NAMBA lipo rules

[lohring]

Lithium polymer batteries are starting a revolution in electric power for model boats. Some very important proposals are being voted on. NAMBA members can vote at www.namba.com This is my explanation of and opinion on these proposals. The first proposal allows lithium polymer and similar types of batteries to be run along with the older nickel cadmium and nickel metal hydride batteries. With the exception of a few classes, it puts voltage limits on the battery power. This allows many different types of batteries to run together in a class. Voting yes on this proposal, proposal one, allows the use of lithium polymer batteries in electric classes.

Proposal two is a little more complicated. The amount of current that can be drawn from lithium polymer batteries is related to their capacity. Currently, the best lithium polymer batteries can supply 20 times their capacity continuously and 30 times their capacity for a brief period. The largest batteries suitable for racing applications have a five ampere hour capacity. This means the battery can continuously supply 100 amps of current. The pack would last about three minutes, enough for a race, at this current. Two of these battery packs in parallel could supply 200 amps of current for the same length of time. To keep this from getting out of hand, proposal 2 limits the maximum number of cells in parallel to two for the smaller classes.

Proposal three is similar to the above but limits the maximum capacity of the battery to 10 ampere hours for the smaller classes and 12 ampere hours for the larger classes. This means that the maximum continuous current is 200 amps for the smaller classes and 240 amps for the larger classes with current technology.

Currently, the best speed control can handle 160 amps continuously and probably a little more than 200 amps for a short period. Most speed controls can't handle much over 100 amps so for now the speed control is the limiting factor. Both proposal two and proposal three will limit maximum power when better speed controls are available. Proposal two is easier to inspect, but is more open-ended since higher capacity cells will become available. Proposal three makes more sense as a limitation but would be very hard to inspect. Neither proposal two nor proposal three is required to allow lithium polymer cells. For the next season, available speed controls will limit power. I believe better power limiting rules are possible.

Proposal four better defines the power allowed for electric 1/8 Scale Unlimited Hydroplanes. Proposal five defines a larger course for electric races. This is one of the standard NAMBA courses and paves the way for electrics to run on longer courses. I am not sure this is really needed, especially in the electric section of the rules.

I believe proposal one is essential for the electric classes. Proposal four cleans up the 1/8 Scale rules if lithium polymer batteries are allowed. All the other proposals are optional in my opinion. Needless to say, more rules will be required to keep up with rapidly advancing battery technology.

Lohring Miller

 

[Mike McKnight]

Normally would not comment on an FE issue but this one caught my attention. I noticed in Proposal #1 that there is a note regarding the potential for fire danger. This is a major concern for me as I have education in chemistry as a Hazardous Materials Specialist in the Fire Service. Given the chemistry of the cells described (Li-Po), the methods of safety that are described to extinguish a fuel cell fire are not adequate. You cannot extinguish a fire from one of these cells with ANY of the methods described. Mainly because of the way the combustion process occurs. The chemical makeup of the cells liberates it own oxygen from the matrix as part of the combustion process. Therefore you cannot stop the combustion process by fire extinguisher or sand bucket as these are designed to remove the oxidizer (oxygen) from the process. Since this liberates it own oxygen from the process those methods are useless. The only way to stop one of these fires is to break the chemical chain supporting combustion. To date there is only one fire extinguisher with material that can do this. It is for commercial use it is not available to the public AND is more designed for exotic metal fires. It attempts to interrupt the chemical process and it is not entirely effective. Plus you should see the size of the extinguishers, they have their own wheels. The standard ABC type extinguishers that are available at any retail store are rated for electrical but his is not the electrical they are rated for. The ABC rating you see on them breaks down like this....

Class A extinguishers are for ordinary combustible materials such as paper, wood, cardboard, and most plastics. The numerical rating on these types of extinguishers indicates the amount of water it holds and the amount of fire it can extinguish.

Class B fires involve flammable or combustible liquids such as gasoline, kerosene, grease and oil. The numerical rating for class B extinguishers indicates the approximate number of square feet of fire it can extinguish.

Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires - the risk of electrical shock is far too great! Class C extinguishers do not have a numerical rating. The C classification means the extinguishing agent is non-conductive.

Class D fire extinguishers are commonly found in a chemical laboratory. They are for fires that involve combustible metals, such as magnesium, titanium, potassium and sodium. These types of extinguishers also have no numerical rating, nor are they given a multi-purpose rating - they are designed for class D fires only.

These cells according to the National Fire Protection Agency fall into the Class D category for more than just one of the one components used.

Anyone that has ever had an old VW Bug that has caught fire can understand what I am talking about. The engine block in those things were made of exotic metals like Magnesium and had a tendency to catch fire due to problem in the carb and fuel system that would ignite and eventually reach a temperature that would get the block to ignite. In my time in the Fire Service I rolled up on over a dozen of these and the only thing we could do was to make sure anything around the car didn't catch because we had no way to put it out. If we sprayed it with water it would flash because, you guessed it there is oxygen in the water, adding even more oxidizer to the fire burning at well over 1000 degrees. As I mentioned before the D extinguishers were huge and way too expensive to carry on an engine.

We have nearly the same problem with the chemistry of these cells. But it is a little worse in the fact that you have an exotic metal AND Polymers used in the chemical makeup of the cell. A lot of Polymers have a tendency to expand as they burn. I have personally seen two of these cells go up and I was impressed by the speed of the combustion and the destruction it caused. One was a foam plane that got blown into a tree and wasn't able to be retrieved before it ignited and took a good portion of the tree with it. Another issue is the toxic fumes and smoke produced by a Polymer on fire. Burnt plastic smell is not even close, this stuff is almost corrosive.

I have heard the arguments about the cost factors of these cells putting it out of reach of many, but that not witstanding, from a safety standpoint alone, I don't see how anyone can advocate the use of this material until the fire danger is mitigated or there is a more feasible way of mitigating a fire WHEN one occurs. A club is not going to be able to afford the extinguishing agents needed even if they could obtain it. The exposure to NAMBA and the members is too great a cost to risk until the technology is safer.

 

[TRUCKPULL]

Paralleling Packs

I am A FE racer, and here are some of the reasons that we want to

Parallel packs.

It is not because we want to pull 200AMPS

It is because we don't want to pull more then 10C

Reason is if you pull 20C you will only get about 50 good cycles out of your packs.

If you only pull 10C you will get over 200 cycles out of your packs. Also safety wise this is a lot better.

Pack life is one of the big reasons that we want to change to Lipos

2P packs is what is going to give us good pack life. staying closer to that 10C

Also If I buy a 2S2P - 7,500mAmp pack to use in a "N2"offshore 4 Min. race.

it is the same pack that I am going to use in my "N2" sprint boat also.

Safety wise the larger mAmp packs that you run, the safer you will be.

They tell us to never use more then 75% of your pack total mAmp.

So to be safer I want to run packs that are 40% over my race setup mAmp.

And my packs are now heavier then my old Sub C’s.

By not passing the 2P rule racers will not be as safe as they wanted to be, and now has to pull a larger C rate out of his packs, running higher temperatures which in turn is not safe,

Pulling this higher C rate will lead to shorter pack life.

Which is what we don’t want.

When racing with Sub C’s we had to replace our cells twice a year.

Lipos if treated right (10C) will give us about two years of use.

This is where the cost savings come in.

Also 2P setups will be a lot safer to use.

Also remember that half of our racing is OFFSHORE

which are 4min. races not 5 or 6 laps.

Larry

 

[TRUCKPULL]

Mike

Do you use a Laptop?

a Cell Phone?

a I-pod?

New type remote Vidio games?

ECT

They all use the same LIPO batteries that we use.

The airplane guys have been using Lipos for years.

All the problems with Liops have been user error.

Over charging or over discharging.(2P - helps the over discharging problem)

The new chargers today are a lot better in controling the cell charge.

Also every Lipo pack today has a balance plug attached to it, that plugs into a balancer,

that is used to keep the individual cells in the pack in balance to each other.

(does your laptop do that?)

Have you ever seen a Nicad pack melt through the bottom of a hull? I have.

Larry

 

[Don Ferrette]

Do you use a Laptop?a Cell Phone?

a I-pod?

New type remote Vidio games?

ECT

This is not even remotely a fair comparision as the lipo batteries in your laptop, cell phones, I-pods etc. will never ever see the load placed on them that a FE boat will pull under race conditions nor are capable of storing AND supplying anywhere near the capacity. I also understand that getting a lipo wet is a very bad thing, is this true?? I'm not against the lipos but do want to see that proper safety guidelines are in place. You guys need to stop making the comparisions between toys, phones, etc. and your floating mini arc welders. Has anyone stopped to think exactly how much energy 200 amps actually is even at lower voltages? Let's just be smart about this fellas.

 

[Mike McKnight]

Guys the batteries in consumer electronics until VERY recently are not Li-Po they are Lithium Ion. By the way did we forget that Sony just had to replace over a million laptop batteries due to heat and explosive failures? Please do not misconstrue my intentions. I am not against Li-Po batteries as long as they are safe. I completely understand the reasons that FE guys want to use them. Everyone wants more speed and longer cell life. But, to date the number of other battery types failures compared to Li-Po over a givern period of time is not even a comparison. Being on the cutting edge of technology is not always a good thing. For example, I remember buying a cd burner wen they first came out. $1000 and all it did was make bunch of $3 coasters. Granted it wasn't a physically harmful flaw but it was fixed within a reasonably quick period of time and now they are extremely reliable and cheaper. The same comparison can be used here. I'm sure in time this will work out the same. There have been enough incidents with RC boat racing in the past year alone that warrants taking a really hard look at this before adding another potential liability to ANY organization.

 

[Kevin Whitehead]

There have been enough incidents with RC boat racing in the past year alone that warrants taking a really hard look at this before adding another potential liability to ANY organization.

For example?

 

[photohoward1]

There have been enough incidents with RC boat racing in the past year alone that warrants taking a really hard look at this before adding another potential liability to ANY organization.

For example?

Yes Please expand on your statement?

I can'y think of One incident on the FE Side...

 

[Mike McKnight]

I didn't say they were on the FE side of boating. Just this last year there was the incident in Florida where a guy was killed in an inflatable raft picking up a dead boat. Granted it was not at an organized racing event but it was at a pond where racing is held occasionally. Previous year I believe there was someone that was hit by a wild boat that came into the hot pits and struck him in the leg causing a debilitating injury. Plus a buch of near misses that never get talked about, some of which I witnessed personally. One of which was at an FE race. At a time when we should be trying to minimize exposures to liability and increasing safety the Li-Po option opens up another avenue for a potential exposure. John Q. Plaintiff doesn't really care whether it was nitro or FE if a major problem arises. What if one these cells and a charger go up and you pit area happens to be near some dry grass? Just an example of what could happen......

 

[Kevin Whitehead]

Granted, you didn't say they were on the electric side.

It was just real easy to assume that. Especially after you mentioned the totally unrelated VW Beetle fire as some sort of equivalent example of a LiPo battery fire. A fire consisting of a chunk of magnesium or aluminum the size of an engine block in no way represents the potential fire a pack of these batteries has in them.

If you have an arguement against using LiPo batteries, present it. But please, keep it on subject and keep it real.

So far, the arguement that you have presented is not very strong. If you argue that adding LiPo batteries will increase potential liability. Then, you must also argue that adding any new racers (without losing an equal number) will also increase potential liability. Adding any number of new races will also increase potential liability. Even maintaining the same number of racers and races, if anyone adds a new boat to their existing fleet the potential liability goes up.

Are you a total status quo guy?

 

[Grimracer]

All the problems with Liops have been user error.
Larry

larry,

Not even close man.. not even close.. <_<

Our team Futaba heli pilot had one go up in the back of his mini van.. it was not under charge and not under discharge, it was just sitting there... as a mater of fact it was a battery for his RX in his 50 machine.. he has MANY MANY hours using lipos... do you have any idea how our company transports and stores our Lipos.. of course not...

Well.. to make a long story short the fire wiped out his machine and the inside of his van.. the van was fixed.. the heli was lost.

the battery just started on fire... :blink:

he now stores all his Lipos in his van parked in the road.. True.. if the dam things start on fire again he will loose the van and not his garage, house or worse yet his life.

Grim

 

[TRUCKPULL]

Grim

A lipo that is not damaged to begin with( involved in a crash)

If it was discharged to far in may start to burn after it rests.( requires a automatic voltage shutoff)

He should have put at lest a half charge back into his batteries before he put them in his car.

This is one of the saftey rules for Lipos.

Also Liop's should be transported, stored, and charged in a Lipo bag or fire resistant contaner.

Also lipo's should not be used for recever packs.

We have automatic cutoffs in our ESC's that shut the pack down if it goes below 3 Volts per cell.

I have not seen a recever unit that has a low voltage shut off in it.

You see all the user mistakes.

Larry

PS - Liop's should be transported, stored, and charged in a Lipo bag or fire resistant contaner.

 

[Don Ferrette]

PS - Lipo's should be transported, stored, and charged in a Lipo bag or fire resistant contaner.

Couple questions- what type of container will completely contain a lipo pack that is burning? Didn't it get mentioned somewhere else the lipo bags are only effective on the smallest of packs? Still want to know what happens to a lipo pack if it gets wet. :unsure:

 

[Kevin Whitehead]

Couple questions- what type of container will completely contain a lipo pack that is burning? Didn't it get mentioned somewhere else the lipo bags are only effective on the smallest of packs? Still want to know what happens to a lipo pack if it gets wet. :unsure:

Metal ammo can or any air tight metal container. Can't burn without oxygen. One of those small home fireproof safes for protecting very important papers.

Needing oxygen is also the reason that a pack fire can be doused with a bucket of sand to smother it.

 

[Ray Sametz]

Talked to a electrician at work who flies a 5000 dollar electric heli. A fully charged lipo pack got knicked by a X-acto knife on his work bench. He had to throw it out the window of his fourth floor apartment. The risks seem to out weigh the benefit for the average boater to use without strick safety rules. Ray :unsure:

 

[Kevin Whitehead]

Another cheap solution:

http://www.b-p-p.com/proddetail.php?prod=1...cc6046e8536d3a9

 

[Mike McKnight]

Kevin you didn't read my earlier post. I likened it to a VW fire in the respect that they burn the same way. As it burns it liberates it own oxygen from the chemical matrix. Even if you lock it in a box with no ventilation it will still burn until there is no more fuel. Normal combustion occurs when you have three elements: Heat, Reducing Agent(Fuel)l, Oxidizer(Usually Oxygen). Take away one and you extinguish the fire. With exotic metals and chemicals you have to add Chemical Reaction to that. Take away one of the four and you extinguish the fire....usually. Except when Oxygen is created by the chemical reaction. The only way to stop it is to interrupt the chemical reaction because you cant take away the heat because you can't remove the oxidizer or the fuel in this case. You can't use any kind of extinguishing agent with moisture because the fire will use the oxygen in that moisture as oxydizer.

Kevin your assessment that my argument isn't very stong is, for lack of a better term, weak. I have presented my case very clearly. If you have a problem understanding what I am saying then tell me what you don't get and I will try and clear it up. To answer your allegation of whether I am a "status quo guy", far from it. I'm all for advancing the hobby but not at the potential for loss of property and potential physical harm. I think that Li-Po cells could advance FE tremendously. The fact of the matter is that in it's current state it is still too volatile to use as a power solution. The technology needs advance to a more stable cell before it should be approved.

 

[Paul Pachmayer]

Hi Guys,

Mike is correct in his explanation of a lipo fire in that the chemical reaction creates its own oxidizer. Having said that I have personally witnessed (caused) lipo fires by overcharging and damaging cells. This was intentional to see what it would take. The lipo sack used in one instance with a 5000 mAh pack worked well to contain the fire but there was a lot of smoke. A 5S pack was damaged and once it cought fire it was just tossed in the water, no flames but the pack still destroyed itself, nothing left but foil. Also only the cell that was damaged burned, the other 4 were unaffected. A bucket of sand tossed over a lipo fire will contain the flames, you will still have heat and smoke but that's it. A simple clay flower pot can be used to store lipos in, this contains the fire but you'll still get tons of smoke.

Everything has the potential for problems, you can minimize the problems by being cautious and respecting your equipment. Heck, I've seen boats blown apart using sub-C Nimh cells. Doesn't happen often but it happens.

Don, I've had lipo packs under water for well over 5 minutes more than once. Not a problem.

Paul.

 

[Don Ferrette]

Metal ammo can or any air tight metal container. Can't burn without oxygen. One of those small home fireproof safes for protecting very important papers. Needing oxygen is also the reason that a pack fire can be doused with a bucket of sand to smother it.

Unfortunately incorrect. The lipo packs contain & produce their own oxydizer, they will continue to burn under water or under a pile of sand until the chemical reaction is complete. If you do choose to store in an "airtight" container it better be strong enough to contain the pressure that will build in this "sealed" container should they ignite. Interesting how some are so quick to defend the use & that there's little risk don't even know how these things burn if they do catch fire. I didn't know this either until I decided to do some research which is why I'm now all over the safety end of this. Like I said, I'm not against them but the potential risks are far greater than some of you imply.

Another cheap solution:http://www.b-p-p.com/proddetail.php?prod=1...cc6046e8536d3a9

This is a great answer. The "battery bunker" seems well thought out with interlocking lid but able to vent gases & pressures. At $20 to $30 this type of container should become a required piece of equipment for an FE racer using lipo's to have in their pit and be mandatory that it is used during all lipo charging cycles.

Don, I've had lipo packs under water for well over 5 minutes more than once. Not a problem.

Thank you Paul. I had been told that getting a lipo pack wet was a very bad thing but have not yet found anything to back that up.

 

[Grimracer]

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