Since I finally got my LiPo charger I thought I would post what I have found so far. As I do more testing and gather more data, I’ll add it to this thread.

To start, the equipment I am using is the DuraTrax ICE charger. There are a couple of advantages to this charger and one big disadvantage. The advantages are it gives you a ton of data… much like the newer versions of the TurboCharger but at a much lower price. The big disadvantage is the maximum discharge rate is 10 amps. I know the limitations of using a 10 amp discharge but it will work for now as I collect some basic data.

Since I just got the charger I decided to just fully discharge the LiPo packs that I have. Since I want to put the 2 packs I have in parallel they both have to be fully discharged before hooking them together. Also, I was doing this in my basement workshop which means the temperatures are fairly cold. The ICE’s temperature probe showed the packs started out a 61F.

The first discharge did not show much about the real performance of the packs since they were only about 1/2 charged. BUT, I did notice once REALLY interesting item.

During the discharge the voltage of the LiPo pack actually went UP! That’s right, the packs started out 20 seconds into the discharge at 6.592 volts. 400 seconds into the discharge the voltage was 6.711 volts. Also during this time the pack temperature rose from 61F to 82F. At this point I am not sure if the voltage rise was due to the fairly cool temperature of the pack at the beginning of the discharge or ???? but I have never seen this behavior in a NiCd or NiMh pack.

Just something to chew on while I do a little more testing… At this time I am cycling a few of my GP3300 packs... they have been sitting for a few months so it may take a few cycles to bring them back to life… hopefully! I will then have some data to compare to the LiPo packs.

Hank,
I had 3300's do that before too discharging them at 30 amps, although its only after the 3300's sit for a few months

Voltage increases as the packs warm up even more so in lipoly. They don not like cold weather.

The ICE uses a constant voltage output so when the pack pack reaches 4.2 volts (per cell) the amps starts to drop. After 2 hours the charger had put out about 4500 mAh but the amp rate was down to 0.12 amps and the pack had still not "peaked".

That just doesn't sound right! They just did a review of that charger in R/C Driver and said they had no problem with multiple 3300 charges. Obviously they are higher voltage than that! However, i guess their LiPo set-up wasn't reviewed. Maybe not even tested. (Don't take this personally but you are sure you had it set for the right number of cells? Sounds almost like it thought it was charging a single LiPo cell) I think I will drop them a line and mention that! Good Luck!

Yes, I have it set properly. Let me quote the instructions from the manual.... once I make a copy.

Here is how the instructions says the LiPo charge works:

The cc/cv charge method is COMPLETELY DIFFERENT than the peak detection method that is used to charge NiCd or NiMH batteries. In the beginning, Ice forces constant current into the battery at the rate which is set in the Main Memory screen. When Li-Po batteries reach 4.20V per cell, or Li-Ion’s reach 4.10V per cell, Ice automatically stops delivering constant current and starts applying constant voltage to the battery. Here, the charger is no longer forcing current to the battery. Instead, the battery is only draining the amount of current from the charger that it can take naturally. As Li-Ion/Li-Po batteries become more fully charged they will take less and less current from the charger. Here, the actual current coming from the charger will gradually drop below the value that was set in the Main Menu.

THIS IS NORMAL!!When charge current drops to approx. 100mA, Ice will beep to indicate that regular quick charge has finished. At this time, Ice will automatically start a unique “LiPo trickle charge” current (based on application of a constant-voltage) as indicated by “Trk” which will flash on the current line on the screen shown above right. When this lithium trickle current drops to 30mA Ice will completely stop all charge current and “Trk” will change to “0.00A”.

Here is how the instructions says the LiPo charge works:

The cc/cv charge method is COMPLETELY DIFFERENT than the peak detection method that is used to charge NiCd or NiMH batteries. In the beginning, Ice forces constant current into the battery at the rate which is set in the Main Memory screen. When Li-Po batteries reach 4.20V per cell, or Li-Ion’s reach 4.10V per cell, Ice automatically stops delivering constant current and starts applying constant voltage to the battery. Here, the charger is no longer forcing current to the battery. Instead, the battery is only draining the amount of current from the charger that it can take naturally. As Li-Ion/Li-Po batteries become more fully charged they will take less and less current from the charger. Here, the actual current coming from the charger will gradually drop below the value that was set in the Main Menu.

THIS IS NORMAL!!When charge current drops to approx. 100mA, Ice will beep to indicate that regular quick charge has finished. At this time, Ice will automatically start a unique “LiPo trickle charge” current (based on application of a constant-voltage) as indicated by “Trk” which will flash on the current line on the screen shown above right. When this lithium trickle current drops to 30mA Ice will completely stop all charge current and “Trk” will change to “0.00A”. hank i really reccomend the Triton charger fro Lipo, It charges every battery on the market including led acid, lith ion, nicd, nimh ect ect... its not as comprehensive of a display as the ice but it does discharge charge cycle, has a temp probe(optional) and has been fine!

The Triton has a max charge rate of only 2.5 amps... it would take days to charge a 8800 mAH pack ;) But I may have other (better) news on the ICE charger... let me finish my test to see what happens.

Is this any differn then any other LiPo charger? From what I've read, LiPo packs are very picky about how much voltage you put to them during charging, that is that they do bad things like catch on fire if you exceed some voltage (4.2v???)...

As far as I know... anytime you limit the voltage on a battery charger, the amp rate will drop significantly as the pack voltage aproaches the voltage level of the charger, etc...

Again... are you/we sure that the ICE is doing anything that any other LiPo charger would not also do? (NOTE I do not know the answer... I know very little about how LiPo chargers operate and/or the saftey mechinsims involved, etc...)

This is the normal and prefered charging method. Astroflight deviates with a pulsed method. Theres nothing wrong with the charger and no reason you can't take the battery off after and hour and go play.

Yeah... you may be correct. It is just different then when using NiMh cells. What I have noticed is that the delivered mAh is within 100 mAh of what the charger puts into the cell. The temp. rise is only about 20F during discharge... much less the a NiMh pack. Less heat means a much lower IR and better efficiency.

Anyways... I let it do a full cycle and it took 4759 seconds to put in 4284 mAh. So the charger may be fine after all.

Should I stick with 1C charge rate or can this be increased?

1C max, .7 C is recommended by some for best longevity. Lipoly does not peak by any means and needs no discharging except maybe to around 3.8V per cell for long term storage (over 1 month). You just have to get used to a whole new way of thinking.

Hank:

Hi,

well I back looking for some avice on LiPo's. Mini is playing airsoft and I am looking for a longer lasting (voltage) type of cell (also hoping for a slight weight reduction). at this time we are running a 8.4 3300 packs. they are matched packs.
and two 12 volt 3300's slightly heavy for CQB in a M15a4.
any help will great.

Thanks

T & Mini

I own both the Astro Flight 109 and the Duratrax ICE chargers, I perfer the Astro Flight 109 due to speed. Both charge correctly, but the AF can put back what was lost in 20 minute race about 15 minutes faster than the ICE.

Don't get me wrong, the ICE charger is a great charger for charging all types of batteries including ni-mh and ni-cd. It is just to slow on charging the 8000 and 8800 mah packs compared to the AF 109.

I own 3 Astro Flight109s and 1 Duratrax ICE.

Sell me a AF charger, Please

Sell me a AF charger, Please

I can get you a Hyperion charger at a good price that does 7A charge rates. That's pretty close to the AF. It will take care of those round cells too.

It is ok to hook cells in parallel (at any state of charge) as long as the cells are equal. They will self balance. Only the parallel cells will self balance.

It is ok to hook cells in parallel (at any state of charge) as long as the cells are equal. They will self balance. Only the parallel cells will self balance.

You do not want to parallel cells with too great of a voltage difference. The higher voltage cell will try to charge the lower voltage cell. Due to the low resistance, the discharge rate of the higher voltage cell could exceed the output capacity. Too large of a difference would be like effectively shorting the pack.

Yep, my "at any state of charge" is misleading, they can be at any state of charge, but both have to be the same voltage. Thanks

I noticed that I was charging my lipo on the "NiMH" charge settings using an ICE charger and noticed it when the voltage read 9 volts (it was an 8.4 volt pack for an RC car). I quickly disconnected it, and ran the next race with it (just to both see what would happen as well as to "discharge it" quickly. At any rate, I ran a 5 minute heat with a Losi XXXT and at the end of the race, the batter was not hot, not swollen and I placed it back on the charger and it read 8.417 volts and thus (since it was "over voltage" still), the ICE charger wouldn't charge it. I discharged it to about 8.35 volts and then placed it back on the charger and it charged normally up to the 8.4 volts.

The question is: Has anyone EVER overcharged a Lithium polymer to 9 volts and had the battery "live to tell about it"? I didn't think it COULD be "overcharged" without damage? Anyone have any information on this?

Gary

4.2 / cell is considered very close to the line of damage. I've heard of damage starting at 4.25, 4.3, 4.35 but yours was 4.5.

It is possible you saw 9 volts only while current was applied, but given the fact you ran it and it rested at 8.4 means that it was indeed "way over" 8.4 resting volts.

I'd consider you have great luck if there's no damage to battery . Puffing cells is a good indication of overcharge. Be very careful and watchful with it.

Regarding the overcharging of the Lipo I reported. It was definitely overcharged, I checked the battery with a voltage meter after taking it off the charger. We've used this battery for our twice weekly 4300 off-road racing (since the overcharge and I don't notice any difference other than it charges to 8.405 volts peak....

When I try to "repeak it" with the ICE charger, this "damaged"lipo will stay at 8.405 and so the ICE charger will say it is "already" too high of voltage to recharge. It is just strange... I did not think that the LiPo chemistry would ALLOW for a greater than 8.4 volt charge.

Gary

I'd keep a close eye on it, the chemistry will allow for an overcharge with damage, but the charger will not. Nice ice, lol.

I've continued using this once overcharged lipo since I first reported the 9 volt overcharging, and at this point, it is doing fine. It is a max-amp 6000 mah (did I mention that I LOVE the max-amp 600? I had 2 5200 mah lipo before but for some reason, my son and I both feel that the 6000s are quite a bit faster - maybe they flow more amps?...)

At any rate, the overcharge didn't seem to have damaged it at this point, I suppose I was very lucky. I hope the rest of the LiPo users watch carefully that they are on LiPo mode before charging. It could have been a "bad day" for us if the overcharging had resulted in a fire, or even simply ruined the battery.

Gary

Thanks, it is nice to hear the feedback. I have 1 that the outer jacket was noticeably pressured up a bit. I'm going to test and use and watch it to see how it is.

Is there anything in the LiPo field that could replace the 4 cell packs?

LiPo's are 3.7 volts per cell so you have either 3.7 for a single cell or 7.4 for a 2 cell pack.

In all the things I have read in the last couple of days I thought that was how it was going to go. In fact with 3.7 volt cells I couldn't see any other answer. SOOOOO, in your opinion, are these LiPo's going to have any future in Oval racing?

IMHO (and this is just MY opinion) I think that LiPos as a cell construction for RC racing will be short lived. I seen some new Li-Ion cells that should blow the socks off of LiPo.

They are constructed in a tube container (like NiMh cells), peak discharge rates of 100C (that's 300 amps for a 3000mAh cell), 100% depth of discharge at 35C rate (100 amps), can be charged to 90% of capacity in 5 minutes and safer to charge (no fire danger) like LiPo. They are 3.3 volts per cell.

One of two things would have to happen for either cell to be accepted in oval racing. One would be to run single cells (3.3v/3.7v), use a receiver pack and run lower wind motors. Or run two cells and higher wind motors.

Again, IMHO, I would think running a single Li-Ion cell with a reciever pack and lower turn motors would be the way to go. Just think, only 5 to 10 minutes to charge a cell between races and there would never be a need to match cells or worry about matching because you only use one cell. PLus lower turn brushless motors are commonly available. Really, think about it, only one cell in your car that is only slightly larger then a current sub-c cell... what could be simpler?

I have to honestly say that I hope that never happens. It would be great for the racer but just look at how many people in our hobby that it would put out of busines!

Changes happen. Strong companies learn to modify their business plan to take advantage of new trends. Brushless is coming on quickly with almost every oval track having a class. I would bet in a couple of years the only brushed class will be stock. Smart business owners will find a way to take advantage of it.

Been thinking about the voltage thing. It should not be that hard to make a voltage dropping device that would take two cells down around the 5 volt range. Handeling the amperage could be a problem and it would have to be built into the battery case to prevent "creative adjusting" but I think it could (should) be done.

I have to honestly say that I hope that never happens. It would be great for the racer but just look at how many people in our hobby that it would put out of busines!

Companies have to adapt or die. Thats how business works. Do you feel sorry about Ford may be going out of business? Sure you do, but you won't start buying their cars to save them do you? People buy Toyota because they believe it is better for some reason... (which is a bull of course but who cares)

Hankster, could you share some more information about the Li-Ion cells you are talking about? I've never heard about them. Is there a website out there where they have more information on them?

Here is the company web site http://www.a123racing.com

As a note: It is interesting that they have a "Turbo Booster" that increases the voltage of a 6.6v pack up to 7.2 to 10.8v. Would be interesting if they would make one that would boost a single cell 3.3v to 5v!

The cells are great, but the "turbo booster" is a dud. I'm not talking about the quality or the capacity of the booster, I'm sure it works great. I'm talking about the concept or idea. It is great marketing though.

Why do you feel the idea is bad?

Why do you feel the idea is bad?
In a post in another forum someone mentioned that that A123 website has a disclaimer that "boost module is only recommended for brushed motors with a max. cont. current of 20A." If that is true, it doesn't seem like enough for the motors (even stockers) that we run today.

OK, let me ask one more stupid question LOL

What about a LiPo receiver pack that would save me some weight in my .09 Nitro car? There were days when we ran 6 and 7 cell packs that have as much or more voltage than 2 LiPo cells and the servos did fine. With todays digital stuff do you guys feel that 7.4 volts is too much for say a Futaba 9550? They only recommend 6 volts.

Guy at my track runs a 7.2V LiPo receiver pack with a Novak Servo Voltage regulator. This:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJJF6&P=7

Many "pros" use 6 cell receiver packs. I know I was supplying them to Mike Blackstock for his 12th scale car. Here is a pic of Vicky Carrubba's car with 6-cells.
http://www.teampowerpush.com/images/2003cleveland04.jpg

But I can't see that the weight savings would be worth the hassle of needing to have a special charger just for a receiver pack.

On the Turbo booster thing, that "brushed motor" statement don't make sense. Brushed motors draw more amps then brushless motors. What would actually be better is a voltage regulator where it takes the 6.6v 2-cell packs and drops it down to 5v.

I think the booster is a bad concept for a few reasons.

User loses 5-10% using the unit regardless of the voltage boost.

It is more complicated than adding 1 or 2 cells.

Hypersonic™ 2300 6.6V (http://www.a123racing.com/racingpacks/hs2s1p.html)
2300 mAh, 6.6V, Lithium Ion, 2S1P
Dimensions: 135mm length x 28mm diameter
Weight: 155g
Output: Up to 30C continuous, 60C pulses
Max temperature: 160F/71C
Features: Balancing connector, Deans Ultra output/charge connector




http://www.a123racing.com/images/spacer.gifhttp://www.a123racing.com/images/racingpacks/4359-hs_sm.jpg (http://javascript%3cb%3e%3c/b%3E:%20open_popup2s1p())


OK I am looking at this and I see that it is only 6.6volts, we are used to 7.2volts. So where is the advantage? Also will it fit in my XXXMF2 that my 4200's just barely fit (with a little help).

I get the feeling everyone is missing something on the voltage booster.

What do racers pay the most for? Packs with the highest voltage.

What is one of the major Li-Po advantages - constant 7.4 Volts.

What if you could add an electronic unit that gives up some efficiency but bumps your voltage into what was the high dollar pack range. When is the last time you saw someone dump in a stock race?

The impact of allowing units to increase voltage cold be a major issue in electric RC racing.

I get the feeling everyone is missing something on the voltage booster.

What do racers pay the most for? Packs with the highest voltage.

What is one of the major Li-Po advantages - constant 7.4 Volts.

What if you could add an electronic unit that gives up some efficiency but bumps your voltage into what was the high dollar pack range. When is the last time you saw someone dump in a stock race?

The impact of allowing units to increase voltage cold be a major issue in electric RC racing.


Li-Po's have a low 'C' amp draw rating you must be careful not to have to high of a draw over the cells 'C' rating.

If you increase voltage then amp draw should increase too thats what we racers want to do is to go faster.
This will increase heat in the cells alot!

Is the weight of the booster worth the extra voltage or is the extra power lossed by the extra weight?

I don't really see an advantage of a voltage booster at this time.

Just better FETs in your speed controller to boost your speed.
Electronics are always getting better. :)

Just think, only 5 to 10 minutes to charge a cell between races . Really, think about it, only one cell in your car that is only slightly larger then a current sub-c cell... what could be simpler?

Hank, do you know how many times I've put my car down with 1/2 a charge because I timed it wrong??? 5 to 10 minutes for a full charge would be AWESOME!!!

As for the 4 cell oval voltage...Some sort of voltage reducer installed at the line (like a transponder) would be great, maybe even installed by the track tech just like restrictor plate racing :thumbsup: .

I would like to mess around with this a bit, so point me in the right direction for purchase. I'll need 2 cells and a charger, what's your recomendations???

After reading more on the 123 site,
2300MaH...If you could reconfigure the 135mm long cell into 67.5 that could work...I can see it now...A new class, brushless Li-Poly. I mean why not, so you have 6.6 volts, just use the 4300 motor, that should make it just about the speed of 19 turn except now you have less weight resulting in less tire wear, a win win :thumbsup: .

Chew on that :thumbsup:

Hey... sorry for coming late to this party... I just caught wind of these new A123-M1 cells... From what I read... they may very well be the wave of the future... It might take some time before car guys buy into these, maybe never... but it seems the plane and/or more significantly Helicopter guys like them for their high current output...

http://www.evworld.com/view.cfm?page=article&storyid=1174

some one asked... what's the advantage for cars... power to weight ratio is better then NiMH... maybe no one really cares about that? Charging in 15 minutes... that would be nice... Two cell in a Oval car and/or 12th scale could be interesting.... more voltage then currently being run, but not as much as the old 6 cell days...

Personally I kinda like the idea of these cells...

Want to build your own??? Get Ten cells for around $130 by dismantling a Dewalt DC9360 36volt battery pack... here's the insides... and more info about the cells...

http://www.slkelectronics.com/DeWalt/packs.htm

I'm not racing these days... but I have to admit these new cells are interesting...
Check out the blurb at the end of this next link, where it's stated that these cells should have lower Internal Resistance over time, rather then higher?

http://www.slkelectronics.com/DeWalt/index.htm

Maybe... just maybe... your cells might improve with use??? But I can see it now, people would just cycle the heck out of them to get the IR to drop further... :)

Here's a bit more detailed info about the cell's specs...

http://site.buya123systems.com/ANR26650M1specs.pdf

Look how flat the voltage curve is in the 40 amp discharge graph... also look at the voltage itself, my estimation from reading the graph is about 2.6 volts per cell at 40 amps... Put two of these together and your really not much higher then the current voltage in 4 cell NiMH...

Too bad they don't list the cycle life performance at higher charge and discharge rates...

All in all, it looks like a very interesting battery... if not for RC, then maybe for other things... I suspect that these cells or others with similar technology are in everyone's future...

It seems that we are in the midst of a heck of a lot of new tecnoligy in our hobby. With Brushless motors, and the new LiPo batteries, it is going to make a huge impack on what we are doing.

My question is; should we jump on the LiPo deal or is the Li-Ion system worth waiting on? Or is it available now?