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Free Sentry Dpv Dashboard Offer!!!

Discussion in 'Logic Dive Gear' started by Jon Nellis, May 1, 2016.

  1. Jon Nellis

    Jon Nellis Captain

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    The new Sentry DPV Dashboards are a couple weeks away from shipping and from May 1 through June 30, 2016 we are offering a free Sentry with any new Genesis DPV purchase.

    The Sentry DPV Dashboard is the first of it's kind to provide real-time DPV operation data to the diver. In addition to precision depth and dive time, the Sentry enables divers to actually execute a dive plan that factors in the power requirements and battery capacity of the DPV, just a like a dive computer helps a diver execute a dive plan for the amount of available breathing gas.

    The Sentry DPV Dashboard continuously displays how many Watts (W) your DPV motor is using, allowing you to manage your power consumption so that it lasts the entire dive plan. The Watt-hour (Wh) display shows your total power used, so that you know how much of your battery capacity you have consumed. Voltage displays show the voltage of a single battery or two battery packs in series, depending on your DPV, so that you can monitor battery charge and identify a weak or abnormal battery before it becomes a problem. The internal water detector will flash the display screen if fresh or saltwater is detected inside the DPV. Data from inside the DPV is transmitted wirelessly through the wall of the DPV to the display on the outside, no hull penetration are needed. The battery on the external display is rechargeable via contacts on the front, without having to open the display. Battery is factory replaceable with an expected 5 year life.

    Specs
    Yellow OLED Display
    DPV Battery voltage: 50V single battery or 100V two batteries in series
    Max current: 30Amps
    Depth in Feet or Meters: 660ft [200m] (slightly reduced accuracy below 450 ft [150m]) Auto calibrates for altitude.
    Price: $690 USD

    [​IMG]
     
    shoredivr and rjack321 like this.
  2. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    60,211
    28,593
    113
    How cool.
     
  3. Randy g

    Randy g Solo Diver

    # of Dives: 200 - 499
    Location: Virginia Beach, Va
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    And right when a guy THINKS he has everything he needs!

    Thanks Jon!... Is it plug and play?
     
  4. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
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    It is a cool idea, I like it, and I like that it can be added to almost any DPV, but I'm suffering sticker shock, and it needs a data logging function.

    For example, I put an Eagle Tree data logger and power panel in my Lexan nose plated Mako for under $100, and I've done the same thing without the data logging capability with a $15 watt meter.

    The data logging function was great as I could pull the data for the power use on any portion of the dive and track the voltage for the entire dive, as well as read the panel numbers mid dive to ensure the voltage and amps used were consistent with the pre-dive prediction, and ensuring an adequate reserve.

    I also hooked it up the other way when charging the battery to measure voltage and amp hours put back into the battery to give me a good idea of the charge state independent of the charger circuitry and that was useful in identifying a cell going bad, before it went bad.

    The major limitation with this low budget approach is that a) you need a Lexan nose cone to see it, and b) you can't see it while driving it. However I never had much need to do that - it was there primarily to:
    1. confirm the initial voltage at the start of the dive;
    2. build a data set to predict the amp hours used for various speeds and run times;
    3. conform that I used what I'd planned to use and had ample reserve at the point in the cave where we parked the scooters; and
    4. monitor the overall health of the battery by ensuring it wasn't falling below the predicted curve on any given dive.

    And if you don't need to/can't see it, a data logger allows the same data to be collected on any scooter.

    However, with that said the leak detection is very nice and adding a depth gauge is nice and both would be worth seeing on the dive. All of the above mentioned data collection and planning functions mentioned above could be accomplished with it - although a wifi downloadable data logging function would be extremely useful and would eliminate the need to keep any notes. And for $690 I'd more or less expect it on something that is already wireless enabled.

    The disclaimer / caution with a device like this is that if cave divers start using it as a "gas gauge" without proper pre- planning for the burn time, ensuring an adequate battery reserve, and without proper gas planning for a possible scooter failure, they're going to get in trouble.
     
    Last edited: May 3, 2016
  5. Jon Nellis

    Jon Nellis Captain

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    You will need to add a small two pin connectors to your older Genesis DPV. New Genesis DPVs come with the connector pre-installed. Other brands will need to add one or two extra leads from their battery(ies) depending on the model.

    For an old single speed Mako DPV, adding a Sentry to it would be like adding an on-board WiFi hot spot and navigation system to a '71 Ford Pinto. Since you have no way to control your power level with only one speed, you are probably better off sticking with your Lexan window and Eagle Tree, since your power level does not change significantly.

    The Sentry is designed for variable speed DPVs or DPV with multiple preset speeds. It allows the user to plan and execute a DPV dive just like the gas plan for the dive, only with easier math.

    -Battery power is a consumed resource, just like breathing gas. You run out of either and your dive starts to suck really quick.
    -Power level is just like SAC rate. Without a DPV you can kick hard and go faster, using more gas and turning sooner or kick slower and extend the dive time. If it were possible to precisely control your SAC rate, you could control exactly how long the gas in your tanks would last. The Sentry gives you the feedback so that you can precisely control your power level and in turn, control how long your battery will last.

    Given a known battery capacity, the diver can use the rule of thirds or what ever they see fit for their dive plan. The Watts display allows you to control your power(speed) so that your outbound scooter power budget coincides with your outbound gas run-time and you turn the dive based either on reaching 2/3 of your gas supply or 2/3 of your battery capacity, which ever comes first.

    Example:
    600Wh battery in DPV, diving to thirds, leaves 200Wh outbound, 200Wh back and 200Wh reserve for towing buddy, surprise current, etc. 3000PSI in your tanks means 1000psi outbound, 1000psi back and 1000psi reserve. If your SAC rate at the planned depth gives you 40 minutes out, you also have 40 minutes to consume 200Wh of battery, which means a constant power of 300 watts. Stay at or below that power level (on average) and you will turn with the planned battery capacity, just like your planned gas volume.

    With a few test dives over a know distance, you can determine what power levels correlate to different speeds and then plan how much range you have for the given run-time, and use that to calculate things like bailout gas requirements, should you have a failure at max penetration in a cave. The Sentry is not about monitoring your battery history to tell when you need to change your batteries (although it will tell you that just by noting the Wh used and ending battery voltages every few dives). It is designed to allow you to execute a dive plan that treats your battery capacity as a consumable resource, just like your breathing gas. Diving a DPV without a Sentry on it is like diving tanks with no pressure gauge and assuming that your experience of your previous SAC rate, the length & depth of the dive and your gas volume, you should be fine not knowing your tank pressure at the planned end of the dive.

    You don't guess on your tank pressure, you have a gauge, but everyone has been brought up thinking that it's OK to guess on your DPV battery capacity remaining. With a single speed scooter that only has one power level, your runtime is almost always the same. That's not the case with a variable speed DPV that can use anywhere from 50 to 1000 watts when moving. A mile off shore in current or 5000ft back in a cave is not a good place to start guessing if you have enough battery to get home.

    There are two reasons there is no data recorder, the first being that on the DPVs the Sentry was designed to be used on, the data chart that it would generate has no real value unless you can also correlate it to what you were doing at that specific time, so unless you overlay the chart onto a video of the entire dive you really don't know what every little spike on the chart was due to. Secondly, adding a data logger and WiFi radio (since WiFi only goes about 0.1mm in water and definitely not through an aluminum scooter housing) would add about $300 to the cost, since software and electrical engineering R&D if not free and this is not a high production item over which to amortize the cost. How's your sticker shock now?

    Cheers,
    Jon
     
    Last edited: May 4, 2016
    Randy g likes this.
  6. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
    11,518
    1,705
    113
    Sorry, but you're made a horrible mistake in your underlying assumption here - and you're telling a substantial portion of your potential market not to even bother with your product as their scooters are too primitive to benefit.

    The fact is that they may in fact find a great deal of benefit in your product as those same "single speed" scooters vary a lot in the power they draw based on the prop pitch selected. I find your approach to be a very strange marketing strategy.

    Specifically, all of the "old tech" scooters using the basic single speed Oceanic motor and cowl along with an adjustable pitch prop are in fact "single speed" in terms of motor RPM, but they vary a great deal in terms of the amps they pull out of the battery and the thrust produced as the prop pitch is changed from 1 to 9.

    You specifically mention a Lexan nose plate which is modified Mako specific, but the same single speed motor, prop and cowl are used on Gavins and many SS scooters, where a Lexan nose is not an option. In other words, if someone were to use your system on their UV-18 they'd still have an awful lot to benefit from by being able to immediately see how much power they were drawing from the battery at any point in the dive as they adjust the prop pitch on their "single speed" scooter

    For example, I'll pull 13 amps at prop pitch 9 with a hot wound 1000 rpm Oceanic motor, which progressively drops as low as 4 amps at the lowest pitch and draws only 1.5 amps when running it out of the water at any pitch setting. Knowing that information helps a great deal in dive planning as well as in noting changes in performance of the battery as it process through its useful life.

    But hey, you're right a UV-18 or UV-26 owner can get all that information after the dive using an Eagle Tree data logger for about $80. So there is no need for them to buy your product - which doesn't log data anyway - and the benefit of seeing that displayed on the dive are not worth $690. It's not my place to disagree with you on that.
     
  7. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    60,211
    28,593
    113
    Dude, do you realize how awesome this would be? That's a collectors edition now, and to have it tricked out with all the cool stuff would be rad! That year they had the 1.5l EnFoMoCo engine in it. Later they put that tinnie 2.3 German POS engine that always leaked oil. Yeah, that would be an awesome car to own. :D Of course, I would modify the gas tank a bit as well. :D :D :D
     
  8. Jon Nellis

    Jon Nellis Captain

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    Nah, just give it a flame paint job and let life imitate art. ...then go wash and wax your AMC Pacer. Now there's a classic! :D

    [​IMG]
     
  9. Jon Nellis

    Jon Nellis Captain

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    Yes, well I'm an engineer, not a marketing pro. My comment was focused on your statement that you have a workable solution that fits your budget and perceived value.

    Exactly, and the Sentry eliminates the need to collect that data with a data recorder on previous dive to be used for planning on future dives, because it displays the power data in real-time. Your argument that you need the data recorded of known pitch vs power levels for use on future dive planning is now irrelevant. You plan the dive however you want and then adjust your power on the fly to fit the plan via real-time power indication, instead of planning around how you think your scooter will perform (based on past performance) and hoping it all works out.

    As for data logging, there's not much that ten thousand data points over the course of a normal DPV dive will tell you, that the Watt-hours consumed and ending voltage of the Sentry won't, when assessing battery life. Data loggers work well for tests like the Tahoe Benchmark that are run at a continuous steady state, in benign conditions where it is easy to spot anomalies in the performance data, but most actual DPV operation is not done going straight down a line at the same speed in ideal conditions the entire time. There are multiple starts and stops, turns and body position shifts that increase drag, changing the power load, plus speed changes and surprises like kelp on the prop, that cause power fluctuations that could never be identified as either external or internal to the DPV, unless you video the entire dive to correlate to. Having a bunch of data with no correlation to the cause of anomalies, is just worthless data and not worth recording, just like most of the data that divers think is so important to down load from their dive computer and then do nothing with, other than note the average depth and run time to determine their SAC rate, which they most likely have to write down the starting and ending tank pressures with a pencil and paper, and then calculate based on tank volumes.

    My dive computer displays an amusing little chart of the dive with depth over time, and deco obligation points and levels, none of which is particularly useful after the dive, but it's a nice sales gimmick. My dive computer (and DPV computer) tells me what I need to know at the time that I need it, not the next day or next year and without guessing. If I want to track my SAC rate at the end of the dive for future dive planning, I still have to write down my pressures off my SPG and do the calculations based on tank volume, the way nature intended. :D While you're writing those down, jot down the Watt-hours and ending voltage and you will have all you need to track battery life.

    As for perceived value, when deciding how far to go from the boat on the third dive of the day or whether to turn back out of the cave due to excessive power consumption on the way in, even though turn pressure has not been reached, that is up to the individual consumer. You can save your money, guess and suffer the consequences if you are wrong, or you can pony up and know for sure you won't be swimming home, towing your scooter with a dead battery. What that is worth varies with each individual and your position seems clear.

    Best regards,
    Jon
     
  10. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
    11,518
    1,705
    113
    We agree on what needs to be collected, but we perhaps just disagree on the approach. For example, my Full Cave instructor was a stickler for remembering my gas pressures and run times at various key points and navigational decision points in the cave. The idea was that if you knew how much gas you were consuming on each leg of the dive and knew how much time if took to get there, you'd have much better idea how much it would take on the return - and you'd quickly spot any anomaly (missed T, etc).

    I disliked the additional task loading at the time, but I've retained the practice and find it to be a very useful planning tool. The same applies to DPV dives were I'll note the time/speed distance and prop pitch used, and the remaining voltage and Ah used at the destination, and at the end of the dive.

    Whether I use a data logger or a real time display, I'll still need to record or remember the conditions relevant to the data. With a data logger, I'll correlate the graphic output with time, speed, distance, and prop pitch data from the dive, and I can also use the dive computer data to identify the times based on the cave profile and depth data, which combined with the distance information lets me calculate the speed.

    If I used a real time panel display I'd still have to note, record or calculate the time, speed, distance and proper pitch data AND I'd have to record the voltage and current numbers as well, rather than just looking at them post dive.

    However, I agree with you that once you've accumulated the data to know how much battery capacity is needed to go how far at a given motor speed, what speed that will produce in the water in a given configuration, and how much farther you can go at a slower speed on a given amount of remaining battery capacity, all you need to make some on the fly planning decisions if the amount of usable power left in the battery.

    But I'm not sure that's relevant either. I always want to leave a 1/3rd reserve in the battery whether it's in a cave or in the water and planing on the fly isn't my preferred approach. I want to plan the dive and then use the display to confirm that the battery is performing as predicted, not make decisions on the fly.

    Simply put, we bought CCRs at DEMA this past year and we'll probably buy new DPVs this year or next year at the latest. As a potential customer for a pair of scooters, your scooters are competitively priced and offer features that interest us, so your products are on the list to review in more detail. Along with that I like what the display offers in terms of monitoring the charge state. But I really like knowing the current being drawn at a given speed, and I like having the data logged at the end of the dive to compare agains the other data available for the dive.

    As a potential customer, I'd be thrilled if your unit had a data along function. Given that it doesn't, I'd be inclined to use a data logger with it. As an engineer, will your unit let me run a data logger in series with it?
     

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