foxnet22 Posted October 31, 2012 Report Share Posted October 31, 2012 (edited) hi lads can anyone advise me on the above.i have obtained a 12v17ah battery for my 170 lamp but there is no fuse in the fuse holder wondering what amp fuse to put in.the bulb is 100 watts thanks . Edited October 31, 2012 by foxnet22 Quote Link to comment Share on other sites More sharing options...
Shot & Missed Posted October 31, 2012 Report Share Posted October 31, 2012 When calculating a fuse rating for my old Matchless motorcycle electrics I used the formula of watts divided by volts = amps. In your case 100 watts divided by 12v would be 8.33 amps, depending on what fuses are available try about 10 amps. Quote Link to comment Share on other sites More sharing options...
handy4454 Posted October 31, 2012 Report Share Posted October 31, 2012 Hi S&M's calculations are spot on but you will probably suffer nuisance blowing with a 10A fuse due to the high inrush of current with a cold lamp,15A would be a better choice. atb handy Quote Link to comment Share on other sites More sharing options...
handy4454 Posted October 31, 2012 Report Share Posted October 31, 2012 Hi S&M's calculations are spot on but you will probably suffer nuisance blowing with a 10A fuse due to the high inrush of current with a cold lamp,15A would be a better choice. atb handy Quote Link to comment Share on other sites More sharing options...
bullet1747 Posted October 31, 2012 Report Share Posted October 31, 2012 When calculating a fuse rating for my old Matchless motorcycle electrics I used the formula of watts divided by volts = amps. In your case 100 watts divided by 12v would be 8.33 amps, depending on what fuses are available try about 10 amps. It's called ohms law Quote Link to comment Share on other sites More sharing options...
Tomm Posted October 31, 2012 Report Share Posted October 31, 2012 Ohms law is voltage = current X resistance tom Quote Link to comment Share on other sites More sharing options...
djgeoff Posted October 31, 2012 Report Share Posted October 31, 2012 or try 10amp anti surge denoted by the letter T on end cap. F denotes fast or quick blow Quote Link to comment Share on other sites More sharing options...
ME Posted October 31, 2012 Report Share Posted October 31, 2012 I like those little round ones. The brown ones are nice and my second favourite are the red ones. Quote Link to comment Share on other sites More sharing options...
harrycatcat1 Posted October 31, 2012 Report Share Posted October 31, 2012 Whats wrong with silver fag packet paper? It normally sorts most things and better than a nail Quote Link to comment Share on other sites More sharing options...
ack-ack Posted October 31, 2012 Report Share Posted October 31, 2012 I like those little round ones. The brown ones are nice and my second favourite are the red ones. You're wrong. The red ones are the best then the brown ones Quote Link to comment Share on other sites More sharing options...
ME Posted October 31, 2012 Report Share Posted October 31, 2012 (edited) You're wrong. The red ones are the best then the brown ones I like talking about them to people from Suffolk or Norfolk, they call them FOOZES. Try it. Edited October 31, 2012 by ME Quote Link to comment Share on other sites More sharing options...
jasper3 Posted October 31, 2012 Report Share Posted October 31, 2012 would you need a fuse... the battery isnt being charged so the lamp is only pulling power..I maybe wrong but i have had the same issue with my fish finder on the kayak..no surge in power..no fuse Quote Link to comment Share on other sites More sharing options...
harrypen Posted October 31, 2012 Report Share Posted October 31, 2012 (edited) hi lads can anyone advise me on the above.i have obtained a 12v17ah battery for my 170 lamp but there is no fuse in the fuse holder wondering what amp fuse to put in.the bulb is 100 watts thanks . P=power in watts I =current in amps V=volts with the 3 formulae :- P=V*I,,,,,,,I=P divided by V,,,,or V=P divided byI You can work out what voltage or what wattage or what amps hth harrypen Edited October 31, 2012 by harrypen Quote Link to comment Share on other sites More sharing options...
ME Posted October 31, 2012 Report Share Posted October 31, 2012 (edited) would you need a fuse... the battery isnt being charged so the lamp is only pulling power..I maybe wrong but i have had the same issue with my fish finder on the kayak..no surge in power..no fuse Sound advice that He should put a fuse in the fuse holder of his lamp. Tune in to next weeks PW big debate "Should I put fuel in my car to make it go?" Edited October 31, 2012 by ME Quote Link to comment Share on other sites More sharing options...
BerettaSV10 Posted October 31, 2012 Report Share Posted October 31, 2012 Sound advice that He should put a fuse in the fuse holder of his lamp. Yes if not only to protect the lamp and wiring also protects the battery. Had a extention of the wiring on a bike once (previous owner wired it up) rain got in and shorted every thing out boiled the battery dry and burnt out the the extension wiring and took out the rest of the wiring close to it. :( Tune in to next weeks PW big debate "Should I put fuel in my car to make it go?" No get the other half to fill the tank up :D Quote Link to comment Share on other sites More sharing options...
Paul223 Posted October 31, 2012 Report Share Posted October 31, 2012 You're wrong. The red ones are the best then the brown ones nah, it may be a bit of an old fashioned idea but the pink ones are defo the most fun Quote Link to comment Share on other sites More sharing options...
Sha Bu Le Posted November 1, 2012 Report Share Posted November 1, 2012 Ohms law states the the current in a circuit is directly proportonal to the resistance and inversely proportion to the voltage. So when wiring things up you have to consider Ohms second law of colouration...............Red to red...Black to black and blue to ******** bits. :friends: :friends: I'll get my coat Quote Link to comment Share on other sites More sharing options...
Sha Bu Le Posted November 1, 2012 Report Share Posted November 1, 2012 (edited) nah, it may be a bit of an old fashioned idea but the pink ones are defo the most fun You lot talking about smarties ?? Ok I'm going for my coat in a minute. Seriously yes you need a fuse to protect other parts of the wiring and equipment from something going wrong and also the lamp if some thing goes wrong elswhere. 10A Anti surge sounds good to me against a 8.3 amp load. Upon switch on there will be a power up current surge that will be quite high for a few mille seconds possibly 15A or even higher. No fuse or a standard type fuse will give problems, No fuse your lamp melts, standard fuse the fuse blows. Sound advice from the sparkies on here. Edited November 1, 2012 by Sha Bu Le Quote Link to comment Share on other sites More sharing options...
Beretta28g Posted November 1, 2012 Report Share Posted November 1, 2012 A cut down 6'' nail will NEVER fail Quote Link to comment Share on other sites More sharing options...
bullet1747 Posted November 1, 2012 Report Share Posted November 1, 2012 Ohms law is voltage = current X resistance tom Lot more to it than that Quote Link to comment Share on other sites More sharing options...
Paul223 Posted November 1, 2012 Report Share Posted November 1, 2012 Fuses are cheap, I'd go with ten amp, carry a spare or two and if you have problems with them blowing then up it to 15, start low and work up, no point in using too high a rated fuse if the cabling won't take the constant current, that will end in something melting rather than the fuse blowing Quote Link to comment Share on other sites More sharing options...
Tomm Posted November 1, 2012 Report Share Posted November 1, 2012 Lot more to it than that Well aware of that thanks as I'm a electrical engineer Quote Link to comment Share on other sites More sharing options...
ME Posted November 1, 2012 Report Share Posted November 1, 2012 Well aware of that thanks as I'm a electrical engineer Quote Link to comment Share on other sites More sharing options...
karpman Posted November 1, 2012 Report Share Posted November 1, 2012 Cut the fooze holder out carry on in blissful ignorance. Karpman Quote Link to comment Share on other sites More sharing options...
jasper3 Posted November 1, 2012 Report Share Posted November 1, 2012 Sound advice that He should put a fuse in the fuse holder of his lamp. Tune in to next weeks PW big debate "Should I put fuel in my car to make it go?" thank you ME it wasn't advice ..but you have taught me soooooooo much (big manly kiss xx) thanks beretta for explaining Quote Link to comment Share on other sites More sharing options...
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