# What lipos?



## alsmith661 (Oct 16, 2005)

I was wondering what a good inexpensive setup would be. Need advise on a charger and what batteries to get. Thanks in advance. :freak:


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## alsmith661 (Oct 16, 2005)

If it helps I will be runnig it in a XXX-S with a 19 turn motor and a Novak Fusion ESC.


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## alsmith661 (Oct 16, 2005)

Is the watt-age charge it all a good charger for lipos?


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## hankster (Jan 1, 1998)

Try Pure Hobby our sponsor. They carry a lot of high quality equipment. http://www.purehobby.com

I like the DuraTrax ICE charger, the Astro is a good charger too.


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## alsmith661 (Oct 16, 2005)

Thanks for the info. what is a good power supply thats fairly cheap?


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## hankster (Jan 1, 1998)

Gee... not sure. I haven't bought one in awhile. Any of the "big" name products should be fine. I believe Novak has one that is fairly inexpensive.


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## alsmith661 (Oct 16, 2005)

I am looking at one of these. Polyquest 1800mah 20C-30Cburst or the 2100mah 20C-30C burst. Would these work for a XXX-S with a 19 turn motor?
Also what else would I need to use them besides a LIPO charger.


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## garyrcdoc (Oct 15, 2005)

Is there actually any POWER advantage in terms of voltage of lipo over the nimh? If the LiPo's have 7.4 volts charged, and the NiMh have an initial volt of 8.4 (or so...) fresh off the charger, then the INITIAL advantage for stock racing (it seems to me) should be for the NiMH batteries UNTIL such point that they drop below the 7.4 volts the LiPo's seem to maintain for so much of their discharge cycle. 

Is this correct thinking or is there some other principle that I'm missing?

The LIGHT weight of the LiPo's seem to be a definite advantage, but regarding the VOLTAGE - is there any initial advantage to the LiPo?

Thanks in advance for the information if anyone knows this. 

I race stock and it seems that I was as fast as a friend with LiPo for pretty much most of the race....


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## cola (Dec 10, 2004)

You will notice the biggest difference if you use brushless motors. But the voltage in a lipo is almost always going to be higher because of their internal restiance. They perform at their best if the are around 80 Degrees at the starting point. Lipo batteries can hold a high voltage when they are under load while nimhs drop pretty low when put under aload. Lipo batteries need to be blanced also, to keep in top form.


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## garyrcdoc (Oct 15, 2005)

*What is the advantage of LiPo over NiMH in STOCK class racing?*

So Cola - I guess I am not really aware of the typical drop in LiPo voltage under, say a 25 or 30 am discharge curve (I'm thinking of the average discharge amperage of an aggressive "stock" racing discharge curve).

When I look at NiMH batteries that I have freshly charged, they seem to come off of the charger with fairly high voltage (8.6v or so) and then, once they "settle" to say 8.3 volts at the beginning of a race, or when discharging, do they REALLY drop below the 7.4 v (charged) LiPo voltage? 

When I use my discharge function on my chargers, it seems that it takes several minutes for the charged 3800 NiMH to drop to the 7.4 volt peak of the LiPO (at the 20 amp discharge that my charger will discharge at...) So, am I to assume that for the amount of time I am racing, and my batteries are at say 7.8 volts during the discharge, that I am faster than the LiPo batteries (which never get over 7.4 volts)? (at least for stock racing...)

Do you see my point? Admittedly the weight advantage of LiPo is very significant, but is the VOLTAGE of the LiPo's any advantage for a typical 5 minute stock race (since presumably the NiMH may not have dropped very far for a good portion of the race...)

I'm not trying to criticise LiPo. I'd actually like to have a speed-related reason to buy them. Perhaps the less weight allows for better acceleration, but does the lighter weight of the LiPo offset it's lower initial voltage in a stock race? I had assumed that the LiPo's would have been better in every way until racing against them in our local stock class, they don't seem to have any speed advantage down the straights side by side with the other racers (however, they may handle better, I can't tell from observation...)

If anyone has any comments regarding LiPo power in stock, please let me know. I'm considering buying them for the ease of maintenance issue alone, but have wondered regarding the power issues (which relate to the voltage in the stock class...)

thanks again for any information or comments.


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## cola (Dec 10, 2004)

A two cell lipo battery or a 7.4v, peaks at 8.4v when fully charged.


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## garyrcdoc (Oct 15, 2005)

*Cola - Thanks for the needed detail*

OK Cola, NOW I get it. I didn't know that the LiPo peaked at 8.4 when charged. That was a detail I needed to understand. I was visiting an airplane RC site and noted that a LiPo battery (single cell) discharged at a 5 c rate dropped to approx 3.75 volt fairly early in the discharge curve and was approx 3.6 volt approx 1/2 way through it's discharge curve. Does this mean that the voltage of this particular LiPo battery ( 1800 single cell - so the voltage will have to be doubled to duplicate the drop of a 2 cell LiPo), under discharge will fall MORE than the typical NiMH (i.e. a similar 2 cell should drop to 7.5 early on and then 7.2 volts later compared to a typical NiMH under a 5C discharge)? 

How would this sort of voltage drop under, say a 5C discharge compare to a 5C discharge of a NiMH? If this single cell LiPo drops to 3.75 for a single cell (7.5 volts for a double cell - 7.4 v LiPo), then how long during a race will my NiMH take to drop to the 7.5 volts (I use 3700s so far)?

I honestly don't understand all of the theory and think the LiPo have some very serious advantages (weight, ease of use, etc) and I think I am so very curious that I'll HAVE to try them, but, in terms of acceleration and power (for a stock motor where I can't "motor up" to take advantage of lower voltage), does LiPo have any power advantage for the duration of a typical race (say a 4100 lipo versus a 3700-3800 NiMH)?

At this point I am so curious that I think I'll simply have to try the LiPo's myself. During my last race day, I did ask one of the stock racers using one of the new Orion LiPo's he said that "Power really isn't the advantage of using the LiPo". I'd really like to try them for the other advantages but hate to take a loss of power and top speed in stock racing in oder to enjoy the other, real and tangible (and significant) benefits of LiPo.


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## cola (Dec 10, 2004)

The voltage drop on a lipo when put under a high load will be higher than a nimh. If a 4500mah or a 6000mah battery was used in a test it would be easyer to see the voltage difference between the two because they have a higher amp rating. It would be more self explantory if you try one out for your self.lol www.maxamps.com has a great selection of lipo's and good prices if you just want to try one out. If you choose to buy a 4000mah, It only has an amperage rating of 48 amps. Instead look at a 4200 or a 4500. They have and amp rating of 60 amps which will provide a higher and more constant voltage.


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## garyrcdoc (Oct 15, 2005)

cola - I very much appreciate the information you've given me. I ordered a couple of LiPo's today and also bought a Duratrax ICE charger and will give the set a try. I am looking forward to using the graphing (charge/discharge) capabilities of the ICE for comparisons (though I'll be limited to a 10 amp discharge and make up the other 10 or so amps c 5 -or more- bulbs) and see what the voltage drops are for these different batteries. 

Thanks again.


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## garyrcdoc (Oct 15, 2005)

I bought a couple Lipo's from PureHobby and it has been an interesting change to try the lipo's. I race Stock buggy/truck only and certainly the LiPo's seem to have more initial punch though the top speed seems to be the same. 
I didn't anticipate the change in setup needed to compensate for the LIGHTNESS of the lipo's however. The LiPo's were 3 ounces compared to the 13 ounce sub c 3700's I had been using. I even wired two of the cells parallel that doubled the battery weight to a bit over 6 ounces (still 1/2 of what the sub C 3700s weighed). 
I think I'll have to figure out how to set up the suspension different to compensate for the weight but I LIKE the very little preparation the batteries need. 
All in all, I am impressed and hope that the light weight of the LiPo's will allow for lighter diff settings; longer lasting tires and perhaps higher cornering speeds - all due to decreased buggy weight.... we'll see. I'm impressed.

gary


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## garyrcdoc (Oct 15, 2005)

*Impression after 2 months of Lipo usage*

I am still very impressed with the changes that LiPo batteries have made in my RC racing. I'm not really any faster or do any better, but the quality of my racing experience has definitely improved.

*1) The LiPo's make racing more simple:* I am SO glad, not to have to worry about peaking a battery; or even if I forgot to charge from the last race - there is mah capacity to spare for 3 or 4 races with a 5200 battery... (I race STOCK class and use approx 800 mah energy per race in the buggy when I 're-peak after a race)

The convenience of NOT worrying about battery peaking/maintenance near the start of a race feels a LOT like having a personal transponder rather than dealing with having to pick up the track transponder at the last minute. It is simply a less "harried" and more relaxed and fun experience (less "work" and more fun) 

I just place it on the charger after the last race and _forget peaking altogethe.. If I FORGET to charge before the next race, it doesn't matter (at my current capacity of 5200 mah)_ This is simply one less thing to worry about.
*
2) The extra capacity has been nice to have:* Today I finished Utah's April Fools race. LiPo was approved for this prestigious race* IF *the entry was of sufficient weight - (I had to add 10 quarters to my buggy and added nothing to the truck to make minimum weight...).

I raced two races, back to back with the same truck and LiPo battery and didn't even worry about changing batteries. I do not think I was at any disadvantage at all. I simply didn't worry... and that was really nice.

*3) I am having to adjust driving style to the different, lighter weight* (I'm not sure if this is "pro" or "con" initially), but The truck is a more responsive (I don't think it's truly _a 'squirrely' feeling_, just quicker to be a bit out of control and back into control...) but all I did when changing to LiPo was re-adjust for 'normal' ride height (since the lighter weight left it sitting higher than normal). The more I drive, the more convinced I am that this change is probably better and not a detriment to my speed.

*4) One DOES have to buy a new LiPo capable charger*. However, in my specific case, I wanted a new charger anyway.... (I bought the duratrax ICE and it has been one of the coolest chargers I've ever had - very, very nice, especially for the price.)

*5) The battery PRICE to enter the LiPo arena was very modest, (actually it was very good).* I bought two 2600s from Pure Hobby for $25 each and was left with a 5200 mah battery for $50. This is about the same as my prior NiMHs, perhaps less. (I DID solder the two 2600 packs in parallel for a single 5200 mah battery)

I do not see myself as EVER going back to NiMH. At least someone will have to point out a reason to do so before I would do so.


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## Craps (Mar 22, 2005)

garyrcdoc said:


> I am still very impressed with the changes that LiPo batteries have made in my RC racing. I'm not really any faster or do any better, but the quality of my racing experience has definitely improved.
> 
> *1) The LiPo's make racing more simple:* I am SO glad, not to have to worry about peaking a battery; or even if I forgot to charge from the last race - there is mah capacity to spare for 3 or 4 races with a 5200 battery... (I race STOCK class and use approx 800 mah energy per race in the buggy when I 're-peak after a race)
> 
> ...


Keep spreading the word!

I have been to watch at Intermountain Raceway a couple of times. I am wanting to race there someday when ever I can remember to take my RC equipment when I travel to the other side of the country.

Keep up the good work!

PS. We have over 30 racers using the Thunder Power TP8000-2S4P 7.4 volt li-po batteries in 20 minute mains. Fast growing class and a great alternative to gas for alot of track time. I also heard you can upgrade a Turbo 30 charger with the software to handle li-pos. Great news!


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## Rocksalt (Mar 15, 2006)

I don't' know if the 3300's I have are not up to snuff or the lipos are really just that good. Before the lipos I could mash the throttle, on pavement, and the car would track straight and accelerate hard. Then the lipo came in.. 8000mah thunder power. Now when I mash the throttle from a dead stop the tires violently spin and balloon up super quick. Not only that, when I am at 1/4-1/2 speed and approach a very small rift in the pavement, then gun it.. it will flip the car. Never did that with nimh. I also had to change the pinion 2 teeth larger(17pinion and 92 spur). Yesterday I ran the car for 15 minutes straight over the same section of pavement. The punch was still there after 15 minutes. It was not 100%, but it was still pulling the front wheel up. This is on a 4wd xxx-4. I don't think a 4wd is supposed to wheelie. It appears that the lipo is holding a higher voltage under load than with nimh. The only downfall I had yesterday was the motor or ESC thermalling after 20 minutes of hard use. I had removed the fan to check how hot it would get without it. It was fine for backyard thrashing off and on. When I really put the screws to it it thermaled. I am still experimenting with battery temp, esc temp, motor temp to see what it will take and won't.

I don't know if the motor I have makes a difference than what you have (4.5Rbrushless).

What I don't understand is if you have a 5800 and it's to much power, why not just adjust the transmitter with throttle curves to compensate for the power? Unless you are running a competition race to make things equal you shouldn't need to buy a higher V/pr. rev. motor to go slower. Am I wrong on this(unless you can't adjust curves in the transmitter)?


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## Craps (Mar 22, 2005)

Rocksalt said:


> I don't' know if the 3300's I have are not up to snuff or the lipos are really just that good. Before the lipos I could mash the throttle, on pavement, and the car would track straight and accelerate hard. Then the lipo came in.. 8000mah thunder power. Now when I mash the throttle from a dead stop the tires violently spin and balloon up super quick. Not only that, when I am at 1/4-1/2 speed and approach a very small rift in the pavement, then gun it.. it will flip the car. Never did that with nimh. I also had to change the pinion 2 teeth larger(17pinion and 92 spur). Yesterday I ran the car for 15 minutes straight over the same section of pavement. The punch was still there after 15 minutes. It was not 100%, but it was still pulling the front wheel up. This is on a 4wd xxx-4. I don't think a 4wd is supposed to wheelie. It appears that the lipo is holding a higher voltage under load than with nimh. The only downfall I had yesterday was the motor or ESC thermalling after 20 minutes of hard use. I had removed the fan to check how hot it would get without it. It was fine for backyard thrashing off and on. When I really put the screws to it it thermaled. I am still experimenting with battery temp, esc temp, motor temp to see what it will take and won't.
> 
> I don't know if the motor I have makes a difference than what you have (4.5Rbrushless).
> 
> What I don't understand is if you have a 5800 and it's to much power, why not just adjust the transmitter with throttle curves to compensate for the power? Unless you are running a competition race to make things equal you shouldn't need to buy a higher V/pr. rev. motor to go slower. Am I wrong on this(unless you can't adjust curves in the transmitter)?


The buggy body is real tight and will not allow good air flow that could alot of your thermalling problem along with the 17 tooth pinion. Drop down to a 16 or even 15 tooth pinion to keep it cooled off. You may even need to upgrade to the Novak GTB system. The Pro Truck racers around here had alot of thermalling issues with the Novak 5800SS.


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## khyron (Apr 2, 2006)

cola said:


> You will notice the biggest difference if you use brushless motors. But the voltage in a lipo is almost always going to be higher because of their internal restiance. *They perform at their best if the are around 80 Degrees at the starting point.* Lipo batteries can hold a high voltage when they are under load while nimhs drop pretty low when put under aload. Lipo batteries need to be blanced also, to keep in top form.


Cola - thanks for all the information in this thread, I've been learning a _ton_ after coming across it this morning! I was wondering though, in the above entry, did you mean to say "80 degrees" as in temperature or "80 percent" as in capacity? While I've read the latter in many other places, the former I had not heard before.


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## Rocksalt (Mar 15, 2006)

I do have the GTB. I took the fan off after I monitored it a few times. What didn't help was using a piece of clear lexan to block off the hole on the bottom of the chassis, right under the motor. I was trying to keep debris out if the chassis. I might end up changing that as well.

As for the 17 tooth vs. the 15 I went from, I tried the lipos with the 15 first and the buggy was incredibly responsive. Winding out very quickly. Figured a 17 couldn't hurt as well as help reduce some of the punch. If I can flip it with a 17 imagine what a 15 would do with sticky tires!


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## cola (Dec 10, 2004)

khyron76 said:


> Cola - thanks for all the information in this thread, I've been learning a _ton_ after coming across it this morning! I was wondering though, in the above entry, did you mean to say "80 degrees" as in temperature or "80 percent" as in capacity? While I've read the latter in many other places, the former I had not heard before.


Hi I meant 80 degrees as in temperature.


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## Vic Nyce (Mar 31, 2006)

garyrcdoc said:


> *5) The battery PRICE to enter the LiPo arena was very modest, (actually it was very good).* I bought two 2600s from Pure Hobby for $25 each and was left with a 5200 mah battery for $50. This is about the same as my prior NiMHs, perhaps less. (I DID solder the two 2600 packs in parallel for a single 5200 mah battery)


where? i couldnt find this. after reading this i was tempted to try LiPo myself. how much is a decent LiPo charger?


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## Craps (Mar 22, 2005)

Vic Nyce said:


> where? i couldnt find this. after reading this i was tempted to try LiPo myself. how much is a decent LiPo charger?


I highly recommend for the serious li-po racer/user to get the Astro Flight 109 charger that will charge at up to 8.4 amps and cost around $110. Next I recommend the Duratrax ICE that can also charge at 8 amps and can charge all the nickel batteries you own too, but is slower at peaking out the li-po and cost around $125. Both of these chargers need power supplies to operate them.

The reason I say 8 amp chargers is that is 1C charge rate recommended by the manufacturers for an 8000 mah battery like the Thunder Power TP8000-2S4P that fits right in the battery tray of a 1/10th scale stadium truck. If you are charging a smaller mah battery like the 4800 mah Orion, you will cut it back to 4.8 amps that will take the same amount of time the 8000 will take at 8 amps to charge.

Good Luck!


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## Rocksalt (Mar 15, 2006)

Craps said:


> The buggy body is real tight and will not allow good air flow that could alot of your thermalling problem along with the 17 tooth pinion. Drop down to a 16 or even 15 tooth pinion to keep it cooled off. You may even need to upgrade to the Novak GTB system. The Pro Truck racers around here had alot of thermalling issues with the Novak 5800SS.



You were certianly right about the body. When I was testing the GTB without the fan I had the lid off the car. I ran it last night with the fan and lid off and it never came close to thermalling. I will have to make some scoops to get more air and possibly remove some body in the rear. I went to the 15T and the car got slower... Friggin spur was to loose. Just for grins I tightened it up a bit. It will now wheelie on command on dry pavement, lol. The strange pulling to the right when gunning it was a c-clip that came off the front shocks damper. This motor, 4.5R, is a wicked little motor.

If you connected to 2600's in parallel to make a 5200, did you make sure they were cell matched? 

Does anyone have a pinout for the extra 4 wires coming from the thunderpower pack? Are they for cell matching? This is one thing I wish I could do with the ICE charger.

One thing about lipos... they recommend not to get them hotter than 90F charging. Charging the thunderpower batteries, thunderpower recommends not to go past 113F. what if it's a hot day, say 100deg. ambient. It wouldn't be hard to see that temp. after a short run. Then if you want to charge them you have to wait several hours?


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## NitroStar (Dec 30, 2004)

Ain't no way I'm gonna run my GTB without a fan. All you have to do is make a scoop. I make mine out of old motor packages. Turn marshals and wrecks don't effect it. Works great. The ESC will last longer if it stays cooler.

Joe


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## NitroStar (Dec 30, 2004)

Well, I thought I attached an image. I'll try again.

Joe


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## Craps (Mar 22, 2005)

Rocksalt said:


> One thing about lipos... they recommend not to get them hotter than 90F charging. Charging the thunderpower batteries, thunderpower recommends not to go past 113F. what if it's a hot day, say 100deg. ambient. It wouldn't be hard to see that temp. after a short run. Then if you want to charge them you have to wait several hours?


Are you sure about that when the competition airplane flyers are pre heating the li-po batteries to 110 degrees for maximum performance?


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## garyrcdoc (Oct 15, 2005)

*vic Nyce - Lipos at Pure Hobby - Seem to be gone*

Vic, sorry not to have replied earlier. I bought my packs from Pure Hobby and they were part of an on-going sale. I re-visited the site and no longer found the packs I had been buying (2600 mah for $25.00) so I assume that they are all gone. You may want to leave an email for sales as you visit the site (Pure hobby) and see wha they do have or if they are expecting another sale sometime soon. 

I thought they were an excellent bargain and so I bought 6 packs total, and soldered them parallel for 3 packs of 5300 mah each. 

unlike the prior poster with the 4.5 brushless, I have not experienced the frank increase in "horsepower" described by the brushless RC drive as I race stock and my son who uses NiMH still is as fast down the straight as I am (as are the other stock users), however I am a bit lighter and think that the handling is more nimble.

However, another positive is the *increased battery life expectancy of LiPo over the NiMH.*

Since we race only 5 minute mains, I would expect that my DOD (depth of discharge) is only appro approx 20% so I expect that the battery life will be several fold that of NiMHs (approx 500 cycles if DOD is 100% and up to 2500 cycles if DOD is only 20% - from the Kokam website info).


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## Scoob (Dec 8, 2005)

I've tried li-po with various motors and I don't see any increase in punch or speed with lower powered motors like a stock motor. With a hot brushless motor though, it seems like the hotter it is the stronger it runs on LI-PO vs. NiMH. With my old ss5800 and now my 6.5, it is a very pronounced effect.


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## Rocksalt (Mar 15, 2006)

*Going by what TP lists on the website*



Craps said:


> Are you sure about that when the competition airplane flyers are pre heating the li-po batteries to 110 degrees for maximum performance?


What got my curiosity what the pre-set stop charge default limit in the Ice charger. It's 90F. The charger manual states to keep them under 95 deg. unless the manufacturer states otherwise, while charging. I went to the Thunderpower site and they have a PDF on the charging specifics. They list the max temp, while charging, to not exceed 113. I find that after running hard for 20 minutes the batteries are about 101 degrees. I read somewhere that lipos are not as efficient at the temps you described. Many documents say the operating range of lipo is 60-100F. At 150F the cells can experiance 'thermal runaway'.


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## NitroStar (Dec 30, 2004)

I have an ICE charger with the optional temp probe. The temp reading is way low. When I was charging some NiMH's the other day, I noticed the temp reading was pretty low. So I got my temp gun and was getting up to 20 degrees difference. I hope it is just the probe that is bad. Yall do some temp gunning and see what yall come up with. Post your findings here please. I discharged a 2400 NiCd yesterday and temped it at 145*. The ICE said it was 124*. I'm going to have to watch it close when my 8000 LiPo comes in so I will know where to set my temp cuttoff.


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## Rocksalt (Mar 15, 2006)

NitroStar said:


> I have an ICE charger with the optional temp probe. The temp reading is way low. When I was charging some NiMH's the other day, I noticed the temp reading was pretty low. So I got my temp gun and was getting up to 20 degrees difference. I hope it is just the probe that is bad. Yall do some temp gunning and see what yall come up with. Post your findings here please. I discharged a 2400 NiCd yesterday and temped it at 145*. The ICE said it was 124*. I'm going to have to watch it close when my 8000 LiPo comes in so I will know where to set my temp cuttoff.


This is probably due to the fact that the ICE charger uses a transistor as a thermal measuring device. If you pull the transistor out of the holder I'm sure you can get a number off the transistor. Order another one for less than $2.00 and try it. Usually when measuring temp you need a thermocouple and a small circuit(such as a AD595CQ, type K thermocouple,3 resistors,2 caps) to measure temp. The method they used is not going to be accurate.


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## hankster (Jan 1, 1998)

I haven't pulled it out but I would guess they use a LM34 Temperature Sensor that is commonly used in a wide range of applications. Stated accuracy is +-1 deg.


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## Rocksalt (Mar 15, 2006)

I stand corrected! Thanks for the info Hank. I just looked up that part. 1.5 +- for the full range from -50 - +300F! I wish I had pulled the transistor before I said anything. They are 13.00+ each. At the price of 18.00 for the temp sensor for the ICE it's possible they are not using that transistor. This info will be good to have for making temp sensors in the future.


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## hankster (Jan 1, 1998)

13 bucks is a HIGH retail price. You can buy the LM34DZ (32F to 212F) for under 3 bucks retail. ( http://www.hobbyengineering.com/H1751.html ). I suspect that in large quanties purchased direct from the manufacturer the cost would be down to under a buck each.


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## khyron (Apr 2, 2006)

Hey guys, another lipo newbie here and rather than start another post this looks like the right place to ask similar questions...

I've read up on lipo and understand the voltages involved and the serial/parallel naming scheme for packs and such and I've noted several online dealers from threads on this forum. The biggest two questions I have involve choosing the right battery pack and right charger for my application.

1) I intend to use lipo battery power in a T2 1/10 touring car with a Novak GTB and either a 5.5 or 4.5 Velociti brushless motor. I see specs on the battery sites about how many amps of draw each pack can handle continuous/peak, but even after studying Novak's site I don't understand how people predict how much current their car's motor and ESC might draw when they're choosing a "safe" to use battery pack. How exactly does one estimate that, or am I missing a chart someplace?

2) Of all the chargers I've looked at, the Duratrax ICE seems the most attracitve to me from a price/features standpoint plus I really like the user interface on it and that I can use it to charge other batteries as well. Can anyone clear up this temperature probe confusion for me though? Does their probe work well, or not? If not, is there a way to use a different transistor or something to make it work well? I don't want to buy a temperature gun and I want to have trustworthy data displayed by my charger.

Thanks a ton in advance to anyone with advice on these points!


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## Craps (Mar 22, 2005)

Don't need a temperture probe charging the 8000 mah! They don't even get warm!


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## Rocksalt (Mar 15, 2006)

I don't think any difference in +- the temp probe gives makes a difference. It's just insurance to protect charging when not watching the batts. If the charger hit your max limit it will stop the charge. A handheld temp probe is a good idea for checking motor/esc temp and gearing.

I don't know the answer to your batt question. I bought a thunderpower 8000mah.. to big to use the stock strap, but works awesome! Going back to nimh is like watching paint dry. Lost spunk is the word for it with reduced top end. I was charging the lipo up and wanted to drive... inserted the nimh and boy was I dissapointed.

I don't know how you would like the 4.5R in a 2wd car! I had to drastically change the throttle speed to compensate for wheel spin. At 1/2 throttle I can mash it and rip the tires loose on pavement. If I am WOT and hit some ripples in the pavement, so that it get's better traction, it will flip the car. This is in a 4wd buggy, 1/10 scale. Diffs have to be TIGHT to use all the power. It's a riot to drive this car!

The ICE charger works great! Wish it had a build in AC/DC converter. Using an old computer supply to run it. Works great at less than 12V too, but will not work at 15V... even though the specs say it will. I must just be over the threshhold with a 15V power supply I tried.


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## khyron (Apr 2, 2006)

Craps said:


> Don't need a temperture probe charging the 8000 mah! They don't even get warm!


Unfortunately, where I'm at it's perfectly normal to hit 100F ambient on sunny summer days - I'd mostly just like a temperature monitor on the battery as an "extra check" to make sure I'm treating an expensive pack as gently as possible. While it's in the car it's got air rushing past it, but on a tabletop it just sits there.

I'm curious about the claims above that the probe that comes as an accessory to the ICE charger is wildly inaccurate. Is there another probe that could be used? Perhaps I should just look into what the cheapest possible temperature gun is...


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## guver (Jul 31, 2002)

All those types of probes have the same problem, it is the relationship to the surface being measured. Getting a good solid connection to the cell is the key to being accurate. I use 3-4 probes with 3-4 charger/dischargers and they will read 10-20 deg F low most of the time. The probes themselves are perfect, just dunk them in water at 100 degF to test, they will be accurate.


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## purehobby (Feb 4, 2005)

I am with craps never really needed the temp sensor. I carry the Hyperion 7i charger that is pretty nice as well that comes with it but really have not used it myself. This charger is much like the duratrax ice.
Nice Pack Craps I use the TP ones as well. We should have a new polyquest product in a couple weeks that will have a thin plastic case around them to protect the battery a little designed for the rc cars. 
It has been awhile since I have been here but I do carry Thunder Power now as well and will work on getting a new banner up here.

Nice to see the lipos are starting to catch some interest in the car/truck world 

Robert
www.purehobby.com


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## guver (Jul 31, 2002)

Yes, the temps should not increase much when chargeing at 1C, It may prevent a fire though if user errors some time.


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## Craps (Mar 22, 2005)

purehobby said:


> I am with craps never really needed the temp sensor. I carry the Hyperion 7i charger that is pretty nice as well that comes with it but really have not used it myself. This charger is much like the duratrax ice.
> Nice Pack Craps I use the TP ones as well. We should have a new polyquest product in a couple weeks that will have a thin plastic case around them to protect the battery a little designed for the rc cars.
> It has been awhile since I have been here but I do carry Thunder Power now as well and will work on getting a new banner up here.
> 
> ...


Good to hear from you again Robert!

My opinion on plastic cases around the li-pos is not necessary in most stadium trucks that have a 4 sided padded battery tray with a good hold down bar or strap. Maybe touring cars or 4wd buggies need the case? I think it is better to see any problem the battery could have with swelling as warning sign without it being contained in a case where it will go unchecked and unseen! Just my opinion that cases are overkill and unnecessary.

Keep the info coming and find us an equal to the Thunder Power TP8000-2S4P packs that are factory built and not home made for less $$$.


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## purehobby (Feb 4, 2005)

Craps,
You bring up a good point about the case. It seems to only be beneficial for some. I for one have crashed a couple of the PQ3s-4400n but only in my T3 where the battery pack shot right into the bolt at the front of the battery compartment. But in my other Rc trucks I have no need for the case. 

I will continue to look for something that will work for us at a lower cost.

The search continues :thumbsup: 


Robert


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## NitroStar (Dec 30, 2004)

I just recieved my 8000 Lipo from Max Amps. It is "freakin' unbelievable!" I ran it for 40 minutes over the course of 3 days in a XXT CR truck with a Sphere/Neo One combo (the original motor - 3 star). Never had my truck do wheelies for that long. I ran it for 25 minutes two times today and then topped it off after each 25 minutes of run time. I use an ICE charger at 8 amps. I had to adapt my battery strap up some. Could have used velcro, but wanted my strap instead. Max Amps sells their 8000 lipo for $129.99 with the connector of your choice installed. I will be getting another one of these. No way I would buy an Orion 4800 for more than what I payed for Max Amps 8000. Besides the 8000 is closer to a regular battery weight. So there is not much difference in the handling. (it is just a tad ligher than a NiMh).

Joe


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## Scoob (Dec 8, 2005)

Yea, they are amazing aren't they. Glad you like it.


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## khyron (Apr 2, 2006)

I am thinking about getting one of the packs from MaxAmps myself, and would love it if someone with some lipo experience could "double check" my thinking on something. I will be buying a 6000mah pack for now, because fitting anything "taller" into a T2 would be a non-trivial effort (even the 6000mah will require a little dremel work on the rear bulkhead since it's designed for round cells to sit under it). I intend to get a Duratrax ICE charger and an LBA6 balancer from Hyperion (and order my pack with a Hyperion tap plug).

Since it's likely that someday I will want to be charging a larger pack, say an 8000mah one, I'd like to get into a habit of behavior that will work with even larger capacity packs. I would probably want to charge such packs at 8 amps since the ICE can do it, but obviously would not use the LBA6 in-line because it only is rated for 6 amps. Instead, I was thinking I could always charge my packs on the ICE directly, but then use the LBA6 in "standalone" mode afterward before running. Of course I would also have a low voltage cutoff of some kind in the car, set to 3.0v.

Can anyone see any potential problems with this "plan"? Thanks in advance for advice.


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## Scoob (Dec 8, 2005)

khyron76 said:


> Can anyone see any potential problems with this "plan"? Thanks in advance for advice.


Yep, don't do it... lol  .

At this time all li-po packs, unless it's stated otherwise, should be charged at 1C or less. 1C is 1 * the amp hour capacity rating of the pack. 6000 Mah = 6 Ah * 1 = 6 amps. In simpler terms, the capacity of the pack divided by 1000 is your charge rate. An 8000 can be charged at 8 amps, 4000 at 4, 2500 at 2.5, ect.. really simple. The same method is used to rate the discharge capabilty. The Max Amps 6000 is rated at 60 amps continuous so it is a 10C pack. 72 amp (12C) bursts.

I think there are a few packs(maybe the Scorpions?) that can be charged higher than 1C but definately very few.


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## khyron (Apr 2, 2006)

Scoob said:


> Yep, don't do it... lol  .


I think you might have missed the part where I said "someday I might want a larger pack". 8 amps would be 1C for an 8000mah pack. Thanks for the caution though. I have no intention of ever exceeding 1C while charging my lithium polymer cells.


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## Scoob (Dec 8, 2005)

Oh I misread. My fault.


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