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Old 11-09-2007, 02:10 AM   #61
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Maybe the governing bodies should ban charging at high rates?
Don't most manufacturers recommend a maximum charge of 1C?

Personally, I charge at 0.5C. I might not get the last ounce of performance, but temps are low, and it's safe.
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Old 11-09-2007, 02:20 AM   #62
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the guy was only charging a 6amps.

i think for new packs for the first few cycles, its best to keep an eye on your packs (or stand back and watch it). And definitely don't charge and leave it unattended especially inside your house.
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Old 11-09-2007, 02:32 AM   #63
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Just wanted to add an arguement for going 5cell.... even though I disagree with PDM, his reasoning and calculations are sound....so hopefully this is the same in reply

The main driver on 5cell was EFRA, and a decision was taken at the AGM last year that something had to be done at stopping equipment failures, and reducing the speed of the cars. The quickest, easiest, and cheapest (so most people didn't have to invest in new equipment) way to do this was by dropping the voltage in the system... The best method avaliable was to go 5cell.

A year on, the general consensous over here in europe has had a lot of fun running 5cell. The cars may be faster round a track, but not faster in a straight line.

Basically, 7.4v and Softer motors simply weren't an option a year ago, when this discussion first came to a head purely as;
a) LiPo was no where near as well understood as it is now (what a difference a year can make)
b) Motor limits don't work in the Mod class

If you run modified, the motor rules are OPEN... meaning that anything goes... yes you can run a self imposed limit if you like, but there will always be a nagging feeling that the next guy has more power, it's simply competitive instinct.

And it's not simply a case of saying "you can't run winds lower than X"... that doesn't work. Case in point, a few years ago when we had a 12t limit, everyone thought great, no more issues with motors....er, not quite.... what happened was people cranked up the timing, geared them to last five minutes, and then watched as the motors nuked themselves with "only" 7.2v....

On a slightly different point...I personally feel the nominal voltages are slightly misleading... peak voltages of the NiMH are much higher than LiPo, so you have 9v+ to hand a car with a fully charged 6cell, compared to Lipo that (i believe) peaks around 8.5v. Admitidly, the through-run performance is difference (bigger drop off for NiMH), however that still doesn't get away from the fact that at the start of a run, there are more V going through the system with a NiMh.

So theres some food for thought. You do realise though, that if the IB's were more reliable, or LiPo was 6v, we wouldn't be having this discussion right now...

regards
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Old 11-09-2007, 02:38 AM   #64
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it comes down toi demand really.... no one to blame but ourselves.

ill explain.

we want faster touring cars so motors and battery technology moves forward. the governing bodies allow this to happen without making changes to the spec of ther equipment.

the batteries had to comply with the brca, efra, ifmar etc etc spec.

to get more capacity in the cells the composition had to change and the strenngth of the cell was forfeited for capacity to keep within the specs.

the tolerence of the battery housing has obviously been reached.

yes we are also to blame for not looking and charging the cells as per the manufacturers supplied information.

eps seem to have addressed this but there cells are slightly bigger. I did notice that efra have increased the specs for cells.

the debate on 5cell v 6 cell v lipo is mute.

UK races 5 cell, because the 6 cell championship a year or so ago, with brushless introduced was fast but the cars handled like a geriatric rushing to a toilet......(not pretty)

now with reduced weight of cars, 5 cell and brushless motors, the cars are infact quicker as that can be driven precisely (by some).

basically, we brought this on our selves by being competitive and trying to squeeze every last volt, mA out of the cells to be faster than the guy next to us.

most cells/manufacturers say dont charge over 3 Amps......bet 99% charge at between 4-6amp with 3mv-6mv per cell cut off.

and im sure that the motto was "always put warm cells in your car as they are faster"........

so blame yourselves for this action....

Yes IB are responsible for the cell construction and the main issue. But If we didnt push the cells and kill them in 3-4 months of racing, and actually looked after them and charged them correctly then perhaps this wouldnt happen.

IB can only do so much, i dont think efra or such stupulate making the cell idiot proof.
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Old 11-09-2007, 03:44 AM   #65
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[QUOTE=OleC;3847217]

HappyHippo (John Lara) has given you guys wrong information, not all racing or activity is stopped. Our federation does not have the authority to do so, nor do they whish to. All races that the federation have responcibility for is stopped temporarily until they find out what to do to improve safety. They do not expect this hobby to ever be completely safe, but in the light of recent events I think it's a wise decision.
And to be sure: This is temporarily, and concerns only federation races, with advice going out to the clubs.

@HappyHippo: Once again you are putting your own oppinion forward as a fact. I know you love to do so and stirr up a mess. On the Norwegian forum we all know you and just ignore the stupid comments you make to stirr things up. Please stop.

I have nothing to with the federation other then that I sent them an email expressing my concerns regarding the safety in our races.

Read my post again, untill you have understood what I wrote. Untill then stop the stupid remarks, please.

I wrote my post to shead some light to what has actually happened. But if you guys donít bother to read other than the stupid comments some people make, then Iím not gonna waste more time here.[/QUOTE

OleC You have to be blind and deaf If you belive that you have me majority og the touring racers behind you on theis isue here in Norway,

That you so incompetent and can't charge a battery say more about you and the shop you are running

Yesterday there was activity at the only open indoortrack here in Norway and most of the 12 scale racers was there to drive

If you actulaly belive that this ban on racing on road electric here will have a happy ending, you are so wrong, since no manufactor will ever come with a "safe" statment on their batterys, and what is so big news on the new list that are som much safer than it is today?

And on the Norwegian forum Why are you and the federation defending your self then? and in the end who's the one that most of the time has right, thats not you


Before you start to say things, you should now what you are doing and since you can't charge a battery right and runing screaming to the federation and say this is dangereus yeah that tell more agian about your knowledge on rc
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Old 11-09-2007, 04:03 AM   #66
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I wont even dignify that with an answer...
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Old 11-09-2007, 04:25 AM   #67
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This one time, at band camp.... Go do drugs or something John...
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Old 11-09-2007, 04:27 AM   #68
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From what i have heard the major problem with exploding batteries concern mainly the last batch of IB cells and most of the matching companies have sent all their stock of these back to IB?? But it is probably allot of these cells already on the market.. Strange thou that nobody is telling their customers about this!?
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Old 11-09-2007, 04:29 AM   #69
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Quote:
Originally Posted by OleC View Post
...
Did you use 6mV peak on the charger you where borrow per Cell ?
or is this per pack ?

From what i can see at Orion hompage this is per cell
mV/cell

http://www.teamorion.com/orion/faq/advantage_gp3700.pdf


Sorry to say this but this is WAY to high

On the LRP pulsar i use 1,12 mV/cell

Alf

Last edited by alf.skaar; 11-09-2007 at 04:44 AM.
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Old 11-09-2007, 04:29 AM   #70
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Quote:
Originally Posted by Ec1 View Post
From what i have heard the problem with exploding batteries concern mainly the last batch of IB cells and most of the matching companies have sent all their stock of these back to IB?? But it is probably allot of these cells already on the market.. Strange thou that nobody is telling their customers about this!?
Actually, the cell that OleC got blown up was a year old or so....
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Old 11-09-2007, 04:38 AM   #71
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Quote:
Originally Posted by MartinSorlie View Post
This one time, at band camp.... Go do drugs or something John...
Are you still alive? instead of talking BS like you normaly do, go racing instead
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Old 11-09-2007, 04:49 AM   #72
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I have read the manual

and it is per cell this is way to high

http://www.teamorion.com/orion/faq/m...i30117_eng.pdf

Alf
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Old 11-09-2007, 05:26 AM   #73
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Quote:
Originally Posted by mac853 View Post
I never heard nitro will blow up during running!
In boatracing I saw boats burned out due to leaks in fuellines!
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Old 11-09-2007, 06:02 AM   #74
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Quote:
That you so incompetent and can't charge a battery say more about you and the shop you are running
Quote:
This one time, at band camp.... Go do drugs or something John...
Quote:
Originally Posted by HappyHippo View Post
Are you still alive? instead of talking BS like you normaly do, go racing instead
hum... you norwegians are so warm and fuzzy...

just kidding, our national forum is the same thing. Somehow internet foruns always bring the worst of us
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Old 11-09-2007, 06:52 AM   #75
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Quote:
Originally Posted by PDM View Post
How is that? It would be true if the cars were slower. But they are faster. To be fast they need watts. watts come from the product of volts x amps.(in simple terms)

For example if you have a car with 1500gr and 375w with 7,2v you will put out from the batteries 52A (375w/7,2v=52A)

If you would like to have a car with 5 cells that is as fast you will need the same power to weight ratio as the other (250w/kg). So for a 1430gr car you will need 357,5watts. this time with 6v you will need to pull from batteries 59,5A
(357,5w/6v=59,5A).

That is why with the same batteries you will have less time to drive. With 6 cells you pull 52A with 5 you will pull 59,5A.

If you aply the formula that relates time with the batteries capacity and currente drawn you have Time(minutes)= Capacity(in amp)x60/discharge rate(amp)

That makes T=4,2(4200mah)x60/52 that makes T=4,84minutes (for 6 cells)

With 5 cells, T=4,2x60/59,5 that makes T=4,23minutes.

These are just invented numbers this is not the real thing but I hpoe I can help understand the stupidity of using 5 cells, at least at big tracks.
The problem with all your calculations is that if the voltage drops (Certainly in Brushed motors) then the current drops as well, and as such the power drops. DC motors don't work like normal electronic circuits.

The runtime has become an issue due to the taller gearing required and only seems to happen more at the larger circuits.

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