Voltage Niggles

[TwoStroke]

Boat setup - twin batteries - voltage check show 12V reading on each. Batteries then go through main switch 1,2 or both.

Engine off - voltage check on dash shows 10V - voltage check from fishfinder lead shows 8.5-9.0V. Engine on - voltage check on dash show 13V - from fishfinder lead 8.5-9.0V. Need between 10-11V for fishfinder to work.

Am going down to boat this weekend - am not sure how I can have such a huge reduction in voltage - it was only a few weeks ago it was working all ok! Voltage check on dash used to show 13V when engine off too! /forums/images/icons/frown.gif Have connected fishfinder direct to either battery - works all ok. Any suggestions as to what to look for here and what could be causing the drop?

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<P ID="edit"><FONT SIZE=-1>Edited by TwoStroke on 25/07/2003 09:45 (server time).</FONT></P>

 

[gonfishing]

hi
the longer the cable runs from battery to equipment the bigger the voltage drop.
so you could try thicker cables, also make sure all connections are clean dry and tight, pay particular attention to inline fuses as corrosion can build up on the terminals
p.s are you sure the batteries are o.k and fully charged?

hope this helps

julian

<hr width=100% size=1>man made it ,man can repair it, i think??

 

[tripleace]

if you have connected to another piece of equipment, it may have very thin cable and thus voltage drop.



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[TwoStroke]

It did cross my mind that the batteries may need replacing as have no idea as to how old they are. Is there an easy way to check them (am not connected to shore power)?

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[martynwhiteley]

Dont forget to check the earth connections as well as the lives.

It's possible that the earth connection has gone completely and it is 'earthing' through another device, e.g. the illumination bulb. You sometimes see this effect on old cars when they put the brakes on and the brake lights earth through the indicators etc.

I would second the view on corroded fuse connections as well.

<hr width=100% size=1><font color=blue> Real boaters do it on the Humber </font color=blue>

 

[gonfishing]

Hi Derrick
have you got a battery center near you? they can usaully do a test free of charge, as can somewhere like ATS etc do battery health checks foc

julian

<hr width=100% size=1>man made it ,man can repair it, i think??

 

[TwoStroke]

I haven't changed anything since having the boat - apart from wiring the gps correctly to the radio (boatyard wired output of GPS to output of radio) - so a little mystified. /forums/images/icons/mad.gif

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[TwoStroke]

Will give the marina call - see if they have someone who can check them for me tomorrow when I'm down. Start at the source and work back. Thanks.

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<P ID="edit"><FONT SIZE=-1>Edited by TwoStroke on 25/07/2003 10:19 (server time).</FONT></P>

 

[TwoStroke]

I wonder if that is why I also have problems with the radio.

When I do a radio test - the marina can hear me clearly - and only occassionally I can hear their reply. They tried for a couple of minutes last time but could never hear them - or is this a radio problem too (would too much squelch be the problem).

Oh, the excitement of boating! /forums/images/icons/smile.gif

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[mainshiptom]

The way I check my batteries if not sure is:

Disconnect battery and charge over night even with a car charger!

A good battery should show 13.4 the next morning!

A bad battery less

One bad battery can make a good one looks bad if connected together!
Tom

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[TwoStroke]

I have a feeling I'll be bringing the batteries back with me tomorrow night and charging them up. I'm hoping the local chandlery in the marina has a tester before I do that and can borrow one of their batteries - then check the voltage at the fishfinder. Beginning to supsect it could be replacement battery time. Thanks.

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[andyball]

Where's the boat? it's v.easy/quick to check with a meter if you're nearby.

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[TwoStroke]

Based in Brighton Marina - moored up on the east jetty. Takes me 25 mins to get to boat. Have checked with voltmeter - showing 12V. Need to place a load on it to check.

<hr width=100% size=1>How much to fill'er up!

<P ID="edit"><FONT SIZE=-1>Edited by TwoStroke on 25/07/2003 11:28 (server time).</FONT></P>

 

[TwoStroke]

Chandlery have come back - no they don't have a tester. Looks as if batteries out and down to ATS (could be Halfords or AA centre now) - I think there is one in Shoreham.

The chandlery sell 75amp for £45.00 each. Is this a fair price?

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[andyball]

Ah...a little too far to just nip over from Hayling then.

I would start at the batterys with a known good voltmeter & check the terminal voltage, first with the switches off, then on etc. If the terminal voltages are ok, move up the circuit checking voltage at each available point 'til you find a sudden drop.

It may be a poor or - connection to the dash area....or dud battery?

Remember that you can "lose" volts on the earth side as well as the side & don't presume that the dash voltmeters are any good .

I'd look for an electrical place rather than tyre/exhaust one for testing. Is there a Lucas service workshop in Brighton?

Price depends on type/quality, so could be pricey/cheap depending on this. Try to check the charging voltage before buying & ideally avoid totally sealed batteries if over 14.2V<P ID="edit"><FONT SIZE=-1>Edited by andyball on 25/07/2003 11:42 (server time).</FONT></P>

 

[Geoffs]

You may need new batteries, won't know until you test. But if engine cranks OK probably alright. If you have 13v on the dash with engine running and only 10ish at the fishfinder, it's not batteries.

Sounds like a poor connection somewhere, along the lines of suggestions already made. Funny voltages often the sign of poor earth somewhere. You should see 13.8 -> 14.5 volts with engine running at battery terminals. Should be same at dash, assuming no heavy current being drawn. Also reckon on 12.5volts or more for open circuit battery, having been left for a while. Much less could be a sign of self discharge.

Best not rely on dash voltmeter, they're not very good. A digital mutli meter best, sounds like you've got one.

If all else fails run a new power feed with 2.5mm2 cable to fishfinder, fused of course. But that is sweeping the problem under carpet, and it may come back and bite you again.

<hr width=100% size=1>Old Chinese proverb 'Man who sail boat into rice field, soon get into paddy'

 

[poter]

Try http://www.tooled-up.com for a tester, I had similar problems with 12v batteries and got a charger/tester it gave battery condition etc.
But agree with previous post that ATS do a very good free battery condition check.

As you say you have not checked anything since getting the boat, I would definitly get the batteries checked/replaced.

poter

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[TwoStroke]

Engine cranks ok - no problem there.

Am using a multi meter as like you don't rely on dash meter.

Did think about wiring in fishfinder direct - but like you said it skirts around the problem - and was working fine a couple of weeks ago.

The boat has been bouncing around a bit and have slammed occassionally so wondering if a connection has come loose. Oh well, time to get the batteries checked and then check the wiring.

Looks as if I know what I'm doing this weekend now. /forums/images/icons/smile.gif

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[BarryH]

If the things cranking ok its a good indication that the batteries are healthy. Nothing shows up a dodgy battery like a starter motor. I'd look to the wiring. I had this last year with my tub. The main feed to the dash was corroded inside the insulation. Someone had used cheapo cable when the feed was run up to the dash. Changed the cables and it sorted it. A lot will depend on how the boat is wired. A lot of the american boats have spare feeds from the ignition. Which makes fault finding easier, but replacing it a pain. Especially if the main wiring loom is at fault

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[TwoStroke]

Wiring loom is in a tube - quite easy to access. Will check batteries first - then switch and then loom. Have to re-wire dash anyway /forums/images/icons/frown.gif as when boatyard wired in compass only left me 1.5 inch movement to get behind dash - so re-wiring compass with more play and can check dash more easily.

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