NiMh or Lipo????

[craigosh]

I've been running Lipo nearly a year now and the only problems i've had was a weird one with a Nosram brushless system. The car would just cut out under power, wasn't the lipo cutoff kicking in, so swapped the motor to a Novak i had and everything was fine!!! Nosram Motor just went in the BJ4 with the nimhs.

Other than that never a problem. The pack has always come off cold at the end of a heat but always gets ten mins to cool down before i put it back on charge.

Personally i cant see why we aren't all using them yet, I've seen them used in consumer electronics for the past 10 years ( yes i know they wont be under as much load, but it shows that the technology aint new!) and saw them in planes at least 3 years ago, so why are we so behind!!??!!

[johnboy]

i think lipo is the way ahead for racing the costs are cheaper they are alot better to maintain. iam going to use them why spend £250 plus on 6 packs of nimh cells when i could get a lipo battery , charger and balancer for roughly £150.

[chris_dono]

Originally Posted by craigosh

I've been running Lipo nearly a year now and the only problems i've had was a weird one with a Nosram brushless system. The car would just cut out under power

Was that with a GTB speedo ? A couple of mates have had issues with that combo as well.

[MattW]

Tom C - from a purely off rd perspective, maybe you're right actually, in that any improvement of cells probably doesn't matter. I'm kind of thinking "Electric racing" as a whole, rather than just off rd - which i guess was actually the question.

Mark C - with the greatest deal of respect, no, the worksop series is nowhere near as competitive as a national championship for example.

From a safety perspective, i am actually not against LiPo. I have this view (and it's maybe a strange view) that a fire (potential LiPo failure) is possibly easier to contain, and potentially less dangerous than an explosion (potential NiMh failure). Although I'm not sure i feel in any way comfortable with the though of fire inside a tent, that is pitched in a dry grass field with a load of other tents.

My safety concern does come when people "discover" what they believe to be a method to improve performance with charging methods. Again, something that doesn't matter until you get into a competitive environment, and again something that you could argue doesn't bring such an "advantage" to off rd.

[mark christopher]

Originally Posted by MattW

Mark C - with the greatest deal of respect, no, the worksop series is nowhere near as competitive as a national championship for example.

not what you said tho matt

Originally Posted by MattW

At the moment, LiPo hasn't been used in any "competative" race series, and you could argue that this isn't going to change in 2008 - because yes technically the touring car pro stock series is considdered "the support".

worksop is a competative race series!
and we will see things in 2008, as outside the uk countries have alloed lipo usage

[SlowOne]

Some support here for MattW - this is the start of an expensive and rapid development phase that is going to cost a lot of money for drivers. As Matt said, a few years ago we were told NiMh was the saviour, and we would be able to charge, race and charge again with no worries - until along came IB with a desire to push the envelope and claim market share...

Read the ROAR rules - only charging in a LiPo sack allowed, only a fixed cut-off voltage allowed, etc, etc. So what happens when someone ups their cut-off from 8.44v to 8.54v because they have a box, full of new batteries, from their sponsor? And, we haven't started with the charging/discharging regimes that will inevitably come out to increase performance.

I get that you don't need all that power in Off-Road, but that puts your class in a minority of one. Everyone else can take more volts at least, and some can take more capacity too.

Let's remember the BL promotors - how it was zero maintenance, how it would level the playing field, how it was cheaper because you only needed one motor and there was no maintenance costs, how it would be easier because we had no brush and spring tuning, how... And now, I don't know anyone who doesn't have at least three motors in their box, who doesn't take them apart to clean them because the dirt gets in the sensors, who hasn't got a couple of rotors to tune to a track, who...

Competition improves the breed, and no manufacturer is going to sit back and let LiPo (or BL) rest. BL (in 12th anyway) has got to the point where we all know what works, so I've dipped a toe in the water and bought mine. It's £80 cheaper than if I'd bought it two years ago, it's developed so that it's much more driveable, and it's the standard combo everyone else has found works.

LiPo is going to go the same way, so knock yourselves out, guys. Once it settles down a bit I might have a dabble if it is of any advantage. But your starry-eyed view of how wonderful it is I, like Matt, don't think is a reflection of reality. I watch with interest...

[mark christopher]

Originally Posted by SlowOne

Some support here for MattW - this is the start of an expensive and rapid development phase that is going to cost a lot of money for drivers. As Matt said, a few years ago we were told NiMh was the saviour, and we would be able to charge, race and charge again with no worries - until along came IB with a desire to push the envelope and claim market share...

Read the ROAR rules - only charging in a LiPo sack allowed, only a fixed cut-off voltage allowed, etc, etc. So what happens when someone ups their cut-off from 8.44v to 8.54v because they have a box, full of new batteries, from their sponsor? And, we haven't started with the charging/discharging regimes that will inevitably come out to increase performance.

how can you say that?

1/ you have not used em
2/ they have been used in planes for years, its NOT new technology! we have them now, the development has been done by the plane guys, bellieve it or not they use them more harsly than we do, they need max power out of them, and they have found no increase in altering charge settings etc
3/ the chargers are set at 8.4 and are non adjustable
4/ you gain nothing at all from discharging them prior to charging, again ask a top plane pilot
5/ i have a box of packs, i dont dick with settings as there is nothing to gain, simply top up and go

the chemistry of the cells is 100% different from nimh (which we (racers) were gunie pigs in thier develpoment) its been tried and tested and thier simply is no benift

some of my packs are out in the field with some top level uk drivers, one has not ben balance for over 6 months, the other has, these two drivers have swapped packs and can not tell the diference in them
6/ racers who bought the original orion packs what 2 years ago now? have the same pack thats sold now
i fully apreciate you have your point of view, but at some stage you have to believe what your told, pretty much as when your mum told you that the colour black was black, you believed it

[DaveG28]

Ok, well I am not an expert on this but some people here are so maybe they can answer some questions! Firstly though, I will be voting LIPO, simply because I:
1. prefer a fire to a bullet (ie what happens when each type goes wrong)
2. Like the idea of leaving one pack in all day and just topping up
3. Think they seem easier to use, eg simple one charging method etc.
4. They don't seem as sensitive as nimh, I have both types and the LIPO's seem to always be good, nimhnot so consistent (for me anyway)

However, a couple of things are confusing me:

1. If we're all so happy with the power in off road as it is, why do I get the distinct impression the top guys still get top cells? If they were quick enough everyone would have bought any old pack of cells wouldn't they?

2. LIPO is quicker, my 2wd is a different animal with LIPO. I think it is something worth considering that it will create more cost etc as everyone moves over to LIPO to keep up.

3. If they don't need balancing, why are people selling balancers?? Even Orion don't seem really clear on this point!

4. if all LIPO is equal and there won;t be a charge for more and more performance, wouldn't we all be just buying the cheapest LIPO right now? If there's no performance changes, how come some have 15C, some 20C etc!?

I am not trying to be rude to anyone (Mark seems very pro LIPO so I guess this comment is for him! ), I am just genuinely interested in whether LIPO really is this nice easy thing where we won't all be chasing more performance etc.

Dave

[Chrislong]

Originally Posted by DaveG28

1. If we're all so happy with the power in off road as it is, why do I get the distinct impression the top guys still get top cells? If they were quick enough everyone would have bought any old pack of cells wouldn't they?

I don't consider this true, far from it infact. Ask anyone who you consider a top guy, and he may be getting his cells supplied - but they are not picked ones. In some instances the sponsors send out the 'Economy' packs to the drivers, and not even the top level off the shelf pack which any customer could buy!....

Go back to the days of Nicads, and I still believe then that cells were chosen, and I have heard other stories too. But with todays Nimhs, when the top brands match them could be weeks before they're taken off the shelf (for team driver or to be sold to retailer), and by that time the cells have deteriorated.... just look how fast IB4200's go off.

What the only difference may be, is that the top guys will be replacing there packs more often - so are driving with packs available to all, but with less use/deterioration in them.

Chris

[Chrislong]

On the Lipo subject, I will not be running the top level pack in 2wd. Granted, it will be 25C but I have chosen to use 3000mah version so the amp draw is less than the 25C 4900mah... its too late to do the sums...

But the only thing I have heard, is with tourers running 5 cells in modified to slow them down, and now with more and more top level guys running 5 cells in 2wd off road; eventually, will this be the norm for all classes including 4wd? (and rule change for 6v packs rather than 7.2v)? Nobody knows what the future jolds, but if that is the case, then where does it leave Lipo - will they be able to develop 6v packs? I sure hope so as other than this possibility, Lipo as a technology is prooving to be far easier and user friendly compared to cells.

I did show a lot of doubt for Lipo in its early stages, but now I have had chance to use them I have changed my mind. I am continueing to run and learn about them, but as it stands with the experience I have had so far, there is no comparison. So I will continue to use them at club events/Belgium GP and while gaining experience, prooving them, its making racing a whole amount easier (and my NIMHs will stay new for nationals all year!!!)

[DaveG28]

Originally Posted by Chrislong

I don't consider this true, far from it infact. Ask anyone who you consider a top guy, and he may be getting his cells supplied - but they are not picked ones. In some instances the sponsors send out the 'Economy' packs to the drivers, and not even the top level off the shelf pack which any customer could buy!....

Go back to the days of Nicads, and I still believe then that cells were chosen, and I have heard other stories too. But with todays Nimhs, when the top brands match them could be weeks before they're taken off the shelf (for team driver or to be sold to retailer), and by that time the cells have deteriorated.... just look how fast IB4200's go off.

What the only difference may be, is that the top guys will be replacing there packs more often - so are driving with packs available to all, but with less use/deterioration in them.

Chris

I am sure you know more than me on what cells they use, but if performance was not key they wouldn;t need to replace them so often would they? Surely we don't equalise/discharge etc just to avoid them blowing up, we do it so the cells are better!?

Having said that, if this is all true I can save some money by just getting sport packs instead of top spec

[Chrislong]

Originally Posted by DaveG28

I am sure you know more than me on what cells they use, but if performance was not key they wouldn;t need to replace them so often would they? Surely we don't equalise/discharge etc just to avoid them blowing up, we do it so the cells are better!?

Having said that, if this is all true I can save some money by just getting sport packs instead of top spec

Hi Dave,
Its not so much about performance but about consistency - as after a few months, pack 1 may have gone soft, pack 2 still powerful, pack 3 has a cell down so retired, pack 4 still powerfl, pack 5 powerful for 2mins then goes off. Which means its hard to gauge how the car will be in the next run. Whereas with regular new cells, the car will be same each run - and then we control the power by choosing sensible motors. Such as Novak Light range, and 6.5 rather than 5.5.

if it was about performance, then we'd be running 4.5's, but we are not. Those who do tend to be slower over a lap as the car is faster than the thumbs, and faster than the track can allow. They just get to the scene of an accident quicker

Two years ago, with a T4, I ran 27T stock around Southport and it was boring. So for the next run I put an 8x2 in, and it was wild, backed the slipper off and I was a lap slower - I continued all day with the 8x2 and my fastest run remained my 27T run.... this is an extremem example, but its just the same with 2wd & 4wd. We don't need the power available to us, we just need consistency in our packs.

[DaveG28]

Ooh, now that I can see, as I said above its one of the advantages I see in LIPO is consistency, I find my nimh an absolute bugger for changing power run to run!!

[Chrislong]

Yes ofcause, it does help. But I am talking from my own perspective, and could be bollox.

I am hoping the new breed of Nimhs is back to how we expect Nimhs to perform.

[hardrider]

I'm all for lipo! Runtime and power.
I took a leap of faith and tried them. Now I'm hooked!
(But I do have a few nimhs for those races which do not allow lipo)

Lipos do not require much maintenance. No need for fancy and expensive, premium labelled chargers and dischargers to get the most out of my batteries.
Pack deteorioration. Nimhs' performance does deteoriorate quite rapidly as compared to my lipos.

Despite the pros above, there are some cons.
Charge times are rather long. About 100mins a pack!
Packs are prone to damage if you do not know what you're doing...
Newer chargers prevent overcharigng.
Low voltage cut off devices prevent over discharging.
Wrong gearing leads to overamping, which leads to pack damage.
I reckon overamping will be the new most common reason for lipo pack damage.

[JCJC]

Originally Posted by hardrider

Charge times are rather long. About 100mins a pack!

All good points, the long charging one I see a lot of - but - charging our NiMh cells at 1C and our playaboutwith Lipo at 1C....ie 4.2 amps & 5 amps makes the charge times much of a muchness, there is a bit of a slow down towards the end with lipo but the battery is pretty much fully charged by then.

[Chrislong]

You don't need to fully charge a pack, it'll be just as good with 60% charge and will have plenty of duration to last the race before voltage drops.

Plus with Lipo, the charge time is irrelevant if you charge at home the week before, use them for first run and then just top them up - doesn't take long atall as at the most I have never gone over 2000mah per run.