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Greetings Frank, I wouldn't think I would be in any risk of a fire starting if I jump all four to full power, since they are not all drawing from the same power source. I would basically have two matching systems, so one pair of thruster on one bank, the same with the other pair. I would just have the ability to switch which battery bank I run either pair on. I would like to see the data you found on the speed controls, and power efficiency some time. It sounds like I'm on the right road. I can see that if I was a long way from home, I might need more then one spare thruster. For my sub if one or both rear thruster go out it wouldn't keep me from diving and doing most things just like a traditional K-250. If one goes out on the side I could use one of the rear ones to replace it, but I suspect I could do just fine on one, since I plan to use the side thrusters mostly for depth control like Alec now does. Now that I thick about it, I could have all but one rear thruster go out and still do pretty good. If that happened I could just use the VBT like Alec used to for depth control. So I suspect the same would apply to your sub, since your running four thrusters in the same basic configuration as I am. Speed would be limited of course, but you could operate. Regards, Szybowski From: ShellyDalg@aol.com Date: Tue, 9 Dec 2008 20:30:28 -0500 Subject: Re: [PSUBS-MAILIST] Lifting K-250 Off Trailer the Hard Way To: personal_submersibles@psubs.org Hi Brent. I agree it makes more sense to get 4 thrusters that match. The cost difference between a 12 volt and a 36 volt isn't that much. ie: more power per dollar with the salt water 101's.
Also, it's easier to keep spare parts/motor on hand if they all match. As for the " burst of speed" using all four at full power.....better be careful as they EACH draw 46 amps at full power! That could start a fire.
All the info I've found concerning the speed controllers that come with them says that running them slow saves a lot of power over using a smaller motor at full speed.
I chose them mostly because of the spares issue. If I'm down in the Sea of Cortez chasing Humboldt squid and I blow out a motor, I've still got three more to continue with until I get back to shore, and can switch/replace a motor easily. I will be carrying a couple of extras where ever I go. Frank D. |