MauiPunter

Electrical Issues

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I am having a couple of electrical issues which may or may not be related and trying to resolve.  

1) When out sailing with the autopilot/chartplotter/radar running, if we start the engine, the chartplotter turns off.  I am guessing this is from low voltage from starting. The chart plotter is supposed to be running off of house batteries which are supposed to be isolated from start batteries, but clearly, they aren't for some reason.  Im thinking of installing a DUAL CIRCUIT PLUS which is supposed to provide total separation between the two circuits (START / HOUSE).  Have any of you installed this kind of power switch in your boat?  These OFF-1-2-1/2 type switches seem kind of a bad idea, but are so common on boats.

2) When out sailing with the autopilot/chartplotter/radar running, and we flush one of the electric toilets the autopilot goes haywire and loses its tracking, but then regains its tracking after the flush has completed.  I'm not sure if this is also related to a low voltage situation.  It seems the house batteries aren't keeping up with usage possibly?  I have three large house batteries (4D Deep cycle). Do I need an additional house battery to keep up with demand? What is the best way to debug this?

3) Oddly, #2 will happen even when the engine is running which is supposed to supply full power to the DC circuit, recharging the batteries.  I'm not sure if we need a larger alternator, but doesn't make sense for #2 to happen while engine is running at a minimum.  So, it may be another issue I am not aware of.  Thoughts?

 

 

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1)     Electronics can also shut down from a voltage SPIKE when alternator starts outputting as engine starts. Can't tell because we don't know what your primary wiring schematic is.

2)  Voltage drop. Batts are not keeping up with high amp demand.

Seems like batt bank is tired, but need details on wiring to go further. First test would be using a quality meter that will record min/max voltage readings while replicating the problems.

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1) I didn't consider the spike as a cause.  I will look into that.  Thanks.

2/3) House/Start batteries are NEW as of 2017.  So, perhaps I do need an additional battery for the bank.  I'm running 12v circuits in my boat.  Is 11-13 the normal range I should see on the meter?  What is the threshold on the low voltage under load?  11v?

3) Would a larger alternator possibly resolve this for when the engine running?

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1. If you have a 1-2-Both switch then your start batteries are only isolated from the domestic in so much as you run off whatever batteries you set it to. So the loads will always be combined, whatever battery you have selected will be used for the engine & the domestic. 
Rather than spend lots, just get yourself a good quality voltage sensing relay to link the two banks together, making sure you that fuse the link between the batteries at the current rating of the relay. You'll also need to remove the 1-2-both switch and replace with individuals. Tons of wiring diagrams online you can search for. 

2. Voltage drop, or maybe the pump is causing interference, they generate an electromagnetic field when running, so if they're close to your autopilots compass that might explain it. 

3. Makes it more likely that its interference from the pump. if so you need to either move the pump or the autopilots compass. 

 

You should never see 11v on your batteries, if you do then they're fucked already. 11v means they're well past 100% discharged. If you only discharge to 50% you should see between 12.2 and 12.7 at rest. 

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3 hours ago, MauiPunter said:

I am having a couple of electrical issues which may or may not be related and trying to resolve.  

1) When out sailing with the autopilot/chartplotter/radar running, if we start the engine, the chartplotter turns off.  I am guessing this is from low voltage from starting. The chart plotter is supposed to be running off of house batteries which are supposed to be isolated from start batteries, but clearly, they aren't for some reason.  Im thinking of installing a DUAL CIRCUIT PLUS which is supposed to provide total separation between the two circuits (START / HOUSE).  Have any of you installed this kind of power switch in your boat?  These OFF-1-2-1/2 type switches seem kind of a bad idea, but are so common on boats.

2) When out sailing with the autopilot/chartplotter/radar running, and we flush one of the electric toilets the autopilot goes haywire and loses its tracking, but then regains its tracking after the flush has completed.  I'm not sure if this is also related to a low voltage situation.  It seems the house batteries aren't keeping up with usage possibly?  I have three large house batteries (4D Deep cycle). Do I need an additional house battery to keep up with demand? What is the best way to debug this?

3) Oddly, #2 will happen even when the engine is running which is supposed to supply full power to the DC circuit, recharging the batteries.  I'm not sure if we need a larger alternator, but doesn't make sense for #2 to happen while engine is running at a minimum.  So, it may be another issue I am not aware of.  Thoughts?

 

 

First one happens all the time.  Nothing wrong with a 3 way switch. Simple, manual and effective.  Bad idea if you've got idiots/guests on board all the time, but if you're mostly alone they're fine.   I like ACRs, they're not expensive and a simple solution to the problem, they have a delay in making connection after charging voltage is detected so in most cases that will solve it on it's own.  I like a (small) dedicated battery for nav/AP/VHF ONLY mounted near the helm with an Echo charger or similar, but that's not realistic in many smaller boats or sailboats.  Quick step to check the plotter connection if you don't know much about the wiring and just want a quick answer: pull the ground wire off your start bank.  If the plotter shuts down you know it's running off that, and that alone.  If it stays on, reconnect the ground on start, disconnected the ground on house.  If it doesn't shut down, your batteries are not isolated, and it is taking power from either, so then you need to explore isolating the banks, and further work will be needed.  

2.  That is often either the motor, or the power wire to the toilet causing the problem.  Crude test: hit something else located at the aft end of the boat, high draw that's on the same bank, if it fucks up it's a power issue.  If it doesn't(and it probably won't) it's interference.  I'd say 7/10 "my AP randomly changes course and then fixes itself" problems are caused by close proximity to power wires.  2/10 user error  undersized pump for the steering, bad wiring etc, sensor mounted in a stupid location.  1/10 there's an actual problem with the sensor or batteries.

If it's interference go get a magnetic field measuring app on you smartphone f you've got one, and start testing, if the sensor is easier to move, test for a low interference location, if the wiring is easier to move, test to get a baseline, test again for level when toilet flushes, move wires away until the levels stay close to the baseline, then sea trial.   Generally I like to mount AP sensors on the centerline, fairly low with no power wires within 36", no big ones within 48"(thruster etc).  Crude fix if you don't have an iphone, move the wires and keep testing until it doesn't screw up.

 

 

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^^^ on #2. Forgot about that, and more probable if system works after running head. Also check amp/voltage draws at motor - if wiring is bad (for whatever reason) motor will draw more amps to make up for voltage being low.

Still need a general schematic of your primary wiring to go further.

Small batts in line in power supplies to electronics used to be common, they sit in circuit un-loaded until voltage drops, then provide the boost needed to keep v constant. Think small motorcycle batt size. Or a power conditioner (12 - 12 power supply) boost low incoming up to standard, but this entails drawing more amps, so wire gauge must be up to added draw to perform.

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I'm with the others on the pump motor for #2.  Probably creating a lot of EM noise, and your autopilot does not like it.

Also, I see what you did there making that issue #2. . .

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A simple and generally good thing to do, would be to go through the power connections and make sure they are clean and tight, and then coat with corrosion protection. 

Start at batteries and work towards the affected units.

You can also use a Voltmeter to check the voltage at the plotter/pilot and see if it's significantly less than at the batteries. 

You would expect a few tenths of a volt drop. You don't expect a few volts drop. If you find that, then you either have bad connections, or undersized wire (fire hazard) 

 

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1 hour ago, LionessRacing said:

You would expect a few tenths of a volt drop. You don't expect a few volts drop. If you find that, then you either have bad connections, or undersized wire (fire hazard) 

first thing I thought of with #2 is the wire is undersized for the load.

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Thanks for all the suggestions and pointers.  I have to dig into this more.   Also, Longy, I dont have a wiring diagram yet but will try to create one based on what I find in tracing this down.  

I have picked up a new battery switch that provides separation, and has three modes:   OFF - ON (ISOLATED) - ON (COMBINED).  

s-l300.jpg

 

Also, I borrowed an EM meter which should help me check if there is any interference around the electronic compass.  I do believe my wires are up to snuff for the volt/amps but will double check all the runs make sure there is no funny business along the way.

 

Cheers!

 

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On 5/21/2018 at 8:04 PM, jgbrown said:

First one happens all the time.  Nothing wrong with a 3 way switch. Simple, manual and effective.  Bad idea if you've got idiots/guests on board all the time, but if you're mostly alone they're fine.   I like ACRs, they're not expensive and a simple solution to the problem, they have a delay in making connection after charging voltage is detected so in most cases that will solve it on it's own.  I like a (small) dedicated battery for nav/AP/VHF ONLY mounted near the helm with an Echo charger or similar, but that's not realistic in many smaller boats or sailboats.  Quick step to check the plotter connection if you don't know much about the wiring and just want a quick answer: pull the ground wire off your start bank.  If the plotter shuts down you know it's running off that, and that alone.  If it stays on, reconnect the ground on start, disconnected the ground on house.  If it doesn't shut down, your batteries are not isolated, and it is taking power from either, so then you need to explore isolating the banks, and further work will be needed.  

Pretty sure you can get those switches with a lock on them, if you have a regular infestation of idiots on your boat.

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22 hours ago, MauiPunter said:

Thanks for all the suggestions and pointers.  I have to dig into this more.   Also, Longy, I dont have a wiring diagram yet but will try to create one based on what I find in tracing this down.  

I have picked up a new battery switch that provides separation, and has three modes:   OFF - ON (ISOLATED) - ON (COMBINED).  

s-l300.jpg

 

Also, I borrowed an EM meter which should help me check if there is any interference around the electronic compass.  I do believe my wires are up to snuff for the volt/amps but will double check all the runs make sure there is no funny business along the way.

 

Cheers!

 

Big fan of those switches. I also add an On-Off switch between the switch you show and the starter. Allow me to positively isolate engine start voltage when performing maintenance while keeping DC power to lights, fans, etc. I like my fingers. 

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Big, red, switch with words on it... "Hey skipper, is it OK to turn this knob I found way under here?"

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You can also get this kind of issue due to a bad ground - high current from starting passing through a bad ground compresses the voltage to the electronics. That being said,the batteries look fucked to me based on the info above.

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On 5/23/2018 at 12:45 AM, MauiPunter said:

Thanks for all the suggestions and pointers.  I have to dig into this more.   Also, Longy, I dont have a wiring diagram yet but will try to create one based on what I find in tracing this down.  

I have picked up a new battery switch that provides separation, and has three modes:   OFF - ON (ISOLATED) - ON (COMBINED).  

s-l300.jpg

 

Also, I borrowed an EM meter which should help me check if there is any interference around the electronic compass.  I do believe my wires are up to snuff for the volt/amps but will double check all the runs make sure there is no funny business along the way.

 

Cheers!

 

Good switch, simple and works...

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Start with a voltmeter on the device showing bad behavior, then do whatever it is that causes the problem. See if the voltage drops a lot (more than a volt) 

Sounds to me like you got a power dropping down while under load sort of thing. That voltmeter will be your friend to finding out why.  

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