2S LiPo and brushless

Hi there, I just joined the forum here and I am looking to see if people share the same opinion as me. I'm a big fan of Mardave circuit racing.
This concerns the use of 1S LiPos. At my club (Gloucester) we allow 2S packs in Mardave and down to 13T brushless motors. I feel this is a much better system to use than 1S.
For 1S to be as powerful you have to draw over twice the current from the battery, through the ESC to the motor. To achieve the same average power this means pulling much harder than this on acceleration from a low speed - something that causes massive voltage drop on a single cell and regulator drop-out. Your PT and servo then stop working. Add a 'booster' and you add cost, complexity and a source of failure just waiting to happen. Even then the stress on the ESC and battery is still a lot more than with 2S.
Add to this that 1S ESCs are way more expensive in the first place and the 1S rule has done just the opposite of saving costs.
Something like the Hobbywing EZRUN controller, which is about £35 works great on 2S (not 1S though). I've also used the Hobbywing micro brushless ESC which only costs £18 on my Mardave, and won a lot of races with it. This is another great ESC that will not run on 1S. If limiting speed is the issue, the best way of implementing this is a motor limit. I.e. nothing over 3000kV. Or a turn limit (17T for example). I concede that a 2S Mardave on 13T is a fast car and only suitable for the better drivers on most tracks.

While 1S seems to be increasingly used in various car classes now, the opposite happened in the electric flight arena. I fly a lot of electric planes and the intention there has always been to limit the stress on the electronics as much as possible. This is done by using high voltage batteries and getting the current draw down. Electric drop outs and thermal overloads crash planes. High voltage planes run cooler, fly better and for longer.

Hi Long Rat

Well what can I say with out saying your going totally the wrong way for mardave racing. . .

If thats what your club wants to run then by all means run it but you will be possable on your own as most clubs run 1s and 13.5 you have to stop some where so why dont your club run 13.5 and 1s like other clubs ?

But Why ?

Mardave racing is meant to be oh so cheap and to be on par with the original Idea of mardave racing When I started looking into a possable brushless system that was on PAR with a Brushed car . . .

Well the end results where a 1s LiPo and 13.5 if you want to run the 2s and 13t as you say then why for what purpose other than BEING FAST AND IF THATS WHAT YOU WANT AND IT SEEMS TO BE then sell up and go touging car mate . . . you have to run what people want and if normal people went to your club it would be a waste of time as they wont stand a chance . . .

IF SOME ONE TURNED UP WITH A MARDAVE AND A 1/12TH FRONT END again where do you draw the line . . .

There is a National series already started and it runs 1s 13.5 the racing is great fun and close and thats where is meant to be

Ok so you run 2s ok so why not run 3s and or 4s . . simple you have to stop some where and if you want to run 2s then run a touring car . . .yes I to fly planes there great fun Im into EDF jets my self there wicked

Gazza

My point is, Mardave is meant to be cheap and equal.
1S is expensive and the equipment is relatively scarce. 2S is cheap and the stuff is everywhere.
I'm not having a go at other clubs who run 1S - I am questioning why the rule was ever introduced. It is technically and economically backwards.
If speed is the problem, this is best regulated by the motor limit. 21.5T for example on 2S not realistically being any faster than 13.5 on a 1S. But MUCH CHEAPER AND MORE RELIABLE. Isn't that the whole idea?

Your view and points are well valed but . . .

100% of people do use the 1s system there not scarce as you say as the 1/12th guys and us have no problem finding them

Its not backwards its mardave racing and meant to be on PAR with a G2 motor thats all

Well turn up and the AGM and put it forward mate see what intrest there is outthere you never know others may like it

I only race locally so I won't be attending any AGMs. I'm really just interested in whether other people also share my opinion, that's all. The fact that you don't is fine.
This all started in GT10 which I used to race, 1S in those is nuts. The cells don't last as long and the ESCs are hugely stressed from the heat as the current is so high. Much bigger cars, so this makes the situation a lot worse than 1/12 and Mardave. I know people are running 1S in these classes, but I think most people in RC would agree these are fringe activities. These classes only have a tiny proportion of drivers compared with the 1/10 on road and off road classes all running 2S equipment. With 2S gear there is bound to be more price competition and consumer choice.

LongRat,

I'm right with you on the 2s idea in a Mardave. PM sent with link to some data I have collected.

Like you, I see many advantages:-

- Higher voltages mean that all other electrical gear (speedo, servo, PTs and receivers) will work to the best of their capability. No need to add voltage boosters to do this and no need to suffer with gear working at only half its potential!
- All servos will work faster on these higher voltages, useful at small, tight tracks (which the majority of RC clubs have)
- All servos will have more torque too, better when trying to hold a high speed turn on a bigger track
- With no voltage operation restrictions on speedos we could specify that only non-turbo ones are used – the GTB2, Nosram Matrix, LRP Spektrum, Fusions, and the whole "Stock" speedo range etc, etc, etc. This will eliminate the worries of blinky functions being “modified”.
- 2s cells are available that have smaller physical sizes and weights, ample capacity, hard cases and are BRCA legal, so our cars will not need massive modifications to take them.
- Weights could be kept similar too and, if really light cells are used, the weight you'll need to add can be a very handy setup tool.
- Hardcase varieties are available (many even have full BRCA / ROAR approval) so they will be as safe as any other LiPo race cell on the market.
- Many of the currently approved brands of 13.5t motors have 17.5t and 21.5t variations so we’ll still have plenty of choice.
- A higher voltage will mean we’ll need a lower current draw to get the same power – all electrical systems will run cooler and will therefore last longer.
- Anyone who currently races any of the other 1/10 classes (Touring car, off road, WGT) can simply swap their gear into a Mardave circuit car and will just need to buy an additional battery. All other gear will be compatible.
- Most important, this gear is CHEAP!

Over the last few months I have been doing a lot of testing between the standard 1s/13.5t brushless system and a 2s/21.5t system. The brief I was given was to see if there was a system available that:-

1. Gave a similar speed to the current 1s/13.5t setup. The speed from this setup is good, you have more grip than power and so it promotes close racing. This works and drivers love it. Ideally I would like to find a setup that is so close to the current 1s/13.5t setup that the two could be raced on the track at the same time. I certainly did not want the speeds to be much greater - that would be likely to result in more crashes, more damage and loose us the close racing.
2. Was cheap. This is the backbone of Mardave racing and needs to stay. However, cheap should not mean poor quality so anything I used had to be reliable and give good value for money.
3. Was readily available. Where possible I would source items from the UK and use gear that was already commonly used in other classes of RC racing. This would be the gear that would be most likely to have good supply. If that was not easy, I would use well kown, reputable overseas sources. No dodgy internet bargains here!
4. Was easy to install. I did not want to have to buy or fit any extra devices. Speedos and motors should have the minimum of adjustments and definitely not need laptops to get them to go!
5. Was compatable with other existing Mardave Circuit rules - car dimensions, weight, shells, tires... This was really just a test of speedo, motor and cells.

Now, when I say that I have done a lot of testing, I do mean a LOT. In fact, to date, I have done a little over 4,000 laps at 6 different clubs to give me a fair comparison between how the two setups compare on tracks of different sizes, layouts and grip levels. Every single lap has been timed, notes have been taken on the cars' setups and data has been recorded on tire wear, motor/speedo and cell temperatures, current draws and re-charge capacities needed. What's more, consecutative runs were performed back to back between the two cars - one run with the 1s car, next with the 2s car, next with the 1s car... And so on. This was done to help eliminate changes in track conditions etc between runs. I even hired myself a local track for a whole day (10 hours) of back to back testing so there would be no unpredictable influences from having other cars on the track at the same time as me. As a final check I have loaned the cars out to other drivers to see how different prople find them.

This is a summary of what I now think is the best setup for a Mardave V12 circuit car:-

CELLS - "mini" sized 2s LiPo cells (the type designed for 1/16 off road buggies. My prefered ones are the hardcased Intellect 1800mAh ones. These are available both in the UK and overseas. UK prices are around £20, overseas prices (inc shipping, tax, customs etc) are a little cheaper at an average of £18. Because these size of cell are the standard power source for another class supply is reasonable. Several companies make equivalent models and most are BRCA legal.

MOTOR - A "Stock" 21.5t motor. By "Stock" this implies one that has no adjustable mechanical timing (you can't loosten screws on the endbell and rotate it to change timing). If a stock motor is used there is very, very little difference between makes and models. After all, that is the whole aim of a stock motor! My prefered one was a HobbyWing version, £34 from UK sources.

SPEEDO - Again, a "Stock" speedo that has no on-the-fly-timing. If the speedo does have this option it should be disengaged or run in 'Blinky' mode. However, I would prefer to see true stock speedos being used because, again, there is little difference between them. There are plenty out there and they are cheap. My one is a HobbyWing "JustStock" and was bought in the UK for just £36.

My results are fairly conclusive. With this setup my two cars were so close on the time sheets that there was really nothing to split them. After the 4,000 laps this is that I have found - average lap times are around 0.08sec different so not enough to split them, the 2s motor comes off around 15'C cooler (so will last longer), 2s cells need around 1/3 of the re-charge capacity (so will, again, last you longer) and 2s tire wear is between 1/2 and 2/3 that of the 1s car (this vaies between tracks, but is always less).

However, the big differences are cost and how the cars feel to drive. The cost of the electrics in my 1s car was around £300 (Nosram Pearl speedo £150, 2x Intellect 1s LiPos £45 each, HPI Flux motor £65). Yes, this was all bought new and is good gear, and cheaper gear might be available... But this gear has proved to be competitive at National level. However, the 2s electrics was only £110 (HobbyWing speedo £36, HobbyWing motos £34, 2x Intellect 1800mAh LiPos £20 each). I very much doubt that you can get a good, competitive 1s setup for this sort of cash!

The other thing is the way the cars drove. The 2s car felt more alive, more responsive. It had more zing. It felt faster around the track, even though the time sheets put it almost identical to the 2s car. I put this down to better handling so I could carry more corner speed (I had to add 140g of lead to get the car up to 950g and this was all positioned lengthwise, dead centre for perfect weight balance) and it did feel like it seemed to have a little more punch out of the corners. To test this we filmed the two cars (both times with me driving) and super-imposed the two files so as to have the cars driving the same track at the same time. A bit like what they do on Top Gear? This confirmed that the 2s car only felt as if it had more punch, even on film there was really too little to split the two cars. The analogy I have used to describe this to others is to go back to the 'bad old days' of running 6-cell NiMH and 27t stock brushed motors in a Touring car. You run thhis for a few weeks and then skim your motor and install new brushes. Lo and behold, the car feels better to drive again. Not faster, just more exciting. And better.

It is not just me that has found this. Several drivers at the clubs I have tested at were so impressed with what they saw that they have switched to 2s/21.5t as well. Oddly enough they were all very keen to try the switch but, to date, not one has switched back to their old 1s/13.t gear. Enough said?

So, a conclusion? I think 1s gives good speeds and close racing, but it is a comprimise and relies on getting its results by lowering voltages to give inefficient running. This, in turn offers up a whole raft of electrical problems that racers have to find ways around. I know there are better ways to do this and 2s/21.5t stock might be that way. Choose sensible speedos and motors and you still get the 'right' speeds but more cheaply and potentially more reliably too. No, this is not recognised at National level (yet) but there is an AGM coming up so time will tell. One thing though, I have passed all the data I have collected to several BRCA members and other figures 'at the top' and have had extremely positive feedback from them all. Some of these guys have already done the swap too...

Hope this gives some food for thought,

James

Nice write-up James.
There we have two different opinions then.
If the 2s/21.5T regulation was enforced as I said before, it still wouldn't affect me as I only race locally, but I would be more inclined to try it and encourage my clubmates to do the same. As it is, I would never be tempted to even try to race outside of my club as I will not invest in 4 cell or 1S LiPo equipment.

Yes but you both have to look on the other side of the fence others wont go the 2s route why invest in that.

1s is what most use and to go from a Dave to 1/12th and now in 10GT as well . . you have the equipment . .
But with more speed as we all found out is more expense like tyre wear etc

Horse's for course's I guess


Jimbo says
1. Gave a similar speed to the current 1s/13.5t setup. The speed from this setup is good, you have more grip than power and so it promotes close racing.

Err what ? so using 1s is the same.. the speed is what your looking for you thinking way out the box again Jimbo

then after this you want a 2s and 10.5 brushless then after that you want a 6.5 then after that you want a 3s then after that you want . . . .

1s and 13.5 is the way with a Dave it took time and effort to get to this stage and 100's of people have bought and already race them there NOT going to buy any thing else im sure so if you guys want any thing else go GT or touring car

Not a lot of people race GT10, more race Mardave but still not many compared with the big 1/10th classes. These are the people that could come to Mardaves if they could use their existing equipment.
I don't think Jimbo is saying everyone on 1S should have to ditch it and go 2S. What he appears to be saying is that if some people ran 2S/21.5T and existing Mardave drivers kept their 1S/13.5T systems the racing would be perfectly fair and close. It's the best of both worlds.

I think a lot of touring drivers would love to race Mardave. I'm one for god's sake, just got back into the Mardave class.
Telling people to p-off and race touring if you don't like the current rules annoys me. I would like to see the Mardave class being the MOST accessible class to race in RC.

"Others won't go the 2s route why invest in that" - wrong. Others HAVE gone the 2s route already. Sure, not many at the moment, but enthusiasm is growing. Fast! A handful have switched from 1s to 2s/21.5t at my club, another dozen or so at the other clubs I have tested at... I've had in excess of thirty more people send me email and PMs on other forums saying they are doing the same. They also comment how other members at THEIR various clubs are also keen. And the word is spreading! Like I said, it is only a small number, now, but each week I get more messages. What's most interesting, as I said in my first post, is how NOT ONE RACER I KNOW OF HAS SWAPPED BACK!

In fact, with a specific example, the 2s setup in a Mardave might well have saved my local club. We had falling members and only raced TCs. We introduced Mardaves running on either 1s/13.5 or 4-cell/G2. This attracted a few new drivers and a few more ditched their TCs to run 1s. We then started some 2s cars and numbers have BOOMED! We now get twice the members at a normal club meeting that we used to get and 2 or 3 times as many Mardaves as TCs. The 2s class is by far the most popular, both for racers and spectators, because the racing is more exciting and still just as closely fought.

"...it is more expensive like tyre wear etc" - again, wrong. And again, in my first post, my testing has shown that tire wear is always less on 2s/21.5t than on 1s/13.5t. On most tracks tire wear when running a 2s car has proved to be about 1/2 that of an equivalent 1s car. More abrasive tracks, and racing at clubs that only allow certain additives can affect tire wear but, at worst, tire wear on my 2s car was still only 2/3 that of my 1s car! Now, that is when you ALREADY have the car and gear bought. What if you are just starting out and have no gear yet? You pay £110 (or less) for a FULLY COMPETITIVE 2s setup. If drivers choose "stock" speedo settings and motors there is no real benefit in spending more. And how much for a 1s setup? £200, £300, more? No, 2s is ALWAYS cheaper when starting up.

And if you have 1/12 or WGT cars already? You just need to spend £20 (or less) on one 2s cell and you're good to go, all your other gear works. The same as a few pints? The same as a few packs of cigarettes? And the TC drivers? They just have to buy the cell too and they can race. They potentially have even more to "save" because they won't have to buy either a 1s specific speedo or get a booster to run their other speedos. No, 2s is cheaper whichever way you look at it.

"...with more speed..." - wrong a third time. The whole point of my testing was to keep speeds the same, or extremely close at any rate. I don't think speeds should be increased because I fear that will not be in the best interests of the class. What I have shown is that 1s/13.5t and 2s/21.5t can be raced back to back, on the same track at the same time and neither really has an advantage. A bit like you tired with 1s/13.5t and 4-cell/G2, Gary. The exception is that the differences between the setups I suggested are far smaller and therefore fairer. After 4,000 laps of testing and to be just 0.08 sec apart, you can't get much close than that! Think of the National series, who runs 4-cell and G2 at the sharp end of the field? No one.

Anyway, speed is not the thing. The 2s setup is more efficient, cheaper, better to drive and potentially more reliable. Simples.

James

PMSL way to kill a hobby James well done keep it up and you will see more people droping off LOL

Ok see you at the agm and vote it in

"I have never seen touring car drivers come to Dave racing..." Well, they certainly do around here! As I said in my above post, my own club has roughly half the regular Mardave drivers as ex-Touring Car drivers. These are guys who have totally given up on TC racing, sold (some of) their gear and bought new Mardave chassis etc. The rest are either totally new to the sport or race Mardaves with us and other classes elsewhere. Now, the guys who have given up and sold their TC chassis are really winning -they don't need to buy new speedos and low current drain 1/12 size servos for their Mardaves to be competitive, they just buy the mini-sized LiPo cells and they are away! Since my club has allowed 2s LiPo to be run alongside 1s cars we have had MORE TC drivers swap because they are also attracted to the 'better' way the 2s car feels to drive. Yes, Mardaves may be "backward" in technology but they are the big leaders in close, fun racing. 2s still allows this.

Some quotes I have heard in the pit lane... "TC racing is too expensive now, I want something cheaper". "You don't race TC anymore, you just survive from one corner to the next or one crash to the next". "We can't race TC close to one another any more, get too close and the other guy takes you out. The cars are barely in control!"

It is a similar sorry at the other clubs I have visited and tested at - TC drivers (and drivers from other classes) seem to want more fun racing, close racing, cheap racing. Mardave racing has always done most of this but the 2s route might offer another fair and equal solution?

"... in WGT did not work...". Ive never tried 2s in a WGT and only ran my 1s car for a year or so so I have no real evidence or data for how these two compare. However, my guess is that there are other factors that might come into play when one version was seen to be failing. What 2s cells were being used? If they were the same 2s packs that TC class use then I'm not surprised the 2s route was not favoured. These cells are too big and too heavy, there is no real compromise as to where they can be fitted in a chassis and they are also extremely expensive. I did try these cells in a Mardave but gave up immediately and went first to the shorty sized packs, then the mini sized packs. Both were better - smaller and lighter so we had options for weight balance, and they were cheaper too! The mini sized ones measure approx 90x30x19mm and weigh just 90g. Fitting them in our cars is no issue, but finding them again when you put them down on your workbench can be :-)

Also, WGT race indoors as well as outdoors. This will have a big impact on the track size, layout and the grip available. With such huge differences it is not surprising that one power setup could have an advantage over the other!

How about their speedos? They run boost, turbo, on-the-fly timing, call it what you will. Again, this affects not just the power the car has, but it's handling (as weight is trasnfered more aggressively) too. My suggested solution for the Mardaves is to run 2s with only stock motors and speedos-no timing adjustment, no settings to confuse things... Keep it simple, even and fair.

WGT also have several types of chassis available -XRay, BMI, Associated.... Although they all look the same, they all handle differently. So, again, one chassis is likely to have an advantage at any given track, regardless of power supply. Then, if you factor in the 'right' power supply for that track in the 'right' car you have a clear winner. My guess is that other racers point only at the power supply as being the advantage, "he's faster, he must have a faster motor and cell combo", rather than taking into account chassis setup and balance, driver ability etc? Mardaves don't get this problem because we only have one, possibly two, chassis to choose from at top end racing.

WGTs also have different weights, front and rear tire sizes, different chassis aspect ratios, balance, geometry on suspension.... to what Mardaves have. Again, with all these physical changes and differences it is hardly surprising that one power setup has an advantage at each track, no fair playing field.

"...kill a hobby...". This time I have to say wrong again, at least around here. 2s is slowly taking off for Mardave racing. It is promoting the class, attracting new drivers as well as tempting drivers from other classes to swap and they love the low costs and close racing again.

James

Ok I can see this isn't going anywhere further.
I know the arguments for both 1S and 2S. I know what makes more sense to me, and won't be commenting further on the thread.
Thanks.

Yo Nick I see you insist on coming out with same ole crap and . .

Well this will no longer be tolerratede and will be deleted as was your last comment . . it's a debate for and against 1s or 2s not what you seem to know or not any more and ill ban you for a week

Like I said it will no longer be tolerated and for the record im not banned at any club . . dont know where you got that from

Now play Nice

Sorry about that Dave

Yea its like I have said horse's for course's you like 2s I like 1s

Its just down to prefrance I guess and what clubs run but its nice to run the same at every club thats for sure other wise you need 2 or 3 cars and setups

Okay delete posts

2s with appropiate motor sounds better then 1s 13.5.

So 2s with 21.5 has anybody tested this yet?

Still cant get my head round this why go 2s and 21.5 if its the same a 1s and 13.5

No booster?
Also you have more weight in the battery
Also i have a feeling throttle would have more of a feel then 1s dont quote me on that tho!

Ps the banned thing was said at a club meeting by somebody to me.

ok no booster . . . I dont run on at the moment as it works with out

Weight in battery yea more rear end grip

throttle err cant see any differance there only speed I guess

as for ban err nope not been there since end of 2010 due to my back problem thats all so cant see why they told you that. . . . thats down to my choice of not going

just been on hinckley web site blimey its changed any way from Dale I had a pm
HRCCC
Sent: Mon Dec 19, 2011 5:01 pm
From: Dale
To: Gazza

Hello Gazza,

HRCCC Mardave almost gone.................please help by racing with us!!!!!!!!!!!

Missed but never forgotten!

So there you go there missing me LOL

Advantages of 2s/21.5t over 1s/13.5t:-

It is cheaper - both to buy and to run.
Electronics work more efficiently.
Servos work faster, centre up more accurately and have more torque.
All speedos work with no need for boosters.
All PTs work with no need for boosters.
Current draw is lower, motors and speedos run cooler and will live longer.
Mini sized 2s lipos have more than enough capacity so we can either run cars light or have more options for weight balance if we add weight.

That is a lot of advantages. Do this and you get a car that can still be raced evenly and fairly against a 1s/13.5t car so we all have a choice. More choice, more drivers join the class?

Simples:-)

James.

Well Dale has left HRCC is the last that i know.

Sounds ideal

Well I have not been to Hinckly since . . . blimey cant re member but possable last time I was there was Feb March last year and dale sent me that . . in December
oh look just found this

The Committee
•Chairman - Dale Knight
•Treasurer & Membership Secretary - Roger Cosgrove
•Secretary - Ian Smith
•Publicity Officer - James Carroll
•Webmaster - Benjamin McQueen
•Competition Secretaries - Mark Stevens and Ben Cosgrove

JimboJames1972 wrote:Advantages of 2s/21.5t over 1s/13.5t:-

More choice, more drivers join the class?

Simples:-)

James.

Then the 4cell and G2 so you will need 3 mardave classs's

Not simples :-)

we been down this route James it's a mine field