How Wakespeed’s WS500 alternator regulator solves complex charging issues, now with NMEA 2000 UPDATE

It’s hard to imagine getting excited over a mundane appliance such as an alternator regulator, but there is a lot to like about Wakespeed’s WS500 device. For me, the primary reason is that this regulator has addressed a gnarly charging problem on Bliss, our 40’ pilothouse trawler. It may help with yours. Let me explain…

A few years ago, deciding to finally do something about uncomfortable rolly passages on our round bottom full displacement trawler, we swapped our 5 kilowatt AC genset for a SeaKeeper 5 gyro stabilizer. The generator had to go to create sufficient space for the new stabilizer. This resulted in an interesting dilemma since 2000 watts of AC power is required to run the gyro, but the only device onboard capable of generating such power was the genset. And that had to be removed to make room for the stabilizer. To support the gyro’s current requirement, we had to upgrade the DC generation system by adding two 250 amp MGDC high output alternators to our single 100hp Yanmar diesel engine. Installation of the stabilizer is very nicely described by Ben Ellison in a previous Panbo post.

Bliss charging issues

This is where the problems start. Initially, we installed Balmar multi-stage regulators. What we did not understand was that almost all such advanced (or “smart”) regulators use battery voltage and percent field current to determine the battery bank charge state, and although the technique has worked well for decades on many boats, it can cause problems on vessels like Bliss with significantly fluctuating electrical demands.

Unlike traditional alternator regulators that cap alternator output to constant voltage (usually between 13.5-14.5V), “smart” regulators have been designed to minimize charging times by using a multi-step approach to implement specific charging regimes recommended by the battery manufacturer. For example, the following graph shows the recommended optimized charging sequence for my new Victron Gel batteries.

“Smart” multi-stage chargers implement these sequences by varying field current while attempting to monitor battery charge state. Traditionally these regulators use voltage and percentage field output to determine the charge state of the battery bank. Although a detailed description of “smart” regulator technology is beyond the scope of this article, Balmar’s site describes their charge sequence tech very nicely.

Consider how the popular Balmar MC-614 used to function on Bliss as configured for our Gel batteries. It drove an acceptance voltage (also called absorption voltage) of 14.2V with a field trigger of 65% max field amplitude. When going through its charge cycle, the regulator starts in “bulk” mode, where the alternator is told to output as much current as it can until it reaches the acceptance voltage of 14.2V. Once in “acceptance” mode, the field current is slowly dropped down until the output reaches 65% of its max. The 65% mark triggers a ramp down to a float voltage of 13.8V, where everything remains until the engine is stopped. If the regulator, while in “float” mode, has to increase its field output to more than 65% in order to maintain voltage, the regulator re-enters bulk (or accept) phase restarting a charge cycle.

The problem with this setup on a boat that runs continuous heavy loads (like mine) is that the battery may be charged to full capacity, but the electrical demands on the house are so high (e.g., running a gyro that requires 2000 watts) that the 65% trigger point is never met. The regulator never enters the “float” state, and the batteries are grossly overcharged. It took us several weeks to discover what was happening to us, resulting in the destruction of our 1800 Amp/Hr sealed battery bank. An expensive lesson, to say the least…

When at anchor, not running the gyro or other heavy house loads, we discovered that we were still having charging issues. On Bliss, we have 1000 watts worth of solar panels allowing up to 80 amps of charge at peak times. Under these peak conditions, the regulator hits the 65% field threshold prematurely, causing the system to enter “float” mode before the battery bank is fully charged. Grrrr….

Finally, there is the issue of RPM. The amount of current created by the alternators is a function of the field provided by the regulator and the engine RPM. If the engine is at a slow idle speed, then the alternator drive field must be increased to yield more charging current. With large battery banks, this can cause issues if you (like me) start an at-anchor charge cycle at fast idle and then slowly reduce the RPM (to save fuel and load the engine) while the current requirements drop. This causes the regulators to possibly overcharge your batteries because, once again, with a large battery bank, the 65% field threshold is not met, and a transition to the “float” state never occurs.

Solar panels, large loads, varying RPM, etc. confuse most regulators causing batteries to be either under or overcharged, resulting in shorter life expectancy and poor performance.

An interim solution was to reprogram the regulator for a lower acceptance voltage and a field threshold of 75%. This allowed us to motor for long distances without frying the batteries, and thus preserving the capacity we had left until we could replace the bank. However, at anchor, we could not charge our batteries efficiently because the system then floats too soon. Very frustrating.

Bliss discovers the WS500 (an Aha moment)

When I discovered that the Wakespeed WS500 uses an amp shunt to measure the actual current going into the batteries instead of using percent field thresholds to manage its charging algorithms, I was instantly sold. I bought two of them straight away.

The ability to measure the current going into the battery bank separates this regulator from the pack. That is not to say that there are no other features that make this regulator quite desirable, but we will get to that later.

With the WS500, you don’t have to worry about heavy house loads, solar panel output, and RPM affecting the charge cycle. The regulator always does the right thing. For my new Victron Gel 1855 Amp/Hr bank, this means that when the current going into the batteries hits 4% of the bank capacity ( that is 1855 Amp/Hr * 0.04 or 74.2 amps) the system instantly goes to float. When in “float” mode, if 20 amp/hours were to be consumed out of the battery — like when a really heavy house load is turned on that alternators can’t keep up without requiring helpt from the battery bank — the system restarts a charging cycle. No-fuss, no mess… the regulator just does the right thing always.

I love the following images. They show how Bliss now moves through the charge stages until she’s happily motoring along while generating 160 amps of current to run the house and the gyro while the batteries are in float mode absorbing 47 amps. The battery bank would continue to float at 47 amps, even if I were to start the microwave and the washer dryer and/or other heavy loads. It’s a beautiful thing to see in action! (More on Simarine power monitoring here.)

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Installation and basic WS500 configuration

Installing the WS500 is as simple (or complex) as any other regulator, with the addition of 2 wires that go to a current shunt on the negative return to the battery bank. Battery voltage sense, regulator power, ignition, field, and, etc. are the same as in most any other smart regulator. Following is the wiring diagram for the regulator.

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The harness that comes with the regulator includes a temperature sensor for the alternator but none for the battery bank. Users will need to supply this if they want the regulator to adjust charging voltages and current based on battery temperature (something you are encouraged to do). Care should be taken to get the polarity of the current sensor correct. If wired backward, the regulator will not work, although there is a way to change the polarity in software using the advanced configuration mode (more on this below).

It is important to note that when connecting the wiring harness to the regulator that the fuses to both the sense and power positive leads are removed. Under most conditions, nothing serious will happen if you forget, but it is possible to damage the regulator if the positive leads establish a connection before the ground leads do.

The WS500 can provide up to 30 Amps of field current output compared to others that only support 15 Amps. 30 Amps allows one regulator to control multiple alternators or specialized alternators requiring very high fields. On Bliss, each MGDC alternator requires 8 amps for maximum output. So while I used to throttle down the maximum field to 90% to maintain the 15 amp limit — and avoided blowing an internal regulator fuse — now I can get full output from both alternators at once. I still find this remarkable. That is 6 kilowatts of DC power out from my small 100hp Yanmar while motoring. More than we ever got out of our 5Kw Kohler genset.

Although the WS500 does have an extensive configurable feature set available through a programming interface (more on this below), most users will find that configuring the unit via 8 dip switches will do the job. Entering the battery type and the battery capacity is all that is required. Note that the regulator expects a standard 500Amp/50mV battery shunt to work correctly. But there is no problem piggybacking off of one that you might already have for your house battery monitoring system (though if your shunt is something other than 500/50 or the polarity is reversed, then the advanced configuration will be required to modify the setup). Following is a description of the dip switch settings from the manual.

Of particular note is switch 8, which limits the current output to 70% and is meant to protect small engines from being overwhelmed by large alternators. It can also be used initially to make sure things are working as expected before turning on the full spigot. And all of the switch settings can be overwritten via the advance configuration mode discussed later on.

One LED on the front of the unit provides status codes via blink patterns. The following enumerates the different error codes and statuses for the regulator.

For most users, that is pretty much it. Connect the ignition, alternator power, voltage sense, and battery shunt current sensing wires. Hook up the alternator and battery temperature sensors. Finally, configure the switches for battery chemistry and Amp/Hr capacity, and off you go to worry-free battery charging nirvana.

A configuration wish list

Having already blown a large battery bank, we wanted better control over the charging sequence. So using the switch settings was not enough. Additionally, we now had the problem that when motoring at slow RPM with low batteries, the alternators consumed most of the engines available horsepower, making the engine sluggish. Specifically, we wanted to modify the regulator settings to:

• Force float via a switch on the dash to prevent overcharging of the battery bank if the regulator misbehaved. As it turns out, this was an unnecessary concern but nice to have for us paranoid types.
• Force alternator output to 30% of maximum via a switch when motoring at slow RPM so that most of the engine power goes to propulsion.
• Implement Victron gel battery specific charging recommendations, including a “post-float” maintenance mode when making multi-day passages.
• Specifying the exact size of the battery bank, max current allowed into the bank, and trigger amperages for entering and exiting the float and “post-float” states.

Fortunately, with some additional wiring and advanced programming, the WS500 can deliver on all of these requirements.

WS500 advanced wiring

First, we tackle the wiring. Here is a picture of hardware switches and LEDs installed on our dash to support the additional functionality.

On-demand reduced alternator output can be forced by shorting out the alternator temperature sensor, in our case by running two wires — one from each lead of the alternator temperature sensor — to a switch on the pilothouse dash . By default, this reduces the alternator output by 50%. For us, however, reducing power by 50% was not enough.

The power curve for our 100 HP Yanmar 4jh2 engine does not show available HP at 600 RPM, but it’s not much. Meanwhile, 4 HP is required for every 100 amps of alternator output, and our system, as configured with a 3:1 pulley ratio, is capable of producing 300 amps at 600 RPM. In other words, at full alternator output when idling, the alternators demand 12HP out of the engine, which leaves close to nothing for propulsion.

So while a 50% reduction to 150 amps (6HP) was not enough for Bliss, the WS500 allows for modifying the output power when in reduced mode via a software setting, and it was not a problem to decrease the output further to 100 amps or 4HP at 600 RPM.

Note that WS500 has a pull-back feature (PBF) designed to specifically address the problem of large alternators overpowering small engines at low RPM. PBF uses the regulator’s stator input to measure engine RPM. The PBF can be adjusted to reduce output based on RPM at near idle speeds. We opted not to use this feature because while useful in motoring situations, we wanted all available engine power to go to charging when at anchor. So for us, a switch makes more sense.

I have heard of other systems using the transmission shift control to activate a relay that then enables alternator stator input into the regulator. This would allow switching between reduced and full power at idle based on whether the propeller shaft is rotating. Although we may experiment with this at a later date for now, we are happy with our manual at anchor/underway mode switch. The stator switch on the dash enables RPM input into the regulator should ever want to use PBF.

Similarly, the force float feature was also easy to set up because the WS500 sports a Function IN line that can be programmed to support this. Running a single plus wire from the dash to the Function IN regulator input accomplishes this very nicely. Although we have never had to use this feature yet, its nice to have.

The ALT on/off switch was initially intended to actuate the ignition wire on the regulator, allowing us to totally disable charging while still keeping the dash alive. At the moment, we have the ignition wired to the key on the dash, so starting the engine enables the regulator. I see no need to implement the ALT on/off switch. However, it’s nice to have it should we in the future wish to (for some reason) disable the alternator while motoring.

Finally, the dash lamps are wired to the regulator so that problems and error codes can easily be detected.

WS500 advanced configuration and programming

If custom programming is required to finalize a WS500 installation, it may seem daunting at first, but it’s really not too bad. To program the unit, you must first remove the cover to access the USB port, which is also required to access the configuration dip switches adjacent to the USB port. (These are the switches discussed above for basic configuration without programming.)

The USB port is the plugged into either a windows PC if users want to use the programming tools provided by Wakespeed or to the OPE Tether, a WiFi access point device discussed in detail in a bit.

Before diving into the mechanics of programming, let me first share the following, which is the WS500 program used to configure Bliss‘s regulator:

#Program for WS500 target version = 222
$SCN:0,Master,[email protected]
$SCA:0,120,0.90,0.70,0.30,0,0,0,10000,0,0,15,[email protected]
$SCT:3,3,-1,[email protected]
$CCN:1,1,70,1,1,1,0,0,0,0,0,[email protected]
$CPA:8 14.1,360,20,[email protected]
$CPO:8 0,0,0,[email protected]
$CPF:8 13.6,-1,1140,0,-24,12.6,[email protected]
$CPP:8 10000,0,-20,[email protected]
$CPE:8 0,0,0,[email protected]
$CPB:8 0.024,-9,-20,45,0,-99,-99,0,[email protected]
$SCO:8,3.7,1,[email protected]
$RBT:@

Basically greek! A description of what all this means is found in the WS500 programming manual found at wakespeed.com. The 0.30 field in the $SCA:0 line, for example, means reduce the power output to 30% when the alternator temperature sensor is shorted.

Wakefield provides Windows-based drivers and DOS-style command-line tools to transfer programs like the one above to the regulator. They also offer a configuration guide with detailed instructions on how to program the units and several templates for predefined configurations. The programming sequence is as follows:

• Download the configuration guide and drivers from www.wakespeed.com
• Plug a USB cord (not supplied) into a windows computer
• Install the USB drivers
• Use Notepad (or some other text editor) to create or modify a WS500 program like the one listed above. Then save the text file into the directory where the Wakespeed tools were installed.
• Run the Windows command-line editor (cmd.exe) and change (cd) into the Wakespeed program folder.
• Run the Wakespeed console-based file transfer utility.
• Check for errors and repeat steps 4-7 as needed.

The process is not too complicated if you are technical and accustomed to coding and using command-line tools.

Introducing the OPE-Tether WS500 accessory

Fortunately, however, there is a much more straightforward and better way to program these regulators using the OPE-Tether, a small WS500 add-on WiFi access point sold by Ocean Planet Energy and providing the following features:

• Mobile-friendly web access to the WS500 via WiFi. No device drivers are required. Works with all web able mobile devices. IOS, Android, Windows, Mac, and Linux compatible.
• Connectivity to regulator via USB or the regulator’s external RJ45 CAN bus connector.
• Easy firmware updates for the WS500 regulators.
• Simple form-based web programming of WS500 regulators.
• Realtime monitoring.
• Logging of all regulator parameters on the internal SD card.
• Connectivity to a vessel network via Ethernet or WiFi.
• Tethering via mobile phone for remote WS500 support from OPE.
• Powered by 9-35V DC. AC/DC adapter is included.

The vital thing to note is that this device requires no specialized knowledge of programming, command-line editors, or text editing to access the full WS500 feature set. All that is needed is a WiFi-enabled computer or device and a web browser.

Time for a disclaimer. I am the creator of the Tether. After purchasing two WS500’s for Bliss, I thought the product deserved a better way for the community to access all of its features.

A full review of the Tether is beyond this article’s scope, so I will focus on the programming of 2 features to give you a feel for this tool. First, we will modify the configuration to provide the regulator with a name and specify the size of the battery bank to accurately define the “float” state and enable the float dashboard switch. After that, we will program the float and “post-float” state settings and activate the program on the regulator.

Before jumping into programming mechanics, let’s discuss the “Remote Support” feature, one of the most powerful things about Tether. It allows a user to tether their WS500 regulator(s) via their cell phone (in hotspot mode) to OPE technicians, who then have full access to the device. So if you run into problems, an expert can diagnose and correct your installation. The Tether’s quick start guide provides details on the tethering process.

Programming the WS500 with the OPE-Tether

After powering on Tether and wiring it to the regulator, you connect to the system via WiFi, login, and then browse to the “Regulator Settings” tab to start the programming process. You then enter the desired settings and save them. Battery Size, system voltage, regulator name, enabling the “Function In” line are defined in this first screen.

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Next, while still in the “Regulator Settings” section, you browse to the CPF (float state parameters) and CPP (post-float state parameters) tabs to enter the desired values. Battery maintenance voltage for the given state, time duration, and exit conditions are specified here. Of particular note are the state exit parameters. We determine that we are to exit the “float” state after 5% of the Amp/Hr capacity of the battery bank has been used or 4% for the post-float state. Settings are then saved for transfer to the regulator at a later date.

To transfer the new settings to the regulator, we now navigate to the Tools tab and push the program button. We then (if we want) verify that the generated program is to our liking and if all is well, push the “Commit” button to transfer it to the regulator. We then wait for confirmation that the program was accepted. The regulator will restart automatically, and the new settings will take effect.

As easy as 1.. 2.. 3..

The Tether UI is pretty much self-documenting, so it’s just a matter of spending time and experimenting with the settings to perfect your regulator setup. When done, you can use the profiles tab to save these settings with a specific name and comment. The Tether can store many profiles, which makes it handy for installers moving between customer boats. Users can also download the settings to their computers, share them with others by emailing them as attachments, and then upload them into a different Tether. This feature can be used, for example, to contract OPE or another vendor to create and email you a custom configuration for uploading to your WS500.

There are many, many more things we could discuss, but I believe that this will give you a good idea of what is required to configure the regulator.

More WS500 features

Before we go, I want to mention a few additional WS500 features not discussed in detail here.

WS500 supports the connecting of multiple regulators via the RJ45/CAN bus on the outside of the units using standard Ethernet cabling. In this configuration, one of the regulators automatically takes over as the master and controls the other regulators as slaves. This allows for multiple regulator/alternator setups to charge one large battery bank in a unified way, which can a nice feature on multi-engine vessels. Engines/regulators can be turned on and off at will, and the system dynamically reconfigures itself to do the right thing.

For users with large alternators and small engines, the American Power Systems, Inc version of the WS500 (called the AP500) has a “white-space mode” that augments the pull-back factor previously described, allowing you to specify alternator output for 8 RPM ranges. The feature allows, for example, the implementation of a table such as:

Finally, for those wishing to see battery state and charging information on your NMEA 2000 displays, the OPE-Tether will soon have an option that bridges WS500 information to a vessel’s N2K instrument network. I will add more information about it in the comments section below as the feature becomes available.

Summing up

Its hard to believe something as uninteresting looking as this can be so important. But it is. I hope you see now why the excitement.

Good luck and happy charging — Luis Soltero, MV Bliss, Currently in the Chesapeake

WS500 to NMEA 2000 update

8/1/2020 — I’m happy to report that the WS500 installed on Bliss is now sending valuable data to my NMEA 2000 network. Here’s the story:

The CAN bus networking used by the WS500 supports the following data layer protocols:

• J1939 — used for engine information, including RPM, and common in cars, trucks, and newer diesel engines.
• RV-C — used mostly by manufacturers of DC and AC power systems, such as battery management systems (BMS) meant to interface with other electronics. 
• NMEA 2000 

Given that NMEA 2000 and RV-C are built on top of the J1939 protocol, there is no electrical impediment for connecting the WS500 directly to your vessel network, and this can be accomplished by making a special cable with RJ45 to DeviceNet connectors, or by purchasing your WS500 harness from Ocean Planet Energy, which comes with a CAN bus DeviceNet connector.

Caution: The WS500 is not certified by NMEA for use on N2K networks, and it may never be. NMEA specifies that CAN bus interfaces connected to N2K networks must be optically isolated, and the WS500 is not. Also, NMEA specifies that only valid N2K data frames are to be used on the network while the WS500 uses non-N2K frames to communicate with other WS500s, plus BMS’s and other non-N2K devices. Like N2K, RV-C also uses PGNs for its sentences. There is some overlap between the N2K vendor-specific PGN range (130816 … 131071) and some RV-C PGNs, which may cause conflicts should the vessel instrumentation use some of these.

So, although it’s unlikely that connecting the WS500 directly to your N2K network will cause issues, be aware that this is not approved or sanctioned by either NMEA or by Wakespeed. Brave souls can try it, and if it works, great. But there are several ways to get better, cleaner, and safer WS500 data onto your vessel’s N2K network.

First of all, an N2K-to-N2K bridge such as the Yacht Devices YDNB-07 or the Maretron NBE100, will do the job. These devices automatically prevent non-N2K traffic on the WS500 side from being propagated on the vessel’s N2K network side while also electrically isolating the CAN bus (and the Maretron bridge is NMEA certified). Other N2K bridge models may do the same but make sure to check the documentation before you purchase to ascertain that they support filtering.

N2K bridges, in their default configuration, will not resolve RV-C PGN conflicts with proprietary N2K PGNs should any exist on the network. However, both of the bridges listed above support custom filtering. For the NBE100 you use a Maretron USB100 Gateway and their Maretron N2KAnalyzer program to block all traffic except the required whitelist sentences (see PGN list below). Creating filters on the Yacht Devices bridge involves creating a text file with program statements stored on an SD card and then inserting it into the device, as explained in the YDNB-07 manual PDF. Yacht Devices technical support was kind enough to provide a YDNB-07 configuration script that should work with the WS500 (after you change the file name to “YDNB.CFG”), although neither Wakespeed nor I have had an opportunity to test it.

Alternately, the OPE-Tether discussed in previous sections above can be purchased with an Ethernet-to-N2K adapter cable that plugs into the Tether’s LAN port providing plug-n-play conflict-free N2K network bridging. (As a reminder, I am the creator of the OPE-Tether.) Like the YD and Maretron bridges above, the Tether isolates the networks and only passes bonafide N2K traffic. Tether passes only N2K sentences sourced from the WS500 and no others, avoiding network conflicts. Additionally, Tether provides WiFi connectivity to the programming of the WS500 and realtime monitoring of over 100 parameters (i.e., much more than is available over N2K).

Here are a series of screen captures showing how my Simrad NSS16 evo2 MFD can list the N2K devices it sees on the network as well as the data it’s able to interpret.

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The lower data screen does not show the specific PGNs involved, but does show the data fields that the NSS understands from them, along with what are known as device and data “instances” in brackets. The default N2K data (and device) instance is 0 and the PGNs that use data instance usually involve boat equipment that there’s often more than one of, like battery banks and engines. So the Battery Current [Battery Instance 0] above showing a current value of 32.8A is the amperage going into Bliss main battery bank. The story is similar with RPM [0] and if Bliss was twin screw, there could be an RPM [1] data line (with the normal N2K instancing of 0 = port engine, 1 = Starboard).

If you dig deeper into NMEA 2000 terminology, several PGNs with Battery in their title can actually reference other DC sources and be given DC Types like Alternator or Solar Cell, and you can see that in action above. The WS500 gives the alternator a data instance (called Battery or DC Instance) of 49 and thus all fields marked 49 are about Bliss’s alternator. In other words, the Battery Temp [49] of 89.60F is the temperature of my alternator case just getting warmed up on an already hot Chesapeake Bay day. It can go much higher and that’s why I’d like to keep a close eye on it.

Most N2K MFDs and instrument displays let users choose among data sources for gauge information if choices exist on the network, at least to some degree. For example, my Simrad NSS16 Evo2 above is showing BATT V, AMPS, BATTMP, and RPM all sourced from the WS500 through the Tether. So I have to choose between Battery Instance 0 and 49 (the alternator V, Amp, Temp) because the MFD can not display the same general type of data from two sources at once.

Fortunately, I have two NSS displays that allow me to configure one with the battery and the other with the alternator info. But be aware, as I’ve demonstrated, that even if you can see data on an N2K display’s diagnostic screen, you may not be able to show it wherever you want. (Also note that VSUPPLY is the voltage actually seen by the NSS, which is quite different than the battery charging voltage.)

My understanding is that NSS evo3 addresses this data display problem and also offers custom labeling of data fields so that BATTMP [49] can be seen on screen as something like ALT TMP. I also know that Ben Ellison now has a wealth of similar Victron generated DC PGNs — battery, inverter, and solar charger — on Gizmo’s network, and Panbo readers will eventually hear about how they display on Furuno TZT2, Simrad GO5, and Maretron screens.

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Here are pictures of my Raymarine i70 display showing engine RPM and Battery status sourced from the WS500/Tether.

The WS500 supports the following N2K PGNs:

• 127488 – Engine RPM
• 127506 – Detailed DC Status including the State of Charge, State of Health, Time Remaining, and Ripple Voltage
• 127507 – Charger Status including the Operating State, Charge Mode, Charger Enable/Disable, Equalization Pending, Equalization Time Remaining
• 127508 – Battery Status including Battery Voltage, Battery Current, Battery Case Temperature
• 127510 – Charger Configuration Status
• 127513 – Battery Configuration Status
• 127750 – Converter (Inverter/Charger) Status including Operating State Temperature State, Overload State, Low DC Voltage State, and Ripple State.

NMEA’s website offers some detail about NMEA 2000, including this somewhat dated PDF describing most current PGNs. Also, some manufacturers like Maretron and Victron include N2K and PGN technical detail in their relevant manuals.

Once you have connected the WS500 to the N2K network, then it’s a matter of configuring your multifunction or instrument displays to show the data. As suggested, the ability to display specific PGNS, and especially with multiple device or data instances, seems to vary a great deal.

My Raymarine i70, for example, can display some data fields from PGNs 127488 and 127508, while the NSS16 evo2 shows support for 127488, 128508, and 127507. 507 tells it the charging state (Absorption currently) and that it’s an Alternator generating the charge.  508 contains battery volts, amps, and temperature, while 488 delivers RPM… nothing fancy but undoubtedly useful.

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These screenshots show how you can program the NSS16 instrument panel with desired instruments, in this case using the “Data Sources” Select menu to choose between displaying alternator voltage with data instance 49 or the main battery bank voltage with instance 0. Note again that the OPE-Tether offers a lot more information via Wifi than via N2K, albeit not as conveniently. 

I might add that I am still enamored with my Simarine Pico system, though it does not yet support NMEA 2000. I have a zillion shunts on the boat, and it provides me with realtime charging and currents coming from both alternators, and into all battery banks. It also gives me temp for the engine, engine and battery compartments, and much other useful information.