<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1433621245176_12450"><span id="yui_3_16_0_1_1433621245176_17013">Thanks for the report Alec, great stuff.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_16539">re the motor controllers; I've been reading a bit about inductance in long wire runs from battery to</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_16538">motor controllers, that harms the capacitors on the controllers.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_21227">This could be a problem that is unique to our submarines & not an issue with things like golf carts</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_21395">& wheel chairs.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_16537">My reading has been mainly about BLDC motor controllers but asume PWM controllers for brushed</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_17637">motors would be similar. Because of the rapid switching on & off of the power to the motor, there is a</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_17640">current surge hitting the capacitors & the longer the wire run, the more the power in the surge.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_17956">A water analogy would be turning a valve off suddenly as washing machines do, sometimes with</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_19350">a "thunk" sound & a rattle of the pipes.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_21700">Hugh mentioned he had problems with his Curtis BLDC motor controllers.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span id="yui_3_16_0_1_1433621245176_23293">Attached is the problem & solution, which is to put capacitors in parrallel along the battery wire; </span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span>however there must be a better way.</span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr">Regards Alan</div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><a href="http://www.rcgroups.com/forums/showthread.php?t=952523" id="yui_3_16_0_1_1433621245176_22798">too long battery wires will kill ESC over time: precautions, solutions & workarounds - RC Groups</a><br></div><div style="width:450px; font-family: 'Georgia', 'Times', 'Times New Roman', 'serif';margin-top:5px; margin-bottom: 5px; background-color: #ffffff;" contenteditable="false" id="enhancrCard_0" class="link-enhancr-attachment link-enhancr-element"><table class="link-enhancr-element" cellspacing="0" cellpadding="0" border="0" style="width:450px; height:170px; position: relative; display: block;"><tbody><tr class="link-enhancr-element"><td class="link-enhancr-element" colspan="8" style="height: 1px; background-color: #e5e5e5; font-size: 1px; 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background-color: #e5e5e5; font-size: 1px; line-height:0px"> </div></td></tr></tbody></table></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span><br></span></div><div id="yui_3_16_0_1_1433621245176_12450" dir="ltr"><span><br></span></div><br> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1433621245176_12453"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1433621245176_12452"> <div dir="ltr" id="yui_3_16_0_1_1433621245176_12451"> <hr size="1" id="yui_3_16_0_1_1433621245176_16536"> <font size="2" face="Arial" id="yui_3_16_0_1_1433621245176_16529"> <b id="yui_3_16_0_1_1433621245176_16535"><span style="font-weight:bold;" id="yui_3_16_0_1_1433621245176_16534">From:</span></b> hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><br> <b id="yui_3_16_0_1_1433621245176_16533"><span style="font-weight: bold;" id="yui_3_16_0_1_1433621245176_16532">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b id="yui_3_16_0_1_1433621245176_16531"><span style="font-weight: bold;" id="yui_3_16_0_1_1433621245176_16530">Sent:</span></b> Sunday, June 7, 2015 12:20 AM<br> <b id="yui_3_16_0_1_1433621245176_16528"><span style="font-weight: bold;" id="yui_3_16_0_1_1433621245176_16527">Subject:</span></b> Re: [PSUBS-MAILIST] Dive report: Snoopy at Seneca<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1433621245176_12454"><br>Alec,<br clear="none">I don't know what type of speed controller you are using, but I like and use Curtis golf cart controllers. They are rated for huge amperage and seem bullet proof. I have an extra 36V controller I can send you to try out. They use a 10 OHM potentiometer for the throttle. They also have a battery protection mode, a sort of get home conservation mode. <br clear="none">I labeled the motor in Gamma for a jumper cable, so that I can get home without the controller. As you said it is electronic and it will fail.<br clear="none">If you want the controller send your address of list.<br clear="none">Hank<br clear="none">--------------------------------------------<br clear="none">On Fri, 6/5/15, Alec Smyth via Personal_Submersibles <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org" id="yui_3_16_0_1_1433621245176_19349">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"> Subject: [PSUBS-MAILIST] Dive report: Snoopy at Seneca<br clear="none"> To: "Personal Submersibles General Discussion" <<a shape="rect" ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org" id="yui_3_16_0_1_1433621245176_19348">personal_submersibles@psubs.org</a>><br clear="none"> Received: Friday, June 5, 2015, 6:16 PM<br clear="none"> <br clear="none"> Hello friends,<br clear="none"> I just got back from a dive trip to Seneca with<br clear="none"> Dan Lance and thought I'd share how it went. This was<br clear="none"> supposed to be a two sub trip with Scott Waters, but<br clear="none"> unfortunately a business emergency intervened and it ended<br clear="none"> up being just Snoopy.<br clear="none"> On the way up the weather was terrible, with<br clear="none"> driving rain so heavy I could barely see the lines on the<br clear="none"> road. It had been raining heavily for several days<br clear="none"> previously. Three times there were emergency announcements<br clear="none"> about floods, large hail, and damaging winds, and the closer<br clear="none"> I got the harder it rained. The problem with all that rain<br clear="none"> is that in your typical lake, the runoff ruins visibility<br clear="none"> for weeks. That is what happened last year when Trustworthy<br clear="none"> and Snoopy rendezvoused at Summersville Lake, and it looked<br clear="none"> very much like this would be a repeat. I'm happy to say<br clear="none"> Seneca must be rain-proof, because the deluge only reduced<br clear="none"> the visibility in the top fifty feet or so, and even those<br clear="none"> were clearer than most lakes.<br clear="none"> Here's a few things we learned:<br clear="none"> 1) Of props and shroudsThe stern<br clear="none"> thruster speed control was dead on arrival, although I had<br clear="none"> tested it successfully before leaving. I opened up the<br clear="none"> enclosure, pressed down all the spade connectors, and found<br clear="none"> it now worked - so attributed the issue to road bumps.<br clear="none"> However, it died within a minute on the first dive. I had a<br clear="none"> spare speed controller, so switched it out. <br clear="none"> The replacement died within five minutes on the<br clear="none"> second dive. This time at least the cause was obvious, the<br clear="none"> prop was jammed by weeds. The current Minnkota props have a<br clear="none"> little twist at the end of the blades, and Snoopy's<br clear="none"> shroud is made with almost no clearance. The little twist to<br clear="none"> the blade tip causes any object coming between prop and<br clear="none"> shroud to jam tight, and had already smoked one controller<br clear="none"> during the convention in the Keys. I'm going to put the<br clear="none"> prop on the lathe and take off the tips to eliminate the<br clear="none"> pinching effect and to reduce the amperage draw a little so<br clear="none"> the motor goes lighter on the speed controller. By the way,<br clear="none"> the speed controller was protected by a fuse rated a little<br clear="none"> below the controller spec current draw, so perhaps those<br clear="none"> specs are optimistic. Anyway, as a result of the double<br clear="none"> failure all of our dives were done on just the side<br clear="none"> thrusters because I was out of spare speed controllers.<br clear="none"> Lesson for next sub: Design the electrical system with a<br clear="none"> controller bypass, so I can operate thrusters with simple<br clear="none"> on/off switches if a speed controller fails. They're<br clear="none"> electronic, they will fail.<br clear="none"> 2) Of air bubbles in compensation oil<br clear="none"> Snoopy is now routinely diving deep (250 ft) and<br clear="none"> this has showed up a puzzling issue with the thrusters. They<br clear="none"> were feeble during dives, one died altogether on one dive,<br clear="none"> and they kept coming up leaking oil. At first we thought the<br clear="none"> seals were failing, perhaps due to some chemical<br clear="none"> incompatibility. We found suitable seals at an Amish farm<br clear="none"> supply store that sold things like tractor spares (viva<br clear="none"> trolling motor simplicity!) When I disconnected the bladder<br clear="none"> hose I got quite well sprayed with oil. The motor turned out<br clear="none"> to be pressurized. <br clear="none"> Previously, I thought if one had a small quantity<br clear="none"> of air left in the system it would not be an issue so long<br clear="none"> as the compression volume of that air could be handled by<br clear="none"> the flexibility of the hose (aka compensation bladder.)<br clear="none"> Wrong. I now think what happens is that if the dive exceeds<br clear="none"> the pressure rating of the shaft seal and there is a bubble<br clear="none"> of any size, you will get water added to the oil and the<br clear="none"> bubble stores the pressure. Upon surfacing, the bubble<br clear="none"> squeezes oil and water back out until the pressure in the<br clear="none"> motor falls to the "cracking pressure" of the<br clear="none"> seal. Thus, you get an oil leak even though the seals are<br clear="none"> fine. Lesson: Zero tolerance with oil bubbles, even a small<br clear="none"> bubble is unacceptable if you are diving deep. I'm going<br clear="none"> to put set screws on the motor caps so I can get rid of the<br clear="none"> bubbles more easily.<br clear="none"> 3) An easy way to add<br clear="none"> buoyancySnoopy's buoyancy is adjusted by<br clear="none"> placing trawl floats in PVC tubes. On one occasion, the<br clear="none"> oncoming passenger's weight required the addition of<br clear="none"> just one float (i.e. the new guy weighed seven pounds more<br clear="none"> than the one getting off). The support diver wasn't<br clear="none"> suited up and the water was 42 degrees, so I just pushed a<br clear="none"> float under the lip of the forward MBT. It worked like a<br clear="none"> charm, and the float even stayed in place throughout the tow<br clear="none"> back to the ramp. Lesson: You can easily add a few floats<br clear="none"> for buoyancy on a standard K sub, no special tubes<br clear="none"> required.<br clear="none"> Most of our dives were along a very steep<br clear="none"> incline, not quite a wall but more like a series of ledges<br clear="none"> and very steep slopes. Between the steep terrain and the<br clear="none"> good visibility, the K250 dome for once offered a really<br clear="none"> good view. We typically made our way down the slopes using<br clear="none"> very slightly negative buoyancy, trailing the back corner of<br clear="none"> a skid on the slope. Looking aft, you could see a zigzagging<br clear="none"> trail of silt hanging motionless in the water and tracing<br clear="none"> our path. The sub compresses with depth, so slightly<br clear="none"> positive buoyancy at the surface turned into slightly<br clear="none"> negative at depth, but we're speaking of just a couple<br clear="none"> of pounds and not anything that caused difficulty. In fact<br clear="none"> at one point we stopped dead in the water four or five feet<br clear="none"> above a flat bottom for about five minutes, just waiting for<br clear="none"> a pre-arranged touch-point call on comms. The sub didn't<br clear="none"> rise or sink an inch, she just hung there completely<br clear="none"> immobile for five minutes. At about 140 feet the visibility<br clear="none"> would improve significantly, and the water changed from<br clear="none"> green to blue. It looked like ocean instead of lake water.<br clear="none"> I'll post a video, but that'll take a few days to<br clear="none"> put together. The only "incidents" we had were a<br clear="none"> cold bath we took when we closed the hatch over a corner of<br clear="none"> the crew's shirt, and when we got hooked on a log at 220<br clear="none"> feet - fortunately reversing got us right off<br clear="none"> it.<br clear="none"> <br clear="none"> Best,<br clear="none"> Alec <br clear="none"> <br clear="none"> <br clear="none"> <br clear="none"> <br clear="none"> <br clear="none"> -----Inline Attachment Follows-----<br clear="none"> <br clear="none"> _______________________________________________<br clear="none"> Personal_Submersibles mailing list<br clear="none"> <a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"> <a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><div class="qtdSeparateBR"><br><br></div><div class="yqt9389914025" id="yqtfd66451"><br clear="none"> <br clear="none"><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a></div><br><br></div> </div> </div> </div></body></html>