Fuses.

[arcturus]

Hi,I would like to change the fuse box on my 6 volt 544 to the modern "blade" type. As this is a 6 volt system would the stated fuse values still hold?

[Derek UK]

Yes. A fuse is a fuse is a fuse.....

[classicswede]

•Fuses - Since your fuses are rated for a 6-volt system's amperage, they will likely not blow when they should. They should be replaced with lower rated fuses. To determine the correct rating, you must determine the draw of your lights etc. There should be some way of calculating it

[123GT-AMAZON]

or use one like this so best of both worlds , can use the same rating as you have now then :)
and its the same style as the oem one.

http://i.ebayimg.com/t/5-Way-Continental-Fuse-Box-6v-12v-Ceramic-Torpedo-Classic-Car-6-12-Volt-Vintage-/00/s/NTAwWDUwMA==/$(KGrHqIOKjwE5vW4KP-EBOkFytLf1w~~60_12.JPG

http://www.ebay.co.uk/itm/5-Way-Continental-Fuse-Box-6v-12v-Ceramic-Torpedo-Classic-Car-6-12-Volt-Vintage-/180735404186?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2a14ab689a

regards

robert

[mikealder]

To calculate the fuse size you need to know the rating in Watts of the circuit it is supplying for example:

W=IxV (W=Watts, I = amps, V = Volts)

100W on a 12V system 100=Ix13,8 so I=100/13,8 = 7,25 Amps

100W on a 6V system 100=Ix6 so I=100/6 = 16,67 Amps

Note the above figures assume engine running with an alternator regulating at the typical on load figure of 13,8V and a 6 volt system using a dynamo - Mike

[123GT-AMAZON]

yup or wire it up in the same rating like for like....

6v system

fuses set to standard rating as oem then all great with a new modern like fuse block.

robert

[arcturus]

Got me a bit confused here. 1800 seems to be saying old style fuses, 12v for 6v circuit are OK. Others saying new style fuses in 6v circuit not OK!
OK, had another look at E bay product. Boxes are claimed for 6/12v but they only list fuses for 12v. Have I missed something?

[classicswede]

You can use the same fuses for 12v and 6 volt but the ratings are not.

6 volt wire will be thicker gauge than 12 volt so provided the wiring stays the say you should be able to use the same rating fuse.

[Bladerider]

To calculate the fuse size you need to know the rating in Watts of the circuit it is supplying for example:

W=IxV (W=Watts, I = amps, V = Volts)

100W on a 12V system 100=Ix13,8 so I=100/13,8 = 7,25 Amps

100W on a 6V system 100=Ix6 so I=100/6 = 16,67 Amps

Note the above figures assume engine running with an alternator regulating at the typical on load figure of 13,8V and a 6 volt system using a dynamo - Mike

This calculation assumes a conversion from 6 to 12 volts and calculates the current.

Fuses blow because of the current drawn, so if on 6 volts and blows at 10 amps then will also blow at 10 amps on a 12 volts. Amps are amps regardless. Unless I'm told different.

[tsetse1986]

The easy answer is use the same current rating (Amps) in your new blade fuse as the fuse you are replacing.

What others have tried to explain is that for the same power (Watts), a 6 Volt device will draw twice as much current (Amps) as a 12 Volt device. You only need to be concerned with this if you are changing over to a 12 Volt system. If you keep your 6 Volt electrics standard and only want modern fuses, then keep each of the fuses the same current (Amp) rating as the originals.

Promoting clarity in electrickery!

Tim

[Ron Kwas]

Tim;

Thank you for this clarifying post! I couldn't have said it better myself...frankly, the thread was all over the place and I was getting a bit frustrated reading all sorts of posts trying to be helpful, yet rather skirting the simple answer like yours!

Finally, regarding the issue of replacing the Fuseblock itself...

Arcturus; ...careful when replacing major components with modern equivalents...sure they're technically the same, and you can do it...you start at "only the Fuseblock", and before you know it you're installing a Rover V8. Please consider keeping it original by refurbishing and reinstalling the original components...it says something about the quality of engineering and materials of the original components, and also YOUR enthusiasm and commitment to keeping a fine old lady on the road when most of her peers have long ago been crushed...

Cheers from Connecticut!

[arcturus]

Ron,This is the original set up with some strange looking stubby fuses. That's why I wanted to replace but as you suggested (almost) I'm fitting a new box with ceramic fuses. (BTW I, didn't put the paint on the wires)

[Derek UK]

It's strange that Volvo gradually reduced the number of fuses as time went by. The stubbies are 25amp and are common to the Amazon 4 fuse box. Only one used there.

[arcturus]

I could do with a schematic which shows original position and function of fuses and values for PV 544?

[Derek UK]

If you PM me a suitable email address I'll send you pdf's of the '57, '59-'60, and '61 handbooks. They are scanned. You should find them useful but the fuse boxes are different in all 3!

If you are very careful you should be able to get out the card insert that is behind the fuses. Yours doesn't look in very good condition but you'll be able to read some of it.

[volvogv]

I agree that the fuses should be replaced with the same values....If you are going to replace them.

When it comes to my car, I lean toward historical authenticity so I ask the question: If you can polish the connections and make them reliable, is there any reason to replace with blades?

They lend a quirky kind of charm to the car.

[arcturus]

Just replacing the fuse box with a new on of the same kind, and want to check that things are as they should be. It looks as though there may have been some changes to the wiring. The paper as you say is still there but too faded to read. Derek, I have a copy of the "hand book" but it doesn't show fuse lay out. Check if yours does. Its the 61 544s B16 6v. My email is on my avatar

[Derek UK]

Handbooks sent.

[Ron Kwas]

Arcturus;

Your picture shows another FB variation I was not aware of...see: http://www.sw-em.com/Fuses,%20Allocation%20and%20Troubleshooting.htm (FIGURES 1, 2) apparently there exist more variations for the 6V444 than later models, so be extra careful in confirming that the wiring diagram you're using is indeed for your vehicle...but your FB and wires look typical and like they are good candidates for cleanup, and refurbishing, and with that, replacement is just not necessary!...nice thing is that they are right there, accessible, not buried somewhere...and a little solvent and light abrasion might remove that paint from wires to clean them up too.

I suggest you inspect for and correct any looseness of terminals, wires and screws and corrosion in the (entire) current path(s). Use ACZP!

Good Electrical Maintenance from Connecticut!

[arcturus]

I intend, when the car is up and running, to test each circuit by pulling each fuse to verify which circuit they control. You are correct about the variations! Thanks for all input.