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blower fuse keeps blowing?
https://www.smwebhead.com/phpBB3/viewtopic.php?f=2&t=1000
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Author:  davemac [ Sun Jun 17, 2007 1:13 pm ]
Post subject:  blower fuse keeps blowing?

Anything I should be looking for that is causing the 5 amp blower fuse to pop??

Author:  jvalich [ Sun Jun 17, 2007 8:45 pm ]
Post subject: 

corrosion at the wire connectors in the bilge by the pump. I'm guessibng the corrosion is causing the high amps to blow the fuse.

Also, make sure the slot the fuse is going in to is clean and corrosion free. The blade fuse panels FW uses can be troublesome after several years.

Author:  davemac [ Mon Jun 18, 2007 5:24 am ]
Post subject: 

jvalich wrote:
corrosion at the wire connectors in the bilge by the pump. I'm guessibng the corrosion is causing the high amps to blow the fuse.

Also, make sure the slot the fuse is going in to is clean and corrosion free. The blade fuse panels FW uses can be troublesome after several years.


Thanks, I'll check. The boat only has 15 hrs on it. There is no corrosion on fuse panel. Since still under warrantee. I'll have the dealer check when doing the 20hr service.

Author:  Txjole [ Mon Jun 18, 2007 6:22 am ]
Post subject: 

Mine does too. :?: About 1 every 6th lake outing.

Author:  Graham R [ Mon Jun 18, 2007 11:20 am ]
Post subject: 

From the physics I was taught at school, (waaaay back!), it is the total resistance in a circuit that determines the current at any given applied voltage; the higher the resistance, the lower the current that will pass. ( Simply Current I = Voltage V/ Resistance R, for DC). So if there was some corrosion/ high resistance somewhere, the current would be lower than in a "clean" circuit. The fuse would not blow.

If on the other hand the circuit somewhere along the line was sometimes getting wet, e.g. water getting into a connector and electrically connected back to the block or battery, maybe even internally within the connector from the +ve to the -ve, that would give a lower resistance, higher current and the fuse would blow.

Also, due to the internal resistance of some of the newer 4" blowers ( e.g the waterproof ones by Attwood), they take 4.4A at a nominal 12V. If the voltage is higher e.g when the engine has just started and the alternator is kicking out max amps at it's max voltage , the internal resistance of the blower stays the same, but the current would be even higher as the applied voltage the blower is experiencing is higher. e.g. If voltage is 14V, which is not unusual when the alternator is charging the battery, that 4.4A current at 12V would become just over 5.1A ! ( 14/ 12 x 4.4A).
Additionally, as motors run they get hot and the resistance usually drops.

Regards,

Graham

Author:  davemac [ Wed Jun 20, 2007 9:43 am ]
Post subject: 

As follow up to my original post, the dealer was familiar with this and advised me to bump from the 5 amp fuse to a 7.5 amp with no worries. Apparently VP calls for 7.5 amp and FW calls for 5 amp, or visa versa.

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