Alltapdout

iTrader: (2)

You run 4, 5 minute qualifiers without recharging??? Why?

Cain

iTrader: (294)

I just took a spin through the manual, but didn't see anything about discharging to a set value for lipo in there. So I put on a battery and set the TCS capacity to 50%. If it stops at that, I'll put it on for a lower TCS capacity of say 30% and see if it just quits, or tries to do a discharge.

It could be though its a limitation of the charger possibly, don't know.

Jason Pelletier

iTrader: (33)

Why not ??

21 min of running on a 4800 isn't unrealistic, during practice i get a 30 min easy.

Cain

iTrader: (294)

My quick test showed that the hyperion doesn't appear to use the TCS feature as a sort of discharge ability on the charger.

So if it has one for a lipo to get to a certain range, I don't know.

Could be something to submit to them for a firmware update if its possible since there is a dataport where you can update the firmware on the charger online.

Stallard

Lipos have many pros and a few cons and one of those cons is a much more limited life. With NIcd's you could expext a 1000 cycles but with lipos you can expect 100-200 race cycles, so one the other advantages of running 4 races on one charge is longer battery life.

Alltapdout

iTrader: (2)

so, what your saying is that nickle metal hydride battery's have longer life span than lipo's

Stallard

No, I said a Nicd. Nicds are by far he most durable cells we use in electric rc car racing. the key to making any battery last is battery usage and maintenance. nicd's biggest draw back (besides capacity) is in maint. they like to be charged/used, slow discharged to .2volt per cell and not recharged for 5 days.

at the amp levels we need from nimh in our cars they can last even less cycles than lipos and their maint is much trickier. Some cells like the 3300mah and 3600mah can be treated like a nicd but can be recharged after they have cooled. 4200mah need special care or they will fail.(Not pleasant when they do it while charging)

Now that we have lipo cells that can handle the amp load we need, they are a god send. As cells get better at handling higher amp draws I think you will see their life cycle go up.

you also have to think about cycles. you will need to charge a nicd or nimh every time you run it. a lipo's low IR helps you use much less mah per run, getting you at least 2 runs per charge. For a racer that double it's life.

Dave H

Stallard, as I understand it, the relatively low cycle count you mention is if the lipo is discharged at a high rate all the way to cut off. If you stay above 20% charge, then the life improves dramatically, with additional but smaller improvements the less capacity you use. To way over 1000 cycles.

Also helps keep the voltage under load up, and helps keep the cells in balance.

Perhaps this concerns some, but for me a very small price to pay for all the benefits of lipo. You only need 50%, if that, to match nicad run time. Personally I can't stand up long enough to discharge one of these puppies 80% anyway. My son and I have even taken turns, after a 7 minute main, we finally packed up and went home. With brushless I should add.

I've noticed that it is difficult to break the habit of discharging for many, not only is it not necessary, it is harmful to a lipo.

BTW, even with special care 4200s are flakey at best.

bilster44

iTrader: (1)

I only have the Orion 3600 carbon lipos, and with a 13.5 bl I get at least 35 min of runtime every time. So 2 or 3 qualifiers should be no problem man.

Dave H

jb, Cain is correct that balancers prevent overcharging an individual cell, I would like to add that overcharging causes fires, that's why it is so important to be aware of. That said, many are not using them, but it is safer.

If you use good quality matched packs (Orion and TrakPower IMO), don't discharge them all the way down, the risks so far appear managable for a 2 cell car batt. But not the best practice. One thing you can do in the interim, is use a voltage meter to keep an eye on each cell through the balancing port or harness. Do NOT let an individual cell go above 4.2 volts.

Dave H

Thank you sir, appreciate the feedback.

Stallard

I agree,

High amp rates and running until or past cut off are the worst things you can do to a lipo. From my experiance though it doesn't really matter if you use 80% or 20%, it is more, amp draw that makes a differance.


take a trakpower 4900mah lipo (One of the best made) for example. they advertise that you will get one hundred race cyles and two hundred practice/race cycles.

They also are rated at 20-25c. If you discharged this pack at a hundred amps it wouldn't last ten cycles, at twelve amps it may last 200.

Dave H

I figured that where you saw those numbers, again they are worst case. Are you claiming that you routinely discharge your battery at a continuous 100 amps in your vehicle? In other words, a full discharge in about 3 minutes? If so, this is something that the alternatives won't do more than a couple times, if even at all. So lipo still seems like a solid choice IMO.

I know fast guys who have to be approaching, if not exceeding 200 race cycles, lots of guys have been running Orions for over a year, and still love them. The same guys used to churn through their previous batteries.

Bottom line thou, we are all free to do as we wish, and as a guy who has been around for a while, the available choices these days, either way you go, are dramatically better than what they used to be.

Cheers!

Dave H

BTW, hang around some of the nationally competitive guys. Especially on road with more traction available, those guys are obsessive with battery perfomance and care. They would be delighted with 100 race cycles, which I suspect is where TrakPowers comments are aimed. They have a lot of high level competitive experience with the fly guys, under the FlightPower name. Everybody else generally claims 1000 of cycles if the 20% rule is followed. Even with high currents that destroy the old stuff.

jokerkd

iTrader: (1)

i've just converted a sin yih ax5 1/8 buggy with a e-savage double moter clutched tranfer case and run 2 3300kv brushless motors.

i get about 20mins run time with a 4100mah 15c 11.1v lipo.

i am making a splitter to run two of them at the moment

should last a bit longer