Instruments turn off when starting engine having added extra battery,

[Sandy]

The circuit as in #66 can be resolved using Kirchhoff's and Ohm's Laws. Gustav Kirchhoff did his research in the 1840's and published his findings in1845 (he was born in what is now Kaliningrad). Ohm's Law is from 1827 although he followed on from work done by Fourier and Cavendish. They are both old stuff from the dawn of discovering electricity and pre-date Maxwell's equations (I had a girlfriend at university who is a related to J.C.Maxwell).

I am not convinced that #66 is the same thing as the OP has. The OP has a VSR and we all know it will split the two circuits once the voltage falls below a certain level. Hopefully, the OP has the VSR set up that when he attempts to start the engine the house circuit is isolated.

My post #86 wonders if the OP has wired up the VSR in the same way as he had before adding the new batteries.

Fourier, that strikes fear into my heart trying to work out what was data in a very noisy satellite signal at uni.

More a fan of Gavin Maxwell, Ring of Bright Water fame.

 

[AngusMcDoon]

I am not convinced that #66 is the same thing as the OP has.

No, I don't know either.

Fourier, that strikes fear into my heart trying to work out what was data in a very noisy satellite signal at uni.

It surprises me how early Fourier did his work considering how complex it is compared to something like Ohm's Law which even I could have probably figured out. Fourier's stuff is like relativity - what sort of brain did it take to come up with that idea from nothing?

 

[billskip]

It surprises me how early Fourier did his work considering how complex it is compared to something like Ohm's Law which even I could have probably figured out. Fourier's stuff is like relativity - what sort of brain did it take to come up with that idea from nothing?

Good job he didn't air his views on this forum......

 

[Sandy]

It surprises me how early Fourier did his work considering how complex it is compared to something like Ohm's Law which even I could have probably figured out. Fourier's stuff is like relativity - what sort of brain did it take to come up with that idea from nothing?

A much better brain than mine!

 

[Iliade]

To the o/p:
Run a temporary (preferably fused) negative from the negative house battery terminal to the negative feed of the instruments, start your engine and observe the results.
If still an issue, disconnect the positive terminal(s) from the house batteries, run a direct temporary positive feed, again fused would be a good idea, and observe the results.

Report back...

I stand by my guns, if the common negative is the only common element in the circuit, then that is most likely to be the cause of your issue. Yes, there could be all manner of weird and wonderful things happening with transient effects, but start with the simple and work up.

Sources of Transients in Electrical Circuits​

There are several sources causing transients in electrical circuits. Sources can be either internal or external to the circuit. The table below outlines these sources.

Internal sources	External Sources
Capacitor switching The operation of power semiconductor switches Internal faults Electrostatic discharge Relay operation Circuit breaker or switchgear operation Load removal or addition Arcing	Lightning External load removal or connection Opening or closing of switchgears in energized systems Switching of capacitor banks Tap changing transformers Loose connections at the utility end External faults Human errors Short circuits caused by animals Bad weather conditions Neighboring circuits

 

[PaulRainbow]

I nominate this thread for the most ridiculous thread on PBO so far this year.

 

[PaulRainbow]

To the o/p:
Run a temporary (preferably fused) negative from the negative house battery terminal to the negative feed of the instruments, start your engine and observe the results.

He already has a negative from the house bank to the instruments.

If still an issue, disconnect the positive terminal(s) from the house batteries, run a direct temporary positive feed, again fused would be a good idea, and observe the results.

He already has this too.

Report back...

I stand by my guns, if the common negative is the only common element in the circuit, then that is most likely to be the cause of your issue. Yes, there could be all manner of weird and wonderful things happening with transient effects, but start with the simple and work up.

If the common negative is the only "common" element, with no continuity between the positives of each system, how can that be the cause of the issue. The issue being voltage drop affecting the plotter.

Starting simple is a good idea, like disconnecting the VSR negative to confirm whether or not the solar charging is closing and paralleling the positives.

 

[billskip]

how can that be the cause of the issue.

There is no argument about what could cause the issue, it's possible that you are correct with your guess
In post 12 (vsr closed) is the cause.

This further discussion (argument.?) is about you saying bedouin is ridiculous with his theory. bedouin's possible reason for
volt drop (I prefer to say reduced potential difference) was stated as nonsense by you and Refuler, which in fact has been proved to be possible, therefore you are wrong in your 'argument ' .

 

[billskip]

I nominate this thread for the most ridiculous thread on PBO so far this year.

Please don't reduce yourself to this Paul, you post some excellent stuff on here.

 

[AngusMcDoon]

This further discussion (argument.?) is about you saying bedouin is ridiculous with his theory. bedouin's possible reason for
volt drop (I prefer to say reduced potential difference) was stated as nonsense by you and Refuler, which in fact has been proved to be possible, therefore you are wrong in your 'argument ' .

The 'Bedouin theory' is analogous to a known problem in circuit board design that have multiple different power rails, some hefty consumers somewhere and only a single ground plane. Although the different power rails are not connected a high current demand on one power rail can give a potential difference drop on another if the component locations are not designed well. It's caused by a common ground path, like the circuit in #66. Some devices like modems can take Amps for milliseconds and this can cause devices on other power rails to brown out. Solutions are separate ground planes connected only at the power supplies, but this adds layers to the PCB and increases cost, or optimise the layout to prevent common ground paths.

It can be frustrating when it occurs as it's not intuitive why it's happening and can cause many 'WTF' comments.

 

[billskip]

The 'Bedouin theory' is analogous to a known problem in circuit board design that have multiple different power rails, some hefty consumers somewhere and only a single ground plane. Although the different power rails are not connected a high current demand on one power rail can give a potential difference drop on another if the component locations are not designed well. It's caused by a common ground path, like the circuit in #66. Some devices like modems can take Amps for milliseconds and this can cause devices on other power rails to brown out. Solutions are separate ground planes connected only at the power supplies, but this adds layers to the PCB and increases cost, or optimise the layout to prevent common ground paths.

It can be frustrating when it occurs as it's not intuitive why it's happening and can cause many 'WTF' comments.

Excellent explanatory post..
(I worked for a pcb manufacturer)
I fully understand what you say.

 

[billskip]

The 'Bedouin theory'

I like that....
50 odd years ago a company had a problem with an industrial machine randomly de energising, this was one specific model out of many.
Muggins here was volunteered to fix it. Well trying to recreate the fault in the factory proved near impossible,then it happened..wtf ..
After much practical and theory arguments with myself I concluded this was not random...Now bare in mind this was at a time many components were being changed to metric and "computer" design specifications changing from imperial " rule of thumb " ....the old machines in the field no problem...the new 'metric ' machine
ffs.....Well it turned out to be exactly bedouin theory.
The 24v latched start relay the common -ve was going high when 4 components excited simultaneously....This wasn't a reduction in the +24v supply, it was an alteration of the PD across the relay because the 'spike' on the common - ve.....reduced the PD to critical level.

The Bedouin Theory.

 

[AngusMcDoon]

The Bedouin Theory.

It shall henceforth and forevermore be known as that.

 

[Refueler]

There is no argument about what could cause the issue, it's possible that you are correct with your guess
In post 12 (vsr closed) is the cause.

This further discussion (argument.?) is about you saying bedouin is ridiculous with his theory. bedouin's possible reason for
volt drop (I prefer to say reduced potential difference) was stated as nonsense by you and Refuler, which in fact has been proved to be possible, therefore you are wrong in your 'argument ' .

I was driving for 10 hours yesterday (5hrs each way) Ventspils - Kaunas ... viewing Winter Park Homes for my Mother In Law who has Alzheimers - need to look after her .....

Mind kept coming back and trying to figure out how having -ve common with no +ve common - could result in any change to domestic when starter circuit is energised.

On my boats - it does not happen as all -ve's go back to the respective battery terminal - not to a -ve busbar. I appreciate that means extra cable and a multi connector on battery post.

I was musing whether if a busbar remote from the batterys was used - as many boats do .... then common -ve cable - especially if bolted to engine block could be carrying the return of starter and domestic.

Before people start firing broadsides - note this was while driving a boring 170km long road from Kaunas to Klaipeda .... it was the only way I could imagine starter circuit could cause any effect on domestic .. even then I have doubts.

I think the argument is coming from whether the effects are FLOW of electricity or static charge ?

Again - just thoughts while cruising along bored !!

 

[billskip]

I was driving for 10 hours yesterday (5hrs each way) Ventspils - Kaunas ... viewing Winter Park Homes for my Mother In Law who has Alzheimers - need to look after her .....

Mind kept coming back and trying to figure out how having -ve common with no +ve common - could result in any change to domestic when starter circuit is energised.

On my boats - it does not happen as all -ve's go back to the respective battery terminal - not to a -ve busbar. I appreciate that means extra cable and a multi connector on battery post.

I was musing whether if a busbar remote from the batterys was used - as many boats do .... then common -ve cable - especially if bolted to engine block could be carrying the return of starter and domestic.

Before people start firing broadsides - note this was while driving a boring 170km long road from Kaunas to Klaipeda .... it was the only way I could imagine starter circuit could cause any effect on domestic .. even then I have doubts.

I think the argument is coming from whether the effects are FLOW of electricity or static charge ?

Again - just thoughts while cruising along bored !!

Thread Drift is part of the workings on ywb forums. The op's problem is possible simply an error.
However that said, bedouin's post could have simply been ignored, but the reaction wasn't to ignore it it was challenged in a way imho to belittle bedouin and suggest he was ridiculous.
The Bedouin theory is possibley not the cause of the op's problem, but to challenged bedouin in the manner that Paul did was not only a challenge to bedouin it was a challenge to all that agreed with bedouin which bedouin was proved to be correct with his theory.
If you or Paul continue to disagree with bedouin that's your choice, but accept that some may disagree with your choice.
What I believe bedouin said is possible under unique conditions and the +ve do not have to be connected as proved by Angus post and my personal experience of fault conditions.

 

[bedouin]

I was driving for 10 hours yesterday (5hrs each way) Ventspils - Kaunas ... viewing Winter Park Homes for my Mother In Law who has Alzheimers - need to look after her .....

Mind kept coming back and trying to figure out how having -ve common with no +ve common - could result in any change to domestic when starter circuit is energised.

On my boats - it does not happen as all -ve's go back to the respective battery terminal - not to a -ve busbar. I appreciate that means extra cable and a multi connector on battery post.

I was musing whether if a busbar remote from the batterys was used - as many boats do .... then common -ve cable - especially if bolted to engine block could be carrying the return of starter and domestic.

Before people start firing broadsides - note this was while driving a boring 170km long road from Kaunas to Klaipeda .... it was the only way I could imagine starter circuit could cause any effect on domestic .. even then I have doubts.

I think the argument is coming from whether the effects are FLOW of electricity or static charge ?

Again - just thoughts while cruising along bored !!

In my case the boat originally had a 1-both-2 switch that of course has separate positive supplies to the switch but a single negative that connects both batteries and goes to the engine that acts as a common ground. When it was set up there was no idea of a separate domestic circuit but just two batteries that could both power the same single circuit that combines starting and domestic duties.

In such a set up it is a very simple task to add a separate domestic switch from battery 2 - leaving the 1-both-2 acting as the engine switch and the "emergency" parallel switch that can connect both banks together. However separating the -ve supply would be more complex. It would require a separate -ve feed to a common busbar and being careful to separate negatives at the switch and engine start panels that are side by side.

So I am left with a length of negative that runs from the rear battery to the front battery and thence to the engine that carries all -ve current for both batteries/circuit. In my case that cable is somewhat undersized by modern standards. That is the cause of the voltage drop (or potential difference for those who want to use the correct terminology).

That wire has a resistance of say 2-3mOhms - not a great deal - but on initial contact the in rush current to the starter is probably getting close to 1000A so that 2-3mOhm resistance suddenly as a potential difference of 2-3 volts across it (Ohms Law). Because that is common to both circuits that voltage drop affects both circuits (that's Kirchhoff's law) so I can and do see a significant voltage drop to the instruments on the domestic circuit causing them either to give low voltage alarms or reset themselves depending.

A couple of seconds later (once the starter has the engine turning over) that current draw probably drops to around 100-150A and the domestic circuit sees pretty close to the full voltage from the domestic.

BTW the moment you turn the engine switch the voltage across the terminals of the starter motor is probably only 5-6V all the remaining going in the internal resistance of the battery (maybe 10-20mOhms) and resistance in the wiring.

This thread has made me realise that a simple fix to this would be to separate the -ve feed from the two batteries - provided they both go to the same common distribution point I don't need to bother about separating other parts of the negative.

 

[billskip]

That is the cause of the voltage drop (or potential difference for those who want to use the correct terminology).

It's not so much the correct terminology (which it possible isn't anyway)I like to think it is a separate analysis for my simple mind.

For example voltage drop would suggest to me the +12v is being reduced to say + 10v due to excessive demand.

With your explanation the +12v is remaining constant, but (albeit momentarily ), the -0v is bing lifted above -0v to +2v therefore the potential difference becomes +10v
which would be then termed a volts drop across the device.

It is my guess and I say "guess" this is the reason "saying volts drop" that confused Paul into the misunderstanding of you post, Paul maybe had on his mind that the +12v on the house battery could not drop (and he is basically correct) without demand, what he seems to fail to understand is it is the common -0v being "lifted" to create a lower PD across the house battery.
That's what I think anyway....

 

[bedouin]

Ah - but then it is incorrect to talk of "voltage drop" of the battery since batteries don't have voltages they have EMFs

I think the term voltage drop is pretty much universally used in relation to losses in boat wiring - certainly there are any number of "voltage drop" calculators out there to help size wire for long runs so I am sure more people understand than term rather than the correct PD. I just over-estimated Paul's (and others) understanding of basic electricity and their ability to read

 

[AngusMcDoon]

Mind kept coming back and trying to figure out how having -ve common with no +ve common - could result in any change to domestic when starter circuit is energised.

It only happens in the very specific case of a section of the negative line being shared by both circuits as in #66. We all agree that the OP, along with most boats, may not be wired like that, in which case it's not the problem. To explain it an understanding of Kirchhoff's laws is required, not just Ohm's law. These laws will probably not be known to most people, even other non electrical/electronic engineers. The effect seen is not intuitive & catches out electronic engineers sometimes as the examples from billskip & I show. Kirchhoff's laws cover both current flow at a point & voltage around a loop. Solving circuits with them by hand is tedious as you end up with a lot of simultaneous equations. Now it's all done by circuit design software, but circuit designers still need to be aware of it.

 

[billskip]

Ah - but then it is incorrect to talk of "voltage drop" of the battery since batteries don't have voltages they have EMFs

I think the term voltage drop is pretty much universally used in relation to losses in boat wiring - certainly there are any number of "voltage drop" calculators out there to help size wire for long runs so I am sure more people understand than term rather than the correct PD. I just over-estimated Paul's (and others) understanding of basic electricity and their ability to read

I'm trying to keep it simple, and not making the same mistake as you by overestimating........