Lowrance EP-85R

Information about Evinrude I-Command, ICON Pro, and ICON Touch Color Displays
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Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 9:26 am

The following is distilled from a prior and much longer discussion about the behavior of the EP-85R.


Failure to record fuel used

About five years ago in 2013 I discovered an anomaly in the function of the EP-85R and Lowrance FUEL MANAGER software, which I describe below. In my boat's NMEA-2000 network it was possible for the EP-85R to be powered and active when the E-TEC engine was not on the network. During a eight-day cruise in 2013, I discovered that the EP-85R recorded no fuel usage during one day of the cruise. I believe that the circumstances in which this occurred were as follows:

  • the network power was left ON for a long period of time after the E-TEC had been shut off, perhaps 18-hours;
  • hours later, when the E-TEC was switched on and returned to the network, the EP-85R did not return to functioning with the E-TEC;
  • the fuel consumed during that day's operation was not recorded onto the EP-85R

I discovered this when I logged the fuel data at the end of the day. All the fuel data (taken from the EP-85R) was identical to the prior day, that is, no fuel consumption was recorded, even though the boat had certainly burned at least three or four gallons of fuel.

My hypothesis for the cause of this omission in fuel flow recording is:

  • with the EP-85R left powered ON, and the E-TEC powered OFF, after a long period of time the EP-85R gave up on communicating with the E-TEC
  • when the E-TEC was much later switch ON and returned to the network, the E-TEC was likely reporting its fuel flow rate to the network,
  • the instantaneous data, like MPG was being computed by the gauge
  • the accumulator data, such a TRIP FUEL USED, SEASON FUEL, and TANK LEVEL were not being updated.

When both the E-TEC and the EP-85R were powered OFF, and, after a short delay, powered back to ON, the operation returned to normal.

Fortunately for my fuel tank level computation, the fuel actually burned on this particular day of the cruise was only about four-gallons at most. The fuel tank is a 70-gallon tank, so the values for FUEL TANK LEVEL and FUEL REMAINING were only off by a small percentage. Also, because I was logging the daily fuel used data, I noticed this problem right away.

Firmware Updates for EP-85R

At some point in the process of investigating how the EP-85 behaved or misbehaved,I applied a firmware update patch to my EP-85R Data Storage module, bringing its firmware up to the 2.3.0 revision level. The updater was applied by using my Lowrance HDS chart plotter. The procedure is as follows:

--copy the firmware updater software file onto a SD Memory card

--boot up the HDS-8

--load the SD memory card into Slot 1

--use the PAGE carousel to navigate the HDS to the FILES option, see

http://continuouswave.com/whaler/refere ... html#FILES

--navigate to Memory Card 1

--expand Memory Card 1 to show its files

--navigate to the updater file

--a soft key option should appear with the legend UPDATE

--push the softkey; the update process should begin, first commenting that the EP-85R has been restarted, then showing a grow bar with the percentage increasing toward 100-percent.

I found that after applying the firmware patch, the EP-85R lost all of the stored data except the configured tank volume. If you want to memorialize that lost data, copy it down before applying the patch. Also, the updater left the EP-85R showing the present fuel remaining level to be the full-tank volume, and the present fuel tank level to be 100-percent full. This was something of a surprise. In my case, the fuel tank was not full and the fuel remaining was less than the tank volume set. I will have to wait until I burn off enough fuel to get back to my actual levels (that I wrote down before updating) so I can then make an allowance at the next fueling.

In my case the tank has about 58-gallons, not the 70-gallons now shown on the EP-85R. I will have to burn off at least 12-gallons before adding new fuel. When I add fuel, I will subtract 12-gallons from the actual amount added to the amount I enter into the EP-85R; this will get the EP-85R back to an accurate fuel tank level. This seems like a cumbrous process. It would have been simpler if the EP-85R update just set the fuel remaining to zero. I could then use the ADD FUEL function to add imaginary fuel to the tank to get it back in calibration.

Readers should be aware that updating the EP-85R firmware as I described above caused all sorts of problems. These problems, and their resolution, are described in detail below in a follow-on article.

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Re: Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 9:35 am

[More from the prior discussions.}

After the 2013 boating season, I applied an updater patch to my Lowrance EP-85R Data Storage Device. When I had the boat on the water for the first time in 2014, and I found that the FUEL MANAGEMENT functions with the EP-85R were fouled up beyond all recognition (FUBAR).

I ran the boat for six days. Every day the EP-85R was re-set to show

FUEL REMAIN = [100-percent of tank capacity or FULL]




In other words, the outcome was worthless for managing fuel.

On a couple of days, I found I had an indication of "INVALID" in the NETWORK menu listing of data sources for fuel management. To make that go away I had to select AUTO CONFIGURATION. This reset everything to either zero or FULL. One day my HDS-8 crashed three times in an hour, so I decided to perform a SOFT RESET to the entire unit. I thought that this had wiped out everything, too. But I am not sure. After thinking I had worked through all the problems, I turned the HDS on to find that, once again, my fuel management data was all gone, and the fuel tank level was set to 100-PERCENT-FULL and fuel used (all categories) was ZERO.

I have no faith at all in the FUEL MANAGEMENT of the HDS and EP-85R after this. I never had any trouble with this before applying the updater patch. The patch I applied was


I do not recommend this patch. It seems to have ruined the operation of the FUEL MANAGEMENT functions of the HDS and EP-85R.

I made many more attempts to restore the FUEL MANAGER to operation in my Lowrance system:
  • re-applied the updater patch to the EP-85R
  • did a hard re-set of the HDS-8, which erased all my user settings and restored the unit to factory default
  • removed the EP-85R from the network, did an Auto-configuration without it attached, shut off power, attached EP-85R, re-did Auto-configuration

None of this changed anything; the FUEL MANAGER function is completely useless. I have written Lowrance via email about this several times, but all the replies I have received are perfunctory, scripted replies, other than one, which told me to do a re-configure. Well, ten re-configures later, nothing changed.

Eventually, I was able to obtain an updater patch for V.2.2.0, a downgrade from the V.2.3.0 that I installed which caused the onset of all the problems described above with the EP-85R. Revising the EP-85R to this level of firmware solved all my problems.

The remedy of the V.2.2.0 updater patch was supplied by unofficial channels. I got nothing from Lowrance even though I explicitly asked them to give me a patch to an earlier version to test. Lowrance sent me nothing, gave me only banal and simplistic advice (i.e., telling me to re-configure the fuel manager, which I had told them I had already done dozens of times).

Fortunately, a good samaritan on the internet read of my problems and supplied the V.2.2.0 patch which provided a remedy to my problem.

It was nice to have the EP-85R working again, but I remain very disappointed with the support provided by Lowrance for this product. I was fortunate to be able to resolve the problem myself with the help of my anonymous firmware supplier. The last advice from Lowrance on resolving this problem suggested I trade-in my HDS for a newer unit and pay $650. This was their remedy.

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Re: Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 9:44 am

The above two articles have been distilled from a much longer thread on the same topic. To read the longer thread, which includes several sidebars and comments from other uses of EP-85R devices, see


K Albus
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Joined: Fri Oct 09, 2015 1:32 pm
Location: White Lake, Michigan

Re: Lowrance EP-85R

Postby K Albus » Wed Oct 10, 2018 10:37 am

While I have not expended the same amount of effort as you have, I have never been able to get the EP-85R to work properly with my Simrad NSS-8 and Yamaha/NMEA 2000 network.

Posts: 7861
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula

Re: Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 4:19 pm

To be clear, the EP-85R has been working just fine the past several years. I believe that the real problems with the device were those I identified above, and relate to the situation where the EP-85R device is powered on and sitting on a NMEA-2000 network, but the engine data source it expects to hear from about fuel flow is not on that network. After some time, maybe hours, the EP-85R abandons hope of every finding its linked engine again, and it goes into a non-working state.

Alternate theory for the EP-85R to come up with bad data: malfunctions in the EP-85R; I think at least one person reported that a replacement device corrected the problem, although it is not clear if the firmware loaded on both devices was the same; or, the firmware in use is not proper for the I-Command, LMF-400/200, or other Lowrance display firmware that the EP-85R needs to communicate with.

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Re: Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 4:32 pm

To explain in more detail about the ERP-85R, I offer some additional remarks:

Fuel Flow Data from Engine

The fuel flow data being sent by a modern NMEA-2000 engine that sends NMEA-2000 PGN 127489 has no data about FUEL VOLUME. That PGN has no field for fuel volume, and the engine cannot send fuel volume in its data.

The data that comes from a modern engine is not a volume of fuel but a rate of fuel flow. In order to obtain a total volume of fuel used, the rate of flow has to be integrated into volume. This function is performed by an external device that is usually called a FUEL MANAGER.

With the (now obsolete) I-Command or Lowrance LMF series digital gauges, the FUEL MANAGER function was provided by a device that was separate from the display devices. This separate device was called by two misleading names. Lowrance called it a DATA STORAGE MODULE, and Evinrude called it a MEMORY MODULE. A few years ago Lowrance realized their name was misleading, so they renamed the device to be the FUEL DATA MANAGER.

The exact method used by the FUEL DATA MANAGER alias DATA STORAGE MODULE alias MEMORY MODULE alias ER-85R is not described by Lowrance anywhere. My GUESS is that the device periodically samples the data about fuel flow rate at a regular interval.

For example, let us say the sample interval is every 10-seconds; the integration of fuel flow rate into fuel volume would then work like this:

  • the engine sends data that says the fuel flow rate is 4-gallons-per-hour
  • this flow rate is assumed to be constant for the last 10-seconds
  • the FUEL MANAGER takes this data and computes a volume of fuel consumed in the last 10-second as 4-gallons/1-hour x 10-seconds x 1-hour/3600-seconds = 0.011111-gallons
  • this value is then added to a previously stored value of FUEL USED

In this way the external device called the FUEL MANAGER or other names, accumulates a totalized volume of fuel use, repeating the integration and totalization function every ten seconds (or at whatever interval the designer of the device decided to use).

As you can easily infer, the duration of the sample time can affect the process of integration of flow rate to fuel volume. The more often the FUEL MANAGER samples the flow rate data, the more likely the computer total volume of FUEL USED will be correct.

It should be clear that when the engine sends the flow rate data, it is done with its part of this function. The data from the engine is created by the engine's control system. The presumption is that the flow rate data is derived in the engine control system by using the stored fuel map algorithms that actually run the engine. The data derived this way should be very precise. There are only two ways the actual fuel flow might not match the expected pre-calculated fuel flow: if there is a fuel supply restriction, the engine might be running leaner than it wanted to run; or a fuel injector might malfunction and not spray enough fuel. In the other direction a fuel system leak could result in the engine using more fuel than it wants to. This could occur, for example, if a fuel injector malfunctioned and was spraying too much fuel into a cylinder, or if there were a leak at any point in the fuel system where fuel was spilling out.

Sensing or Computing Fuel Tank Level

Now none of this has anything to do with how much fuel the instrument tells you is in the fuel tank. There are two methods to deduce tank level: direct tank level measurement, and indirect tank level measurement by monitor outflow of liquid.

Direct Tank Level Measurement by Sensor
The tank level can be deduced by direct measurement of the level of the fluid in the tank using a sensor. The calibration of this actual tank level sensor is outside of anything to do with a modern NMEA-2000 engine. Usually the sensor converts an electrical signal such as current, voltage, or resistance into a NMEA-2000 digital datagram. A NMEA-2000 sensor will typically be capable of being calibrated to associate the input electrical signal with a certain tank level, such as empty, full, and one or more partial-full steps in between empty and full. The calibration of the sensor is typically provided in a gauge or display that is made by the same manufacturer as the sensor, and the gauge or display will have a software routine to perform the calibration with input from the user.

Indirect Tank Level Measurement by Flow Rate Data

The tank level can also be inferred by tracking the flow of fuel from the tank, and deducting fuel from the tank level as it flows out. The method can be implement in two ways: with a direct sensor that monitor fuel flow, or by using engine flow rate data.

Fuel flow on the output hose of a fuel tank can be routed through a flow sensor, usually a mechanical spin-turbine sensor which creates an electrical signal proportional to flow. This is converted to a NMEA-2000 datagram and sent as a fuel flow rate. Sensors of this type can often be adjusted or calibrated to improve their accuracy. The calibration process usually involves make adjustments to the firmware in the sensor that is converting the electrical signal into a flow rate, and typically the manufacturer of the sensor will also make a suitable display or gauge with a user interface so the calibration can be accomplished.

The fuel flow data can also be taken from a modern engine, for example, from an E-TEC. The engine sends a NMEA-2000 datagram that gives the fuel flow rate. (More details below about this datagram and its units.) The flow rate is integrated over time to get FUEL USED data. The FUEL MANAGER computes the TANK LEVEL by deducting most recent increment to FUEL USED from the previous tank level. Note that the previous tank level is just a value in software, which was initially SET by the OPERATOR. If the operator set an improper value of fuel in the tank, then all future calculations of tank level using this indirect method will be wrong. When fuel is added to the tank, the operator has to invoke a procedure to ADD FUEL, and then enter data into the FUEL MANAGER to tell it how much fuel was added.

For several years I have had an E-TEC engine and three ways to determine fuel tank level:

--a direct indicating tank level gauge operated by a float mechanism in the tank;

--a Lowrance EP-85F FUEL DATA MANAGER that used fuel flow data from the E-TEC to track fuel volume used and tank level; and

--an ICON Pro RPM gauge with its own FUEL MANAGER that also used fuel flow data from the E-TEC to track fuel volume used and tank level.

Of the three methods, the direct indicating gauge was always reliable and had good accuracy.

The ICON Pro RPM gauge was always accurate, as long as I, the operator of the boat, was 100-percent diligent and 100-percent accurate in entering data about the fuel level in the tank at the start and any fuel added to the tank.

The Lowrance EP-85R was generally not reliable at all until, after about a year of fiddling around with its software revision levels and its network power supply management, I finally got it to work reliably and accurately.

Now all three sources of fuel tank level on my boat agree quite closely. The Lowrance and ICON fuel managers differ about 1 to 3-percent in their calculations of FUEL REMAINING. I can only suspect that this difference is due to the difference in the algorithms being used, the difference in the sample intervals, and differences in their math routines to handle very small numbers.

Variation in FUEL REMAINING calculations

If more than one device tracks the fuel remaining or tank level, the situation is like the old saying about a man with two watches: he never knows what the time is. That is, the two (or more) methods of tracking fuel used come up with different answers.

To understand why there could be two devices that track the FUEL USED using the same method (integration of flow rate data over time) and the two devices come up with different values for FUEL USED, I can see several variables.

The first is the time between samples of the flow rate. If one device samples every 60-seconds and the other every 6-seconds, the device with more granularity in samples might be more accurate.

Another possible cause of variation is the handling of the mathematics. The NMEA-2000 protocol calls for the flow rate to be sent in units 0.0001 cubic-meters/hour. There are 264.172-gallons in one cubic meter and 3,600-seconds in one hour.

If a modern engine engine is idling along at 0.2-GPH, the flow rate in cubic meter would be

0.2-gallons/1-hour x 1-cubic-meter/264.172-gallons


0.000757082506852-cubic-meters in one hour.

Now if the sample time is every 6-seconds, then the volume used would be

(0.000757082506852-cubic-meters/3600-second) x 6-seconds


0.000001261804178-cubic meters

The FUEL MANAGE has to do some addition, adding this value of fuel consumed to the running total of FUEL USED. This involves a lot of addition of really small numbers, and I suspect this is where some errors might occur. If the math is not done to many, many decimal/binary places, some rounding errors could occur. That is a rounding error every six seconds of running time. Over ten hours of running time that means 6,000-rounding errors. Maybe that adds up to a possible variation of a few percent in the outcome.

You might ask how can there be an error in arithmetic in a modern device? All this math is being done in binary arithmetic, and that means the numbers have even more places, more like 50-places. How accurate the addition and subtraction becomes depends on the algorithm used. Maybe the code in one device is more elegant and strict than the code in another device. And that accounts for a difference of one or two percent in their outcomes.

The other place were an error can occur is much easier to understand: the operator did not correctly input the initial tank level or any subsequent additions of fuel. This is more likely. This is particularly true because if a mistake is made in data entry of fuel added, there is no method to correct the mistake in the gauge's options. For example, if 10-gallons of fuel are really added to the tank, but the operator enters the fuel added value as 11-gallons, that mistake cannot be corrected. Or the mistake may go unnoticed.

The only error in fuel added entry that can be fixed (if the operator notices the error) is entry of a value that is less than actual; you just repeat the fuel added routine and add more fuel to make up the difference. If you make a mistake in data entry and enter too much fuel, there is no recovery. If you forget to compensate for this mistake, you eventually might run out of fuel because the FUEL MANAGER is working with bad data.

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Re: Lowrance EP-85R

Postby jimh » Wed Oct 10, 2018 4:45 pm

I don't have any idea if Lowrance support is offering these updater patch files for the EP-85R at this time. In case anyone wants them, you can get them from the links below:

For EP-85R:
Update to v2.2.0
Update to v2.3.0
Update to v2.4.0

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Re: Lowrance EP-85R

Postby jimh » Mon Oct 15, 2018 6:29 am

For more information on these firmware updates see

EP-85R Data Storage Module Updaters

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Re: Lowrance EP-85R

Postby jimh » Mon May 18, 2020 7:38 am

The comprehensive installation and operating instructions for the Lowrance EP-85R or DATA STORAGE MODULE or FUEL MANAGER MODULE or the Evinrude MEMORY MODULE are no longer available from Lowrance's site. Below is a link to a working source of this document:

EP-85R Storage Device
Installation and Operating Instructions