captain stacker

iTrader: (10)

besides the duo3 and pulsar 3, which other chargers that are cheaper that can charge a 2s lipo to 8.44 volts? My track does not tech batteries.

Nilks

You don't get any performance by doing so, so why risk it?

But as far as I remember, my Orion TwinSpec can.

captain stacker

iTrader: (10)

so why do roar tech the batts at major events to check if they are not over 8.4?

Nilks

Because it is dangerous to overcharge lipo batteries!

Buckaroo

iTrader: (3)

When you make a statement like that, wether you like it or not, people hear "No one is checking, so if I can get away with it, I'm going to cheat"

If that alone didn't piss you off, please read on......

In the early days lipo batteries were poorly understood by the RC industry and racers. No one really understood about graded cells or chemistry generation.

Preheating of cells and packs was originally thought to be safe, but that proved false, even when done by people who understood WHY, HOW, and WHEN to do it.

The ROAR standard was ALWAYS 4.20vdc/cell +.02vdc/cell to COMPENSATE for voltmeter tolerance. RACERS incorrectly made 4.22vdc/cell the standard. With Gen 1 and 2 chemistry Lipos, 8.44 was thought to be safe even with tolerances in the voltmeters, but that was really only for grade A and B cells. Usually only the most expensivie packs are/were made with A/B cells. Few of the early packs were put together with matched cells (capacity, discharge curve, charge curve, and internal resistance). Many of the Gen 3 and newer chemistry packs are much closer in overall tolerance, and it's much faster and easier to match cells for packs, which is part of what makes 2S2P packs possible.

That's before we even get into the discussion of charge rates! Heck, some super high select grade A cells now can be charged at 3C+. DON'T try that with budget D/E cells from Hong Kong, though, they'll puff with a quickness.

Preheating + overcharging of low grade cells = LOTS of lipo fires. Since a lipo fire is an alkaloid fire, adding water instead of using a dry chemical fire extinguisher = BIGGER fire. Most people see FIRE and react with water, so all it takes is one newbie for things to turn really bad really fast.

Gen 3 and successive chemistry Lipos are much more thermally stable, effecient, and SAFE at 8.40 volts due to the way that they're formulated.

The early experience with equipment damage from lipo fires, coupled with better chargers, better batteries, lipo charge sacks, and a better general understanding of lipos has lead to the generally accepted max safe charge for all single lipo cells at 4.20 volts per cell. 4.20 volts DC per cell pretty much maximizes effeciency and safety, balanced with longevity for the racer. Thus, the current ROAR standard, 2S packs at 8.40 volts MAX, +0, -whatever you want. Thus, the "voltmeter tolerance" was removed from the rules and brought the wording and working of the voltage rules in line with the intent.

The primary purpose of end voltage adjustable chargers is to be able to fine tune the instrument so as to compensate for circuit tolerance and component quality to ensure that, when confirmed with a high grade voltmeter, that you're actually getting to 8.40 volts DC for a final charge vice 8.3something instead, NOT for overcharging. RTFM, it'll tell you the same thing.

.04 volts total in a pack might not seem like much, but it removes your safety margin, puts your equipment and other people at risk, especially if you have an older, or damaged, or cheaper quality, or charge abused cell pack. Gen3+ cells are much more tolerant of overcharging and overdischarging, but if there's anything suspect in the cell or the pack, that will reveal the weakest link, usually quickly and dramatically.

In any case, I would think that you would WANT to have a legal car, in all aspects, wether anyone is looking or not, but that's your morallity. If you win, you still have to face yourself and wonder if it's because you're the better driver with the better equipment, or because you cheated. If someone figures out that you're cheating with battery voltage (no matter how slight), it calls into question EVERYTHING else that you're doing at the track, no matter where you finish.

Bottom line, it's a safety issue. You may get lucky and nothing will ever happen, or you may strike it rich and burn down the whole facility.

Personally I own several ProTek branded iChargers. One I have to adjust to 4.23 to get 4.20, the other 4.21 to get 4.20, verified with a calibration checked Fluke 77BN.

RC MARKET

iTrader: (12)

iCharger can easy to adj. chrage volt 0.01-0.1 per-cell to stop !
2 cell can setup up 8.41-8.6v

georgec

iTrader: (8)

Great info Buckaroo!

captain stacker

iTrader: (10)

when I say no one is checking about the lipo's, I dont mean it in a way to 'cheat'. First off, we do not race to ROAR, so if I do it, if I dont do it, I'm not cheating.

Yes we race spec class, and I'm sure everyone who is half competitive would want to squeeze every 1% out of their cars powerplant. I would say I'm a pretty decent driver who can lap within tenths of a sec per lap, every lap, so it's not like I need to work on consistency, I'm looking to legally max out my equipment, safely. I'm sure if my opponents knew they can get an extra 0.04 volts out of their lipos, without risk, then they would do it, and they probably do, I dont know, I didnt think of the chargers until up until now, and having said that I will have a look down the pits next time. I'm at the moment currently using a no name HK charger, does the job, but whether it does the job well has not been tested,(misplaced my MMeter).

to the point in relation to safety, do you know any charger that can damage a lipo due to overcharging...........no. Not even the cheapest chargers from HK overcharge lipos, they all have overcharge protection. Most lipo fires come from charging cheap lipos, not from the charger fault, not from overcharge.

please tell me how preheating lipos is dangerous? Trinity makes a lipo heater, if this is not safe to use, why would they put their reputation on the line?

Does anyone know if the lrp pulsar touch have the same 'competition' feature as the pulsar 3?

theisgroup

iTrader: (10)

you can set the hyperion chargers to what ever peak you want, but you will need to run the balance plug to get that to work. ce has new software that also has adjustable peak.

btw, at the snowbirds the limit was 4.22/cell and i saw very few that were below that when i went through tech.

Chaz955i

iTrader: (5)

At the Halloween Classic I didn't pass tech after my battery showed 8.49 after a full charge cycle on my cheap charger. Not sure which was not calibrated correctly but I now use a multimeter to play it safe instead of just letting the charger figure it out. I think you are right that there is some variance from 8.4 that is still safe but if it is allowed there will be the people that want to push it even further.

captain stacker

iTrader: (10)

ok, have decided to get a icharger 206b, nearly half the price of a lrp pulsar. I'm not expecting much of a difference, but hey half a car length, is half a car length !