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Catalina/Capri 25/250 Sailor's Forums

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Fuse Block for Battery Charging

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britinusa
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Initially Posted - 12/25/2011 : 07:04:26

Just replaced both batteries, they both blew their independent charging fuse.

I have in line fuses about 6" from the + terminal of each battery.

The issue I'm having is the need to remove the battery bay access panel to get to the fuses, I'm not a heavy guy, but reaching in their is a pain.

Wondering if it would be ok to install a fuse block below my charger on the bulkhead in the aft berth so that I could check them with comparitive ease.

Options are.
1: just replace the blown fuses in the in-line holders.
2: move the inline holders so that they are outside the battery bay.
3: add a fuse block below the charger with the plug in type fuses.

other options?

Merry Festivus to all.

Paul

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

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Happy D
Admiral

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Response Posted - 12/25/2011 : 11:22:38

From what I read, and I can't remember where I read it, there is supposed to be a fuse at the charger and a fuse at the battery. Think about it, if the fuse at the charger blows, the wire is still live comming from the battery so both sources, the battery, and the charger, need to be fused.
I have fuses at both ends. I put explosion proof fuses at the battery incase of hydrogen buildup in the battery compartment, unlikely, but just in case.

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Voyager
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Response Posted - 12/25/2011 : 23:29:07

Paul,
Hope your festivus was very festivualistic!

What was the fuse rating of your blown fuses? For a plug-in battery charger, 20A is typical, at least for short periods. If, when you replaced the batteries, you reversed one of the batteries (+ to - and - to +), you'd have blown just about any type of fuse. For starting an outboard, it would not be unusual to draw upwards of 60A for a brief period.

Netting it out, I have a 60A fuse on the + terminal in line with the engine starter cable, a 30A fuse in-line with the house and if I had a permanent plug-in charger, I'd probably use a 25A fuse, unless the documentation recommended otherwise.

The fuses are meant to protect the circuits they are connected to. The 60A protects the battery, the feed cable and the engine starting circuit while the 30A fuse protects the house power panel and battery. I also have a solar panel 7A regulator protected by a 10A fuse.

If you can't reach the fuses, you could add a short length of cable (2-3 ft more) to mount the fuses in a more accessible spot. But before I replaced the blown fuses, I'd try to determine what blew the fuses in the first place.

Like I said, reversed + and - would do it. If you had a dead short someplace, remove the battery cable and measure the Ohms on the circuit. With all switches off, you should get an open circuit. If you close the house lighting circuit, you should measure between 10 and 100 Ohms (unlit light bulbs have high resistance).
Do not try to measure Ohms with the plug-in charger plugged in and operating. If your engine circuit is shorted, you might have a problem with the starter or charging circuit, or with the cables to and from the engine.

Finally, check each battery in isolation with a voltmeter. Each should between 12.5 - 12.8 volts. If you get an extra low voltage (e.g.: 11.5V or less) there could be a problem with the battery itself.

Good luck with your circuits. If you can construct a schematic wiring diagram, that would help a lot.
Bruce

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britinusa
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Response Posted - 12/26/2011 : 04:30:02

For certain, one battery was shot. (at least I'm guessing the bowed out sides of the battery suggested that) and that is what probably blew the 20A fuse from the charger to the battery.

I changed out both batteries, the other fuse was ok.

Not wanting to start another project before we head out this weekend (plenty to do already) I'll just replace the fuse.

FYI, I have sized rings on all of the battery connections, it would be possible to put the larger ring on the wrong thinner battery stub, but not the other way around. Also I have oversized wires from the off-1-all-2 switch, correctly colored. I'm a bit OCD about power cables... not a bad thing.

I'll dig out the schematic that I drew when adding the Solar controller.

Paul

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britinusa
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Response Posted - 12/28/2011 : 04:29:02

Don't laugh, but I could not find the right sized fuses for the inline fuse holders that I installed 5 years ago.

So I purchased two inline ATC fuse holders, complete with waterproof (splash proof) covers.

Spliced inline, all done, new batteries already charged up within 24 hours. Now have 150AH.

Now if only I can get the boat ready for an early morning pull down to Biscayne Bay.

Paul

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Voyager
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Response Posted - 12/31/2011 : 18:35:51

Good luck Paul on your trip! Happy new year.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.