Are LiPo batteries safe for HW robots?

Are LiPo batteries safe for HW robots?


I know it is a strange question as it depends on lots of different things. Not least on your own view on what€™s safe!
But I am concerned that with the saint or some other hitting weapon robot a LiPo battery may be ruptured and catch fire rupturing other cell in close proximity.
Do the EO€™s have plans and equipment to control dangerous situations like Lipo fires?
Are there any design considerations like steel battery containers to house these battery types in the robots.

Just wondering about this

Thanks
Craig

Lipos arent allowed in heavys. The only lithiums allowed in heavys are the A123's.

The FRA rules on batteries are currently being rewritten to allow new advances in technology. But this will not include LiPo batteries in the heavyweight category. But since they are allowed in FW and Ant categories, roboteers should bring the necesary equipment to deal with any accidents to each event.

Further to Alan's post the A123 technology is based on LiFePo (or LFP for short) chemistry not a Lithium polymer chemistry which is nowhere near as stable. As the FRA rules stand A123's are only allowed in feathers or below with the exception of the long running trials in Thz and KO, but this will be changing soon.

There is a need to re-write the build guidelines to cover the use of A123 cells in heavyweight
robots after the extended trials. Ed Wallace offered to re-write the relevant section for review and
agreement at the next meeting. - from last FRA meeting minutes.

Thanks for clearing that up Alan so LiPo batteries will never be allowed for HW. :proud: thats got to be good.
Do Lithium 123 batteries have any problems with safety if they get wacked? I know Nicad get very hot and smoke if shorted out, do 123 batteries do the same?

i don't see why they arn't allowed, there allowed to run in feather and ants and they running spinners what can cut them up, also the reason why the lipo's go up is not charging them right and mishandling, lead acid batteries go up alot worse, a few of us have had lipos falling out the sky 100ft with no damage, a 10s lipo which is 37v with a 5000mah could run a heavy and they are the same being used in feather's

Well I think I'm the expert on buggering over A123 cells. I can quite safely say that all that happens when they go is they get hot but thats it.

I have had a cell get so hot it split open but absolutely nothing else happened.

Hornets disc went through a A123 cell of Plofbox2 and nothing happened there either.

I have been using lipos in feathers for over 3 years now. A similar rated pack to what turbulence used to run in Nicads.
equivilent of 24v @ 5000mA and never had a problem. They are perfectly safe as long as your not stupid with them.
As regards to charging them, do it properly and you will never have a problem. Its not actually very likely a lipo will catch fire either. They need to be almost fully charged and punctured to have a good chance of catching fire (i know, i've tried it myself :lol: ).

If they go up in the arena, well who cares? The fumes are less toxic than nicad fires, and the robot needs to have a metal base to run lipos anyway. So it cant harm anyone.

They need to be charged in a metal box of some form aswell (personally prefer in the robot myself)
so it shouldnt matter if they go up when out of the arena either due to bad charging.

When I read
Hornets disc went through a A123 cell of Plofbox2 and nothing happened there either.
And
I have had a cell get so hot it split open but absolutely nothing else happened.
My fears are certainly helped.
I don't want to cause any fires from hittingThz or KO. I had visions of me burning down the arena :uhoh: :uhoh:

the fires arn't has bad as people think, its not like it sets on fire, it has a type of thrust fire when pressure is released for a few seconds and moves onto next cell and repeats till all the cells have gone

Little Spinner ran a 37V 3.3Ah LiPo at its last event. That in its self is big enough to run some heavyweights also. It does seem a little daft that a feather weight has no limit on the size of LiPo pack but a heavy cannot run any. Maybe a pack capacity limit is needed or sooner or later someone will have a featherweight with a 20Ah 10 cell pack in it.

are we limiting it to 9cell lipos then :proud: lol.

I think Mark has a very valid point.
What size of LiPo batteries are considered safe by the FRA or the EO€™s. :?: :?:
If the size of the LiPo battery, could run a HW, but is in a featherweight why is this considered safe, but the same LiPo pack in a heavy is banned!
I€™m sure their people out there with opinions on this point. :idea: :idea: :idea: :proud:

I think as the popluarity of lipos in featherweights increases as it is doing then time will tell what the FRA/EO's feel safe to run.
So far, there are lots of robots running them, and have been for years without a single problem or fire. One point that should be considered with using lipos for an event organiser is whether the user is knowledgable of the correct usage and competant enough to follow it through. Its part of the tech check to make sure all safety precautions are in place, and as long as those guildlines are followed then i cant see any reasonable size lipo being much of a problem. I have seen a fair few nicad fires, not a single lipo fire at an event yet!
I do think a few rule changes needed to be made, as at the time no one had any proper knowledge of lipos in use, and i believe most people are a little scraed by the horror stories and videos floating around.

Grant there are those people like yourself who know what they are doing and will look after their packs, but then we know that there are those who won't. If LiPos were opened up to the higher weights there will be people who have huge current demands so need bigger capacity than one pack from a feather even though there are packs with very impressive specs. I think it is several packs all going up at the same time that people are worried about. Especially say after an event on the way home, the robot is chucked in the car, not balenced charged or otherwise. In a feather you pull over and pull the feather out quickly, not possible with a heavy. Maybe you have a separate transport box, but the one time you forget to take them out of the robot, bad things happen.

But keep the comments coming they will be disscussed at the next meeting.

I think the problems with heavyweights would come if someone like me fancied running a second version of Hive with 2 eteks plus a weapon running off a few packs and then you throw in my history with battery packs and high current motors.

Perhaps proof that you can run Lipos in featherweights safely along with a capacity limit would be in order for a heavyweight. Throwing in a requirement for a steel container inside the machine seems somewhat pointless as it negates the weight saving from Lipos.

At the end of the day its the event organisers decision as to whether or not a robot runs in the arena.

if the pack is balanced charged everytime and kept in a metal box, and is not mishandled they should be fine, they supply the current alot better.

if they could be a check in the tech check of having a balancing unit for the lipo that would be good also

if you don't think lipos are good for you then use a123's, also don't get cheap and tacky lipo's with lipos you get what you pay for, look into flightpower, thunderpower and outrage lipos these are some of the best

Kenny I think thats the point there will be people who buy cheap packs and abuse them, but good point about the tech check which should be checked anyway even though not currently written specifically in the rules with regards to the tech check.

It is already written in the rules regarding proper charging and balancing equiptment.
With the saftey aspects in place, with almost anyu size lipo fire i can't see where there would be in a problem. They are either in a metal case, or in your robot at the times they are likely to ever catch fire, which is very rare for that to happen.

I think people underate lipo's ALOT.

Gary- you could easily get lipos to power an etek powered heavyweight pusher. If it can be done with a123 it can DEFINATLEY be done with lipo.

Why put a limit on pack size? theres never been a limit for any other type of battery? Apart from voltage, Which still stands at 37v i believe. If you want 100amps then have it.

360 pulls more current then alot of heavyweights, its pretty much constantly pulling atleast 160amps. and probably over 250 when the disc is spinning up. And my tiny little 5amp pack doesnt even get warm after 3mins of abuse.

I think it should be part of the tech check to make sure whoever is running lipos is 100% compitent to use them. AKA the tech checker must have experiance with lipo's themself.

Currently all the people using Lipo's in featherweights seem to know the dangers, the advantages and the risks involved aswell as which brand of lipo to stay clear of. As kenny said thunder power and flight power seem to be the only brands used so far that i can think of. You get what you pay for.

LS + sabertooth = flight power
360 + ploughbot = Thunder power.

Both thunder power and flight power use the same cells. Just a different brand.

Id like to see lipo's being used in heavyweights- it would give a massive impact on the progress of the robots being built. I think the FRA should watch a few RC heli crash's and see the abuse they take there, They dont seem to explode after a 100ft smash into the floor.

My main concern would be fire load.

It's ok to say they hardly ever explode but simple fact is the potential is still there for them to do so.

Using Hydra as an example where we had a short on the Nicad battery packs. It was realtively easy to deal with with very little heat or flame except very locally to the packs. It was easy to pick up and run out of the building with and it was realatively easy to keep cool whilst we got the packs out (one went first and then with a cascade effect took out the others and tried to set them on fire too). That said they didn't stop trying to catch fire again until out of the robot and completely taken apart from their mounting brackets.

In the event that someone has a large lipo in their robot it has potential to explode. It happens before you know about it and then you are dealing with a fire rather than smoke. If there is more than one pack in there and one explodes what do you do? Do you go in and fight the fire in the full knowledge that there is a further pack in there which may explode or do you leave it and contain it and risk it spreading and burning down the arena and sports hall? (and worse disrupting the show!!)

IMO there are safer packs to use and absolutely no reason for anyone to take a risk on LiPo's in heavies.

Andy

First off, A lipo cause a burst fire, that is hardly an explosion. These fires create a violent flame but die out very fast as well, as the the chemical fuel runs out. That being said I see no good reason to put Lipo in a heavyweight other than a weight advantage.

I think as LiFePo4 develops, the market for LiPo will steadily die out. Batteries need to become more stabile, and in the power to weight ratio LiPo wins for the moment, but that difference will decrease as production and research improves.

Leo, although your 100% right about the safety side of lipo's, i dont think the A123 or similar technology will be catching up any time soon.
The new range's of lipos that are beginning to hit the shelves now are getting seriously good. 40C continous and 65C burst ratings! in a 6000mA pack that featherweights can easily use would mean 240A continous, and 390A burst. In a 6s (equivilent to 24v) pack, you would be able to run a good amount of heavies with a battery pack that weighs about 800g, and fit in the smallest space :lol: . If your robot cant contain a fire from a lipo for 30-40 seconds, then it shouldnt pass a tech check with one in!

Oh just forgot - check out these new Hyperion Lipos..... :proud: http://www.fast-lad.co.uk/store/hype...r /> <br /> 5C

Quote:

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Originally Posted by grant_ploughbot

Leo, although your 100% right about the safety side of lipo's, i dont think the A123 or similar technology will be catching up any time soon.

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We'll see about that.

We'll see about that.[/quote]

The point is.. Lipos with amazing spec's are already availible. Hence i use them. why wait for a123's that might not be as good in the future?

Imagine what a robot such as tiberious could do with lipos considering it currently runs on SLA's.. he would be saving about 10kg.. Thats 10% of the weight allowence of a heavyweight. The possibilities to improve upon todays current machines is huge.

Quote:

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Originally Posted by mr_turbulence

We'll see about that.

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The point is.. Lipos with amazing spec's are already availible. Hence i use them. why wait for a123's that might not be as good in the future?

Imagine what a robot such as tiberious could do with lipos considering it currently runs on SLA's.. he would be saving about 10kg.. Thats 10% of the weight allowence of a heavyweight. The possibilities to improve upon todays current machines is huge.[/quote]


Exactly god knows what he would do with an extra 10kg, Sam has caused me enough pain in the last 12 months as it is. :mrgreen: :mrgreen:

Quote:

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Originally Posted by mr_turbulence

Quote:

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Originally Posted by leo

We'll see about that.

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The point is.. Lipos with amazing spec's are already availible. Hence i use them. why wait for a123's that might not be as good in the future?

Imagine what a robot such as tiberious could do with lipos considering it currently runs on SLA's.. he would be saving about 10kg.. Thats 10% of the weight allowence of a heavyweight. The possibilities to improve upon todays current machines is huge.

---

Where in my posting have you seen me make a judgement on the use of LiPo's in heavies one way or the other? I am stating what I see as the future that Lipo will phase out as LiFe or similar chemical compounds will improve and give a better and more stable. Grant is of another opinion. Neither opinion has anything to do with weighclasses.

As for why wait? If you don't need the extra weight, SLA is still a lot cheaper option than LiPo or LiFe. If you do need the extra weight advantage, there is weight to be saved with A123 too, so instead of calculating how much weight you save from SLA to Lipo, calculate how much weight you save from LiFe to Lipo. That difference is a lot less shocking as you make it out to be.

Perhaps it's time for the FRA governing body to stop precluding technology that is generally available and legal to use. What the FRA should do is make recommendations for or against the use of a technology and possibly impose conditions of use if justified (assuming they have the knowledge to make an informed view). Risk of fire, well IC engines and petrol is allowed so what is the greater risk? For me, it is down to the EO to decide along with the venue hosts what can and what cannot be used surely?

Exactly Paul

This will be discussed at the next FRA meeting, please comment further!

I'll put my view down here so it can ve discussed at the meeting if i'm not there......

I have been using large lipo's in feathers now for about 3 years or more, and in other things for a while too....
Just a couple of facts about lipos -

Lipos DO NOT explode, the catch fire for about 40 or so seconds and then burn out quickly. The Flame is hot, and sometimes quite big if FULLY charged and in good condition, but it doesnt last very long.

In 99% of cases, a lipo wont catch fire. It just puffs up and then needs to be disposed of. Using a puffed battery can then result in fire whilst charging if your very unlucky.

Whilst charging a lipo wont catch fire unless you are charging it wrong, or it is very out of balance. Firstly, to pass a tech chek you need to have the correct charging equiptment (which shouldnt allow you to charge them at the wrong voltages) and balancer. This is the number 1 cause for lipo fires whilst charging, using incorrect chargers.

If a lipo does catch fire whilst charging it should be in a metal box if you work by the FRA rules (i also think charging in the robot should be allowed as long as you can connect a balancer to the pack and visually ceck for any swelling). In the robot is the safest place for batteries!

When in use, the lipo wont catch fire unless its punctured, or the cells are not matched at all (this only happens to the extreme when multiple packs are linked together - i dont think any more than 2 packs should be used in series or parrallel unless all have identical ages and cycles). Over discharging a lipo will get it hot and swell up, permanently damaging the lipo, but it wont catch fire from this. Kenny and I have tried to make a lipo catch fire from an over discharged pack, and its physically not possible.

A Lipo can catch fire if its got a good charge and shorted out for a good period. I wont pass a tech check in a featherweight if a lipo doesnt have a fuse directly inline thats rated less than the peak discharge of the pack. Hopefully that will stop any possible fires from shorts.

If a lipo does catch fire in the arena, then the arena and even organisers should be easily capable of dealing with it - otherwise theres big problems with safety for any fire!
The lipo will most likely have burnt out by the time you enter the arena anyway, but if not then just treat it as normal - its no more dangerous than a normal fire if you have some basic common sense (i.e dont pick up the robot with flames coming out the top!)

In the rules it states that the robot should have a 2mm metal base with lipos anyway, so no problems with setting the floor on fire.

I have crashed alot of helicopters with lipos in the front, and litterally bent them 45 degrees or more. They dont catch fire from it. Alot of people even bend them back and keep using them, although that really shouldnt be done, it proves they are alot safer than people think. Alot safer than pneumatics in the wrong hands!!!

As a tech checker for our events, if i dont believe the roboteer is capable of looking after lipos correctly or dont have any knowledge on how to charge and dispose of them corrctly i wont allow the robot to run for obvious reasons. Also the same with pneumatics, we try not to let people with no experience and understanding of them re-fill bottles or mess around with them without someone experienced checking over them....

I have a more generic issue with the role in the FRA governing body dictating build rules. The constitition states:

5.5 Governing Body meetings shall rule on all FRA matters including guidelines and regulations for the safe and enjoyable involvement in robot build, operation and events. These meetings shall set the policy for activities of the Association and its representatives.

The recent issue over the 40MHz band and LiPo's are two examples of where decisions have been taken without consulting the membership. I feel the Governing body should address its role in determining the rules, in particular build rules. This could be by being open with its thought process with publishing data that supports its stance, for example a risk assessment that justifies the non-use of LiPo's in Heavies but allows them in Feathers. The FRA Governing body could change its role by making recommendations for or against technologies that are available and legal to use and possibly impose conditions of use (for the Roboteer and / or Event Organiser) following a published risk assessment. The FRA build rules have become too prescriptive and the FRA Governing Body too quick to make decisons that affect the Roboteer directly either through time or money. There is considerable expertise within the community that should be utilised in ensuring that the build rules in particular are reasonable.

The FRA used to have an Electronics Technical representative (Paul Hunt IIRC) but no longer lists one so how can the membership be confident that the FRA Governing Body is voting in changes that have been reasoned and properly presented to allow an informed decision to be made?

Copyed from RFL Forum
There are new UN Lithium laws coming possibly as soon as Oct 1st 2009 which will make it more difficult to obtain all Li cells
The new regulations, which are quite readable, are available here:

http://www.nexergy.com/media/pdfs/TRANS_UN_38-3.pdf
Packs are going to need to be tested at a special lab.
These are the tests
Storage at 10% of atmospheric pressure
Rapid thermal cycling between -40 C and 75 C
8g vibrations
150g shocks
Complete discharge through a short circuit while pre-heated to 55 C
Having a 20 pound weight dropped on it from a height of 2 feet
Being over-charged at double the rated current for 24 hours
Being force-discharged (like an unbalanced cell in a pack)

I dont know a whole lot about big lipos , as ive only ever used lipos in antweights , but id just like to say , even when a little 400 mah lipo gets punctured , in the one time that it happened to me there was a 1 ft flame , a roar and the thing set the hdpe shell on fire , melted the rubber bands holding it down and shot around the floor a bit , before eventually just smoking and bubbling with heat for a minute or so , i wish i had taken a picture it was incredible ! This put me of using lipos for a long time , so if lipos are made legal , could i suggest that there is a minimum casing thickness for just the lipo , to avoid puncture .

I started this thread having a fundamental misconception about A123 and LiPo batteries I thought wrongly they were basically the same this error was brought to my attention early on in this thread, many thanks for this.
I think it would be interesting for us (who are not particularly interested in the micro-spec of the different battery types) to have a grid of €œIf this happens. This will result.€
For instance if you overcharge, drop, puncture, etc a LiPo, NiCad, SLA or A123 this would be the likely result.
Also the LiPo size in Featherweights, should there be a limit of capacity or voltage? I remember someone saying his LiPo pack would run a heavyweight! If this is true why not let them be run in heavyweights?

Pneumatics
Also off the subject slightly perhaps some safety information and instruction on pneumatics would be a good idea, as a mechanical engineer I found it quite frightening the way pneumatic systems are handled in the robot scene. Many people have been killed by pneumatic systems in the past and they were much less powerful than the ones used in fighting robots, Perhaps some pneumatic circuits that could be advised by the FRA, stating capacity of components and manufacture part numbers etc so there is a minimum standard for components and circuit design. It would be a practical help if we knew this has been tested and approved for a fighting robot. Do the systems have a safety valve that can be tested in the robot at an event?
Hope this helps


Craig

While everyone is on about lipos on here

in my expierence i found them fine just treat them well etc,

saying this i am selling some lipos http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0451474172

as i now do not need them not for any safty reasons

More from RFL Forum
Wal-Wart just got fined $350K for not having the proper DOT training....scoff if you like, these rules are coming.

http://prba.org/laws_and_regulations/un ... fault.ashx

did the talk go through about lipo's in heavys? i'm currently designing a heavy and theres no point building without lipos as the weight saving and the spec's i need to run the parts it will have in it

Copyed from Robotmarketplace this is on all there li poly battery packs


At this time, the battery does NOT conform to the UN T1-T8 tests as required in sub-section 38.3 of the UN Manual of Tests and Criteria for lithium-based batteries. Therefore, we are unable to ship by any method until this particular pack has been tested and approved.