Schematic - draft for new ignition panel

[rigspelt]

This my amateur attempt to plan rewiring a new ignition panel on the old boat. Alternator output goes direct to Battery post on starter, and house and engine batteries will be separated. Feel free to comment on wire sizes or anything else.

Warning: Seek professional advice before modifying your boat. I posted these sketches to seek advice for my boat, not give advice to others. I am not an engineer or mechanic.

UPDATED 31 Dec 2009:

[rigspelt]

Editted to clarify:

I am still trying to figure out ignition panel harness wire sizes and ignition key amperage specs. For a typical Atomic 4 setup, what are the following current draws?

1. Yellow/red wire from ignition key "S" to starter solenoid: __ amps inrush, __ amps cranking.
2. Purple wire from ignition key "I" to coil positive terminal: __ amps.
3. Ignition key spec for maximum amperage: __ amps.

Thanks.

[High Hopes]

Rigsy,

I love this stuff.

(1) The starter probably doesn’t draw more than 125 amps. That’s well over a kilowatt of power. I can turn the engine with my hands. I’m not 1 KW strong.

I don’t know what inrush means. If it is the current at the very instant the key is turned, I suspect the draw is about 800 amps – about what a modest battery can deliver (cranking amps). The starter is pretty much a dead short when it isn’t turning. Battery voltage sags. But as soon as the starter starts turning, back-EMF will cut the current way back.

Solenoid – maybe 8 amps? Just a guess. Refer to others for definitive answers on this question.

(2) Coil is 3 ohms, so that comes out to 12 volts/3 ohms = 4 amps. But with a, say, 50% dwell, this is closer to 2 amps.

* I like the way you have the blower on the house battery. I will be installing a fume detector (some day) and it will run off the house battery and turn on the blower if it trips.

* Fuse (verb) the wire to the ignition switch with the 20 amp fuse where you show a 40 now. 40 is overkill. This will eliminate the 20 amp fuse for the coil. Use #12 wire instead of #10.

* Use a 5 amp fuse for the instruments where you show a 20. The instruments are all low current, maybe 1/2 amp each which is mostly for the illumination bulb. #24 gauge wire is fine for all of the instrument wiring (assuming it is fused at 5 amps). I will use heavier wire though, just because the 24 wire seems fragile in the marine environment.

* Your ammeter circuit looks like a short to ground. Not sure what you are trying to show here. The voltage for an ammeter is read across the shunt, not to ground.

* I’m not sure about your fuel gauge wiring. Usually the tank sensor is an isolated variable resistor. I don’t see any B+ in your drawing.

* If you do not fuse the alternator circuit, use a #4 wire. It is still part of the starter circuit and what is good for the goose is good for the gander. When something goes wrong, the alternator should heat up inside – a relatively safe place to burn things. That being said, I am opting for a fuse because I intend to buy a hefty inverter and I don’t want to smoke the alternator if I get carried away plugging things in.

*You show a #14 wire coming off the ignition switch which is fused at 40 amps. This is underspec’d. It should be at least 12.

*The voltmeter will always be powered. Is this intentional?

* You show independent wiring circuits for each meter except for the blue wire which is shared. When I needed to remove my fuel gauge, I found a rat’s nest of interconnected meter wiring. This made it impossible to disconnect one meter without affecting othes. Make all gauge wires independent (not one blue wire. (I'm not sure what the blue wire does).

* You may want to loop the gauge power input to the gauge bulb directly on the back of the meters. See below. [A] goes to the ignition switch.

Nice drawing. What tool are you using?

Steve

[rigspelt]

Rigsy, I love this stuff.

Excccellent! Let's get at 'er...

I don’t know what inrush means. If it is the current at the very instant the key is turned, I suspect the draw is about 800 amps – about what a modest battery can deliver (cranking amps). The starter is pretty much a dead short when it isn’t turning. Battery voltage sags. But as soon as the starter starts turning, back-EMF will cut the current way back. Solenoid – maybe 8 amps? Just a guess. Refer to others for definitive answers on this question.

Sorry, my question was not clear. I was talking about the yellow/red wire from the ignition key switch to the S terminal on the starter solenoid. Inrush is the initiial current. I found little about the current consumption required by starter solenoids during cranking. One auto site mentioned 35 amps inrush for microseconds on turning the key to start, then I think it said about 10 amps during cranking. Seems like a lot for a solenoid that simply closes and allows the big current to flow from the battery to the starter motor through the big terminal, but... ?

(2) Coil is 3 ohms, so that comes out to 12 volts/3 ohms = 4 amps. But with a, say, 50% dwell, this is closer to 2 amps.

Good logic for determining the current draw in the purple wire from the ignition key to the (+) terminal on the coil during running. I'll try to confirm it, unless someone else can.

* Fuse (verb) the wire to the ignition switch with the 20 amp fuse where you show a 40 now. 40 is overkill. This will eliminate the 20 amp fuse for the coil. Use #12 wire instead of #10.

This is why I am trying to pin down the current draws in the ignition panel. I'm not sure why I've seen 40A fusing on the red power wire from the big battery terminal on the starter to the ignition panel. It supplies the yellow/red wire to the starter solenoid during starting (which is unprotected in my drawing except by this fuse), the purple wire to the gauges (which I think only draw 0.1-0.3 amps each, even illuminated??) and could be redundantly protected by the 10 amp fuse. That red main power supply wire to the ignition panel seems oversized at AWG#10 and 40 amps, but I need to verify the draws first.

Initially I thought that if there is a fuse on the red wire where it leaves the big terminal on the starter to supply the ignition switch, then that fuse should protect everything downstream, so additional fuses downstream were redundant. However it then occurred to me that the logic could be that if a fuse-blowing fault develops in the ignition panel gauges, then that smaller fuse in the purple gauge wire would blow first but let the engine keep running, which is much preferable on a boat. So, I've just talked myself back into fusing the purple wire to the gauges. Similarly a smaller fuse on the purple wire from the ignition switch to the coil will blow at a lower current draw than the big fuse on the red wire at the starter solenoid, protecting the primary ignition circuit at a lower maximum current draw than required to blow the bigger fuse.

* Use a 5 amp fuse for the instruments where you show a 20. The instruments are all low current, maybe 1/2 amp each which is mostly for the illumination bulb. #24 gauge wire is fine for all of the instrument wiring (assuming it is fused at 5 amps). I will use heavier wire though, just because the 24 wire seems fragile in the marine environment.

I think I show 10A for that fuse (purple wire to the gauges from the key switch). I agree that 14 seems big for the gauges. AWG#16 is minimum (for strength, as you say) and sufficient I think (for the draws).

I still have trouble understanding the logic of fusing. Some say fuse to the wire capacity, others say fuse to the device capacity. Makes sense to me that fuses should be just larger than device capacity, but electricity is slithery stuff, especially when wire runs get longer.

* Your ammeter circuit looks like a short to ground. Not sure what you are trying to show here. The voltage for an ammeter is read across the shunt, not to ground.

Correct, an ammeter shunt interrupts the wire to measure current flow in the wire. You may have been looking at an earlier version of the diagram, where I showed a shunt in the output wire from the alternator to the big battery terminal on the starter motor. I have decided to give up on that shunt and just use voltmeters in the cockpit and cabin to monitor the alternator. Low volts = low/no output, high volts = blown regulator.

* I’m not sure about your fuel gauge wiring. Usually the tank sensor is an isolated variable resistor. I don’t see any B+ in your drawing.

Good point. The gauge needs power for its light. The sender wire runs from the tank's sender to the gauge.

* If you do not fuse the alternator circuit, use a #4 wire. It is still part of the starter circuit and what is good for the goose is good for the gander. When something goes wrong, the alternator should heat up inside – a relatively safe place to burn things. That being said, I am opting for a fuse because I intend to buy a hefty inverter and I don’t want to smoke the alternator if I get carried away plugging things in.

The alternator only puts out 55 amps tops, which is why I was thinking the output wire only needs AWG#6 or maybe even 8. #4 seems oversized, since this wire will never carry more than 55 amps?

*You show a #14 wire coming off the ignition switch which is fused at 40 amps. This is underspec’d. It should be at least 12.

Which wire were you looking at?

*The voltmeter will always be powered. Is this intentional?

I am going to be using a Blue Sea distribution panel that has a switched digitnal voltmeter/ammeter. It will be off when the battery selector switch is off.

That reminds me, you and I are hot on the Blue Sea 7650 combination on/off combiner switch and ACR. The switch is nice because it is so simple (on or off). The bad part is that it means the engine start battery cannot be selectively turned off, leaving the house battery and circuit on, for example when at anchor or sailing. My habit has always been to turn off the engine start battery when the engine is not needed. The alternative is a simple on/off switch for the engine start battery, but then we are back into multiple switch settings, although still simpler than a 1-2-both-off switch.

* You show independent wiring circuits for each meter except for the blue wire which is shared. When I needed to remove my fuel gauge, I found a rat’s nest of interconnected meter wiring. This made it impossible to disconnect one meter without affecting othes. Make all gauge wires independent (not one blue wire. (I'm not sure what the blue wire does). You may want to loop the gauge power input to the gauge bulb directly on the back of the meters. See below. [A] goes to the ignition switch.

The blue wire supplies the light bulbs in each gauge.I thought about bussing each blue wire independantly, but it seemed like an acceptable compromise to daisy chaiin that wire, given I plan to bus the power and ground wires indpendently.

Nice drawing. What tool are you using?

Corel Draw. I keep changing the drawing in my original post as I learn more (or think I learn more).

[High Hopes]

Wow. So much to say. See my responses labeled with a >>>. Here we go….

Sorry, my question was not clear. I was talking about the yellow/red wire from the ignition key switch to the S terminal on the starter solenoid. Inrush is the initiial current. I found little about the current consumption required by starter solenoids during cranking. One auto site mentioned 35 amps inrush for microseconds on turning the key to start, then I think it said about 10 amps during cranking. Seems like a lot for a solenoid that simply closes and allows the big current to flow from the battery to the starter motor through the big terminal, but... ?

>>> Your suspicions are correct. Anything measured in milliseconds is transient. Fuses won’t have any time to get hot and blow. The solenoid draws current proportional to the inverse of the resistance. I suspect there is little different between the pull current and the hold current on the relay. The starter MOTOR is a different story.

This is why I am trying to pin down the current draws in the ignition panel. I'm not sure why I've seen 40A fusing on the red power wire from the big battery terminal on the starter to the ignition panel. It supplies the yellow/red wire to the starter solenoid during starting (which is unprotected in my drawing except by this fuse), the purple wire to the gauges (which I think only draw 0.1-0.3 amps each, even illuminated??) and could be redundantly protected by the 10 amp fuse. That red main power supply wire to the ignition panel seems oversized at AWG#10 and 40 amps, but I need to verify the draws first.

>>> I have seen 40 amp fuses and 20 amp fuses. This may be due to confusion with an alternator fuse which, for an old alternator that puts out 35 amps max, uses a 40 amp fuse.

Initially I thought that if there is a fuse on the red wire where it leaves the big terminal on the starter to supply the ignition switch, then that fuse should protect everything downstream, so additional fuses downstream were redundant. However it then occurred to me that the logic could be that if a fuse-blowing fault develops in the ignition panel gauges, then that smaller fuse in the purple gauge wire would blow first but let the engine keep running, which is much preferable on a boat.

>>> CORRECT!!! The idea of fusing is not only to stop smoke and fires, but to keep some systems running even when others fail. Sometimes entire separate circuits are employed, such as for bilge pumps. S o m e t i m e s …. People will have one set of circuits for the house devices and another for the engine.

I still have trouble understanding the logic of fusing. Some say fuse to the wire capacity, others say fuse to the device capacity. Makes sense to me that fuses should be just larger than device capacity, but electricity is slithery stuff, especially when wire runs get longer.

>>> Yes, fuses should be larger than the device need. A standard rule of thumb is a fuse should ne 140% of the normal operating current. The wire should be able to support this 140% current, that is all. This is true even when heavier wires are used. You still need to protect the device.
>>> Put another way, if the runs get very long, the fuse still stays the same size. Larger wires are used to help prevent a voltage loss. Current computations do not change.

That’s all for now. I have to run.

Steve

[rigspelt]

New panel cut out

I made the new panel over the weekend. The ignition key and top right three gauges are new from MMI. Gittin' there...

Update 08 March 2009: Dryfitted, now that the painting is done.

[sastanley]

nice!

Nice looking panel! I think I am going to do the same thing as you and put the tach up in the panel on deck, but put the ammeter down in the engine compartment somewhere to keep the big fat wire runs for the charging circuit short. (I currently have an aftermarket tach taped to the galley counter and oil pressure, water temp & ammeter in the cockpit) If the volt meter indicates a funky reading, then I can go down and pull the cushions to get at the motor and inspect the ammeter readings more carefully.

edit - I just saw your pics of the ignition detail with the wood block..thanks for posting stuff like that...the simple solutions make the most sense!

-Shawn

[High Hopes]

Rigsy,

Nice work. What is the material you used for the panel? It looks great.

I was wondering, seeing as how we both incorporated an ACR in our wiring, what should the voltmeter read in our systems? I decide to use a single pole, double throw switch to select which battery will be routed to the voltmeter. And I also will use the LED indicator circuit of the ACR to let me know when the unit is active. I haven't mapped this all out yet, but I think it will tell us what I need to know.

I had a house battery with a low charge, so the ACR went into lockout mode. When I connected the batteries together using the battery switch, the low battery started to charge and the voltage was raised. Then the ACR connected them. When the battery switch was turned off, the ACR kept the batteries connected.

I was thinking of mapping out all the possible scenarios. I could use some help. Do you want to do this together?

Steve

[rigspelt]

What is the material you used for the panel?

It is a very strong plastic used by a local factory that builds conveyor belts. The plastic is a bearing surface for their huge belts. I hope it will perform OK int the outdoors and with UV. We'll see.

I was wondering, seeing as how we both incorporated an ACR in our wiring, what should the voltmeter read in our systems? I decide to use a single pole, double throw switch to select which battery will be routed to the voltmeter. And I also will use the LED indicator circuit of the ACR to let me know when the unit is active. I haven't mapped this all out yet, but I think it will tell us what I need to know.

Good question. My thought is that I only want to know if the alternator is charging, and that it is not over-volting. So it does not matter to me whether it is reading voltage of the engine start battery circuit, or paralleled engine-house circuit. I have a new Blue Sea panel in the cabin that has a digital voltmeter with a switch that allows me to select circuits, but I'll have to think through the ACR issue now that you raise it.

I had a house battery with a low charge, so the ACR went into lockout mode. When I connected the batteries together using the battery switch, the low battery started to charge and the voltage was raised. Then the ACR connected them. When the battery switch was turned off, the ACR kept the batteries connected.

So the ACR is working as advertised? Sounds like the charger was on the house battery, and the ACR recognized that the battery being charged was low? Let's move this to the new thread -- see below.

I was thinking of mapping out all the possible scenarios. I could use some help. Do you want to do this together?

Steve, I agree that we should start a new thread on the ACR, since others might be interested, and clearly you and I are bumping into issues as we figure out this new technology. I started one here: http://www.moyermarine.com/forums/showthread.php?t=2877.

[Baltimore Sailor]

Digging up an old thread here, but I"ve been reading it this morning and I have couple of questons about it.

I've moved all my gauges from near the cockpit floor to a new panel on the cabin bulkhead outside (so I don't have to bend down to check them) and I have a couple of questions about Rigspelt's schematic.

First, I see he's got a 14 gauge purple wire coming off the I terminal on the alternator and running to bus B3. I also notice an E terminal on the alternator that has nothing attached to it. What are the E and I terminals on the alternator? On mine (the 35A model) there are only the main output terminal and the yellow line that connects to the positive terminal of the coil.

Secondly, where should the house power come from? Should I just run another 8 gauge red wire from the big terminal on the solenoid, or is there a better way?

[rigspelt]

First, I see he's got a 14 gauge purple wire coming off the I terminal on the alternator and running to bus B3. I also notice an E terminal on the alternator that has nothing attached to it. What are the E and I terminals on the alternator? On mine (the 35A model) there are only the main output terminal and the yellow line that connects to the positive terminal of the coil.

Thanks for another pair of eyes on that schematic. I am just about to start wiring, now that the deck and bottom painting are FINALLY coming to an end, and your questions are a good chance for me to recheck my thinking.

My understanding is that "E" refers to a ground terminal ("external ground"?) for running a ground wire from the alternator to DC ground. This wire is not required when the alternator grounds through its frame, which to my amateur understanding is a common configuration.

The "I" terminal ("ignition" or "excite") on an alternator is a terminal that can be used optionally in some configurations to excite the alternator and turn it on when the ignition circuit is hot (engine is running), by sensing from a wire running from "I" to the positive terminal of the coil. Your 35 amp alternator already has a yellow sensing wire, probably running from the positive terminal of the coil to the regulator attached to the alternator. See my old Motorola alternator below, with the regulator opened to expose the wires:
Yellow - exciter wire to (+) coil.
Green - field sensor (alternator to regulator).
Black - regulator to ground on alternator casing.
Red - I used to know. Maybe allows the regulator to sense the battery.

I drafted the schematic you refer to (November 8/08 version) for my new 55 amp API alternator from MMI. See http://www.moyermarine.com/forums/showthread.php?t=2781 for comments about the names of the terminals, in particular the instructions Don attached to his post. He notes that the purple 14 gauge wire from the "I" ("ignition sensing") terminal to the positive post of the coil (which is listed in the instructions) is optional, since that 55 amp alternator self-excites.

[rigspelt]

Secondly, where should the house power come from? Should I just run another 8 gauge red wire from the big terminal on the solenoid, or is there a better way?

I can't comment on this question without knowing how your boat is wired to deal with house power. Do you have one of the older configurations using an ammeter on the panel, with house power secondarily coming off the panel ammeter?

My draft schematic for my charging system is described in a different post here: http://www.moyermarine.com/forums/showthread.php?t=2695 Notice that in my case, I am abandoning the old ammeter circuit and feeding the house panel directly from a dedicated house battery.

[Baltimore Sailor]

I can't comment on this question without knowing how your boat is wired to deal with house power. Do you have one of the older configurations using an ammeter on the panel, with house power secondarily coming off the panel ammeter?

My draft schematic for my charging system is described in a different post here: http://www.moyermarine.com/forums/ed...st&postid=9882. Notice that in my case, I am abandoning the old ammeter circuit and feeding the house panel directly from a dedicated house battery.

In my case, since I'm moving everything from where it was to a new location where everything is within a foot of everything else, I'm basically doing a complete rewiring, and I'm planning on leaving the ammeter out of the circuit entirely. Don and others have convinced me that it's not a necessary requirement for monitoring the health of the system, so in the interests of the KISS principle I'm leaving it out.

So in that case, what would be the KISS-most way of getting house current to that panel? Everything from ignition key to gauges to the house breaker panel are going to be right next to each other.

[Baltimore Sailor]

Thanks for another pair of eyes on that schematic. I am just about to start wiring, now that the deck and bottom painting are FINALLY coming to an end, and your questions are a good chance for me to recheck my thinking.

My understanding is that "E" refers to a ground terminal ("external ground"?) for running a ground wire from the alternator to DC ground. This wire is not required when the alternator grounds through its frame, which to my amateur understanding is a common configuration.

The "I" terminal ("ignition" or "excite") on an alternator is a terminal that can be used optionally in some configurations to excite the alternator and turn it on when the ignition circuit is hot (engine is running), by sensing from a wire running from "I" to the positive terminal of the coil. Your 35 amp alternator already has a yellow sensing wire, probably running from the positive terminal of the coil to the regulator attached to the alternator. See my old Motorola alternator below, with the regulator opened to expose the wires:
Yellow - exciter wire to (+) coil.
Green - field sensor (alternator to regulator).
Black - regulator to ground on alternator casing.
Red - I used to know. Maybe allows the regulator to sense the battery.

I drafted the schematic you refer to (November 8/08 version) for my new 55 amp API alternator from MMI. See http://www.moyermarine.com/forums/showthread.php?t=2781 for comments about the names of the terminals, in particular the instructions Don attached to his post. He notes that the purple 14 gauge wire from the "I" ("ignition sensing") terminal to the positive post of the coil (which is listed in the instructions) is optional, since that 55 amp alternator self-excites.

I'm attaching a photo of my 35A alternator. You can clearly see the exciter wire and orange output wire in the picture. In your schematic you show the exciter wire connected to Bus B3. In that setup, is the current flow from the B terminal on the solenoid up to the B terminal on the ignition key and down to Bus B3 via the purple wire off the I terminal and thence to the I terminal on the alternator AND the positive terminal of the coil?

It seems to me that the key to the entire circuit is the red 8 gauge wire from the big terminal on the solenoid (where the orange wire from the alternator is connected) up to the BATT terminal on the ignition key switch, and from there the current gets distrubuted to wherever. Is that correct?

[rigspelt]

what would be the KISS-most way of getting house current to that panel?

Why do you need house power in the ignition panel?