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These use the same A123 cells and are packaged with a charger. Could be suitable for a feather.
If you only need 10 Volts it would be convenient way of getting everything you need. £145 + DUTY for 6 cells and a balancing charger (Two 3S1P Starter Kit). Best to avoid the Turbo Voltage Controllers - presumably mainly just a device to switch off the power if they get close to fully discharged.
For comparison, the DeWalt 36V packs (10 A123 cells) go for around £70 on ebay.
http://cgi.ebay.co.uk/3-DeWALT-36-Volt-Battery-Packs-DC9360-36V-NEW-BATTERIES_W0QQitemZ140197210251QQihZ004QQcategoryZ 20794QQssPageNameZWDVWQQrdZ1QQcmdZViewItemhttp://cgi.ebay.co.uk/3-DeWALT-36-Vo...W-BATTERIES_W0 QQitemZ140197210251QQihZ004QQcategoryZ20794QQssPag eNameZWDVWQQrdZ1QQcmdZViewItem
Its 10 months since testing of these cells was sanctioned by the governing body and during this time chargers and balancers have become easily obtainable ... no doubt due to the increased usage of A123 type cells in various applications.
So in the absence of ...as far as I know ... any SAFETY issues should they not now be ratified as suitable for ALL weights of bot?
(Message edited by woody on February 10, 2008)
I am in favour of ratification of A123s in all weightclasses. As I was 1 year ago.
I support that motion to accept the A123s in all weightclasses.
So do I.
I support it as well
It seems the DRG is not opposed to the A123s in all weightclasses.
What is the RFL view on the A123s?
The Aussies use them actively for more than a year now. And no safety issue came up with them.
i also support it
Main question is: Whats taking it so long???
Cells, chargers and balancers are commercial available. So is there any argument left to reject it?
(Message edited by tough_as_nails on February 11, 2008)
http://www.hobbycity.com/hobbycity/store/uh_listCategoriesAndProducts.asp?catname=LiFePo4&i dCategory=218&ParentCat=85http://www.hobbycity.com/hobbycity/s...cts.asp?catnam e=LiFePo4&idCategory=218&ParentCat=85
Anybody any comment yet, why it would not be allowed?
gonna need um soon
gotta get a few packs
how much we talking?
i am just waiting for an answer just like you Jeroen.
I dont see any reason not to allow all robots to use them either. Yes they have issuses, but not safety related (at least no more than current batteries) and if people want to try them the worst that can happen is they damage them by incorrect use and loose money, but thats the roboteers choice. I guess it will come up in the next FRA meeting, if there are alot more interest then perhaps the FRA commitie can do this by Email to resolve it sooner.
What is the discharge rate like on A123s compared to good quality nicads?
I would possibly think about an upgrade but my nicads work well as it is and I wouldnt want to lose any performance.
http://www.flyelectric.ukgateway.net/lithium-a123.htmhttp://www.flyelectric.ukgateway.net/lithium-a123.htm
Suggests 30C
A123 Blurb ...copy & paste ..
Nanophosphate is a positive electrode material of remarkable rate capability, critical to high power systems. Our high power products are able to pulse at discharge rates as high as 100C and deliver unmatched power by weight or volume. With their low impedance and thermally conductive design, A123 cells can be continuously discharged to 100% depth of discharge at 35C rate, a marked improvement over other rechargeable battery alternatives.
as far as im aware they arent as good. Like its been said, theyre light weight and safe enough, but the performance is alittle bit dull unless you put some more in parallel
Its pretty simple, to get the same performance with nicad you need 3 Nicads since 1 A123 cell is 3.3V. Therfore much heavier. Good Nicads can however deliver more in short bursts than A123s can. But still, thats not a safety issue, that is up to the roboteer if that is sufficient.
I run Hannibalito 3 on 4 A123 cells in series (13.1V) with 2 Speed 900s for drive and I can do about 2 fights with them on 1 charge. So more than enough for 1 fight, and I have no complaint about performence. and for a 350 gram batterypack thats nod bad at all.
perhaps the FRA commitie can do this by Email to resolve it sooner.
I think that there is enough interest to warrant expediting this and swiftly ending this long winded safety issue.
I agree. I know of at least 2 heavyweight teams that are on the virge of buying new batteries and would like to go to A123 but this hold-up now means they might be forced to go with different ones. We already went for new SLAs instead.
For the record, no one of the organisation of DRG has any objections to the use of A123 in all weightclasses. Nicad fires are not an issue with these cells, and neither is thermal runaway. This has been told to me by a person who designs and builds chargers and balancers for all types of batteries including Lithium nanophosphate.
btw Gary: 2 cells A123 parralel is still lighter than 3 cells nicad in series (to get roughly the same voltage), and then the discharge figures are more in favour of A123.
true but the bank balance figures are then in favour of the nicads. This is when including the price of a lipodapter and cells.
I think I am going to stick to nicads for the time being and see how the A123 cells perform when run in multiple machines.
I am however all for the acceleration of this issue which has been ongoing for a good 9 months or so if you look back to the start of this thread.
The difference in Thz speaks for itself, but that is mainly due to the increased voltage. I think that when the rule is passed we will be looking to go with the A123s at the higher voltage aswell.
Gary, Having tested out A123s and obviously knowing how Bot-packs perform, all I can say is about the same at best.
I feel the FRA is right in researching these cells in order to provide appropriate guidelines and not taking the manufacturers claims as face value which was as it turns our rather wise in my opinion. 70A continuous discharge, no chance in the real world, the main issue is temperature rise. I look forward to seeing the FRA recommendations as soon as they are available.
Wether or not the performance is or is not the same is not a safety issue. There is no safety reason for these cells not to be allowed in all weight classes. Wether or not a roboteer will use them should be up to the roboteers.
When Nicads came into the picture no roboteers were forced to go to nicads, if they wanted to stay on SLA that was fine.
When NiMh became more interesting for feathers, no one forced roboteers to go to them, if you wanted to stay on Nicads or SLA thats fine.
No one is forcing anyone to go to A123 cells, if you want to stay on NiMh, Nicad, or SLA, that is fine. But do give the roboteers that do want to use them the chance to do so.
Decisions on the investment of batteries, packs, chargers, balancers should be up to the roboteers, in the end they are the one that will have to care for their investment. Those that want to invest in this should be allowed to do so.
Even now a lot of roboteers stay on cheap SLAs like the Yuashas or over here, the PBQs. Even if the NiMH technology is matured a lot with a subsequent lowering of pricetag.
The A123s, in safety issues are even safer than the NiCDs of days past. I remember a certain machine shorting out the very expensive (for the day) NiCd botpacks. Without more issues than a lot of money gone up in smoke.
If roboteers want to smoke up a lot of money in abused batteries, without aggrivating arena safety issues, who cares.
Leo, Perhaps the FRA insurers will take your statement There is no safety reason for these cells not to be allowed in all weight classes. Wether or not a roboteer will use them should be up to the roboteers as gospel and not require any further evidence of due diligance but I doubt it. Not often I come out in support for the FRA but for once, I am encouraged to see proper research being undertaken on what is a new technology. There is little point in harking on about what we all did years ago and got away with, it is what is expected today from a professional body that counts.
Paul, all research on these issues have been done, and results of these tests have been shown here in this thread and all over the net. This is not a cell that just hit the streets 3 months ago, LiFePo4 has been in use for various automotive applications since 2005!
Paul wrote: There is little point in harking on about what we all did years ago and got away with, it is what is expected today from a professional body that counts.
Granted, but these are the first batteries to undergo this kind of scrutiny. The question is, have they been proven safe enough and why does it take so much time to give this verdict?
What I think we can agree on is that NiCds can be quite dangerous when they start burning. How responsible is it of the FRA to allow them for future use if the pose a proven risk? How will the FRA insurers respond if an accident happens with a battery type of which we know there can be safety issues? I can expand this discussion to the whole ruleset, but lets not go there.
is it true that with these batterys you cant stay in after a fight for another one?
my dad said something like it but hes prob trying to get me not to buy any lol
when robot wars is back on tv ill def get some
but at shows i like to just stay in fights if i can fight in the next fight??
as with any batterries it depends on the capacity of your pack.
thats if its still working LJ
normaly now days its stops mind you the sidwinder has done 7 events now :) a record
just gotto sort flipper out and marios sorted that bit :)
Ok,
I have a question, and i wonder if someone can answer it if they know.
I run 2 x 24v Nicads in Ripper.
If i Swap to These new batteries what will i gain?
How much will they cost?
How much are the chargers / balancers going to cost?
I believe my voltage will go up to 30v, correct ?
What will be my weight saving?
will I need more space?
I am starting to think about the Uk champs and getting my hardox armour on ripper, but it means a drastic diet to get it in weight, thats why i am asking.
I know that we havent got any thing finalised, but if someone knows approx values so i know.
John
What drive does Ripper Use? Gear ratio, speedo and motors.
What Ah are you replacing?
2 bosch 750, 10.5:1 ratio, roboteQ
Replacing 2 x 24v 3amp nicads
JOhn
I normally calcualte the A123 as 3.3V 2Ah (even though they are a bit more). They weigh 70 grams each cell.
so 24V/3.3V = 7.2 cells, so 8 cells would do 26.4V nominal, 28.8V peak (3.6V per cell).
8*70 grams=560 grams, with shrinkwrap and balancing leads and 4mm2 wire say 650 grams.
3 of these packs will easily get you through a fight, so 650 * 3 = 1950 grams or 2 kg.
With 8 cells you have the advantage that you can use the cheap unitedhobby charger with integrated balancer.
For the same Ah and aboutish V rating you need 3 8 cell packs A123s parallel. Each cell is aboutish £7 and weights about 80 grams.
24*80=1.92kg (remember a 12V 7Ah SLA is 2.65 kg or more)
Total charged voltage is 26.4V and youll have 6.6 Ah at your disposal.
how much does a 24v nicad pack weigh?
Thanks for the info.
John