Battery types for model subs

[JWLaRue]

<<Originally posted by "itolond">>

Hi forum,

I heard Li-po batteries we a poor choice for submarines- what is recommended, any guides ?

[JWLaRue]

A number of us have converted over to LiPo's for our r/c subs. Just keep them dry and you should have no problems.

You'll also enjoy the benefit of added run time for a given physical size battery.

-Jeff

[JWLaRue]

<<Originally posted by "Larry Kuntz">>

If you need the weight and have room NiMH (Nickel Metal Hydride) are also a good choice. Decent power and fairly safe to use. I replaced a lead acid battery (2.2 amp hour) on my Neptune due to short run times and poor performance with a Li-Po (6.0 amp hour). I got 3 times the battery in the same size by using a Li-Po but had to add lead since it was so much lighter. Treat the Li-Po's with care and they are a fine choice also as Jeff said.

[vasily]

How about the newer technology LiFePo4 ? A 12V, 7-10ahr pack weighs less than two pounds, and is something like 5 by 3 by 2.5 inches. They're completely contained, don't outgas, and don't mind water. They also recharge 2,000 times, more than twice a LIPO.
I had a LIPO fire and deflagration in a model a while back, and have been approaching them with trepidation ever since. They outgas during charging, too, so you're not supposed to charge them in a confined (read "watertight") space.

[southern or]

The problem with Lithium based batteries is how they burn in the event of a fire. Your typical ABC fire extinguisher (Wood, liquid, electrical) can only stop the fire from expanding and won't put it out. For these fires you need CO2/class D extinguishers. The plane groups make charging bunkers out of bricks to charge their li batteries. I personally stay away from them because if there was to be a fire in my sub with a li battery, all the water will do is act as an oxidizer for the fire.

[tsenecal]

guys,

given the amps that model submarines draw, the only way you are going to get a lipo battery to go thermal is to 1) short it. or 2) charge it incorrectly.

if you are truly paranoid about a thermal run-away, use a LiFE battery. due to the phosphates used in their construction, they are incapable of a thermal run-away.

all batteries outgas when charging. NO battery should be charged in a closed in space, regardless of its type of construction.

as to charging cycles.... can anyone here say that they have actually charged a model submarine battery a thousand times? or two thousand?? i have a set of three 2200mah kokam batteries originally bought in 2004, which are still working fine. they are so old they don't even have balance jacks. just like any other battery, if you take care of them, they will work fine. the biggest advantage i know of with lipos is that they will hold a charge forever. i can charge a battery in june, and it will still be ready to use in a boat or sub in august... or next june.

[salmon]

When you read the "proper" way to dispose of a LiPo battery is to throw it into a bucket of salt water. I have done that with no issues.
That being said, if we did not use technology because of fear, we would not do subs to begin with. We rely on our technology and LiPo batteries has been tried and tested by those with a lot more experience and knowledge than me.
Some submariners use only NiMh batteries and their subs run great. I have 1 sub that uses NiMh and one that is being built that will. My other subs are all LiPo. My learning curve was charging them properly (which almost made me want to abandon them). If you did a survey, I would hazard a guess that more than half use LiPo with no problems.
The benefit is the density of power in a LiPo battery. Some of our smaller subs to get them RC'd is only possible with LiPo batteries.
Southern or, you probably have enough space in your wtc to go either way. If weight becomes an issue or run times are short, consider LiPo.

[Ralph --- SSBN 598]

I too have NiMh in a running boat and I have LiPo in my newest boat.
I am new to the LiPo thing and I invested in a good charge that balances the cells as it charges.
I have heard all the stories of the problems.
I took me a couple of days to figure out how the charger worked, then I found a video showing how to set it up.

Read the display on the charger and followed it step by step.
It takes about 50 minutes to completely charge a 2600Mah batter.
Much faster than my NiMh little 900Mah that takes most of a day to fully charge.

I am not a trail blazer, I read what those I think are trail blazers have to say.
Then I might try it.

[southern or]

I'm not against Lithium batteries, I use them in our planes because that's what works best for them. I use HC NiMh batteries for the boats (surface and sub) because I'm lazy and use them as ballast-plus I've had crap ESCs short out and quick drain the NiMh batteries without a serous problem. I've even had a NiMh that should have exploded and didn't when the ESC short caused the battery wires to fry (after that episode I've switched to one make of ESCs for all my boats so I can avoid all the "fun" of cheap ESCs). When Li batteries are stored, charged, and used properly, they will be just fine.

Ralph, I don't know what's up with your charger, but mine charges my 4,200Mah batteries in 5 hours.


Almost forgot, the plane guys use bunkers or sleeves when charging their batteries for safety. I'd feel really bad if someone's house burned down because I didn't mention it.

[Ralph --- SSBN 598]

My charge is setup to charge from a 12vdc car battery.
Never in the house or other buildings.
I wheel the battery out side on a hand truck.
Many years ago, I one of four large truck battery explode down in the well between the truck frame rails.
No one was hurt but a bit of clean up to do.
The display says it charges are a max 2 amp rate.
That's what the instruction manual said to use for the batteries I have.
I don't think it's using the max but is seemed rather quick to me.
The display tells me about balancing the cells and when done it says charge is FULL.

[drschmidt]

I use LiFePo. Work quite nicely....

[bwi]

I use Lipo batteries for years in my RC cars without any problems.
The most important thing when using Lipo's is the charger....you have to buy a good descent charger with good charging software in it.

I use my lipo's back to back the whole time (charge one, drive the other one) sometime over more than 6 hours without any problem. But I only charge them a rate of 1C.

I use 2s LiPO's 4000mA/ 25C and I run a 6.5t brushlessmotor in a Losi offroad buggy, so the LiPo’s are getting a severe load.
I have my packs almost six years and they are still running @ full capacity.
Most cars ESC have built-in LiPo guards, that is a musthaver for the LiPo's battery without it, you will damage them.

I have recently bought LiFePo batteries for one of my TX, but to charge them you need a charger that can handle LiFePo. Mine did not.
As it were only TX batteries I bought a cheap one that does do the job perfect.

I recently started to bring our, for years neglected RC boats into the 20th century. I modified them to brushless and LiPo, my father and myself can sail for 1,5hrs, on the same LiPo Batteries. The upgrade cost me 30$ each (motor and ESC).

So my intention is to go LiPo in my sub (hopefully next year she will see water).

Grtz,
Bart

[greg w]

I am in the process of changing my Skipjack to a lipo. I will be using a car stlye hardcase pack. I have added a breather tube that I can cap off and siliconed the wire penetrations and the case seam. The difficulty that I see is protecting the balance wires but I came up with a small tube with end caps for that. Time will tell if it will work.

[corsaire]

Can anybody tell me How long a LIPO battery is supposed to last? I have a Tenergy LIPO 11.1V 5500mAh Battery with PCB - I run my boat today for about 15 min., not even, and the battery got already drained. I've been using the Team Tenegy TB6B Synchronous balance charger/discharger to charge it at a low rate of 1.6, it was supposed to be fully charged for today's run in the pond but, not even 15 minutes??? Can somebody advise what's going on? Thanks.

[JWLaRue]

The chemistry of the battery doesn't really come into play when discussing run time. On the other hand, there are a number of factors that can effect run time. The first thing I would check is to see if you have too much binding in your drive train. Next, it would be very useful to understand what the amperage draw is on the battery when the motor is running with the prop(s) in the water.

Finally, do you have a second battery that you use. It is possible that the battery isn't holding or taking a full charge.

-let us know and we'll try to (continue to) help,

Jeff

p.s. what is it you are running?