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LiPo batteries

R/C Submarine modelers

LiPo batteries

Postby tincanrider » Mon Mar 09, 2009 12:25 pm

Hi. I need some info/guildance with LiPO batteris. I have a OTW type VII & WTC radio is ROBBE F-14 and am thinking of using two 11.1 V (3 cell)in a seperate WTC hooked up in parellel, I have a NOVAK 3 cell smart stop which cuts off at 9.375 V which is above the 8. V that OTW uses for their fail safe, which means the U-boat can dive/surface but no motor power, hence my concern. Would I be better using different batteries or would the new LiPO guard sold by CASWELL be a better way to go.
Keith.
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Postby KevinMc » Mon Mar 09, 2009 2:43 pm

Hi Keith,

Since the LiPo Guard is a gizmo of my own divising of course I have a bias towards it. With that said, I hope you won't mind me throwing my 2 cents into the discussion.

I'm not specifically familiar with the ESC you mentioned, but to my knowledge the low voltage warning mechanism on most LiPo-compatible ESC's is chop your throttle back to idle and hold it there until you command an idle, then let you ramp back up on the power for a while. While this may be clear for an aircraft that's speeding along and dependant on a significant amount of power to keep it airborn, I was concerned that while gliding along at near idle just under the surface this warning could easily go unnoticed. I wanted a signal that was a little more positive that it was time to come home, thus I designed the LiPo Guard to bring a boat to the surface when the batteries were depleted. It also has the advantage of allowing me to continue using my existing ESCs.

I'd be surprised if the Novak actually hard-locks you out of power to the screws, but if that is the case the consequences of having this happen while you're out in the middle of the pond are obvious to the point that there's no need for discussion.

Smaller capacity packs can certainly paralleled together for increased total capacity, and doing so will have no ill effects on any low-voltage cutoff devices be they built-in to an ESC or seperate like the LiPo Guard.

LiPo batteries are certainly not essential for a sub- the hobby has gotten by for years without them. Having said that, they are a great solution for volume (or weight) constrained submarines. I like them to the point that I won't plan on using anything but LiPos for future builds, but that's my opinion, your mileage may vary.
Kevin McLeod - Oscar II driver
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Postby fung pang » Mon Mar 09, 2009 5:12 pm

app for LiPo battery.
park flier.
rc heli
high speed rc boat
torpedo
very small submarine, 1/72 type 7 and smaller.
me like play with fire!
google under LiPo fire!

any rc sub longer than 3' don't really need LiPo battery.

KISS, OK







:D :D
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LiPo

Postby tincanrider » Mon Mar 09, 2009 6:22 pm

Hi Kevin.
Thanks for the info, the OTW WTC came with two sub-sonic ESC`s, the NOVAK is a seperate item that plugs between the ESC and the rec. the instructions says the unit will start interruping the throttle as LiPO volts near safety voltage and if crital voltage is reached it will COMPLETELY SHUT OFF the ESC throttle signal, so you can see my concern.
With your design, this cuts off signal to the OTW WTC built in fail safe which pumps out the ballast tank. Will have to order one of your units. Is the pitch control/fail safe your design, if so could you help me with a problem I am having?
Thanks for your help. Keith
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Postby KevinMc » Mon Mar 09, 2009 7:43 pm

Yes the ADF is mine too, and absolutely I'll try to help. Please PM me with a description of what's "out of sorts" and I'll do what I can to help set things straight.
Kevin McLeod - Oscar II driver
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Postby Pipes » Mon Mar 09, 2009 8:07 pm

Quick Question

I have started a builders thread on the S-51 having built subs twentyfive years ago in the days of round 2 volt Lead Acid gell cells. I have politly been called Rip Van Winkle.

I am well versed in the LiPos for RC aircraft using the Speed 400 sized Outrunners by E Flite as I have a small hanger full of planes using 3cell 2000 ma batteries.

My question is on the subject of ESC for boats. Are they out there for boats to use the lipo batteries and brushless motors? If so what is recommended
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Postby tsenecal » Mon Mar 09, 2009 11:09 pm

Pipes,

I have 6 of these in use in 3 subs, all of them use either the eflite 370 or eflite 400 outrunner motors.

http://www.horizonhobby.com/Products/De ... dID=CSESDM

for more info:
http://www.castlecreations.com/products ... micro.html


CC likes to brag about them, but I limit myself to a 2s lipo, I do use the built in BEC, and I think they are capable of handling 25 to 30 amps. they replace a unit that is rated at 25 amps, and these are supposed to handle more...

if you were to use a 3s lipo, i would probably use an external BEC.

Tim
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Postby Sub culture » Tue Mar 10, 2009 8:53 am

The Lithium A123 batteries, also known as nano-phosphate lithium cells are the ones to look at for model submarine use.

these do away with a lot of the disadvantages of Li-po batteries. They are slightly heavier, but that is not much of an issue with subs, and a bit more expensive. They also need special chargers.

More on these batteries here-

http://www.flyelectric.ukgateway.net/lithium-a123.htm
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby Chuck Chesney » Tue Mar 10, 2009 11:21 am

Sub culture, thanks very much for the information on the Lithium A123 batteries. They sound like they may make a real dent in the problems associated with Li po's, and should be able to take the worry out of running, charging and dealing with high capacity, light weight batteries.
Chuck

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Postby junglelord » Tue Mar 10, 2009 11:33 am

A123 batteries power the killacycle...worlds fastest motorcycle.
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Postby aquadeep » Thu Mar 12, 2009 10:07 pm

In my opinion Lipos and even more expensive types are great for helis,cars ,planes and speed boats and small subs.

But for large subs 2 to 7 plus feet there is nothing better than sealed lead acid batteries or Nimh packs,there ease of use and the fact that the SLAs can run in the wet and all the sizes and voltages available make them perfect for those subs.
Long run times ,verey inexpensive ,no special charger and they also serve to counterballance the sub.Instead of adding dead weight to counter ballance might as well be usefull power.

No safety concerns as bad as Lipos have and if you run them too far down lets say in an emergency return to port ,well there toast and alot of bucks down the drain!.

I have run SLAs in water and in the casing for years now ,just dont charge them sealed in! :roll:

For the money and for large subs there the ticket,that if you want the best bang for your buck and still have bucks left over :wink:
And no nueclear meltdown with fire,it sounds like the Alfa story ,they had to have the reactor running all the time or the bisthmus metal cooling fluid would solidify ,ruining the reactor/sub ouch not good engineering.

My OTW Type VIIc ,Oscar II ,Typhoon,Type XI,Type XXIII OTW,U-32,Octura,SB-2,Galatheand Grupner Shark and ARk M Red Shark all use or will use SLAs and NIMH,most of these subs have 2 plus hour run times.

:D
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Postby junglelord » Fri Mar 13, 2009 9:50 am

My Robbe Seawolf calls for a sealed lead acid battery.
I will pick one up as it does need more ballast.
Thanks.
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Postby ConcreteTurtle » Mon Apr 20, 2009 10:27 pm

I agree with sunworksco. I recently bought some DeWalt 36v packs for just this reason. You get 10 2300mAh A123 cells in each pack, and can split them up as you see fit.

There are a bunch of how-to guides around the net for making the packs. (Look up "Making A123 battery packs", there is a great thread over on rcgroups).

As for a charger, there are quite a few which now handle the LiFePo4 chemistry, I've been using a middle of the road Hyperion myself to great effect.

CT.
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