Electrics.....

[cngarrod]

Hi Guys,

OK... have replaced the Domestic battery (as discussed earlier in the week...) have opted for one at mo... too many other bills to pay.

So fitted the 105a/h battery, and the FM stereo now works... and there is power to the cable for the VHF.

But...

The Isolater switch doesn't disconnect the battery power.... and the power cable for the VHF keps blowing a fuse.. (7.5 amp)

This is where i get confused....

When i sea trialled her initially the original VHF radio had power and so on, but the display was broken and the radio itself was not working correctly... also the FM stereo was funtioning...

Survey said the domestic batt was dead.. so now changed that

Rating for old and new VHF are the same...

2 Things have changed since the sea trial....

New Battery, just fitted today
Mechanic fitted a 12v "lighter" socket - fused - at the helm..

So i now cannot isolate the domestic battery (am sure this is a simple task to over come) and the new fixed vhf won't operate cos the in line fuse keeps blowing...!

What could cause a power overload to the power cable of the vhf?

How do i reconnect the isolater up to the battery?

Cheers,

Craig.

PS - Other than that... had a very productive day cleaing the hood, top sides and seats... well to be fair SWMBO and the youngest did some of that too!

 

[ccscott49]

Are you sure the battery is connected the right way around silly but just check, amuse me. The battery should be connected to the isolator switch, on the back, it should tell you where to connect the positive connection from the battery, it's obviously on the wrong side. if the switch doesn't operate, or the switch is buggered. Two leads should come to the back, one from the positve of the engine battery and one from the positive of the domestic. The negatives, probably both go to the engine and are normally shorted together. I don't know what is causing the fuse to blow, It's virtually impossible to check from this distance, saying that an ammeter in series with where the fuse is now would show you the current being drawn by the VHF, place it in circuit and switch on the radio momentarilly and read the current! Switch it off as soon as you have read the current, quickly!! If theres a short you'll burn something up if you dont cut the switch! If it's drawing a bunch, 10 amps on transmit, something is amiss inside! You need an electrician to look at this, make sure you get a good one, not sure about this mechanic fitting the socket, didn't he notice something amiss?

 

[andyball]

isolators are just as effective fitted in the negative feed.......they're not always in the +ve.

If it's a 2 battery isolator/selector switch, it'll have at least 3 terminals....one for each battery,one for the output (and sometimes 2 more for the alternator field disconnect).

If the isolator switch isn't a 2-battery type, then possibly it was originally wired to isolate only the engine battery(to stop it from going flat along with the domestic one)....in which case get yourself a proper 2-battery one.

blowing fuse? double check that the vhf's connected the right way round

 

[ccscott49]

But are usually in the positive feed, as the negatives normally go to the engine, if its a usual boat without insulated returns, mine has full insulation, but it's not the norm. I also meant there are usually two main FEEDS to the switch, as I was saying on another thread, very difficult to do this kind of thing when ones' a few hundred miles away. I still say get an electrician to look at it, we can go on like this for ever and still not know the problem. With electrics, things go bang fizzle very quickly! I shouldn't hasve even mentioned the ammeter thing, it could all go pearshaped very quickly!

 

[halcyon]

VHF power, is it via a plug, if so remove plug, does the fuse blow ?

if yes, the fault is in the supply, anything from a screw through two cables onwards, but check wiring of cigar socket.

If the fuse does not blow the VHF is faulty, take it to your local marine electronic people.


What sort of isolator have you ? engineer did not have to touch this to fit a new battery.


Brian

 

[cngarrod]

Hi,

Battery is connected the right way round... no probs there!

Re the Isolater switch... there are 2, one for each battery.. the engine one works fine, but the other seems to be not connected to anything!

As with all these lovely things... it is in a really handy place to get to... like out of sight (At the back anyway!) - reckon it a job for a "skinny" mate of mine... he may stand a chance!

Re the radio, as i cannot isolate the battery everytime i connect the battery up the "in line" fuse goes pop... so no way of telling why on that score... went and bought a multimeter today so will see what current is getting to the fuse...

Then will remove the instrument panel and see if anything is touching anything it shouldn't...

Something is wrong in there somewhere..

While on the subject... maybe i am being dim here (nothing unusual!) but my understanding is that the electrics should be set up something like this...

Batt 1(or batt bank 1) - Engine starting
Batt 2 (Or batt bank 2) - Everything else!

I thought that i how mine was set up... but it appears only the stereo and the vhf are on the service battery...

What is the concencus of opinion here on what should run from what?

Cheers,

C

 

[cngarrod]

Hi Brian

Fuse blows without plug being there.. so must mean too many amps to the fuse... but i cannto comprehend why!

Will take instrument panel out and look from there...

Isolaters are the "std" red key push and turn type...

Cigar socket runs off engine battery... as it appears does everything else...

Cheers,

C

 

[ccscott49]

Until you get this sorted out, I would disconnect the domestic battery, something is amiss here and I don't want your boat burning up, you don't either!! The domestic battery should run all of your "other" stuff, but the normal way, ios one baterry switch, with batt 1, batt, 2, off, both. This allows you to charge both batteries, use domestic or engine or both to run the boat. Two switches is also ok, but they need to be wired correctly. As I said I beleive it is time now to bite the bullet and call a professional, please. The fuse blowing without the radio switched on, means there is a short in the cable to the radio or just inside the radio, before the on/off switch, I'd go for the cable! Disconnect the cable from the radio, make sure the ends do not short out, put fuse in, if it blows, replace the cable, if it doesn't get the radio looked at, simple, innit!

 

[cngarrod]

Think you might be right!

Thanks for confirming what i think i kinda knew already... this could get pricey!

Oh well... it is boating after all!!!

Cheers,

Craig

 

[halcyon]

Assume therefore the plug is not in vhf, the fault must be between the fuse and plug. It cannot be between the battery and the fuse, this would not blow a fuse, therefore check the cable from fuse to plug. If you now have a multimeter, leave out the fuse and check the resistance between output side of fuse and ground, if plug is out of vhf it should read mega ohms, if it read around 1 ohm you have a short.

What rating fuse are you fitting.

Sounds like the boat was built as a single battery installation, or the owner has done a quick fix to get over the dead second battery.

If there are no wires on the second isolator switch, were does the leads of number two battery go.

How many wires on the other battery switch ?.

It's going to be a matter of finding what you have, then you can decide were to go.


Brian

 

[cngarrod]

Hi,

Fuse is 7.5 amps, the correct rating according to the vhf manual...

The boat was initially a 2 battery installation, but after talking to boatone last night we kinda came up with the same opinion that it has been "hot wired" to overcome the domestic battery being dead.

Agreed plan of action..

1. Check ohms at the VHF power cable
2. Check wiring under instrument panel to see if any obvious faults
3. Check wiring to the engine battery
4. See if any wires connected to domestic isolator
5. Trace the wires for domestic battery
6. Run a quick trial and error on what is powered from what
7. Write it all down and think about it before deciding next move!

Cheers for input,

Craig.

 

[chippie]

RE the VHF: Could the power lead be shorting in/on the chassis of the Vhf? It could be possible to blow the fuse even if the switch is off.
Good luck anyway.

 

[halcyon]

Fine with fuse, just incase it was to small.

What boat is it ?

While checking around look for the split charger system.


All the best

Brian

 

[cngarrod]

Hi Brian,

It is a Falcon 23... single engine...

I "know" it is supposed to have a split charging system... and will have a root about for it.

Reckon that a previous owner took the domestic battery out of the ring main and wired the vhf and radio / cassette to it directly... either cos he was stupid or because the domestic battery was dead...!

Thanks for your help,

Craig.