1s lipo and ESC [Archive]

Dozey83

26-03-2009, 12:40 PM

hi all, just wondering what 1s lipo people are planning on using? i was thinking about getting saddle pack lipo and just using one of them but not sure thats allowed, clarrification from BRCA folk would be good! :) as there is only 1 on the lipo list, but there are plenty of saddle packs to choose from!

also, what ESC are people running on 1s lipo?? as most of them the 1s lipo is below there opperating range, or can this be got around by using a reciever pack as well?

any thoughts would be rgeatly appreciated! :)

NiMo

26-03-2009, 02:59 PM

been reading this up on a US forum with 12th cars (4cell 17.5 and 1S 13.5), some use a receiver pack some don't, those that do say to put a switch on the RX pack, leave all wires intact, turn on the RX pack only (leave ESC off), this overides the voltage issue in the ESC's.

Skiddins

26-03-2009, 03:03 PM

NiMo

26-03-2009, 06:18 PM

I always do my research before I post facts :D

Dozey83

26-03-2009, 06:24 PM

so am i right in saying that as long as you have a reciever pack to give the signal wires 6v then it doesnt really matter that the 1s lipo is only 3.7V that will only affect the motor ??

PDW

26-03-2009, 09:48 PM

Spot on Rob. If you're concerned about the switching, then put a piece of tape over the speedo switch to remind you not to switch it on. If you turn both on accidentally, then some receivers issue smoke signals to warn you! :D

All the tales I have seen of people running 3.7v with certain speedos, and no receiver pack, refer to 12th cars, so that might not apply with the higher steering loads of a GT10 car, especially on carpet. However, voltage doublers will soon be appearing (Novak has one due soon) that will replace receiver packs with a reliable device that doesn't need re-charging. Watch out for those, as they are the best bet by far. HTH :)

MarkB

26-03-2009, 10:11 PM

Pete and Nigel beat me to it. If running an rx pack then use the switch on that only and all will be well. However if it goes flat then you'll lose steering and drive, so it means keeping on top of the charging.

I've not seen a 1S pack run in either 1/12th or GT10 yet. Based on what I know of 4-cell NiMh running, some speedos cope with the lower voltage better then others. I suspect we'll find some work ok on 1S LiPo. However there is one more thing to think about...

LiPos don't like being run flat. By that I mean there will be a voltage below which a 1S pack shouldn't be run. Would need more research to know what that is, or how to fit similar protection to the voltage cut-offs most brushless Speedos have for 7.4v 2-cell LiPo packs.

Cheers
Mark

MikeS

26-03-2009, 10:17 PM

Mark, the safe minimum cell voltage for LiPo chemistry is 3.0v per cell.
A a 1S battery has one cell in it so will be 3.0V, for the 2S pack, it's still 3.0v per cell, and so 6V.

PDW

27-03-2009, 07:43 AM

It is rumoured that Tekin will have modified software to give a 3v cut-off in the not too distant future. There is also a Novak device (http://www.teamnovak.com/products/smart_boost/index.html) that steps up the voltage, and also claims to have a LiPo cut-off incorporated. HTH :)

Dozey83

27-03-2009, 09:46 AM

cheers guys, huge help! :)

pete, thanks for the advice on the switch! :) i was thinking that you still needed to turn the speedo on aswell, good job i havnt actually got a 1s yet! lol, i am hoping to run my GT10 in the torc series, but i would only be running in GT2 as i already have all the kit (apart from a 1s lipo) to do that and i cant afford to buy new stuff at the moment, i had seen the novak voltage booster and am hoping that they come out sooner rather than later! :)

in the cells front, will people just be running one of the saddles of a saddle pack lipo?? still slightly confused about that one as the GT10 rules state max 1s lipo size and i dont think there are any saddle packs tha one of will fit into those rules! as i say, still confused! :S

PDW

27-03-2009, 08:12 PM

Rob, I don't think it matters too much what you run, but other LiPo veterans may disagree. The thing to watch our for is protecting the LiPo. If you run one cells of a 7.4v saddle pack and it is cased, not problem, If you're using a BMI with its caged cell area, less problem. If you're running a 10R5 which has almost no cage around the cell, make sure it is a cased one.

As MarkB and others have pointed out, the BRCA Rules are their to guide people, as we don't have any National sanctioned events. I believe that the SMC 1S cell has been added to the BRCA 'approved' list, and that comes with a case that locates in the slots (used for NiMh cells) found in all GT10 chassis - it's the one I would recommend. HTH :)