Third Swollen LiPo

[Brushless]

I run an RC18t with a Dynamite 9000kv brushless on a Mamba 25 esc. I have hex adapters and run the 1/10 scale touring tires. I was introduced to lipos a few months ago, and put an Apogee 3s 1100mah pack in the car without changing the cut off voltage on the esc.

Swollen Pack, my fault! (I didn't know any better at the time.)

I went to to the LHS and picked up a MaxAmps 1550mah 3s pack and reset the esc to the proper cut off voltage. On the second run, the pack smoked and I barely got it out of the car before it caused any damage.

Smoked Pack, who knows.

I called MaxAmps who told me that I may need a larger pack for a 9000kv motor. I purchased a Common Sense RC 2000mah 20C continuous, and 30C burst lipo. After just one partial run, I didn't even fully run the pack out, I noticed that the pack is swollen.

I have the Mamba set to the lowest possible setting for acceleration, and the longest possible battery life to minimize battery strain. I charge on an Ice charger, and balance with a small chip before and after runs. I don't know what I'm doing wrong, but it's getting to be an expensive mistake!!! Any help and or ideas are appreciated.

[Mr. Fusion]

what is the LVC set at?

The setup and battery choice seems ok to me.

[Brushless]

I'm not familiar with the term LVC.

[admin]

LVC.........LOW VOLTAGE CUT OFF..... a two cell li-po will have an LVC of 6.0 volts or 3.0 volts per cell and a 3 cell pack will be 9.0 volts. If your going below the LVC point your gonna kill the packs.

Admin

[Brushless]

LVC is set at 9V per the mamba esc setup instructions. After the problem I had with the first pack, I set it immediately and double checked all of the other settings as well. Could my gearing be too high? I'm running a 13T pinion.

[Brushless]

Does anyone have any ideas? How can I tell if I'm drawing more than the lipo will support?

[Brushless]

Thought I'd share what's been eating my packs.

http://www.tradingassistantsoftware.com/images/IMG_3285_1024x683.JPG
http://www.tradingassistantsoftware.com/images/IMG_3287_1024x683.JPG

[velociti]

Wow! That's a very nice pack eater... I mean truck! :D
Looks like it cost quite a fair bit to put together.

[admin]

With out a watt meter of some type there really isn't any way to determine how many amps the set-up is drawing but from the amount of damage your doing to packs I would say you are way over 31 amps which is the max Constant current for our 3S 1550. I would definitly gear it down, way down until you can get a read on it. The only other thing is to ask around and see if any one else is running the same system and see how they have theirs geared.



Admin.

[Brushless]

Is there an onboard system that would tell me my max current draw? I found the Eagle Tree Systems unit, but wondered if there is an alternative. My current tester only measures to 10AMPS, and won't engage the mamba esc when its inline. Ideas?

[Bondonutz]

With out a watt meter of some type there really isn't any way to determine how many amps the set-up is drawing but from the amount of damage your doing to packs I would say you are way over 31 amps which is the max Constant current for our 3S 1550. I would definitly gear it down, way down until you can get a read on it. The only other thing is to ask around and see if any one else is running the same system and see how they have theirs geared.



Admin.

Super nice 18T !!!!
GEAR WAY DOWN Try 8T.
The gears are 3.00 each on avarege,buy 5-6 different counts to experiment, WAY cheaper than 3s's.
Your top end will decrease some , but you will not miss it. Check you temps.

[M-CHASSIS-NUMBER1]

Hi folks, cant you work out average current draw by dividing pack capacity by run time???, ie; a 3000mAh pack with an average draw of 3000mAh on it should run for 1hour, its not accurate but if you are using an 1100 that has a max continuous delivery of 31 Ah you should get 16 minutes or more of run time to stay within the packs capabilities . also check the specs that come with the motor system , it should give the continuous and peak current draw.
please correct me if i am wrong folks , mcn1:D

[Brushless]

I'm currently running a Dynamite C4 9000kv motor on a 13T pinion and a 60T spur. Even with that gearing, I can barely keep the nose down at half throttle! Can I even fit an 8t and still get a mesh to the spur?

[Brushless]

My temps are super low! Almost cool to the touch on both the speed controller and the motor. The C4 specs are absolutely useless for data.

http://www.dynamiterc.com/Products/Default.aspx?ProdID=DYN3715#specs

Is anyone running a 13T/60T combo on the Mamba 8000?

[Bondonutz]

You mave have to experiment with spurs and pinions ? I had a 18T couple years back when the mamba compX first came out and I ran 2100mah 2s and I had all kinds of problems with eating packs and heating issues untill I geared down to 8-9 T.
With your motor choice and set-up being so different, I couldn't say with confidence what your problems are. But I think it's a safe theory that your gearing may be excessive ?

[Bondonutz]

Thats a Horizon Hobby product correct ? They have some pretty sharp guys over in Tech. Give them a call and see what the have to say, they might have some insight ?

[BRIAN C]

im not sure why your packs are smoking ....but i race regularly with the minis ....your gearing should be fine ...there are plenty of people running similar set-ups ....there is a guy who regularly runs his c4 9400 on all types of packs ....i dont know exactly what the problem is ...but things just arent adding up ....have you tried swapping the mamba esc ? like i say there is something going on there ..but it shouldnt be your gearing ...maybe your esc or the charging process? just my .02 and ive seen about every mini run on some stupid configs ....:eek:

p.s. maybe also your motor could have an issue?

[M-CHASSIS-NUMBER1]

im not sure why your packs are smoking ....but i race regularly with the minis ....your gearing should be fine ...there are plenty of people running similar set-ups ....there is a guy who regularly runs his c4 9400 on all types of packs ....i dont know exactly what the problem is ...but things just arent adding up ....have you tried swapping the mamba esc ? like i say there is something going on there ..but it shouldnt be your gearing ...maybe your esc or the charging process? just my .02 and ive seen about every mini run on some stupid configs ....:eek:

p.s. maybe also your motor could have an issue?
yeh thats why i asked about run time, i cant see why the mamba 25 could draw that much current for a prolonged period without getting too hot and shutting down?

[Mr. Fusion]

The small eagle tree is the one to get... only $69, small and it's solid. I had a esc short out and smoked the wires right off the eagle tree... but a re-solder job and it still works.

What tires/wheels are those? Pretty tall for a 1/18.. but looks pretty cool.

[Heath M]

I don't know because I dont run any 1/18th scale stuff but if the motor is cool I wouldn't think that it was gearing. My need to check your roll out to be sure. Three different packs with the same result does sound bad seems like it may be in the charging process or some kinda short in the ESC or line but you would think that would produce some heat. Ok, I don't know..... that does suck though.

Heath

[Brushless]

Something REALLY obvious just occured to me. If I'm running a 25A esc, and 31A max continuous lipos, how can I be swelling packs because of current draw without blowing the esc?

[Corporeal]

I'd start to suspect that it's not drawing 25amps with that C4 but rather over 30. Check the temperatures of the ESC's mosfets and try and get a read with a wattmeter. you could be overworking the ESC aswell.

1:10 wheels + 9000kv motor = a LOT of current pull.

[Mr. Fusion]

The Mamba25 is capable of much more than 25 amps... it should be called mamba35 or mamba40. The components used on current units are much better than when it was first released so it's underrated at 25 amps.

This is straight from the guys at Castle.

[M-CHASSIS-NUMBER1]

thats what i have been saying! if you are getting less than 16 minutes of run time you need to get a pack with a much higher continuous rating, .
although i regularly use Kokam packs rated at the same as your max amps packs and pull 60Ah from them with no problems yet,i also wonder how castle are getting away with selling something that actualy has a different performance to that claimed on the box,, unless it is the other brand motor that has taken the max continuous to beyond the speedo specs.
hope you get to the bottom of this, its got me very curious. mcn1

[Brushless]

I just ordered the Eagle Tree unit to see exactly what the draw is on my setup. I'll let you guys know as soon as I get the first run in.

As far as runtime goes, I've never run a Lipo pack all the way down. I end up getting tired or bored of running for that long in the same place. At the end of my last run, over a week ago, I put the pack on the bench and didn't touch it until I read through this last night. I went back and tested the voltage on each cell, they were all at 3.7v

[M-CHASSIS-NUMBER1]

Hi again Brushless, please do keep us informed, i am in the market for a couple of brushless set up for my mini inferno's, its not so good that you have to be the test dummy but all us who are looking at the castle will find this info helpful(castle should have really done all the testing !), i have had a look at the instructions for the 25 and it clearly say's 'up to 25Ah max continuous current' , ,they seem like a fairly thorough company and i wouldn't have thought that they would put out a product that would have such a large difference from that specified, curiouser and curiouser, i look forward to the eagle tree getting there, cheers ,mcn1:confused::D

[Brushless]

I just got the eLogger today, and set it up on the bench. I also spent almost 45 minutes on the phone with Castle and one of the most helpful reps I've ever spoken to! He confirmed that Castle puts all of their equipment through rigorous testing and then underrates their capacity. When they say that the Mamba 25 esc can handle 25A, it can handle 25A for 24 hours straight.
They also just replaced a FULL Mamba Max setup for me today at no charge. I had purchased the set on eBay and when the esc smoked on me I sent it in for repair. Not only did they replace it no questions asked, but they even changed the setup from the 7700 to the 5700 when I asked. Truth be told, I got my first RC car (XR-311) when I was 5 in 1980, and today Castle earned a customer for life!

I'll keep everyone posted on the progress.

[Corporeal]

Nice to hear.

When I first got my brushless system, I looked at the esc rating and bought a battery with a constant current rating that was almost double the ESC's current rating. (44 amps for a 25amp ESC rating)

seemed to have worked out well.

[xxx-t chuck]

The problem you are having is the oversized 1/10 wheels and tires. unless you realyy gear it down those tires will remain your problem. I found this out the hard way when I smoked the two motrs in my E-Maxx by running 7 inch tires on it. Once I changed from the stock 18 tooth pinions to 12 tooth the problem went away. So, either put the stock size tires back on it or change your gearing. I also smoked a Max Amps 4k pack in my rustler with the Castle 7700 system. I went up three teeth on the spur gear and down two on the pinion. Problem solved second 4k runs for 20 minutes without a problem. You have to gear down because your brushless motor turns more r.p.m.'s the your stock motor and you have to gear it so it can turn those high r.p.m.'s easier then your stock gearing can.

[Bondonutz]

The 1/10 scale tires on the truck have almost the same roll out. They are barely
taller IF at all.

[Corporeal]

they may be the same diameter but they have more mass than an 18 scale tire/wheel combination.

it's like putting 30 size wheels on a 2.2 truck.


The guy's gonna keep killing packs if he doesn't gear down.

[M-CHASSIS-NUMBER1]

in my opinion an extra 5 gram's per wheel cannot account for the damage that this guy is suffering, to test your theory i have just been running my mini inferno with 1/10 tourer wheels , i lost 1minute of run time from a usual 24 minutes, or about 5%.
this cant account for the blown packs, it can only be under rated packs or a dodgy speedo me thinks? just my opinion.
have a happy holiday and a MERRY CHRISTMAS.
MCN1:D

[Bondonutz]

For what it's worth I agree with MCN1. I had a 18T couple yrs ago and I noticed NO difference between the stock tires compared to TC tires ?

I do however think gearing could be a slight issue ?

Happy Holiday's Gentlemen

[M-CHASSIS-NUMBER1]

For what it's worth I agree with MCN1. I had a 18T couple yrs ago and I noticed NO difference between the stock tires compared to TC tires ?

I do however think gearing could be a slight issue ?

Happy Holiday's Gentlemen
i would also look at reducing the ratio a touch, if the motor/speedo temps were too high, but Brushless did say that the motor and speedo were pretty cool after each run! weird huh,, perhaps it is just a bad charger? the eagle tree should reveal all.
hope you are having a fine crimbo everyone.
mcn1

[Brushless]

Here are the results from the 13/60 gearing combo with the eLogger.
http://www.tradingassistantsoftware.com/images/13-60_1220.jpg

I'll post the results of the 10/60 gearing combo as soon as I can get a run in with the new setup.

[Mr. Fusion]

The graph shows this battery can handle 35-40 amps, but any more and it's dropping volts too low.

It looks like this setup can pull about 20-25 amps constant... during sustained full throttle running. The 60 amp peaks are pretty impressive for a 1/18 :D but that's 40c on a 1500mah pack. :eek:

So, the battery is holding up ok at 20c (30 amps) but not really so good at 30-40c. To keep dropping the pack to 2.5v/cell is not a good thing. Whether it will kill it or not I don't know... I have seen packs survive worse.

[Corporeal]

well there's your problem.

your pack is having to deliver 62 amps peak. that's murder on any pack that's rated less than 2000mah. I think you should probably be looking at getting a motor that's less than 8000kv, otherwise you'll have another swollen pack on your hands.

[M-CHASSIS-NUMBER1]

would two packs in parallel allow enough current at the required volts without over load occurring?

[Brushless]

Correct me if I'm wrong, parallel would double the pack discharge ratings but there's no room for a second pack.

I'm going to post the results of the 10T run as soon as I get a chance to test. I'm still running the same CommonSenseRC pack to do all of the testing which is a 2000MaH pack, but only has a 10C continuous rating and 30A bursts. It's a cheap pack to use for testing purposes, and will let me tune without ruining the pack I will ultimately run full time.

I hate to say it on this forum, but I'm looking at the ThunderPower 2100MaH pack. It has a 31.5A continuous and 50A burst capacity that may be more in line with what I'm running. I really don't want to change motors, but if the gearing doesn't help, I'll probably go to tires next and change to a 6800 or 8000 as a last resort.

[M-CHASSIS-NUMBER1]

Correct me if I'm wrong, parallel would double the pack discharge ratings but there's no room for a second pack.

I'm going to post the results of the 10T run as soon as I get a chance to test. I'm still running the same CommonSenseRC pack to do all of the testing which is a 2000MaH pack, but only has a 10C continuous rating and 30A bursts. It's a cheap pack to use for testing purposes, and will let me tune without ruining the pack I will ultimately run full time.

I hate to say it on this forum, but I'm looking at the ThunderPower 2100MaH pack. It has a 31.5A continuous and 50A burst capacity that may be more in line with what I'm running. I really don't want to change motors, but if the gearing doesn't help, I'll probably go to tires next and change to a 6800 or 8000 as a last resort.
as far as i know it should give you double the current with them hooked up in parallel,,if i was you i would go for two packs ,one on top of the battery strap and one under, tape them to the strap, you should have plenty of room since you are running a truck shell,
as for the thunder power pack i dont think that 0.5Ah is enough of an improvement, aim for at least 10Ah more at least!
here is a thought, get max amps to make you a saddle pack like the 7.4v 3300 for the mini inferno but get it as 11.1v made to order, it should fit in with the packs snugged up together and give more than enough juice for the job at hand with a enough left over to fit higher gearing( more top speed) if the motor and speedo are staying cool like you said earlier in this thread you should have no more problems,
all the best ,mcn1:D

[Brushless]

I hadn't thought about mounting the batteries above and below the strap. The CommonSenseRC pack is only rated at a 20A continuous discharge rate with a 30A burst. The Thunderpower pack is 31.5A continuous with a 50A max. I think that I'll get within those ranges with the pinion change. The only thing that concerns me about the dual packs, is the "dual weight" that goes along with them and the raised center of gravity from the second pack mounted above the battery bar. The other option is to use the MaxAmps 1290MaH pack.
http://www.maxamps.com/Lipo-1290-111-Pack.htm
The combined length of two packs is just under the 100mm mark and I can easily fit the width after my mods for the CommonSenseRC pack. If hooked in parallel, and my math is correct, they should yield:

30mm X 98mm X 37mm
11.1V
2580MaH
39A continuous discharge rate
??A max discharge rate
222 grams

The pack would be 41 grams heavier than the heaviest pack I've used, but provide almost double the current continuous discharge rate available from my test pack and more than any other pack currently available.

Can anyone confirm my math is correct?

[M-CHASSIS-NUMBER1]

i wouldnt worry too much about the weight, especialy if it means you are no longer killing batteries, your maths looks ok to me.the burst rating may still fall a touch short but going down by one or two teeth on the pinion would sort that, just!
i hate to have to say it but Kokam do 30c rated packs http://www.overlander.co.uk/products/default.asp?pid=2194
its 107mm in length so might not fit but they might have something that will, keep the info coming, mcn1

[bdebde]

How about:
2100mah
21.3 x 35 x 100
177 gr
52.5 A continuous 105 A max

[Brushless]

You have my attention! Manufacturer?

[M-CHASSIS-NUMBER1]

thats an impressive set of figures, more info please,
http://www.overlander.co.uk/products/default.asp?cid=2&scid=40&pid=2276
this may also do the job ,
http://www.electrolite.eu/direct/index.php?main_page=index&cPath=1

[Rod Sanata]

Are you running the packs cold, What is the temp of the packs at start up, If you run in cold weather or a cold climate. You may need to literally warm the pack up. If they are to cold on start up it can cause damage and puff the packs. If the pack is less then 50 degrees, I warm my packs to 110 degrees for running my boats in cold weather. Just another possibility.

[Brushless]

I'm in Florida, and it's currently 80 deg F outside right now. I just came back from Dallas Texas where I would bring the packs inside to charge (in a Lipo Sack ofcourse) before a run to avoid them starting at too cold a temp. It was a high of 47 deg F when we were running. One thing I did notice however was that my "puffy" CommonSenseRC pack actually shrunk in the cooler weather.

[M-CHASSIS-NUMBER1]

ive been running all my li-po's at -4deg and haven't had any issue, ive never heard of warming a pack, doesnt it cause an increase in internal resistance of the cells and thus a drop in voltage like you get with a ni-mh cell? (still learning)

[Brushless]

I think that all batt's have a min and max operating temp. I'm still learning too, but I remember "freezing" packs in the old ni-cad days of the 80's to increase capacity.

[M-CHASSIS-NUMBER1]

i too used cooled ni cads back in the day, more for fast charging rather than to push capacity, found it helped with n-mh too , but warming a pack prior to use sounds alien,,
does any one know if this is a recomended practice??

[Mr. Fusion]

Yes, correct. Most batteries perform like **** when they are cold and this includes lipos. So it's best to keep them warm.

I would recommend keeping them at room temp or above. You will get the best performance when the pack is around 100*F. It's our little secret. ;) I have done test runs with the micrologger and there's a noticeable difference in voltage drop between 60-70* and 90-100*.

It doesn't hurt the battery at all... unless your setup is so hard on it that it gets really hot during the run. But that's rare. Usually there is only slight warming during use.

[M-CHASSIS-NUMBER1]

Thanks for that Glassdoctor, i will give it a go.:D

[M-CHASSIS-NUMBER1]

Hi all, i stored my li-po indoors rather than in the workshop last night so they were at room temp and took the 2wd buggy out and it was definitely slower than when they are stored in the work shop !!
i am guessing here but i think the internal resistance increases faster as the cells get hot faster when they are already at room temp before you even start running.
correct me if i am wrong on this please.

in total it cost me 5 laps on a 6 minute run on my wee test track compared to a cold pack!!!:confused:
:D take it easy y'all.

[Mr. Fusion]

Very odd.... how different are the temps indoors vs workshop?

Lipos do perform better when hot. In fact that is one way that mfg can fudge the numbers and show fantastic discharge graphs... by starting the discharge at a warm temp and pushing the pack beyond it's limits and overheating it in the process. If they did the same test with a cold pack, there will be a bigger dip in voltage early in the discharge until the pack heats up, and the voltage increases.

In the real world, our setups rarely push a pack enought o get it hot, so it's not a problem to pre-warm it before a run. In my 1/8 car I was keeping my pack around 90-100* in the pits and it was only 110 degrees after a 30 min run.

[M-CHASSIS-NUMBER1]

the workshop is pretty much at out door temps over night, -4 the past few nights, indoor is at about 18deg(65c ish).
i actualy pulled the motor apart to check that there wasnt a problem elsewhere but all is fine.
i will give it another go to get better reference info, if its working for you it should work for me too,:D

[aaron r.]

This is all good info guy's keep it coming.
Thanks.

[Brushless]

I haven't forgotten to post my results guys. I shipped my truck to Texas for Christmas, and I'm still waiting for it to get back home. I'll post as soon as it arrives and I can test!

[M-CHASSIS-NUMBER1]

I haven't forgotten to post my results guys. I shipped my truck to Texas for Christmas, and I'm still waiting for it to get back home. I'll post as soon as it arrives and I can test!
good man, let us know what pack you go for too.

[Brushless]

I still want to know what packs bdebde was talking about back on page 2!

[Brushless]

Here's the data from the 10/60 combo. Still a little on the high side, but it appears to be within the thunderpower pack range. I think that I'll just retire that Common Sense RC pack now that I have a manageable draw.

http://www.tradingassistantsoftware.com/images/rc18t_10-60.jpg

[M-CHASSIS-NUMBER1]

I still want to know what packs bdebde was talking about back on page 2!
me too, i hate when folks type 'how about this ,blah blah' then dont give any info!! and thanks for keeping us posted and providing the graphs,
just goes to show us all that the battery manufacturers mean' max continuous when they say max continuous'
cheers,mcn1:D