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Author Topic: Li-lo, LI-Po or L-ion?  (Read 2344 times)

pettyofficernick

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Li-lo, LI-Po or L-ion?
« on: December 18, 2012, 10:14:42 pm »
Good evening,  I am about to start building a Deans Marine Pibber ( Vietnam PBR as in Apocolypse now) with a Graupner water jet drive. I intend to power it with an Mtronics Hydra 15 brushless motor and ESC combo. Now, seeing as how my main interest lies in steam launches, I am not too Au-fait with the latest battery technology, so I was wondering if any of you electrical experts could recommend a suitable Li po or L ion battery, space is at a premium, needs to be as light as possible but still give a decent running time, and to complicate things further, it could do with being in two parts, so I can fit one either side of the waterjet.  :-)) :-)) :-))
Thanks in advance,
Nick.
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essex2visuvesi

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Re: Li-lo, LI-Po or L-ion?
« Reply #1 on: December 19, 2012, 08:02:09 am »
If you are going for a jet drive then I don't think that motor would be suitable as its only 1000Kv (approximately 11,400rpm at 11.4V (3S lipo) and is more suited to a prop drive
Which graupner Jet drive are you using?
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pettyofficernick

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Re: Li-lo, LI-Po or L-ion?
« Reply #2 on: December 19, 2012, 10:27:27 am »
Good morning, I am using the Graupner Minijet, the smallest one they do. The impellor is only 20mm dia, the  recommended  motor. is a 500. The good people at Mtronocs reckon the Hydra 15 should be fine, but I could use the Hydra 30 instead....
http://www.cornwallmodelboats.co.uk/acatalog/graupner_jet.html
Many thanks,
Nick.
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Subculture

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Re: Li-lo, LI-Po or L-ion?
« Reply #3 on: December 19, 2012, 11:49:57 am »
500's come in many winds. Some do very low RPM some very high.

The picture you linked to shows a 500 Race which revs to over 20000RPM.

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essex2visuvesi

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Re: Li-lo, LI-Po or L-ion?
« Reply #4 on: December 19, 2012, 01:59:25 pm »
Ah right in that case may I suggest a 1:10 buggy upgrade motor, dimensions would be the same an there a 100's of choices of winds and prices.
These would be a direct fit into the minijet and will give ample power for your needs
something like this one:-
http://www.ebay.co.uk/itm/eZRun-13T-3000kv-RC-Brushless-Motor-Hobbywing-1-10-12-car-buggy-/160934493868?pt=UK_ToysGames_RadioControlled_JN&hash=item2578717eac

Along with a watercooling coil and a watercooled ESC you should be fine.

watercooled esc
http://www.ebay.co.uk/itm/TURNIGY-MARINE-35A-BRUSHLESS-WATER-COOLED-BOAT-ESC-FAST-POST-UK-STOCK-/200660314676?pt=UK_ToysGames_RadioControlled_JN&hash=item2eb8496a34
might be wise to go up to a 40 or 50A one tho

7.4v 2 cell lipo saddle pack
http://www.ebay.co.uk/itm/Ansmann-Racing-4000Mah-7-4v-20c-LiPo-Saddle-Battery-Pack-/321031307345?pt=UK_ToysGames_RadioControlled_JN&hash=item4abef50051

should make for a speedy little package running a little over 21,000rpm
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Subculture

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Re: Li-lo, LI-Po or L-ion?
« Reply #5 on: December 19, 2012, 02:19:14 pm »
If you're using a waterjet, a reversible esc isn't really necessary, as you won't get a revrse unless you employ a bucket style mechanism. That will shave a few quid off the cost of the speed controller.
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essex2visuvesi

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Re: Li-lo, LI-Po or L-ion?
« Reply #6 on: December 19, 2012, 06:42:02 pm »
Quote from: Subculture on December 19, 2012, 02:19:14 pm
If you're using a waterjet, a reversible esc isn't really necessary, as you won't get a revrse unless you employ a bucket style mechanism. That will shave a few quid off the cost of the speed controller.

Good point... forgot about that  :embarrassed:
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tony23

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Re: Li-lo, LI-Po or L-ion?
« Reply #7 on: December 20, 2012, 08:38:46 pm »
also consider a LiFe battery  O0
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Subculture

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Re: Li-lo, LI-Po or L-ion?
« Reply #8 on: December 20, 2012, 09:01:22 pm »
Be aware that Life batteries need a charger designed to work with them, as they have a lower cell voltage than lipo. Good batteries, lower energy density (so a bit heavier for equivalent capacity), but longer cycle life.
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