Jah2000

iTrader: (6)

I'm new to RC and my first and only batteries are LiFePo4 packs. I didn't want to deal with the "high-maintanence" (storage charging, etc) of LiPo packs nor its' potential fire, puffing, blowing up, dying, etc., etc., etc..

So, I went with the safer and more worry-free LiFe - can be stored at any capacity (some even say totally 0% empty and 100% full), very stable and not going to blow up or catch fire, etc..

I'm very happy with it. It's been running very well the past 2 or so months I've used it, and I am having zero problems at all with it. My ESC is even set to a regular and "higher" voltage-cutoff meant for LiPo (6.2v) and it still lasts for 2-2.75 hours. LiFePo4 voltage-cut-off is supposed to be set, or can be set, much lower than LiPo, at around 5.5-6v iirc; but I am fine with it running with LiPo cutoff since it's still running for a super long time (2+ hours).

I'm using a cheapy Turnigy 4500 30C 2S from ebay (I think Zippy makes a similar one).

Only thing I really want/wish for (purely for aesthetic/appearance reasons) is.... a Hard pack (can't seem to find any LiFe Hard packs)


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syndr0me

iTrader: (32)

Interesting. Other than the lack of a hard case, its dimensions are right for a TC, and the price is very reasonable. Might be the one to try.

http://hobbyking.com/hobbyking/store...ePo4_Pack.html

valk

iTrader: (13)

Heh. Running flat lipos with the current draw of mod sounds dangerous.. most of my batteries can sag under 3v coming onto a straight section..
Life would surely be safer but but not even close to the current draw capacity for mod. Would be much safer to run a lower spec esc and motor than play with your batteries.

Just practice sqeezing less. The biggest thing for me was relearning how to input commands to the car. Learning to be much much smoother with throttle and steering.
Negative expo helps for sure but ideally you want to aim for no driver aids at all.

PutAwayWet

iTrader: (1)

Interesting, Adam.

http://www.maxamps.com/proddetail.ph...4500SS-66-Pack

I've looked at this pack before but have never bought it--I guess mostly because I'm flogging some old Thunder Power 5300's that don't want to quit.

Chris Adams

But its not dangerous. Ive been doing the lower voltage on every track I have raced over the last 3 years and never had an issue. Sometimes you just have too much power, especially for a small carpet track.

syndr0me

iTrader: (32)

I don't think there's anything wrong with tuning your equipment to be as easy to drive as possible. It's what I've done with success in the slower classes. My approach to mod is the same. Of course I can always be a better driver, but if there are things I can do to make the equipment work for me instead of against me, I'm going to look into it. When the Europeans went to 5 cell for better drivability, did people also tell them to "squeeze less?"

Geez, it's $100 more than the Turnigy pack. Good to know it's out there though in case the LiFe thing is viable and I need a hard case.

syndr0me

iTrader: (32)

Exactly. And for me, where the power happens is the hardest part to deal with. A car with a ton of punch up front is miserable to drive. I want something soft and forgiving on the bottom, but with more rip as I squeeze the trigger.

To put it another way, I want the power delivery of a 13.5 for the first 75% of the throttle and a mod for the last 25%. There are various ways to achieve this kind of feel. ESC programming, motoring/timing down and running flat batteries are all things people do to create a more calm car. I'm just considering taking that a step further with even lower voltage, because for me, running flat packs gave me the best improvement in overall feel.

fathead

We also went to 5cell in mod near the end of NIMH, went from running 6cell/4.5T to 5cell/4.0T to keep the speed, car was just easier to drive with 5cell, plus we got a small weight break as well.
5cell with a lower turn motor has a different feel to 6cell with higher turn, a bit smoother, this was before esc went super crazy with adjustable this and adjustable that, had 5 essentially fixed profiles in the lrp

DesertRat

iTrader: (2)

Sounds to me like some motor manufacturer should start making light winds again. Remember those? Light winds used less wire in their windings, for a higher internal resistance but still very low inductance, so a low-turn light wind will have the top-end charge of a big motor, but be significantly softer on the low-end, allowing a more aggressive driving style. It also cuts some weight.

Old obsolete but still informative link:

http://www.teamnovak.com/products/br...hts/index.html

A Band-Aid method you may try to take some punch out of the car but still have the top-end speed would be wiring the motor up with 16 gauge wire instead of the 12 gauge mega wire seen almost everywhere today. This is worth less and less the shorter your power wires are and in modern cars they are pretty short, so it might not be worth your time.

locked

iTrader: (1)

If you can't find a reasonable priced LiFe pack, you could probably wire up four 18650 LiMn batteries in a 2s2p config. Can buy 18650 batteries at any decent e-cig/vape shop.

Personally I like running a slightly boosted 4.5 with fully charged 2s LiPo on even the tightest of tracks, but I'm a bit of a weirdo.

hanulec

iTrader: (28)

Charge to 7.8 or less.

DamianW

iTrader: (5)

Going to 5 cell was not to reduce power but to reduce weight.

It was common to use a 2.0 or 2.5T motor with 5 cell and the cars had just as much power if not more as well as higher corner speed due to the reduced weight.

LiFE was tried and wasn't the magic bullet some people think it was going to be. All that happened was MOD racers used lower turn motors which increased current and reduced reliability.

What I found worked for me was to increase the air gap between the rotor and the stator. The larger air gap increase reluctance of the magnetic path resulting in slightly less power but most importantly smoother and more controllable power delivery.

You can do this by using a smaller diameter rotor or find an older MOD motor that has the larger internal diameter stator ie 14.5mm.

I would start by trying a 12x7.25mm rotor in your current motor if there is one available.

Jah2000

iTrader: (6)

I'm getting a hold of just the hardcases themselves, to convert the Turnigy/Zippy softpacks into hardcase (for aesthetics/looks) ...I have a source helping me out with some

Skiddins

Don't know if you run Sanwa, but if so, have you tried the Arc function as well as Expo, can remove a lot of bottom end and you can set how much and how low.

MattW

5 cell mod was in my opinion the best mod formula that we ever had. Sure, the cells them self were a massive pain, but that wasn't dependent on the number that you had.

Myself and a few others did try LiFe at around the same time. The pack came from GM / Graupner, and it was very similar in feel to 5 cell mod. Probably a touch more kick at the start of the run (as the voltage was a touch higher) but more drop off as the discharge curve wasn't as flat.

However, by that time, LiPo was fully established, and despite a couple of manufactures being keen to go down the LiFe route, it didn't happen. I thought it might happen if there were a lot of serious safety issues with LiPo. There have been a few for sure, but not as many as I thought there might have been.