Simes
regular
Reged: 19/01/2005
Posts: 76
Loc: IofW
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I just can't believe this, 10 days ago the generator threw a power spike. The Sterling 50 Amp 12 v Charger dipped and then ran back up to 14.2 volts. However the Charge controller (Cedrc) is now reporting 14.4v and 0 Amps.
I talk to Sterling Tech Support who ask me to check the voltage at the charger and at the batts, both were at 14.2 so Sterling tell me that the Charger is running fne and there is probably a spot of corrosion on the PCB of the charger that is affecting the Amp readout.
4 Days ago and we seem to be consuming a vast quantity of Amps and volts the batts are down to 12.2 and falling, despite running the Genset for three hours.
I check the volts at the charger 14.4 and again at the batts 12.2, how can this be? There must be a break in the circuit somewhere. Where?
Last night with the batts down to 10.6v I tried passing some volts across the Big Charger fuse (60A 32v Fuse) I push 12.8v in at one end and I get 10.83v out at the other. Problem found and problem solved by installing spare fuse.
Question, what can cause this? What could cause the reduction of volts across the fuse?
Is it about to fail? (increased impedence)
Could there be a small short inside it?
The fuse was stone cold.
Als where can buy a replace ment fuse, this is a big bugger!?
Many thanks
Simes
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jimbaerselman
regular
Reged: 18/04/2006
Posts: 1672
Loc: Greece in Summer, Southampton ...
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Some types of enclosed fuses blow, leaving a light metallic deposit around their container. This deposit is high resistance, and will cause a voltage drop which varies with the current - no current, no voltage drop.
This feature is always a sod when trying to trace high resistance failures - corroded connections etc. Voltages look good - until currents (don't) flow! Checking a circuit's resistance helps, but sometimes the resistance itself is affected when a current is applied . . . so you have to check voltage drop across a 'suspect' while the current is flowing.
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Jim Baerselman
http://www.jimbaerselman.f2s.com/ or Google 'jimb sail'
Compares the Cruising areas of Europe
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wotayottie
regular
Reged: 01/07/2007
Posts: 1856
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Quote:
Last night with the batts down to 10.6v I tried passing some volts across the Big Charger fuse (60A 32v Fuse) I push 12.8v in at one end and I get 10.83v out at the other. Problem found and problem solved by installing spare fuse.
Question, what can cause this? What could cause the reduction of volts across the fuse?
Simes
most likely the fuse was open circuit and the voltage you got at one end was the voltage of the batteries.
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William_H
regular
Reged: 28/07/2003
Posts: 3502
Loc: West Australia
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I fyou were checking the fuse when removed and connected one end to a 12v supply and measure d the voltage to neg. with a digital multimeter then the results you got are not surprising.
The multimeter probably has an input resistance of 10megohms.
That means it will sniff a voltage without drawing much current.
(12/10000000 of an amp. )
With that current flow you had a voltage divsion of aprox 2 volts dropped in the fuse and 10 volts dropped in the meter. In other words the fuse had a resistance of 2 megohms aprox. At 12 volts that will allow about 6 microamps to flow. (which is almost nothing)
The resistance in the fuse (conductivity) is almost certainly as a result of molten metal spattered on the fuse casing. So yes the fuse is dud. well spotted!!! It shows the trickyness of digital multimeters with very high input resistance. They are great for electronic circuits but can be misleading for boat electricals. olewill
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markdj
regular
Reged: 31/07/2002
Posts: 636
Loc: Ulster
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If it's an ANL fuse, you can get one from Power Store or if it's a "Mega" fuse you can get one from Furneuax Riddall.
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Princess Owners Club
www.princessownersclub.com
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