Yes, and as you know so far the Mill Pond is sort of home base for me, but I'm branching out of course, but I could easily just plug the thing into the inverter in my truck or put one in the car, Your right, I could always charge during the surface interval.Originally Posted by Slüdge
I wonder how LIPO batteries take to "surface charging"
The Lithium Polymer batteries in the Viper, Minnus, Minnus 1.5 and the Magnus do take longer to charge than the lead acid batteries. It's more a trickle with the LP charger, whereas you can put 8amps/hr into the LAs. If you're going to do two long dives a day and expect to crank up the charge during your SIT, think LA and not LP. With a Watts Meter (any old meter will actually do) and the larger capacity LPs, charging during your SIT may not be necessary, depending on what you're doing.
My suggestion is to contact Rodney at SS and get his advice. He may lend you a unit to try or you might just rent one from a local shop. With the price of these units, and especially with the battery technology quickly changing, I would suggest you err on the safe side and buy a used older unit until you're ready for those pushes. Also, more and more of the units you are considering will be showing up on the resale market and that means lower price when you're ready. BTW, the SSs do have excellent resale values.
FWIW, I sold my UV-18/26 after 10 years and picked up a Minnus this year (used the resale to help pay for the new one). There really isn't much comparison. The added thrust, lower weight and size, and increased burn time is amazing. Changing speed on the fly is awesome, and I wouldn't go back. You might even consider picking up a Minnus and upgrading to a 1.5 when the time is right.
You mentioned weight. I used to use a hand truck for my 18/26. Now I carry the Minnus in one hand and an AL 40 in the other. No big deal and I'm no spring chicken.
Bill Ripley
Rebreathers are something that we have to go to in order to dive the way we want to dive. They are not something we go to for any other reason.
Just a note, the Minnus, Magnus, etc., don't have gears. Yes, you can "mechanically" adjust the speed by varying the prop's pitch. But you change "gears" electronically. The motor's shaft is the prop's shaft. The "shifting" is electronic, simply giving more "juice" for second and third "gears." In other words, the motor just tuns faster for 2nd gear, and even faster for 3rd gear.
Hope this helps.
Bill Ripley
Rebreathers are something that we have to go to in order to dive the way we want to dive. They are not something we go to for any other reason.
Magnus = Excess wretched excess!!!!!!!!!!!!!!!!
I LOVE IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Mark
Unless I'm mistaken the Minnus is a high speed brushless motor run through a gear reduction unit, whereas everything else is direct drive. I believe therefore the minnus can have a lighter drive train, motor especially and running at a higher RPM you can get the motor at or near it max efficiency speed. Don't quote me though.
One way the Toyota Prius has such a very long battery life is is the computer never deep cycles the battery. Prius until very recently is a NiMH battery, but principle is the same. A high quality LIPO battery if discharged to 3.8 V per cell has a cycle life limit of about 450 cycles. I think but have not verified that the battery protection circuit of SS LIPO scooters actually may pull the battery further than that. But if a LIPO is only discharged to about 50% of it's capacity before being recharged, you more than double it's life expectancy. So with these LIPO battery replacements costing what they do, it seems that having way more battery capacity than needed is beneficial from the perspective of battery life.
Or at least I have found an excuse to buy more scoot than I need anyway.
You are thinking of gasoline engines. Electric motors put out the highest torque around stall speed. Look at the prop pitch of a scooter, compared to an airplane. They are just the opposite.
No, I'm not talking about max tq., but the point to where the most work is done relative to the amount of power being supplied, I believe a small brushless motor operating at a relatively high RPM is more efficient in developing the same power output of a larger brushless motor operating at a lower RPM. To get the same power output, you would have to have a larger motor if it's turning at a lower RPM, even with the gear reduction losses, I think the high RPM motor would be more efficient.
But that is what I think without any data, somebody like Rodney would be able to tell us I'd beat as he or another scooter manufacturer would have data surely
That's all pretty accurate.
The Minnus has a gear reduction which allows a much smaller more efficient motor and hence smaller scooter.
However the gearbox does consume some energy so you end up about even for efficiency with a direct drive motor.
Yes LIPO batteries will last longer with shallower discharge... so a larger pack will last longer when doing identical dives. However the small Minnus pack costs less to replace so the choice is not clear cut. The Minnus is perfect of ocean dives and places like Ginnie. But for a dedicated cave scooter I would look to the scooters with larger packs, such as the UV-26, Viper, Magnus or the Minnus 1.5
-Rod
Rodney, thanks for the clarification. My bad.
Bill Ripley
Rebreathers are something that we have to go to in order to dive the way we want to dive. They are not something we go to for any other reason.
Well I am now the proud owner of a Magnus, can't wait until I've taken the class and can use it.
Now, the real problem, How do you address the "how much did it cost" question from the better half?
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