you cant though.. as the current rule is 7.2v.. and lipo isnt.. so its either one or the other unless the barrier is increased so 7.2 is still allowed.. however i can't see this happening my self as of yet.

For me, iv just purchased a trakpower 4900, balancer and new charger dedicated for lipo. Iv purchased this lot specifically for use in my Rb5.

The reason being, i decided a few weeks back to run 2wd and 4wd both on club days. It will give me twice the tracktime, however twice the hassle of another car to get ready. For me the selling point was leave the cells in the car, and just stick them back on charge when needed. No swapping cells over, no equalising, less hassle :cool:.

The bonus being, my lipo could be charged weeks in advance and be ready to run without needing re peaking etc. Tbh it was a nightmare trying to run 2 cars as i really had no spare time. If lipo helps its worth the extra outlay in my opinion.

For me personally, less hassle is good, i run brushless for this very reason in both cars, and im now contemplating using a spare sanwa gemin tx rx set just to save swapping the modules over on the Ko and changing the trims etc on model memory. The lipo just compliments the easier maintenance schedule and more time to concentrate on other things.

My aim this year, is to learn to drive more consistently and more importantly to learn how to set a car up (basics only :D;)). Less time with cells more time to learn other things.

Col.;)

not if the rule is changed to " a max nominal voltage of 7.4 volts" that allows both.
if i turn up at a national and run 5 nimh cells to current weight im legal yes? so as i read it i can run up to 7.2, no rules saying i must only run 7.2

the big problem with the lighter weight lipo batteries is that you are reducing the amount of weight on the tires which in turn reduces the size of the contact patch of the tire touching the ground. Suspension settings can not change this, only car weight, downforce (only at high speed) or tire/insert compound changes can change the tire contact patch. Going to an even softer compound tire would not be good if the races were made longer to take advantage of the increase of battery capacity. I feel the best solution would be to leave the existing weight rules in place. Racers could add weight to bring the cars to legal weight for the time being. Car manufacturers could then use the weight savings of lipo to design the car parts stronger and more durable, strong enough to last the longer races that lipo can provide. This would really help bring in new racers with the benefit of longer runtimes and stronger cars.

All batteries have a cycle life time, it is the nature of the beast. And the harder you use them, the quicker they degrade. Also, the higher the amp rating the higher the cost, so there we go, right away, you can have budget packs, but they just won't have the build to survive.

First, voltage:
NiMH sub-c cells are still referred to "1.2V" batteries because that's their traditional name. If you read the label on matched IB4200 World Championship cells, you'll find many labelled at 1.3V average (discharged at 30 or often 35 amps). I don't see how a six cell pack made out of these cells can be called a 7.2V pack.

2nd, go bang:
Some LiPos do go bang. It's true. I think ultimately there will be a real need for race organisers to sort out which LiPos are safe and which are not (and its probably safe to guess it will be a long and complicated process, involving cloned products, all sorts of certificates and stickers, danger awareness campaigns, and accusations of bribery, corruption and foul play) so that even accounting for user idiocy, the abused packs will just let out the magic smoke instead of exploding.

no, it isn't up to race organisers, it is the umbrella organisation (in the UK, the BRCA) who set construction rules and checks suitability for a cell that has been sent for homologation. Then a race director has a definitive list from which to work from, exactly the same as Sub-C cells.

My 0.02
 

In my Helis and Planes I only run Lipos and brushless and have just recently built my first buggy (D4).

The danger with lipos is incorrect charging (Cells Not Balanced), usage (used below 3V/cell) and storage (shorting out, either terminals or internal when cells are damaged).

There is a lot of info in the Aero forums (RCGroups,...)

I vote to keep the weight limit and voltage up to 7.4V nominal.

I am sure over time models will come out to take advantage of the weight distrbution options permitted by lipos.

The Li technology in the new round cells (ABC and others) coming out for power tools seem to be more robust but the V/cell (3.6) is lower than the Li poly gel cells (4.2). These cells are a different size to SubC.

Cheers Jeff

it has been said on here that if the weight limit was reduced car set ups would need to change, as cells have increased in weight from say 3300 to 4200's has the set up of cars changed to suit that?

For me it's the voltage that's the biggest issue. Can they not be made to a nominal 7.2V?

nope its how thay are constructed, your seriously saying .2 volt is going to be a noticable advantage on the track?

the main thing is a lipo will hold its voltage over a 5 min run where mimh will drop off, but thats an advantage as it allows all to have good cells

DP delete please

Y E S

But isnt a decent matched pack around 1.24v per cell, 6 x 1.24 is over 7.4v.

so ur saying chris if i run lipo at 7.4 and you run nimh 7.2 im going to beat you all of a sudden? me thinks not!! u will still woop my ass prob even if u run 5 cell.

the other question, could you use the .2volt with the horse power we have in buggies what would you gain?

could with 4wd, if the cars were to be allowed to go lighter, softer tyres wouldn't rip up and you can, 2wd, no.

but myself and others are sayijng keep the same weights we have now!

Stop trying to ram these bloody things down our throats! Go back to selling double glazing.

7.2v vs 7.4v is clearly different. Regardless of what magic the matchers work on them, the nominal voltages are different, there is a reason.

Aye, it does feel like a roundabout... :D :D

In off road I agree most of the time grip is out biggest limiting factor but battery voltage can still be hugely important. If only they could be 7.2V that would be fine with me. Whilst perhaps nimh have crept up past 7.2V nominal, what would then stop Lipo from creeping up past 7.4V nominal.

Unusually on the weekend because of the grass straight line speed (particularly in 2wd) was more important than normal. If I was maxed out for speed and someone was breezing past with Lipo I wouldn't be very happy.

Perhaps in my mind I can't get past how much quicker Jimmy's car was at the vintage with Lipo comparred to our 7.2v cells, the difference as I recal was very noticable.

The rest of the technology personally I'm OK with and recognise they form a large part of our racing future, just such a shame they don't compete on a completely level playing field.

Personally I think Lipo will come but I cant see it being mainstream before 2010+

tut guess some peeps are still stuck in the 80's:mad:

they could do that now if they were running a better motor or got the gearing spot on.

in a stock motor class they will have an advantage especially if there not run to the same weight limit

no, I disagree there Mark, the extra voltage allows you to run the same motor with taller gearing so it drives the same out of the corners, but where as you top out half way down the straight, they keep accelerating.

It isn't so much the nominal voltage, but how the power is produced too. The two couldn't sit very comfortably together, and in a competitive series, would mean everyone buying LiPo.

so you have seen then run side by side in a series?

i have and there is little differance and lipo did not wipe the floor, nimh was just as fast, and this was in 19 turn where voltage would help

with IB cells, and 19t, voltage is a killer not a saviour Mark....

Well, personally i'm very anti LiPo. Nothing to do with the voltage. At the moment, there is little or no development in the LiPo RC market (at least not the development that we can all see in the NiMh market). However, i've spoke to a few poeple in the know and they assure me that if the development was required (i.e they were actually used for racing) then that development would be at a pace that we have never seen before. I said this before - and i believe Mark C started that thread as well.

What i will say though, is that i have run LiPo back to back with IB NiMh cells, and i have to say i didn't notice a difference. In fact, if i'm really being honest, i think new ish Ib's are probably faster. This is a point that was confiremd by a friend of mine at my locak club last week. He's been running LiPo for ages, but bought a couple of packs of NiMh as he needed them for a BRCA meeting.

i have an opinion, i gave it, i don't really need the personel insults, at no point did i plead ignorance to any other cell going bang, i am pointing out that these cells require a little care when in use and when charging and that that is different to the current cells.

voltage differences, yes you can buy nimh packs with nominal voltages of each cell being higher than 1.2v, thats why people spend hours looking through new cells to find those elusive high voltage ones, its why matching companies exist. i just checked the figures on a 6 pack of ib4200 the total for all 6 is 7.41v, thats a top spec and top price matched pack and it equals any 2cell lipo, you would assume therefore that a top spec top price lipo will of course be higher than 7.4. i cannot see how two batteries with different nominal voltages could race together without one racer believing he was at a disadvantage. if your saying that there is no performance difference between these packs then that begs the question why would you fit one, i don't need anymore duration, i would need a different charger and they cost more. not exactly appealing at the moment. so what advantages would buying this type of battery give me?

it was not meant as a personal insult, but any cell is danjerous and in no way are lipo anymore danjerous as a normal nicad/nimh in use or charge,
its been said on here by many and i will say it again, if you run them in the correct way they are not danjerous, if i abuse nimh they can be danjerous.

they are dearer pack for pack yes BUT two packs will see you for a weekend racing, with no loss in performance
most chargers can do lipo and a good one can be had for £50 which i have posted in this thread along with the other advantages!
weight = can be placed where you want it if you need to run to current weights
need less packs
no need to discharge equalize
no perormance loss over thier life span
can be charged weeks before and dont loose power, fit and go

what does amaze me though is the amount of posters who know all about them but have not actually used them:o

i have both lipo set up and good nimh so either way im not bothered where it goes, though i do enjoy the lipo ease of use.
i just wanted to see 6 months on how lipo was percieved. more clubs are allowing them and definatly more manufactures (rc ones) are producing/selling them. as i see it many do regionals and not nationals and to me (note to me) they should be allowed at club and possibly regionals.
my stipulation would be only lipo in a hard case, and if using lipo proof should be shown your charger is lipo compatable and poss even a 6 volt cut of is used weather an external or a speedo device (though if you have half a brain the last one is not needed)
i have found that off road electric to be the freindlyist class i have raced this year, with the least amount of rules (only sensible fair ones used) the cheapest by far and dam good fun.
lipo would make it better for me personally but in no way is off road broke or full of borats nieghbours!!

It's called research and reading manufacturers technical specification that gives you a grounding on how a particular item works, it isn't rocket science.

You forget to say that most NEW chargers are lipo enabled. I have two chargers here that are not, and four that are.

I will come back to my original concern with the cells, is that, unlike all other cells previously, they could all be charged with older chargers, LiPo can't and needs a specifically LiPo programmed charger, plus, running them below voltage causes issue's too. This is where the crux of the problem is, for me. Where as the educated racer will know what to do, the majority of bashers and club level racers wont. There is no backward compatibility in them.

Thats because most racers on here race at BRCA sanctioned events, therefore cannot justify buying LIPO packs that cannot be used. However, we can still read up about them.

is that why club numbers are down? thay all do nationals and no club racing?
how many national racers chargers are lipo ready?

Mark, this has a veil of you trying to provoke discussion/argument.

Lots of clubs run to BRCA rules, so LiPo ain't allowed, period, till they are allowed and then it will be at the clubs discretion.

No matter how much you 'Big Up' LiPo, till people are comfortable with a totally new power source...... you are wasting bandwidth.

The nominal voltage of Nickel coupled cells (NiCd and NiMH) is based on the electrochemical couple which is around 1.20V. The actually running voltage depends on the load mostly but the age of the cell also reduces running voltage. Cell manufacturers can also add additives to both the electrodes and electrolyete to increase voltage, usually at the expense of another performance attribute (this is one of the reasons why IB4200 cells have such high voltage but they dont last very long in terms of cycles).

For Lithium ion and lithium polymer cells, the voltage is based on the average voltage when the cell is discharged at the 5 hour rate and this is typically 3.6V or 3.7V (Some of the cylindrical 18650 cells developed for power tools are now 3.8V) at this 5 hour rate.

Personally, i think lithium polymer is the wrong cell technology for RC cars, the 18650 (18.0mm diameter and 65mm height cell) which has been used in notebooks for the past 10+ years is now finally making it's way into powertool although the cells are only around 1.5Ah in capacity due to their need to deliver high currents.

A 2S2P 18650 battery pack would be ~7.4V 3000mAh and could be manufactured in either stick or saddle pack, have built in electronics for over voltage protection and over discharge protection (like a power tool battery). The current situation in which cells rely on the user to protect them is not a good one. It would not be entertained in the "real" world of consumer electronics and OEM electronic products. I wont let a lithium ion battery leave our factory without adequate protection and customer who want unprotected cells are told to buy them from someone else...

There are great LiIon possibilities for RC cars but i think the technology should be adopted from the powertool market in the same way as NiCd and NiCd was (because if it was not for powertool, the Cs cell would not exist).

The last bit of my rant is about transport. Did you know that transporting Lithium ion cells or batteries is being controlled more and more, they have to undergo many safety tests before they can be transported on aircraft. Any modification to these cells or batteries woudl mean a re-test. Anyone who buys cells and makes their own battery and then takes them on an aircraft woudl be breaking international law. Pre-tested, assembled battery packs are the only way this can go in the future.

N

Hi Mark, email Charlie Fraser who is the secretary for the BRCA with the proposal of Lipo at regional level for the AGM. Next, make sure you go and attend the AGM later this year and be the one to vote it, it may get seconded and approved or there may be valid reason that it can't be - if so, they'll be explained... either way, will you be content?

Spoiling of a thread with many arguements isn't healthy, and surely the above should be done before it really is worth continueing with any discussion.

From my point of view, I will not consider buying Lipo until it is allowed at nationals, and proven to me that it is better (purely performance wise) than Nimphs.

Chris
your red questions is answered in my previous post (in red)
there is no point in proposing it if the majority of racers on here dont want it (most on here would be at the agm),if its not wanted by the majority i have no intention of trying to force/push lipo in.
as i have put off road aint broke and i have all the eqiupment i need to run either cell format!
as i have put before i was interested in what had changed with drivers views now they are more "out there"
it seems to me those who have them like em, those who dont are either not sure or go on what they read resulting in some for and some against.


DCM i have asked for it to be discussed is that not what a forum is for?

Im no lipo fan either, i have run them in the TC a while ago and at the time they did give a slight performance increase, but this only helped to throw a wind quicker so therefore rendered them useless.

In off road we dont need more runtime, we dont need more "power" and frankly if i wasnt charging cells between runs i would have nothing to do once i go brushless.

My local club runs 19t buggys indoors on polished wood, I would quite like to see Lipo purely from a maintenance factor. It would leave me free to do more work on the car or help some of the other members.

I do agree with Neil Oliver that I think the packs should come pre-assembled perhaps with just the option of a splitting a stick pack and have discharge protection circuitry built into the battery itself. You very well may argue that this is unessecary as some speedo's have it but the fact still remains a lot of speedo's do not have the lipo protection.

i cant see where people are coming from with having more spare time by running lipos.. how long does it take to press the bloody start button with nimhs?