P Spec Tunnel Data

[lohring]

To give everyone a reality check, below is a snip of data from my ICE 100 data logger during a tune up race with Jerry Dunlap's P spec boat. The speeds were typical of normal race speeds under perfect conditions. Contrary to popular opinion, the motor and ESC are fine. I expect to run both all season at these currents. Jerry's Top Speed 3 ran the same prop at similar speeds, so I bet the currents were also similar. He used a Turnigy Marine 120 ESC.

Lohring Miller

 

[hugh hargett]

Looks good what was your peak? around 123 or so? wat motor? Very little ripple, very nice Lo. What batts you running? caps?

 

[SeanKewley]

Can the ICE give average amps for the entire logged run? If so, please post.

 

[hugh hargett]

yes it can . Hes put the data into an excel graph

 

[jayt]

The normal ICE output does not give any averages for the run, but since Lohring exported the data into Excel he could plot an average line...but why bother? The running current was clearly a bit over 100 amps most of the time.

Since the voltage ripple was not shown - maybe not even logged - we have no idea what it was. The resolution of the pack voltage is too low to see it based on pack voltage alone. Based on my extensive logged data on P-Limited setuops, I'd expect to see ripple spikes of up to 10% depending on battery quality and wire length. Interestingly, my P-Limited Sport Hydros normally pull between 80-90 amps during a race, my motor has lasted three years so far.

.

 

[hugh hargett]

Yead id agree a better resolution would be more accurate but I clearly see dips in the voltage.properly interpreting the graph would take understanding by the visual indication of the scale and whats known; meaning we know the starting voltage was around 16.8 appx 17 for the scales sake, well from 17 to 20 is small so thats your scale 3 units volts to that small space. At the first dip it would be easy to see he likely dropped a volt and a half or better. Didnt know the ice wasnt like my new v2's which show average. Looks like you were slipping to me almost as much hooking up, choppy day lohring?. I interpret the slips where rpm goes up but current goes down. The ensuing "GRAB" almost always leads to an amp spike. I see the ripple dont you? looking at it if there are 19 dashes as indicated bye the scale it looks like it may have dropped more than 1.68(10percent) volts in a few places. The castle graph looks much better on my end - plus you can crop a box around the specific part of the graph you want to see and it will zoom in on it . As far as wire you need to look a gauge as well as length. If you wanna get smart you can look at the strands is it ofc wire yadiyadi da. Post A run Lohring .Nice info

Im like you shawn id want to know an average too; to see how close im continuously running amp-wise with respect to my esc.

agreed the actual ripple plot is of a larger scale.

 

[lohring]

The average current for the entire ICE graph of four heats was 36 amps. That includes lots of motor idle and off time so is completely useless. That graph I posted is of a couple of clean, full throttle laps on a short course with 120+ amps in the corners and around 90 to 100 amps in the straight. I was off the throttle at the beginning and end of the graph. You can tell the boat's speed from the rpm. The X axis is an arbitrary scale. I'll need to look up the sample rate for the exact time scale. The water conditions were perfect. Since there were only two boats it was very smooth.

You may wonder why my motor still runs after a race at these currents. Electric motors can be seriously overloaded if heating is controlled. I don't know what the conditions were when the UL-1 motors were rated, but I do know the conditions of my test. I think this shows the currents most of the people I race with run. Currents may spike higher if it's rough.

Lohring Miller

 

[hugh hargett]

how do you explain the points of low current and high rpm :huh: ? I hear you on the ul 1 - like I said youve done a nice job there. Great info.

 

[SeanKewley]

I agree that higher amp loads are possible on tunnels because the motor is exposed to outside air flow, but readers need to understand that inboard UL-1 motors are not capable of these same currents for heat racing setups. Another important take away is that you are using a Turnigy 120amp ESC. I don't think an AQ UL-1 ESC is capable of lasting under these same conditions.

Here is an eagle tree chart from my heat racing P-Ltd Tunnel (Turnigy 120amp ESC also). Averages for speed and amps are at the bottom of the chart.

 

[jayt]

how do you explain the points of low current and high rpm :huh:

By using physics - this is always the case with FE motors. As you load the motor, the rpm goes down. As the motor unloads the rpm rises. These two parameters cannot be otherwise - if accurately measured. Rpm will drop over the run as battery voltage drops off. The ICE does not measure current directly, but calculates it based on pack voltage drop.


.

 

[D. Newland]

how do you explain the points of low current and high rpm :huh:

...The ICE does not measure current directly, but calculates it based on pack voltage drop..

This is interesting. How accurate do you think the amp logs are? Lohring spends a lot of time saying how much the UL-1 motors can take, but if the logging accuracy is questionable...so's his conclusion.

 

[Andy Brown]

How much of a problem is it concerning motor damage or shortened life being exposed to the elements from blowovers when mounted on a tunnel like this?

 

[hugh hargett]

D, I dont know with the logging, I thought possibly that my castle esc possibly had a topology supporting foc commutation but after Jay's comment about how they approximate current I really dont know. If they were using foc topology and commutation algorithm they to me it would be accurate enough coz current would be measure through shunts on at least 2 of the leads fed through an array of op comparators and op amps voltage would be captured through a simple voltage divider .

What he suggest leads me to believe it would be a sensorless top using trapazoidal back emf to sync the motor and the logging is simply a coding trick. A sensored design ipliments hall and likewise would have a near 0 ohm resistor and a camparator to do the current sense work. Even though I think I know a little about esc design which Jay will tell you I dont, Brian is Jays pal and has deep ties with castle so maybe Jay knows something I dont :unsure: .Cant argue with him here d coz I havent opened up my castles nor do I plan to. Jay? Brian?

The eagle tree Sean is using uses a current shunt so it pretty acurate what they cry about on his is is the gps accurate? I say just compare it to theoretical pitch speed .

Im not going to say jay is wrong but i have my doubts this is why - im my programming software for the icehydra hv v2 you can set the curren limits HOW could it know and acurrately monitor it without some type of fault topology even with code tricks gotta have the topology to support the tricks. If they already have some thing like that accurately measuring current of course they use it. I believe there is way to much current tailoring in my esc programming software to not have some type of current shunting topology. The 400.00 dollar retail price supports this theory as well.

Here again Im not saying Jay is wrong It is just quite hard for me to believe. I hope we can continue this conversation as fellow boater trying to learn. Jay If im dead wrong I look to learn not be the smartest.

Think about it there are no hall sensors so its gotta be looking at the leads to get rpm :huh:

Hugh

D you believe this if you believe nothing else - something is better than nothing at all. Get yourself ,if you havent already, some data logging equipment . It is invaluable as a tool on knowing whats going on in a fe or nitro thats what almost all the top tier race vehicle have datalogging and some type of telemetry.

Im a curious to the answer of this question as you are .

 

[SeanKewley]

How much of a problem is it concerning motor damage or shortened life being exposed to the elements from blowovers when mounted on a tunnel like this?

The only real concern is the bearings corroding. Some guys just drain the water out of the motor and spray with corrosion X. I remove my motor from the lower unit after the race, spray it out with compressed air (key board cleaner), and spray with ACF-50. Otherwise the water doesn't hurt them a bit.

 

[lohring]

I have no idea about the accuracy of the ICE data logger. An interesting test would be to run an Eagle Tree data logger at the same time. We ran two Eagle Tree loggers on our full size electric hydro as well as a GPS speedometer. All three speeds agreed within 1 mph and the voltage and currents from the two data loggers was close even though they were connected to different battery packs. We also ran a Garmin GPS in our gas hydro and compared its peak speed with a radar gun. The GPS was always a few mph slower.

In any case there has been a lot of argument with no data to back it up. Many of you have the equipment to see what's happening. What do you see with your boats?

Lohring Miller

 

[Darin Jordan]

I'm curious, however, how an EagleTree affects the current measurements itself, since it's generally placed inline between the battery and ESC??

I e-mailed Eagle Tree and they assured me that on my V3 version (150A) that the current sensor type had no effect on Voltage drop and added no resistance. Hmmmm.. The extra lines and connectors have to, though.

 

[hugh hargett]

The resistor value in a shunt like that is near zero . It is negligable. Heres the thing run one without it and see how close you are to accurate just guessing. The data logging and gps both are good and accurate enough to tune your boat- what they are intended for. To know whether its accurate is to know how it actually being capture then go from there. Im personally very pleased with my castle esc's. Ease of programming and lots of custom taloring current wize amongst other things. I just install an external cap bank and forget about minimal losses. The amperage reading just tell me where i need to go on propeller or set up - bigger/smaller wetter/drier. If you dont want to buy 5 300 plus dollar esc's by one and use it as diagnostic equipment . Once you know where you run at you might safely be able to swap it out for a turnigy or something for the race. I think the readings are accurate ENOUGH. These guys dont just throw this stuff together . They are engineers trust me accuracy means something to them. They mathmatically analyze every node of the circuit. You have nothing to worry about Just go out and enjoy the privledge of owning datalogging equipment or go get you some if you dont have any.

Hugh

still havent heart back from JT on the topology of a castle ice :mellow: .

 

[SeanKewley]

I'm curious, however, how an EagleTree affects the current measurements itself, since it's generally placed inline between the battery and ESC??

I e-mailed Eagle Tree and they assured me that on my V3 version (150A) that the current sensor type had no effect on Voltage drop and added no resistance. Hmmmm.. The extra lines and connectors have to, though.

Darin,

Seeing that you have an Eagle tree also, do you have any charts to share for your P-Ltd tunnel setup?

 

[hugh hargett]

I'm curious, however, how an EagleTree affects the current measurements itself, since it's generally placed inline between the battery and ESC??

I e-mailed Eagle Tree and they assured me that on my V3 version (150A) that the current sensor type had no effect on Voltage drop and added no resistance. Hmmmm.. The extra lines and connectors have to, though.

Darin,

Seeing that you have an Eagle tree also, do you have any charts to share for your P-Ltd tunnel setup?

Not trying to be funny Sean but I want you guys to realize your brand of logger doesnt really matter the components and the specs of those components are what they are no matter the brand. meaning a shunt is a shunt. im not sure if thats what you meant by"seeing that you have" if you can pull a model number of the shunt itself I can quickly tell you its accuracy its no mystery requiring graphical analyzation.

just sayin

Anyway im still waiting to hear about the topology of a castle esc Since someone seems to know.

 

[hugh hargett]

:mellow: