4- T-1275 for my propulsion bank, they're the same height as my Duracell GC 6 volt house batteries.
 
May 20, 2016
3,015
Catalina 36 MK1 94 Everett, WA
Les,
The fuse should be at the power source, in the case of a charger the source is at the charger.
Nope. The charger is self regulating (same as alternators) and if sized correctly can’t deliver more than the wire can take. That same wire can’t stand up to the 100’s of amps the battery can supply if there is a short

Mahalo
 
Jan 11, 2014
13,998
Sabre 362 113 Fair Haven, NY
Dave, regardless of where you may think the power comes from, in your case the charger, consider when it is off. Then you have this battery that is the SOURCE for large currents in the event of a short, usually in the wire. Les is right, fuse at the battery end. Most chargers have fuses inside them, too.
Stu, Yep, you're correct and my batteries are wired with a fuse at the battery end. :banghead:

Actually I have 3 fuses between the battery and the charger. For some reason I thought Les was suggesting 2 fuses on the battery charger, one at the charger and on at the battery thus protecting the wire from both directions.
 
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
Les,
The fuse should be at the power source, in the case of a charger the source is at the charger.
I know you clarified this above but I just want to reinforce where the dangerous current comes from...

A battery charger is considered a current limited source just as an alternator or solar array or wind generator would be. This means that in a failure mode it can't exceed its output capability. With properly sized wire your charger, alternator or other charge source can't fry the wires but the battery bank end sure can.

A typical marine house battery bank is capable of feeding multiple-thousands of amps into a shorted wire where a 30A charger might be capable of 32A -34A into the same short. A single Odyssey G-31 battery is capable of 5000A into a dead short, a bank of four is capable of approx 20,000A into a dead short....

Over-current protection for battery chargers, alternators and solar arrays always goes as the battery end of the positive cable. If you want additional fusing at the charger, alt or solar end that is up to you but the charging source end fuse will never trip, if sized correctly, so it just means more terminations, potential for corrosion and unnecessary voltage drop.