Agreed mark i dont think there would be an advantage in off road but there might be 1 event that eats the cells.

Is it possible to police the mah ruling or is it just a case of trust?

I know they are already charging at more than 1C at the super stock series at the nationals :(

As for policing charging, we have to do that for both types of cells, as the BRCA recomends only 1C for NiMHs and I know for sure that most don't. I think you can only take a certain amount of measures to make things safe, you can't police everything, and the racer/pit bitch has GOT to take some responsibility into the process, otherwise it all becomes very unmanageable.

The limit to 5000mAh is more to do with what is legally transportable on a airplane, to do with the volume of a certain chemical inside the cell.... just go ask Worsle or Chris Hardisity.... I did, I had info overload!!

C rating, I don't think a maximum limit should be set, but I really do think a minimum limit should be set, as to low you are really hammering the cells.

Roar have many tests for Lipo cells to pass before they can go on the 'list'. One of these tests is over-charging. If we adopted the same or similar rules then I would assume we would also have an over-charging test.

This means that any Lipo legal at a meeting will NOT be volatile/explode/set fire to everything/etc otherwise it would not pass the tests.

So if someone wants to over-charge their Lipo to get 40% more power so be it, all it means is they will crash 40% quicker and ruin their Lipo all in one, and if they are found out they should also have another punishment.

In off-road we can over-power our cars, so there is no real argument for having to over-charger any cells. So why would anyone want to over-charge Lipo purposely to get extra power when they could just drop a wind or 2?

In my opinion I would say the advantages of Lipo are: Easier to use, Less Needed, More Performance, Lighter.

From that list the only 2 that effect car performance are useless. Our cars are already over-powered so we would just go up a wind to account for the extra power. The weight of them, we will all run to the same weight limit, and some people already add weight to their cars with NiMh cells.

So to me I see no reason why Lipo and NiMH can't run together, the same way Brushed/Brushless did, eventually one will become the driver's favorite and 95% of the people will run it, like they do with brushless.

What cars can lipos not fit in ?

xx4/s4 to name 2

3200 Saddles will fit both of those.

XX4, just turn the cell brace over.

S4/S44, either side of the prop - I think Craig or Jonathan will describe how, they were used in Belgium.

Edit: if anybody want to test fit Lipo in their car, please come find me. I will help with pleasure and usually have most choices of Trakpower packs with me at any one time.

to be pedantic, lipos fit xx-4's.......and the trakpower saddles fit conventional 4wd chassis, and lipos fit in X-5's too.

looks like it's just the S4 then!

?????

Hey MC, I think CB just typed his post while I posted mine.

that would make sence.

There is exactly the same discussion going on in German forums at the moment too. It's funny to see this thread raging on and having exactly the same arguements pop up.

It seems as though we now have a proposal in Germany most people agree on for offroad. It reads along the lines of:
- minimum 3000mAh and 20C
- max 7.4V
- free format
- LIXX tech (allowing, LiFePo when they become readily available)

and leaving everything else open.

If anyone wants to blow their cells up by overcharging, then so be it. The newer cells will just swell and not blow.
The same goes for charging at over 1C. Some manufacturers already allow charging at 2C and it does nothing for the power delivery apart from heating the cells a little more before they go in the car and reducing the charge time a little. If you want to be really anal you can warm your pack to about 45-50°C before driving to get max power out of it but doesn't make a huge difference either.

Seriously speaking, for offroad there are no real advantages to using anything over 5000mAh as it just results in more wheelies on grip or more wheelspin on slippy surfaces.
I now run 3200mAh cells in 20C flavor and have been going just fine with them. Even whole races with practise on 1 pack, recharging about 1200-1400mAh into it between heats. This was with a B4 with a 7.5 brushless on astroturf and the car was plenty quick! I try and rotate packs a little but that one race had to run one pack as others had not arrived.
During that race the pack did not once come out of the car hot, nor did it ever feel "different" to the other runs and is still going strong.

Quote:
Originally Posted by Chrislong http://www.oople.com/forums/images/buttons/viewpost.gif
3200 Saddles will fit both of those.

XX4, just turn the cell brace over.

S4/S44, either side of the prop - I think Craig or Jonathan will describe how, they were used in Belgium.

Edit: if anybody want to test fit Lipo in their car, please come find me. I will help with pleasure and usually have most choices of Trakpower packs with me at any one time.

Quote:
Originally Posted by burgie http://www.oople.com/forums/images/buttons/viewpost.gif
to be pedantic, lipos fit xx-4's.......and the trakpower saddles fit conventional 4wd chassis, and lipos fit in X-5's too.

looks like it's just the S4 then!



I ran a Atomized B44 with 4800 Trakpower saddle pack lipos while we were at the Belgium GP :thumbsup:

With the S4 the only problem with converting it is that it would need a small diameter propshaft, something similar to the steel B44 one, as the Jconcepts aluminmum one is to large a diameter to get everything in the chassis.

i will be ok with my s4 though as lipo's won't be legal for off-road anyway:lol:;)

nice to see some proper debate, tom cockerill is correct when he points out the racers will use whatever they think is best for them, brushless or brushed last year and this year 95% brushless. as i said you can fit lipo into most cars, but only one the trackpower 3200 saddle. is there any other saddles on the horizon from any one else?. every one seems happy about the charging issues, yes you can overcharge them and no doubt someone will but that doesn't make it any different than the current situation. costs, lipo is cheaper?, well yes and no individual lipo packs are more expensive but you need less of them, i currently take 10 packs to a national for two racers so approx £400, do lipo and say two packs each around the £240 mark. still need a charger but no need for the smart tray and no need to seperate those that have been discharge/equalised etc.

i currently use lipo in a b4, i would use it in the 4wd cars but i would like a choice. joe's x6 and dans s2 could take lipo but as we cant use them at national/regional or club at the moment there doesn't seem much point. one question i do have is if EFRA go lipo for off road surely we must as well?

Playing devils advocate:


I dont think we need too unless it is proven that there is a performance advantage to running lipo, people are saying there is none. ;)

There are plenty of choices of saddle lipos. Trackpower, Yuntong, Corally, Reedy to name just the ones I can think of right away.

You can also by two 2500mAh singles and hook them up as a saddle like a lot of pro10 guys here do.

am i missing somthing? are you saying two packs are £240?
the 3200 retail at about £45 if you say two packs and £100 for charger/balancer units

i said 2 packs each which is 4, 4 3200 are indeed £45 each but others such as the 4800 are more expensive up to £75

There's the rub, Mark. No way of telling what's been done in charging, unless you have a voltage check before going on the track - soon there'll be more officials than racers!! :D :D

It isn't the top drivers who take liberties, it's usually those in the B, C, D, trying to make a better final. If you can afford it, overcharging a LiPo gives a performance benefit, and after a few cycles, you bin the pack. Who's to bet this wouldn't happen at EFRA/IFMAR level, where no voltage checks are in the Rules?

NiMh (and NiCad) used to suffer from people injecting things into the cell through the vent, but then we brought in the weight checks and that stopped. Then we had the '10A blast charge' but as motors got more powerful that stopped. LiPo has a few of these to go through, but it'll live.