Endurance Times with LiPo batteries - feedback is appreciated

[tim morris]

Does anyone use Lithium polymer cells in a WTC? do they need oxygen to work? or is a WTC 3.0 dry space OK? i know there are AMP draw issues and low voltage cut off issues so as not to damage the cells--but thats where the speed control question comes in.

does it matter because our speed controls are not suitable for this kind of battery?

i use these batteries on my park flyers and they go many times longer than NiMh for the weight. it seems a person could use enough of these to cruise all day with a WTC 3.0

this is not a simple question i know because i have had to do some reading just to get up to speed on how to safely use them on the planes. but holy cow--talk about run times. i have a new charger that is automatic once you pick the type of cells--Nicad-Nimh or Lipo. its pretty easy to use but dont press the wrong button!

i am slowly replacing all my full size stuff with all the new goodies available for the WTC and i think its going to make the Sturgeon seem huge inside. all that money may not seem too safe unless you are pretty comfortable with the WTC--but i think this is the way to go--i used larger everthing to start with. and things are pretty tight--

[tim morris]

i guess its just too

i guess its just too easy to use something simpler. doesnt look like anyone has tried it.

[dietzer]

Hi Tim,

I haven't installed

Hi Tim,

I haven't installed them yet, but I bought LiPo batteries to put in my 1/96 scale Balao. They should be fine inside the WTC. The only issue I can think of might be heat. If your current draw exceeds 3X-4X, the battery might start heating up too much for the enclosed space. But at 1X-2X current draw, I would think it'd be OK. But if your current draw exceeds 3X-4X, your battery isn't going to last too long anyways...

I plan to use a two-cell 3AH LiPo for the motors, and a 1AH LiPo for the electronics.

Let me know how they work for you!

Carl

[anonymous]

These lithium polymer batteries sound

These lithium polymer batteries sound interesting and EXPENSIVE! True?

A long endurance is a great engineering exercise, but remember you will likely get tired before the model does. Unless you run your model at an isolated body of water (a remote mountain lake?) that does not have a nearby source of electricity to recharge your batteries, these lithium polymer batteries would seem useful only in providing a way of affording several runs in the water between recharges on a long weekend.

Also remember your transmitter batteries (Tx) will need the same endurance too or the whole thing is a wasted exercise. The advantage to me it would seem with Lithium polymer cells might be to create much smaller submarine models with equal or more endurance of that of a proportionately larger model. Imagine a 1/96 Sturgeon 637, then imagine a 1/96 DSRV sized model with equal endurance and/or speed! Or say a 1/72 r/c homing torpedo that gets it's target simply by out lasting its much larger equally fast model target!

Another way to extend endurance too is not just more life from your batteries but also more efficient small motors. Increase battery capacity or reduce the energy demand - or both!

Until fuel cells become small and cheap, it might be we have achieved a comfortable plateau in battery technologies thanks to all the electronic gadgets we enjoy in these modern times, and especially from lap top computers.

Better time and effort in this hobby might be spent pursuing different and interesting new hull kits to increase the variety of submarines that could be sold and modeled. Just my opinion only.

Steve Reichmuth

[koeze]

I'm considering lipo's for my

I'm considering lipo's for my transmitter because my nicd is nearly dead and I never liked the time it gave me with the tx. Changing to NiMH sould improve things quite a bit but not as much as Lipo though.

I will have to look into thing like dimensions and stuff.

I'm not going to use them in my boats because of the simple fact that a lead-gel battery is much heavier that those lipos. Size is not an issue in my 1]http://www.subcommittee.com/forum/icon_question.gif[/img]

EJK

[anonymous]

Nickel Metal Hydride Batteries (NiMH)

Nickel Metal Hydride Batteries (NiMH) is the way to go. The heavy draw on the lithium polymer batteries sounds much too dangerious to have to deal with. I am basing this conclusion on just what I have read here only.

If this poor chap lost his car and nearly his dog, imagine what might occur at some point if he had been traveling on a commerical flight with one! Either death by fire or a life sentence in prison assuming he survived. Kill a terrorist for me.

Steve Reichmuth

[dietzer]

Plus I've heard that Lipos

Plus I've heard that Lipos take punishment like heavy current draw very badly (to the point where they catch fire). I'm sure that the current draw from my TX is pretty constant. My sub however may draw up to 30 amps with a stopped engine (weed in propellor etc.)

Sounds like a good reason to add FUSES to me...

BTW, I plan on having over/under voltage protection and over-current and thermal protection circuits for my LiPo batteries. They are expensive enough that I want to baby them and get all the life out of them I can...

Carl

[wayne frey]

I just ordered a Ni-hydride

I just ordered a Ni-hydride for my Alfa.I do not profess to knowing what I am doing.This will be my first sub that gets wet.But,I will give it a try and post the results.It will be a few months though.
In true american fashion,I ordered more battery than I need probably.A 3000 battery.With shipping,it was around $75.00 form tower hobbies.I will probably get one for the transmitter too to take advantage of the extra time.Being an Alfa,it has the 3.5 wtc,so I will be running the battery wet.Again,this will be an experiment(on my new boat!).Think anyone forsees a problem running it in the wet?
The Thor speed controller has been mounted on a cpu heatsink also.That came out nicely.

[koeze]

Taken from RC Universe
Also Check

Taken from RC Universe
Also Check RC Universe

Just a fuse is not enough to operate LIPO's safely.
Or do you want to use your sub as a torpedo .......

Hey..... Idea

lithium ion or likthium polymer battery were developed and applied to mkobile phone application eventhough there is a danger of explosion or fire.as you mentioned a lot of chemical trials and electrical trials protects battery from that danger so far.
most of liion battery uses aluminum or steel can plated as a package.when and if the battery is overcharged more than 4.25 volt/cell or overdischarged under 2.0 volt,the chemistry inside battery will be degradated so that will generate gases and heat which cause explosion and fire.
To avoid such accident makers install safety module(print circuit module)/specific charger.
Radio control area has different requirement on battery., high discharge rate and quick charge.To fulfil those requirement conventional safety devices can't be applied.specially can type lithium battery is extremely danger of explosion and fire.
lithium polymer battery is better safety mode but still with danger of fire if the user doesn't keep the right track.The best way to enjoy lithium polymer battery will be,

-choose best makers' product
-special lipo charger use(don't use nicd charger or equivalent)
-special safety guard which can be connected with charger shall be used
-keep the recommendable discharge rate
-pre assembled pack shall be used by proven maker

[dietzer]

IMHO, to safely use LiPo's

IMHO, to safely use LiPo's in a sub you must]http://www.subcommittee.com/forum/icon_biggrin.gif[/img]

Carl

[jeffg]

Carl got most of it

Carl got most of it pretty good.

Few things to add

Current limiters are no longer necessary.

New larger LiPo cells have very high discharge rates. I am building a new Alfa and using 4.4 amp cells 11.1V nominal. The discharge rate is allowed at 10C (ten times capacity) or 44 amps continuos. Cheapbatterypacks.com has cells at 3.7 amps rated for 15C continuos discharge rates.

With two cells in parrallel I will have a 8.8 battery pack without the wieght of typical lead acid or Nickel based cells.

When LiPo cells are loosing thier voltage they act a lot like the old Nicads in that the current just falls off. You will know when the battery voltage is getting low.

LiPo cells are also enviromentally better. No acids no heavy metals. They recommend you pierce the cells with a fork or ice pick and soak in water for 24 hrs then thow in the trash can.

STILL USE A FUSE FOR SAFETY

LiPo chargers are easy to get and inexpensive, I got one for $49 and it fast charges then slowlly tops off then blinks the complete lamp. All while I do something else. Then while the epoxy cures on my sub project I fly my electric plane.

Bottom line don't be afriad to use LiPo cells.

[anonymous]

I run a li-poly packs

[color=#000000]I run a li-poly packs wet in my type seven. Although it's sealed in a rubber bag the connectors are wet.

There is no problem at all running them wet. I don't use any fuses and just treat them like any other battery pack. There's a lot of wise tails out there but most of them don't occur from experience.

Dave Welch is where the concept came from as he was the first I know to run them wet and recommended it to me. I was reluctant at first but now am a true believer.

I also run them in my big twin engine F-15 and a few other of my EDF electric jets.

I have had no trouble with fires or over charging. The 3 rules to follow are]

[bigdave]

Not to reiterate what Steve

Not to reiterate what Steve said I have been using them with success for over a year. Just to make it clear, the batteries do not get wet. They are sealed. But the connectors are out in the water. Dave.