Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 11-03-2016, 02:25   #16
Registered User
 
bill good's Avatar

Join Date: Oct 2006
Location: Brisbane Australia
Boat: sold
Posts: 721
Re: Magic DC

& what happens when you disconnect the battery charger with only the + batt term connected??
__________________

__________________
bill good is offline   Reply With Quote
Old 11-03-2016, 06:05   #17
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,310
Re: Magic DC

So, so far we have suggested:

1 - It doesn't matter that the battery (-) isn't connected current still flows because there is a "potential"

2 - The current is jumping out of the disconnected (-) cable and flowing up the battery case to the terminal to complete the circuit

I'm not really accepting either of these. The facts still remain that the (-) cables were disconnectet so how could a circuit to the battery be completed? If the answer is that the circuit is getting completed via the AC ground system wouldn't that mean the batteries would always discharge through it?
__________________

__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 11-03-2016, 06:49   #18
Registered User
 
NahanniV's Avatar

Join Date: Mar 2011
Location: On the Boat
Boat: Finnsailer 38
Posts: 1,143
Re: Magic DC

Quote:
Originally Posted by sailorboy1 View Post
So, so far we have suggested:

1 - It doesn't matter that the battery (-) isn't connected current still flows because there is a "potential"
....
Just to reiterate what has already been said:
#1 is FALSE.
The potential generated by a battery is between it's TWO posts ONLY.
Current in the negative side will always equal the positive side of the same battery.

Quote:
Originally Posted by boatpoker View Post
...noticed recently that all of what we think of as known science in electrical matters is still noted as "theory" in serious scientific journals.
Every scientific explanation is a theory; The theories relevant to this problem have stood for hundreds of years; I doubt very much that any theories will need to be altered when the cause of this problem is discovered.

Suggestions:
1/Stop thinking MAGIC !
2/Measure the current
3/Measure the voltage across the device.

Cheers,
JM.
__________________
NahanniV is online now   Reply With Quote
Old 11-03-2016, 07:10   #19
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,374
Re: Magic DC

Quote:
Originally Posted by Paul Elliott View Post
No.

If the battery negative terminal is unconnected then there is no positive potential anywhere. A battery with a floating (-) terminal has absolutely no effect on the rest of the circuit.
OK. I had to think about this again. I extrapolated from other non-complete circuit situations like static electricity. Shuffle across a carpet, build up a charge on your body and touch a doorknob. There is a definite potential and flow of current but there is no complete circuit from one origin and back, + and - poles, etc. so I reasoned the same thing could happen with a battery.

So, grabbed a couple of batteries and a meter and tested it. I set two 9V alkalines side by side but not touching and put the meter leads between the + of one and the - of the other and I did read a voltage. It was tiny fractions of a volt but definitely there. Tried the same thing with one battery and the AC ground in an outlet and got the same results.

This may not be the cause of Sailorboy's problem but there is a measurable potential difference from an isolated battery terminal to some outside point.
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 11-03-2016, 07:30   #20
Registered User

Join Date: Jan 2016
Posts: 429
Re: Magic DC

BMV 600 was nearest I found. Runs on as little as 1ma apparently.

Touching the negative battery terminal with just your finger might start such a sensitive meter.

Set a multimeter to around 40V DC, hold neg. probe between your fingers and touch nothing else with your body.
Touch pos. meter probe to 12V battery pos.
I read 6V on mine with dry fingers.
On a low enough setting the meter will respond without actual contact, just proximity.
__________________
unclemack is offline   Reply With Quote
Old 11-03-2016, 07:30   #21
Registered User

Join Date: Oct 2010
Location: Abaco, Bahamas/ Western NC
Boat: Nothing large at the moment
Posts: 820
Re: Magic DC

I will second a very low capacity ground through the bonding system. Most instruments just need millivolts to get a reading.
__________________
Tingum is offline   Reply With Quote
Old 11-03-2016, 07:36   #22
Registered User
 
NahanniV's Avatar

Join Date: Mar 2011
Location: On the Boat
Boat: Finnsailer 38
Posts: 1,143
Re: Magic DC

Quote:
Originally Posted by skipmac View Post
OK. I had to think about this again. I extrapolated from other non-complete circuit situations like static electricity. Shuffle across a carpet, build up a charge on your body and touch a doorknob. There is a definite potential and flow of current but there is no complete circuit from one origin and back, + and - poles, etc. so I reasoned the same thing could happen with a battery.

So, grabbed a couple of batteries and a meter and tested it. I set two 9V alkalines side by side but not touching and put the meter leads between the + of one and the - of the other and I did read a voltage. It was tiny fractions of a volt but definitely there. Tried the same thing with one battery and the AC ground in an outlet and got the same results.

This may not be the cause of Sailorboy's problem but there is a measurable potential difference from an isolated battery terminal to some outside point.
Static electricity would not keep the device operating, unlikely that it would even light the display.

For the device to turn on and remain on there needs to be current flowing.

In your example with the two batteries, set up your meter to read current; There will no measurable sustained current until there is a circuit.

Cheers,
JM.
__________________
NahanniV is online now   Reply With Quote
Old 11-03-2016, 07:43   #23
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,310
Re: Magic DC

I think there is a big difference between a potential and actual current flow.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 11-03-2016, 07:45   #24
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,310
Re: Magic DC

Quote:
Originally Posted by skipmac View Post
OK. I had to think about this again. I extrapolated from other non-complete circuit situations like static electricity. Shuffle across a carpet, build up a charge on your body and touch a doorknob. There is a definite potential and flow of current but there is no complete circuit from one origin and back, + and - poles, etc. so I reasoned the same thing could happen with a battery.

So, grabbed a couple of batteries and a meter and tested it. I set two 9V alkalines side by side but not touching and put the meter leads between the + of one and the - of the other and I did read a voltage. It was tiny fractions of a volt but definitely there. Tried the same thing with one battery and the AC ground in an outlet and got the same results.

This may not be the cause of Sailorboy's problem but there is a measurable potential difference from an isolated battery terminal to some outside point.
But if you remove the connection to the (-) what happens?
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 11-03-2016, 07:58   #25
Registered User
 
NahanniV's Avatar

Join Date: Mar 2011
Location: On the Boat
Boat: Finnsailer 38
Posts: 1,143
Re: Magic DC

Quote:
Originally Posted by unclemack View Post
BMV 600 was nearest I found. Runs on as little as 1ma apparently.

Touching the negative battery terminal with just your finger might start such a sensitive meter.

Set a multimeter to around 40V DC, hold neg. probe between your fingers and touch nothing else with your body.
Touch pos. meter probe to 12V battery pos.
I read 6V on mine with dry fingers.
On a low enough setting the meter will respond without actual contact, just proximity.
According to the manual BMV600 needs 4mA @ 12v :
https://www.victronenergy.com/upload...S-SE-IT-PT.pdf

Try your finger experiments while measuring current to see if there is any real potential.

Cheers,
JM.
__________________
NahanniV is online now   Reply With Quote
Old 11-03-2016, 07:59   #26
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,310
Re: Magic DC

I have thought of one possible source:

I have a small solar panel that supplies the start battery. It could be possible that there could be some leakage across the isolator into the house system and a circuit could be completed via the solar panel itself.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 11-03-2016, 08:13   #27
Registered User

Join Date: Jan 2016
Posts: 429
Re: Magic DC

@ sailorboy

Curious to know how it's possible that you haven't yet solved this yourself?

You seem happy to deny the possibility of anyone else's suggestions being relevant.

Odd when the clues you've provided are almost non-existent.

Victron doesn't state whether its device's memory is non-volatile and I saw no indication of its production years - but it does appear to have been superseded.

Many early devices had memory caps and timed shut down reset by a single pulse.

My last.
__________________
unclemack is offline   Reply With Quote
Old 11-03-2016, 08:14   #28
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,374
Re: Magic DC

Quote:
Originally Posted by NahanniV View Post
Static electricity would not keep the device operating, unlikely that it would even light the display.

For the device to turn on and remain on there needs to be current flowing.

In your example with the two batteries, set up your meter to read current; There will no measurable sustained current until there is a circuit.

Cheers,
JM.
Agree, I never claimed that static electricity would operate any device, just using it as an example of potential and current without a closed, complete circuit. Of course static wouldn't keep a device operating but it could certainly fry the ICs in it.

I did say in my previous post that the voltage measured would not (I think I included a probably) activate the device but there was a definite potential measured IE more than none or zero as has been claimed.

And I did test for current. My good Fluke meter is on the boat so used the cheapo spare. Got a very brief blip of the - polarity LCD but no digits. Might have been a very small, short lived current as in micro amps but nothing significant.

For similar reasons (a very small potential difference at best) I think the idea that the monitor activates due to a circuit from the battery + to the - terminal completing through contamination on the battery case would be unlikely. The contamination would have to be extreme.
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 11-03-2016, 08:20   #29
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,374
Re: Magic DC

Quote:
Originally Posted by sailorboy1 View Post
But if you remove the connection to the (-) what happens?
Still got a reading. Smaller 0.2 mV but still showed a voltage potential.

Here's another question (or two). Don't you have an always on circuit directly to the battery and bypassing the panel for a bilge pump? Is that connected when you see the monitor come on?

What about the battery charger? Is that operating when this happens?
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 11-03-2016, 08:36   #30
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,310
Re: Magic DC

Quote:
Originally Posted by unclemack View Post
@ sailorboy

Curious to know how it's possible that you haven't yet solved this yourself?

You seem happy to deny the possibility of anyone else's suggestions being relevant.

Odd when the clues you've provided are almost non-existent.

Victron doesn't state whether its device's memory is non-volatile and I saw no indication of its production years - but it does appear to have been superseded.

Many early devices had memory caps and timed shut down reset by a single pulse.

My last.

WTF, you go onto the "special" list
__________________

__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Navtex for PC - Magic box? Moerer WIB2 switchcat Marine Electronics 5 12-12-2008 14:48
Magic Words to Use in Italy Quijote Europe & Mediterranean 24 21-07-2008 01:30
Magic Stainless Steel Cleaner otgadventures Deck hardware: Rigging, Sails & Hoisting 13 27-06-2007 08:15
The magic 50 Catamount Meets & Greets 1 04-12-2005 07:30



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:51.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.