Automatic Power Selector... why?

So I have been doing more hunting around the boat recently trying to identify parts of the electrical system that I've been ignoring for the past 8 years. Here is an example that has me stumped.

This Automatic Power selector is installed on the boat and feeds the house circuit that, controls the power to the solenoids that connect the various high loads to their respective batteries. This device is really unknown to me but appears to be used primarily with ZF Microcommand controls. I can understand its application for that, as it helps to ensure that if you lose power in one battery bank, it will quickly switch to the secondary bank so that you still have control over your engine.
ZF Automatic Power Selector

The thing is, I don't have electronic controls on my engine. They are cable. The throttle is a cable control. So the only reason I can see for having this is to be able to power the solenoids that keep the engine connected to its battery, the thrusters to their bank, and the House bank to the house battery. It is setup with Source #1 as the House, and Source #2 is the start battery. I don't have a problem with this being there other than it takes up extra space on the DC bulkhead AND it looses about .6v. The output from the Load is about .6v less than the input.

So my question... is this normal behavior for these things? If so, that seem odd. If not, is it a sign that this thing is failing? I would be tempted to just get rid of it. However, I'm going to swap the house agms for lithium and I suppose there is the very small chance that their BMS could shut them down, then it would be nice to have that circuit fed by another bank.

I would get rid of it for 2 reasons;

1) It drops half a volt which is way too high for a switch.
2) The max load is 70 amps. Seventy amps? You must be joking. Probably another reason it drops half a volt.

dhays said:

So I have been doing more hunting around the boat recently trying to identify parts of the electrical system that I've been ignoring for the past 8 years. Here is an example that has me stumped.

This Automatic Power selector is installed on the boat and feeds the house circuit that, controls the power to the solenoids that connect the various high loads to their respective batteries. This device is really unknown to me but appears to be used primarily with ZF Microcommand controls. I can understand its application for that, as it helps to ensure that if you lose power in one battery bank, it will quickly switch to the secondary bank so that you still have control over your engine.
ZF Automatic Power Selector
View attachment 158691
The thing is, I don't have electronic controls on my engine. They are cable. The throttle is a cable control. So the only reason I can see for having this is to be able to power the solenoids that keep the engine connected to its battery, the thrusters to their bank, and the House bank to the house battery. It is setup with Source #1 as the House, and Source #2 is the start battery. I don't have a problem with this being there other than it takes up extra space on the DC bulkhead AND it looses about .6v. The output from the Load is about .6v less than the input.

So my question... is this normal behavior for these things? If so, that seem odd. If not, is it a sign that this thing is failing? I would be tempted to just get rid of it. However, I'm going to swap the house agms for lithium and I suppose there is the very small chance that their BMS could shut them down, then it would be nice to have that circuit fed by another bank.

Click to expand...

Find out what it powers. Disconnect the load side and see what doesn't work.

What do your engines require to run? An electric fuel solenoid in an energize to run system? Any electronic engine controls, not throttle and shift.

If it drops half a volt at 70 amps it is dissipating 35 watts. Thirty five watts on some little contacts will get really hot.

The Automatic Power Selector likely does not feed the house circuit, nor are the thrusters likely connected to it as a load.

It does what its name implies, selects the higher of any two connected power sources (they don't have to be batteries) to power whatever you connect to it as a load. The load is often just the ZF Microcommander controls, nothing else, unless you also deem it critical (your VHF?) by connecting it as a load.

The controls for shift and throttle are what most people would consider critical. As a result, it would be nice if they had a back up power supply. This device does that by selecting the highest voltage of either of the two power supplies (batteries) that are connected to it, thats it. Nothing more. The batteries themselves are never connected together.
This way the engine controls hopefully have a separate, secondary, workable voltage source.

Even though your engine's throttle and your gear's shift selection is done by cable at the engine/gears, the fact that you have this device tells me that these cables only go to a box about 10" square and 8" thick, likely in the ER, which is only wired to your controls at the helm(s). Inside the box are the motors, cable connection hardware and controls that actually pull/push the cable. You are almost "fly by wire" as your actions at the helm only produce an electrical signal. No control cable is pushed by the helm levers.

This device is a diode based selector and as a result the voltage drop through the device is said to be 0.35 to 0.45 Volts depending on load. If you are measuring 0.6 volts, make sure no voltage drop from the conductors is included.

The device, although branded ZF is likely made by Newmar out of Newport Beach CA. which uses as a motto "A Mission Critical Electronics Brand." How fitting!

Here is a link to their info. on the product. Doesn't it look similar? Stickers are easy to make.
Newmar generally mades good stuff, albeit you won't find it on your phone.


If it was me, I would confirm what powers it (both feeds) and what are the loads. Once I'm happy with that, I would keep it as it provides a useful service.

It may also be powering the engine electronics. I assume you have a common rail engine, it will stop instantly without 12V power.

Ignore everything I wrote, the cables threw me.

Indeed there is a ZF Mathers control box that takes cable inputs and uses servo motors to do cable outputs. Only 3 grand each.

....poor post

luna said:

The Automatic Power Selector likely does not feed the house circuit, nor are the thrusters likely connected to it as a load.

It does what its name implies, selects the higher of any two connected power sources (they don't have to be batteries) to power whatever you connect to it as a load. The load is often just the ZF Microcommander controls, nothing else, unless you also deem it critical (your VHF?) by connecting it as a load.

The controls for shift and throttle are what most people would consider critical. As a result, it would be nice if they had a back up power supply. This device does that by selecting the highest voltage of either of the two power supplies (batteries) that are connected to it, thats it. Nothing more. The batteries themselves are never connected together.
This way the engine controls hopefully have a separate, secondary, workable voltage source.

Even though your engine's throttle and your gear's shift selection is done by cable at the engine/gears, the fact that you have this device tells me that these cables only go to a box about 10" square and 8" thick, likely in the ER, which is only wired to your controls at the helm(s). Inside the box are the motors, cable connection hardware and controls that actually pull/push the cable. You are almost "fly by wire" as your actions at the helm only produce an electrical signal. No control cable is pushed by the helm levers.

This device is a diode based selector and as a result the voltage drop through the device is said to be 0.35 to 0.45 Volts depending on load. If you are measuring 0.6 volts, make sure no voltage drop from the conductors is included.

The device, although branded ZF is likely made by Newmar out of Newport Beach CA. which uses as a motto "A Mission Critical Electronics Brand." How fitting!

Here is a link to their info. on the product. Doesn't it look similar? Stickers are easy to make.
Newmar generally mades good stuff, albeit you won't find it on your phone.

Automatic Power Selector | 12V DC | 24V DC | 48V DC | 70 Amps to 160 Amps | Mobile Mount | Newmar Powering the Network

Automatic Power Selector by Newmar Powering the Network: 12V DC, 24V DC and 48V DC, 70 Amps to 160 Amps. The Automatic Power Selector (APS) is a solid state device which enables installation of a seamless, redundant power system for critical electronic loads. It selects the higher voltage of two...

www.poweringthenetwork.com

If it was me, I would confirm what powers it (both feeds) and what are the loads. Once I'm happy with that, I would keep it as it provides a useful service.

Click to expand...

I’ll second all of the above.

Engine control systems often have provision for dual power inputs so they keep running even if one power source fails. Classes commercial boats require this, but not recreational boats. When building my boat I went to some extent to make sure all these dual power supplies we actually connected and used. I think it’s even MORE important to have if one of you banks is LFP with a BMS disconnect possibility

My vote would be to disconnect the output wire and see what doesn't work. Then decide whether you think it needs protection. Do this at the dock .

Ted

Delta Riverat said:

I would get rid of it for 2 reasons;

1) It drops half a volt which is way too high for a switch.

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I agree that half a volt is a lot. That is why I was wondering if it was failing as I can't imagine accepting that much of a voltage loss.

Delta Riverat said:

2) The max load is 70 amps. Seventy amps? You must be joking. Probably another reason it drops half a volt.

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The amps aren't an issue here. As near as I can tell, it isn't handling the loads, but the circuit it is controlling only powers up the Blue Seas solenoids that control engine start, genset start, fore and aft thrusters, windlass and crane. Each of those solenoids only draws 1/8th amp. So if all 6 are activated, that is still under one amp. In fact, both of the source wires and the load wire are protected by 10 amp fuses. I've tapped into that circuit for two other relays. One draws 33mA and the other draws about 150mA. So even if all are activated, that is still under an amp.

Assuming Luna is correct and this is a diode based device that's where the 1/2 volt is going. Diodes to that.

It sounds like you know what it powers. Those sound to me like systems I would not want to loose. I'd keep the device and let it do it's job.

O C Diver said:

My vote would be to disconnect the output wire and see what doesn't work. Then decide whether you think it needs protection. Do this at the dock .

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Portage_Bay said:

Find out what it powers. Disconnect the load side and see what doesn't work.

What do your engines require to run? An electric fuel solenoid in an energize to run system? Any electronic engine controls, not throttle and shift.

Click to expand...

DDW said:

It may also be powering the engine electronics. I assume you have a common rail engine, it will stop instantly without 12V power.

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I think all it powers are the solenoids I mentioned to @Delta Riverat . It is only fused at 10amps, so the most it could power would be a relay or solenoid. I will check though to make sure that it isn't controlling any engine components. There aren't any electronic controls in the system.

Delta Riverat said:

Ignore everything I wrote, the cables threw me.

Indeed there is a ZF Mathers control box that takes cable inputs and uses servo motors to do cable outputs. Only 3 grand each.

Click to expand...

That is what this APS is used for most of the time I believe. However, there are no ZF Mathers controls on the boat. I am positive on this as I completely took apart and relubricated the cable system a few years ago. I checked the controls from both helm positions all the way back to the engine.

luna said:

The Automatic Power Selector likely does not feed the house circuit, nor are the thrusters likely connected to it as a load.

It does what its name implies, selects the higher of any two connected power sources (they don't have to be batteries) to power whatever you connect to it as a load. The load is often just the ZF Microcommander controls, nothing else, unless you also deem it critical (your VHF?) by connecting it as a load.

This device is a diode based selector and as a result the voltage drop through the device is said to be 0.35 to 0.45 Volts depending on load. If you are measuring 0.6 volts, make sure no voltage drop from the conductors is included.

The device, although branded ZF is likely made by Newmar out of Newport Beach CA. which uses as a motto "A Mission Critical Electronics Brand." How fitting!

Here is a link to their info. on the product. Doesn't it look similar? Stickers are easy to make.
Newmar generally mades good stuff, albeit you won't find it on your phone.

Automatic Power Selector | 12V DC | 24V DC | 48V DC | 70 Amps to 160 Amps | Mobile Mount | Newmar Powering the Network

Automatic Power Selector by Newmar Powering the Network: 12V DC, 24V DC and 48V DC, 70 Amps to 160 Amps. The Automatic Power Selector (APS) is a solid state device which enables installation of a seamless, redundant power system for critical electronic loads. It selects the higher voltage of two...

www.poweringthenetwork.com

If it was me, I would confirm what powers it (both feeds) and what are the loads. Once I'm happy with that, I would keep it as it provides a useful service.

Click to expand...

That is a great explanation of how the device works. Thanks. I will double check the voltage drop. If it is really around .4v then I will assume the device is working well.

There are 10 amp Class H or K fuses there now (not sure which, I'll have to check). I really don't like the fuse holders as they use a screw down clamp connecter on the 10 AWG wire. I would much prefer a ring terminal connection. I will check to see exactly what type of fuse are used. Unless there is a specific reason for that type of fuse, I'd prefer to change it to something with more secure wire connections.

I think I got it now, it's a diode combiner as opposed to an isolator. 2 diodes forward direction to the middle. If one bank is low, the other automatically shares. But you wouldn't know you had a battery problem either.

I think I'd prefer a switch.

dhays said:

The amps aren't an issue here. As near as I can tell, it isn't handling the loads, but the circuit it is controlling only powers up the Blue Seas solenoids that control engine start, genset start, fore and aft thrusters, windlass and crane. Each of those solenoids only draws 1/8th amp. So if all 6 are activated, that is still under one amp. In fact, both of the source wires and the load wire are protected by 10 amp fuses. I've tapped into that circuit for two other relays. One draws 33mA and the other draws about 150mA. So even if all are activated, that is still under an amp.

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Then I'm very confused how this device is being used.

twistedtree said:

Then I'm very confused how this device is being used.

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I think it is like this.

There are low amp switches at the helm that control Blue Seas L series solenoid switches. An example is one that connects the thruster bank to the aft thruster. The battery and the thruster are located in the back of the boat. So rather than a long run of 4/0 wire from the stern to the helm and back again, the battery and the thruster are connected with a solenoid switch. That way a low amp wire can run from the helm to the stern and activate that switch.

This works great as long as there is enough voltage in the house bank to activate the solenoid. I think the APS is there in the event of a problem with the house bank that causes its voltage to drop below the required 9v for the solenoid. If the house voltage is low, it will use the start battery to activate that circuit, enabling me to still connect the thruster bank to the after thruster.

Don't know if this helps, on my John Deere, the dealer was emphatic about wiring the computer power supply directly to the battery. He said the cranking voltage drop from wiring it to the starter lug could make the computer kick an error code for low voltage. Clearly the computer leads were designed to be wired that way.

May something on your engine requires protection from cranking voltage drop.

Ted

If the device has silicon diodes, 0.6 or 0.7v drop is normal. For Schottky, 0.3 - 0.4V. In either case, that kind of voltage drop in the application you are describing is completely acceptable and without consequence.

The notion that the control circuits for the solenoids that energize and reverse the thruster motor are powered by anything but the thruster's battery bank seems absurd.

Let's see, if the thruster's battery bank is at 12.7 volts the few Amps taken from the thruster's battery bank to operate the coils in the solenoids to energize the thruster motor have no meaningful consequence in the thrusters performance. A properly designed system will have the thruster motor thermal out just before the battery bank is depleted. Don't cut that too close, lead battery capacity decays.

On the other hand, if the thruster's battery bank was at 9 Volts, regardless of whether the control circuit for the solenoids that energize the thruster motor was connected to a battery at 12.7 volts, say the starter battery or the house battery or even the depleted thruster battery bank, the thruster would not run for long, if at all.
The switching might work fine, but there simply is no power in the thruster's battery bank to run the thruster motor. You will have to find another way to go sideways.

Having the battery bank that provides the grunt, also provide the control power is a tried and true method that works. You just need to keep the battery bank charged.

The same applies to the start battery, and any other battery onboard.

Used in the way you have described, what is the upside for this electronic complexity?

luna said:

Having the battery bank that provides the grunt, also provide the control power is a tried and true method that works. You just need to keep the battery bank charged.

The same applies to the start battery, and any other battery onboard.

Used in the way you have described, what is the upside for this electronic complexity?

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Keep in mind that I didn't design this system, I only inherited it when I bought the boat. This stuff is very far from my area of expertise to the best I can do it guess. However, this is a guess I can come up with.

As I mentioned earlier, the idea of using solenoid switches is that it allows you to control a large amp load with a small amp circuit. There would be nothing wrong with running a feed from the thruster bank battery to the helm position to power the solenoid switch controls for the stern thruster, the bow thruster and the windlass. Then you could run another feed from the Starter battery forward to power the solenoid switch controls for the Start battery, and run yet another another feed forward to power the solenoid control for the genset battery. This would give you what you suggested, the bank that provides the grunt, also provides the control power. This means 4 feeds from various battery locations to the helm position to do essentially the same job, power solenoid switches.

Or, you could run one feed forward from the main DC board near the batteries forward to the helm position to power them all. One wire run instead of 4. Then if you wanted an added form of redundancy, you could use an automatic power selector to chose from two battery banks to ensure that this one feed always was going to get power.

Again, not my design, but I'm trying to make a guess as to how they came up with it. I know that I would much rather do 1 wire run than do 4.

dhays said:

Keep in mind that I didn't design this system, I only inherited it when I bought the boat. This stuff is very far from my area of expertise to the best I can do it guess. However, this is a guess I can come up with.

As I mentioned earlier, the idea of using solenoid switches is that it allows you to control a large amp load with a small amp circuit. There would be nothing wrong with running a feed from the thruster bank battery to the helm position to power the solenoid switch controls for the stern thruster, the bow thruster and the windlass. Then you could run another feed from the Starter battery forward to power the solenoid switch controls for the Start battery, and run yet another another feed forward to power the solenoid control for the genset battery. This would give you what you suggested, the bank that provides the grunt, also provides the control power. This means 4 feeds from various battery locations to the helm position to do essentially the same job, power solenoid switches.

Or, you could run one feed forward from the main DC board near the batteries forward to the helm position to power them all. One wire run instead of 4. Then if you wanted an added form of redundancy, you could use an automatic power selector to chose from two battery banks to ensure that this one feed always was going to get power.

Again, not my design, but I'm trying to make a guess as to how they came up with it. I know that I would much rather do 1 wire run than do 4.

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Yes, trying to determine what is going on in an electrical system that you did not design, have a schematic for or installed is usually not easy.

Your second paragraph I think generally describes what happens on most boats our size. Wires are run from the solenoids to the helm(s) and back to the solenoids. It's also likely that this solenoid wiring makes a stop at the load center where a circuit breaker is installed in the circuit. There are usually methods used to group the supply side loads to reduce the amount of wire runs.
At the helm(s) there will be a manual switches that are used to activate the various systems.

On my ride the 24 V thruster/windlass bank powers the thruster's solenoids from 2 locations, the windlass solenoids from 3 locations, while the 24 V engine start banks power the engine start solenoids from 3 locations. Yes, lots of wire runs. My house and gensets are 12 V and are wired the same way.

In your 3rd paragraph you are correct, you could use a system as you have described to energize the multiple circuits that activate the various device solenoids using one Blue Seas solenoid for each system (you said you have 6 of them) who's coil only is powered through an APS.

But what is the point.

You still need Helm mounted switches and the CB that have to be in the circuits so you can actually turn the various systems on. These Helm mounted switches in your existing system need the same amount of wires and carry the same amount of current as they would need if they were controlling the circuits without all of this APS and additional Blue Seas solenoids.

One difference is that in your system the coils of the 6 Blue Seas solenoids could be fed power from a different source than that of the Blue Seas solenoid's pass thru power, but I'm still unsure of what advantage that brings. In effect what this does is it tries to ensure that an electrically powered switch has power to it so the switch can work, but it does not ensure the power that this switch is actually switching, even exists.

The other thing it does is introduce a failure point. If the coil fails, you have no power to the control circuit of the system.

On any of these systems, say the thruster, where is the pass thru power to the Blue Seas solenoid sourced from?

Are there any switch(es) to control the APS protected coil in these 6 Blue Seas solenoids, or are they always on?

Seems like two battery banks are the input to one load. Have you confirmed this? Do you have two separate house banks? If yes to two banks then this would keep house loads running if one bank drops to a low level.

luna said:

The other thing it does is introduce a failure point. If the coil fails, you have no power to the control circuit of the system.

On any of these systems, say the thruster, where is the pass thru power to the Blue Seas solenoid sourced from?

Are there any switch(es) to control the APS protected coil in these 6 Blue Seas solenoids, or are they always on?

Click to expand...

I have a circuit diagram for how the boat was built. I'll try and scan it to give you an idea. I think I'm doing a terrible job of explaining it, likely because my understanding of it is poor.

SteveK said:

Seems like two battery banks are the input to one load. Have you confirmed this? Do you have two separate house banks? If yes to two banks then this would keep house loads running if one bank drops to a low level.

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Not exactly.... All the APS does is connect the battery with the highest voltage with the load. In this case that is either the start battery, or the house bank. The "load" in this case is one small circuit, limited to 10 amps, that does nothing but provide power for the solenoid switch coils in the boat.

It doesn't keep the house loads running if the house bank goes down. It simply ensures that all the solenoid switches will be powered. A simplistic way to look at it, is that it ensures that the current can flow where it needs to go, but goes guarantee that there will actually be current to do the flowing.

I suppose the switching is done by the battery with higher voltage, as in if the engines are running the start battery may be 14.4 while house may be 12.8 or vice versa. A solution perhaps brought on by an event where just one bank failed to provide the needed power (house bank too depleted in the morning).
In my case I run the windlass off the start battery as I only use it while the engine is running. If I had thrusters they would also come off the start battery for same reason.

Interesting use of an aps device. I guess the installer was concerned about the solenoids dropping out from voltage drop. Doesn’t hurt I guess, until it fails. If it’s easy to get to I’d leave it alone.

That device does not do any switching. It does what's called diode "ORing" meaning that whatever is connected to the "load" terminal will get power from "source 1" OR "source 2" and assuming at least one source is present, it gives uninterrupted power to the load. There's never any switch time where voltage is dropped to the load. I would not worry about why it's there, if the engineering team that designed the electrical system of the boat deemed it necessary, they clearly felt there was a need for uninterrupted power to some circuits and I'd defer to them. As others stated .6V loss is normal and it's not failing. There are only two active components inside that box and since it's fused at 10 amps, it is being very lightly loaded and should last forever. If one of the diodes were to fail, the load would still get power from the source connected to the good diode, so it has built in redundancy.

Mischief Managed said:

That device does not do any switching. It does what's called diode "ORing" meaning that whatever is connected to the "load" terminal will get power from "source 1" OR "source 2" and assuming at least one source is present, it gives uninterrupted power to the load. There's never any switch time where voltage is dropped to the load. I would not worry about why it's there, if the engineering team that designed the electrical system of the boat deemed it necessary, they clearly felt there was a need for uninterrupted power to some circuits and I'd defer to them. As others stated .6V loss is normal and it's not failing. There are only two active components inside that box and since it's fused at 10 amps, it is being very lightly loaded and should last forever. If one of the diodes were to fail, the load would still get power from the source connected to the good diode, so it has built in redundancy.

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Thanks. That makes perfect sense. Can you think of any reason why they would have chosen to use Class H or K fuses (I'm not sure which is there)? The fuse holders use a screw clamp to secure the stranded wire. I'm not terribly happy with how secure they are. One of the wires simple fell out as I was looking at it. Granted, it had been there for 14 years, but still... If there isn't a reason for a class H or K fuse, I'd just as soon replace those with something more secure, and easier to keep spares, such as in-line blade fuses.

dhays said:

Thanks. That makes perfect sense. Can you think of any reason why they would have chosen to use Class H or K fuses (I'm not sure which is there)? The fuse holders use a screw clamp to secure the stranded wire. I'm not terribly happy with how secure they are. One of the wires simple fell out as I was looking at it. Granted, it had been there for 14 years, but still... If there isn't a reason for a class H or K fuse, I'd just as soon replace those with something more secure, and easier to keep spares, such as in-line blade fuses.

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I have no idea why they chose a fuse like that. 10 amp blade fuse would work fine.

Mischief Managed said:

I have no idea why they chose a fuse like that. 10 amp blade fuse would work fine.

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yeah I just ordered a 4 way ATO blade fuse holder to replace what is there. It will be a cleaner install, and I always have 10amp ATO/ATC fuses on hand.