New Batteries?

Hi

I found something which might be of intrest to people. I have found a 6000mah (6amp) 12v Rechargable battery which weighs only 400g and can do 30amps. they are called Lithium Polymar batteries (li-po)

They have been around a long time now and I have used them in antweights but I was looking into them for my no money limit feather vapour bot. They are possibly affordable and usable in a featherweight but are possibly beyond most Normal peoples reach.

For this 6amp 12v Pack it would be 144pounds including delivery to anywhere in england.

You would also need a charger but they can be simply made by most people. (if your intrested please contact me for a circuit diagram)

What do people thing? I know the price is high but the weight is very low.

Regards
Ian Mc Donald

cant supply enough current for alot of robots, alpha can pull over 50amps, the Nicads get very warm after a fight so i wouldnt like to run Li-Pos.

These batteries were going to be my first choice from my battery sponsor, but then I found the general stats-
They are pathetic at giving any high currents, and when they do, they get VERY hot... The actual fluids etc are some of the most dangerous in any battery. The price is VERY HIGH. They take around 14 hours to charge a pack!
Cheers, Ewan

Already been and looked at these - for now I think theyre going to have to stay as Antweight technology as they just cant supply enough current for even a wiper-motor powered feather.

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

I think your slightly wrong there ed and ewan.

Ewan.
It takes 1hour to chare li-pos from dead. The do not get very hot at high currents once you keep them under the rated currents youll be fine. The 1500mah batts are rated at 5c with a peek of 7C so if you try and draw 100amps out of them they will get hot. But if you try and draw anything up to 7.5amps youll be fine.

Ed.
They can supply enough current for my pusher. It runs drills on 150mm diameter wheels and it does not even draw 30amps. So they could be used.

In general i dont think they are really suitable for featherweights at the moment. But considering 6months ago you could not get a Li-po that could do more than 1c discharge they are advancing rapidly.

By this time next year we might see cells as good as some ni-mhs who knows

regards
Ian Mc Donald

Ian, if youre using drill motors on 150mm wheels and you think each motor is only drawing 15amps PEAK then youre living in cloud cookoo land mate !

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

Ive been saying that for ages Ed :P

Well ed my total bot when stalled does not draw more than 30 amps on 150mm diameter wheels. This is not theory its fact!

Regards
Ian Mc Donald

How do you know this fact ? I presume you have monitored the current using a clamp meter, or you have calculated your motor constants and evaluated your motor performance for the given circumstances at stall ?

Explain how you know this as a fact.

Sounds highly unlikley to me Ian !

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

Well i stalled both motors by driving them straight into a wall at top speed. The 20amp fuse blew but then I fitted a 30 and it did not blow when i did the same thing on fully charged batts.

If you dont wanna believe me then thats fine but its true.

regards
Ian Mc Donald

Ian, if your motors stall when your robot drives into the wall then something is VERY wrong ! You should be able to wheelspin.

What I suspect is happenning is that your batteries simply cant supply the current that your motors are asking. So yes they are drawing a maximum of 30 amps, but thats not the stall current of your motors, its that the batteries are limiting the performance of your robot as they cant supply enough current to do the business.

..... trust me Ian - I might *just* know what Im talking about.

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

Ah, Eds got it right again!

please note the just! The chance are your fuses are slow blow as well, so may peak above the 30amps. also your motors are drawing 30amps each, therefore 60 when stalled.

That a 30A continuous or 30A blowing fuse?

Hang on - were talking vapourbots - whats the point? Its an imaginary fuse.

no comment

Have to agree with Ed here, by the sound of it your batteries aint kicking out enough current to stall your motors.

Micro Mute used to run two NCC-70 speedos on its motors, and we unfortunately current limited at the batteries. MM could easily draw well over 100A per motor (yes they were BIG motors), however the battery could only give out 100A max.

Dont rely on batteries current limiting because in a 5 minute fight they get VERY VERY HOT.... we lost 2x 24V 2.4Ah NiCad packs to over heating.

Micro Mute - the one and only battery cooker :)

What good is all that power when you carnt stop before you hit a wall? :)

regards
Dave moulds
Team Turbine

in micro mutes case, in the pit!

had a custom made LiPo made for one of mine by a company that leads the world in the technology, and sent direct from Korea, but it never arrived.
been on to them and apparently its not safe to ship the way I wanted it (ie, cheap) in case it is knocked and cracked, it will explode....
asked how this is ok for robots and they seemed to confuse robot fighting with robot stangin there looking nice but doing nothing.

current, is limited by the size of cell, if you want more current get bigger cells, that was my plan, and I could have 45amp for 5 minutes (comprable to NiCDs we use in feathers). had to have special cell made, but is possible.

price, if youve got it flaunt it, if you havent... well.

at the end of the day, do what you want, but no offence to people who may show up with these in future, if you have a LiPo in your feather, dont expect me to allow you to run. Dont like exploding robots, and dont fancy wasting my fire extinguishers on a dead cert bonfire.

for now, ants seem ok, but until they can protect these lipos, I cant see them being safe.

BTW, arent they used a lot for electric flight with high current, high performance motors? Sounds like they can produce some useable power.

My batt sponsor (http://www.countybattery.comwww.countybattery.com) has every type of battery you could imagine, exept Li-Po. They store their batteries in an air-conditioned warehouse and carry them around in or on crates by forklift truck. If a single small pack fell off a forklift truck,then boom! You could imagine a heavyweight bot with VERY large Li-Po cells come up against Storm II. The forces involved would almost definately leave the packs ending up in smoke...
Cheers, Ewan

- if a single pack fell off a forklift - then boom. I cant see a Nicad Pack going boom if it fell of a follift truck. LOL. Unless it was poorly made and shorted it self. Bit ott ther Ewan.

Ive never seen how a Li-Poly will react to if it got cut by a spinner from another ant weight or something - so cant comment on how safe they are etc. Nicads and Ni-Mh are bad enough. I see soo many packs in the pits with their wires hanging lose etc- i just wanna faint. LOL. Ive witsnessed many Nicad fires, even had to control one at Inspire. Nasty things when they do what they want.

Id REALLY hate to see something like Storm 2s nicad packs short them selves out or something. I know it aint gona happen too soon with all that 6mm and 12mm ti, but imgaen someone else with lots of nicads like that - wouldnt want to get too close to that.

Ne ways some people would call us sad speaking on the net on new years eve - bye all, im going to a party, have a nice Night. Cya.

Mr Stu

I was talking about the Li-po packs going boom...
Cheers, Ewan

Ive played with Lithion Polymer packs - I dont know where the scaremongering is coming from that if one fell off a forklift theyre blow up.

Check your laptop, mobile phone, pda, mp3 player - I could go on. Li-Ion Polymers are everywhere. Theyre a safe non spillable battery type and physically theyre fine for RW

Why are they in things like laptops, phones and pda ? Because theyre good at giving a sustained low current output - hence why theyre also ideal for antweights. Sadly at present theyre just not up to the job of running a featherweight - theyre getting close, but its not there yet.

So no need to panic if your friend drops their mobile phone or laptop with Li-Ion battery - luckily its unlikley to explode !

Im off to a party too now - happy new year everyone !

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

I just know from expirence that you can never be to confident with Li-Po batts. (this IS a true story) One minute I was typing on my dads laptop, then the next, the battery port was smoking. It had fallen off my lap, and hit the floor, causing the contacts inside the battery to knock together. I quickly ran down stairs and got the fire-extinguiser from my workshop (in the cellar). By the time I got upstairs flames were visable but it was easily put out. If the flames had got a chance to get into the cells then it would have been a case of... Boom
The short-circuit had put to much stress on the battery causing the fire. Cheers, Ewan

Li-po packs in laptops and cell-phones are fitted with internal failsafe measures against shorting out. Fact is, if that countermeasure doesnt work they will heat up like theres no tommorow, en eventually explode. It does take a while to reach that point, its not a firecracker or grenade, but it will happen.

at AWS a Lipo pack got damaged (by a crusher i think), there was alot of smoke.

If Li-Po packs do ever come to give out high enough currents, even for a heavyweight, Im personally going to stick to ni-mh and ni-cads.

Ewan - what sort of true story is that about batteries and how unsafe Li-Ion Polymber batteries

It had fallen off my lap, and hit the floor, causing the contacts inside the battery to knock together

Well duh - if you short any battery it risks explosion. What do you think the release vents are for in the top of a NiCad cell, to drain water ?

If the flames had got a chance to get into the cells it would have been a case of Boom....

WTF are you talking about Ewan ? Youre making out that Li-Ion cells are the only cells that can explode ?

Ive been trialling some Li-Ion cells and theres no indication that if you drop them they blow up. Theyre just as safe as NiCads. I dont understand why people are trying to make out theres this super-unsafe technology thats so unstable they could explode at any moment ?

Alan - watch a NiCad pack get crushed - lots of smoke there too.

Leo - Im sure you know that a NiCad pack has built in failsafes, which if they fail results in the cell going bang.

.... why are people making out that Li-Ion cells are different and super dangerous

Sounds like rumour and mis-information to me !

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

Its just all I know, Im not a battery expert, according to every source I have heard from, Its just the stuff inside the cells (the acid or whatever it is) that makes it more dangerous than other cells. I do admit that I havent witnessed any ni-cad fires myself, so for all I know, they could be just as dangerous.
Cheers, Ewan
P.S. Are ni-mh batts likely to provide enough current when short circuited to create a fire?

Yeah, as are alkalines, SLAs, wet lead acid, lithium.....

Right. Intrigued by this Lithium Battery witch hunt, I consulted my triton charger hand book. When I oponed the box, the first thing that dropped out was a sheet of A4 with Important warning concerning the use of li-ion and li-poly cells Stating that The Li-io/Li-poly chemistry is a very volatile mixture. Misuse can quickly result in Li-ion/Li-poly cells getting hot, exploding, or igniting, which could lead to serious damage or personal injury. When I got the charger out, there was a sticker on it saying exactly the same thing. When I oponed the instruction manual, which details how to charge the types of batt that the triton can charge- Nicad, Nimh, Li-ion, Li-poly, SLA etc, under the Li-ion/Li-poly section, it says right at the top, in bold Important warning concerning the use of li-ion and li-poly cells Stating that The Li-io/Li-poly chemistry is a very volatile mixture. Misuse can quickly result in Li-ion/Li-poly cells getting hot, exploding, or igniting, which could lead to serious damage or personal injury.

I get the impression the triton manufacturers are trying to tell me something. I then spoke to some folks at Sussex Model Centre. The conclusion was the same. Whether or not the explode when you look at the, as some ppl seem to be claiming, it is clear that they are more dangerous than the other battery types, and whilst we all strive to be as careful as possible with our batteries anyway, extra care should be taken when using these.

As a bare minimum, ensure all your li-ion/li-poly batts have obtained UL1642 approval (quality of construction) and I would say you also want to ensure it has a built-in protection circuit. When draining this things quickly, and charging them, there is a much much greater risk of them exploding than there is with Nicads or Nimhs and so on.

As with most things like this, ensuring you use the safest and best practise (and I would be dubious as to whether or not use in a fighting root is safe practise) then there shouldnt be a problem.

Happy new year,

Eddy

Li-Ions certainly need to be treated with care - however the suggestion from Ewan was that merely falling off a pallet would cause them to blow up !

There is no doubt that you should not abuse Li-Ion cells, what you gain in weight must be paid for in respect. They should only be charged using a proper Li-Ion charger for example, but then that is the case with all batteries - we would never think of putting a NiCad on an SLA charger so its common sense that you wouldnt put a Li-Ion on a NiCad charger !

Yes you need to be careful, read the instructions and know what youre doing - but that doesnt make them inherently dangerous. A NiCad pack in the hands of someone who doesnt know what theyre doing is pretty dangerous !

So long as you follow the instructions and best practice, there is no reason why a Li-Ion pack shouldnt be as reliable as a NiCad or NiMH, which I think is what Eddy is saying - so long as you play by the rules, youre fine.

..... bottom line is they are NOT going to blow up if they fall on the floor !

Ed
http://www.stormrobot.comhttp://www.stormrobot.com

True, and as one of my friends whos into RC boat races will tell you, a lot of NiCad packs have entered the water without a boat during events.

On some occasions even more than inside a boat. :)

I was simply saying before, that if they fell off a pallet etc, AND it shortcircuited, Like what happened in my laptop accident, that then bad things could happen. But I do aggree that for fuse protected Li-Ions, the chance of them shortcircuiting is VERY low.
I think that Li-Ions may come into use someday for robots, but the technology needs to evolve to cater for high current needs etc.
THE END :)

The reason In my opinion why Li-pos are slightly more lightly to get damaged is that they do not have a super though outer shell like a ni-mh/ni-cd/sla etc. The shell on them is some thin foil type thing. This helps to keep the weight down but does not make them as secure.

Li-po technolegy has come along way. The first came with soft bendable tabs now the tabs are pcbs. They first came with no safety warnings now they do. It was like when ni-cds came out first. People did not know how to treat them correctly hence alot of fires. Now people know how to treat Ni-cds we see alot less fires.

In my opinion Li-pos are where Ni-mhs were about 3-4years ago. Now look at Ni-mhs. The new Gp 3300cells have almost the same current handelling capabilities as the 2400mah Ni-cds. Things are constently advancing.

But as i said it is possible to use them but I dont have to money to use them nor do most people.

As for if a li-po gets punchered. Well its simple you get a bucket of water and add salt then chuck the battery into the bucket for 1-2days then just throw it in the trash.

Every battery is dangerous. I got a 3rd degree burn from a 700mah 4.8v Ni-cd battery when it shorted. In featherweights now people are using 24 and 36v 2400mah ni-cds the short circuit current is much higher. We have to respect batteries. If you dont you will get hurt. As they say if you play with fire you will get burnt. If we treat all our batteries nicely we will never have a peoblem. If you dont then you do so at your own risk. One of the antweight guys who is an electronic engineer told me he got a really bad burn from a AAA alkaline. Most of us would class this as a safe thing as it never crosses our mind what they can do.

Regards
Ian Mc Donald

Well, heres examples of both sides of the arguement:

http://www.rcstuff.us/battery/lipo/lipo_DNA.htmlhttp://www.rcstuff.us/battery/lipo/lipo_DNA.html

http://www.robotwars101.org/~robotwars1/phpBB/viewtopic.php?mode=viewtopic&topic=94&forum=1&star t=330http://www.robotwars101.org/~robotwa...iewtopic&topic =94&forum=1&start=330 (3rd post down)

We need some industrial standards to refer to.

Wow someone actually remembers them posts, I thought that they got totally ignored. lol

But yes the battery can be pierced, crushed, heated and hit but it dont tell you if they connected it up to try it lol because if its connected it might be a whole different story.

Ive now seen this warning posted :

-------------------------------------------------------------------------------- ------------------

WARNING
Safety precautions for Lithium Polymer and NiCd cells/packs

1. Never fast-charge any battery type unattended.
2. Never charge LiPo cells/packs at any rate unattended.
3. Only charge LiPo cells/packs with a charger designed specifically for lithium polymer chemistry.
4. LiPo cells can ignite because of unmatched cell capacity or voltage, cell damage, charger failure, incorrect charger settings and other factors.
5. Always use the correct charging voltage. LiPo cells/packs may ignite if connected to a charger supplying more than 6 volts per cell.
6. Always assure the charger is working properly.
7. Always charge LiPo cells/packs where no harm can result, no matter what happens.
8. Never charge a cell/pack in a model. A hot pack may ignite wood, foam or plastic.
9. Never charge a cell/pack inside a motor vehicle, or in a vehicle€™s engine compartment.
10. Never charge a cell/pack on a wooden workbench, or on any flammable material.
11. If a cell/pack is involved in a crash:

a. Remove the cell/pack from the model.
b. Carefully inspect the cell/pack for shorts in the wiring or connections. If in doubt, cut all wires from the cell/pack.
c. Disassemble the pack.
d. Inspect cells for dents, cracks and splits. Dispose of damaged cells (see below).

12. Dispose of cells/packs as follows:

a. Discharge: with the cell/pack in a safe area, connect a moderate resistance across the terminals until the cell/pack is discharged. CAUTION: cell/pack may be hot!
b. Discard:

- NiMH: place in regular trash.
- NiCd: recycle (cadmium is toxic).
- LiPo: puncture plastic envelope, immerse in salt water for several hours, place in regular trash.

13. Handle all cells/packs with care, as they can deliver high currents if shorted. Shorting by a ring, for example, will remove a finger.
14. Always store cells/packs in a secure location where they cannot be shorted or handled by children.
15. When constructing a pack, use only cells of the same capacity (mAh).

-------------------------------------------------------------------------------- -----------------

And you might also find that there is also now safety guard electronics to prevent overvoltage when charging LiPo packs with a current-regulated LiPo charger just incase you accidentally apply a too-high voltage or charge for too long which you can see from the video and pictures on RCStuff.us causes a scary firework show

https://www.fmadirect.com/site/Detail.htm?item=1779&section=28https://www.fmadirect.com/site/Detai...779&section=28
http://www.rcstuff.us/battery/lipo/lipo_DNA.htmlhttp://www.rcstuff.us/battery/lipo/lipo_DNA.html
http://www.robotwars101.org/~robotwars1/phpBB/viewtopic.php?mode=viewtopic&topic=94&forum=1&star t=330http://www.robotwars101.org/~robotwa...iewtopic&topic =94&forum=1&start=330

Chris - http://www.featherweights.org/forum Im So Evil Im Worshipped By The Devil

Ed - It is true that lots of portable consumer devices such as MP3 Players, PDAs and Mobile phones do use Li-on/Li-po technology and they are indeed classed as non spillable. But they are certainly more volatile than most other battery types, and there have been quite a few fire/explosion incidents - especially in mobile phones:

http://www.theregister.co.uk/content/68/33828.htmlhttp://www.theregister.co.uk/content/68/33828.html
http://www.theregister.co.uk/content/68/33879.htmlhttp://www.theregister.co.uk/content/68/33879.html
http://www.theregister.co.uk/content/68/33990.htmlhttp://www.theregister.co.uk/content/68/33990.html

It seems that overcharge,internal failure and short circuit are more likley to cause a li-po/li-on battery to fail, rather than impact.

As far as robot use goes they should be fine, if they do happen to explode or catch fire, better if it happens in an R/C metal box than while in your hand pressed against the side of your head!

Ewan - If your laptop hit the floor hard enough to damage the battery, id be more concerned about the state of the hard drive. :D


Dominic

http://www.ukrobotics.comhttp://www.ukrobotics.com

Yep, the Lap top got off abit bad aswell...
A month at a repair service did the job :)
Cheers, Ewan

Does anyone know anything about silicone lead batteries? i am thinking of getting them but need to know if they can be charged on my Supernova. These are the batteries I am considering http://www.overlander.co.uk/detail.asp?categoryid=55&ID=354http://www.overlander.co.uk/detail.a...ryid=55&ID=354

Joe Townsend
Team Cut Corners