Electrical Leak - where to start looking?

[demonboy]

Hello,

After leaving Esper on the hard for three weeks not connected to shore power I noted a leak in the house battery system. I'd been aware of this for some time but this was an opportunity to make a note of the loss of power. Over three weeks the battery monitor indicated a drop from 100% capacity to 92%, dropping from 13.5v to 12.3v, with the rate jumping between 0.0a to 0.2a.

Since I've noticed this problem the only thing I have installed is the Navtex to the instrument circuit and the aerial to the mizzen. Also I connected a serial cable for the laptop coming from the Navtex junction box. Other than this nothing has changed to our electrical system.

My first question is how likely is it that the Navtex is causing the leak and, if so, how can I check?

Second question is if it's not the Navtex what are the standard procedures for checking for an electrical leak? Of course when I left the boat all CB were off. As far as I was concerned there was nothing 'on' when I left the boat but of course I understand that this amounts to nothing when it comes to a battery leak. If only it were that simple!

 

[angelsson]

Had a similar challenge with mine, only thing left on is the bilge pump, actuated by float switch direct to the batteries, only thing using the power is the green diode on the panel telling me it has power available if I have water ingress, which does not consume even a measureable amount of power.
I was advised to disconnect the small spade terminal from rear of alternator, was explained at the time why, but now no leakage when I do.
Am sure you will receive more expert advice soon.
Good luck

 

[ccscott49]

Do you have an on all the time gas detector? That could cause the miniscule amount you are seeing. I would also want to be checking your fridge circuit, seeing as you are having problems with that as well. Finding this leak is not going to be easy. Only way really is to disconnect anything that is not going through your switch panel and check it all.

 

[demonboy]

I have a gas detector but it's never been working so it's not that (another winter job).

You could have hit the nail on the head regarding the fridge. There are some strange things going on with the fridge but until I understand what's going on there I can't knock that off the list as a possible cause of the leak.

That aside, what should I be looking for? Do I use the volt meter on each appliance in turn when it is turned off? How likely is it that it's a circuit on the circuit board? Is it possible that despite the leak being contained within a CB it is still leaking?

 

[cliff]

With the main breaker off, disconnect the circuits hardwired direct to the battery bank then put an ammeter in each circuit in turn to see which is drawing the 0.2 amps - one of the cheap digital multi meters should do the job.

Such circuits could include VHF, Navtex, Gas alarm, Digital radio/cd player, Eberspacher, charger/invertor, auto bilge pump, alternator lead etc ........
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[ccscott49]

Yeah forgot an invertor draws a wee bit even switched off. But Cliff is right, thats the only way to find it.

 

[savageseadog]

You should have <u>everything</u> wired through switches (in a panel) then these things can be easily isolated. You also need a main battery isolator switch where off is off. I realise you may have some 24/7 circuits but there's nothing to stop them being switched too. Are you certain the ammeter reading is true? The sort of voltage drop you are talking about happens to all batteries after use/charge. They will drop slowly from the on-charge voltage to a steady quiescent voltage. Just because a battery drops from 13.5 to 12.3 doesn't mean you've lost 8% of your capacity.
Another good reson for using switches is that you can put all the switches off and just step through across the back of them and view the current.

 

[Bodach na mara]

The installer of my Eberspacher insisted that it be connected directly to the battery via a fuse and not routed through a switch. This ensures that the clock time is maintained (not important) and that nobody kills the power while the hearer is on (very important.) If the Eber is on, it is hot, and when turned off via the control unit the flow of coolant is maintained until it has cooled down enough.

The advice from Cliff stands, isolate the lot from the battery and locate the culprit by connecting one circuit at a time. You may even see a wee spark before you need to look at a meter!

 

[halcyon]

The battery capacity 92% and 12.3 volt do not match, 12.3 volt is nearer 60%.
Disconnect all leads from battery/batteries and let stand, then recheck 12.3volt. If stable at 12.3, do not trust gauge, or have the battery/batteries checked, may be a duff one.

Brian

 

[demonboy]

My apologies, I didn't mean 12.3v - it was closer to 12.8. I'm typing this thread in one place whilst my voltage notes are back on the boat. Apologies for misleading you.

This leak is only a recent thing. Up until a few months ago the battery monitor (a Mastervolt, to accompany my Mastervolt smart charger...so a pretty accurate) was showing NO leakage. What I'm trying to do now is isolate what I have added since the problem started and my first guess is my Navtex. Heading back to the boat now......

 

[cliff]

Any update on the "leakage"?
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[ShipsWoofy]

Sounds about right for a car stereo memory??

 

[demonboy]

None as yet. Rigging issues have had to take precedent, involving bruised partner being hoisted up the mast three times a day! I'll keep you posted on the leak though. I have a few jobs on my list I need to update forumites on, but you know how it is with that never-ending list of jobs that need doing......