Will 20C rated Lipo work on new E-maxx Brushless ??

[rcar4fun]

Hi,
Unfortunatly I just realized that order that I placed for 4 x lipos is for a 20C rated one and not 30C.

I ordered ***** ********* 2S 5000mAh 20C for E-maxx 3908, you guys think is it going to be OK to use them or just sell them and get the proper ones, I dont want to burn any electronics?

Any input will be appreciated !!!

Thanks,

[makaveli72]

Without having any hands-on experience with the Brushless E-Maxx/Lipos and it's operations as yet. I'm going to make an educated comment from what i've learnt so far on this great forum since my return a couple weeks now and say that the MMM system will be slightly underpowered as the system is capable of demanding up to 120A. That batt. pushes out (5000mAh/5) 5 x 20 = 100A

And also, due to this the batts., ESC and/or Motor will most likely suffer from over-heating. Which is not good for the system. I think the batts. would suffer more from over-heating though, as it would be working hard to supply the power that the system is asking for; while the other components such as the ESC and Motor could possibly be damaged.

With a higher rated Amp battery the entire system will run more efficiently and cooler.

The more experienced guys will chime in and share their comments.

[vxlrocket]

using the minimum C rating is ok if you don't overgear the truck. I started out with all 20C packs, but did eventually switch over to 30 and 40C packs.

the motor won't run any hotter with a lower C rating, but it could shorten the life of the esc and potentially cause lipo issues if you're over geared, so start out with a lower gear ratrio. i found with my G-Maxx that 68/19 was good for the packs and the rest of the system. if i went much over that, the esc fan would come on in just a few minutes. (which tells me it's already at 150 degrees) 68/19 would get me almost a full pack, though.

you might be able to call HK's customer service line and get the order changed.

[Bandit_Kaine]

20C for 5 ah lipos is fine. the worse that will happen is the batteries will run a little hotter then if they were 30C but you will not damage your ESC or motor or batteries unless you run full throttle 100% of the time.

[filmmaker]

20C for 5 ah lipos is fine. the worse that will happen is the batteries will run a little hotter then if they were 30C but you will not damage your ESC or motor or batteries unless you run full throttle 100% of the time.

I agree those packs you bought should work just fine..

[rabbithazen2]

your safe, i run my ryno 2s 20c 5000mah packs as hard as my better packs. it true you dont get as much juice out of them and packs will get a bit warmer but your fine.

[ohiowoodsrider]

i run those exact 20c s2 5000mah ******* packs i must say they do come out little warm sometimes. but i do use 18/68 gearing and really need to drop down to a 62T although with the power of brushless in 4s makes it hard to tell. i'm guessing the esc pulls those packs fairly hard at this gearing. i noticed the price of some of ******* and ********* packs is actually coming down. like the 5200mah 30c 2s packs that are 22.00 bucks hard case to. but out of stock. i had a slash before the e revo ..so it was just easier to buy 2 more of the same pack. when i made the jump to my new e revo

[makaveli72]

I say why risk it?

[Hughes500Bob]

I say why risk it?

Agreed! The ERBE forum is riddled with posts on this issue. Joe Ford from Castle Creations openly says 30C 5000 is the minimum he reccomends.

Early generation MMMs were especially bad with this. Ripple effect is the root cause of failures. Good quality high C rated packs will handle ripple much better than low C packs because they have less IR (Internal Resistance) and can take current (braking) and give current (throttle) much more efficiently.

Bob

[rcar4fun]

Thank you all for your replies, I think I am going to play it safe and as soon as they arrive (today or maybe tomorrow), I'll post an AD in the "for Sale" section and sell them for the price I paid and I'll eat the shipping costs too, so will ship it in US for free.... will loose probably around $45 (shipping cost getting them to US and to sell them...) but thats the price I am willing to pay for not payong attention.

[rcar4fun]

I agree those packs you bought should work just fine..

Do you have the same Packs with Castle Brushless ? I just want to see if you have tried the same configuration or not !!

Thanks,.

[john01374]

My neighbor has the ERBE and he's been running 2S 5000 20C *****'s in his for several months now without and issue. The packs do get to about 100F after 20 mins or so but that's not gonna hurt them.

[vxlrocket]

Thank you all for your replies, I think I am going to play it safe and as soon as they arrive (today or maybe tomorrow), I'll post an AD in the "for Sale" section and sell them for the price I paid and I'll eat the shipping costs too, so will ship it in US for free.... will loose probably around $45 (shipping cost getting them to US and to sell them...) but thats the price I am willing to pay for not payong attention.

just a word of caution, but it's against the rules to try to sell non traxxas equipment at the marketplace. they'll most likely delete the thread and give you warning points. ebay might be a better solution.

[hexitnow]

those cells will work absolutely fine. i use the EXACT same battery packs and my truck does standing backflips at half throttle. heck you can use nimh cells if your light enough on the throttle, but what fun is that :P

[filmmaker]

Do you have the same Packs with Castle Brushless ? I just want to see if you have tried the same configuration or not !!

Thanks,.

The truck comes with Nimh packs that have less amp output than 20c lipo packs do..

[filmmaker]

Agreed! The ERBE forum is riddled with posts on this issue. Joe Ford from Castle Creations openly says 30C 5000 is the minimum he reccomends.

Early generation MMMs were especially bad with this. Ripple effect is the root cause of failures. Good quality high C rated packs will handle ripple much better than low C packs because they have less IR (Internal Resistance) and can take current (braking) and give current (throttle) much more efficiently.

Bob

ripple effect?
they had bad or low quality capacitors that caused failures (voltage spikes)..
these trucks come with lower C rating Nimh packs than using 20c lipo packs

[rcar4fun]

just a word of caution, but it's against the rules to try to sell non traxxas equipment at the marketplace. they'll most likely delete the thread and give you warning points. ebay might be a better solution.

Wow, thanks letting me know, you see I am a member of electric heli forum called "helifreak.com" and its not affiliated to any manufacturer, and vendors have ad's in it and users could sell almost any heli related items in the right section and post all their questions /concerns and critics towards anybody or any manufacturer without being censored , of course with mutual respect towards eachother.

Any way I decided to keep the Lipos and if I want to sell anything in the furue I'll make sure I read the forum policies before posting them.

Thansk ,

[danielhr77]

20C is not enough... I have 6 ***** 30C 5000mAh LiPo packs and are just fine (but on my ERBE they get warm and they get swollen with the time)... I will buy 40C next time just to be on the safe side...

[makaveli72]

The truck comes with Nimh packs that have less amp output than 20c lipo packs do..

That's a good point, but that doesn't mean it's the best thing to do to run under-rated batts. IMO. From my own experience when I had my Rustler XL-5 w/ MM7700 using a Maxamps 4K TQualifier (8.4v) batt. pack I could recall after my runs the batts. being very, very hot. (Apparently the MM systems are power hungry) And I was using normal gearing..close to stock if not stock; I never had a temp. gauge so I had no clue of what the exact degree of heat was, but it definitely seemed above normal. And we all know that too much heat damages components.....

By the way, question for anyone; for Lipos, and the MMM sytem, what is a normal/highest ~avg. temperature for them?

[hexitnow]

20C is not enough... I have 6 ***** 30C 5000mAh LiPo packs and are just fine (but on my ERBE they get warm and they get swollen with the time)... I will buy 40C next time just to be on the safe side...

weird bcuz all i ever run in my truck is 20c batteries. they never get warm enuff to even dictate taking the temperature. mine are zippies to actually.

[makaveli72]

^^^ Right...I was gonna say in my post above. I guess this all depends on how you run your truck, and your setup.

[danielhr77]

weird bcuz all i ever run in my truck is 20c batteries. they never get warm enuff to even dictate taking the temperature. mine are zippies to actually.

You don't drive it hard enough...

[filmmaker]

That's a good point, but that doesn't mean it's the best thing to do to run under-rated batts. IMO. From my own experience when I had my Rustler XL-5 w/ MM7700 using a Maxamps 4K TQualifier (8.4v) batt. pack I could recall after my runs the batts. being very, very hot. (Apparently the MM systems are power hungry) And I was using normal gearing..close to stock if not stock; I never had a temp. gauge so I had no clue of what the exact degree of heat was, but it definitely seemed above normal. And we all know that too much heat damages components.....

By the way, question for anyone; for Lipos, and the MMM sytem, what is a normal/highest ~avg. temperature for them?

In keeping with the thread.. big 20c packs will work in this truck..
the batteries that come with the truck are rated at 10c nimh
but if you want more then go for it, and again 20c will work

[hexitnow]

You don't drive it hard enough...

hehe worn output shaft's/gears (which i have no idea how i did altho epoxy fixed her right up), busted a-arms, busted shocks, busted shock towers, twisted drive-shafts, they all like to argue otherwise Anyway I was super suprised at how well they ran together. I had to make all my friends feel the motor as well to make sure cuz I almost didn't believe it myself. I was also running it thru tall grass w/some high speed passes, dang cars outside my house encouraging me to race em. Summer time, when I rebuild my track, and start running 6s will definitely be a better test tho.

[filmmaker]

20C is not enough... I have 6 ***** 30C 5000mAh LiPo packs and are just fine (but on my ERBE they get warm and they get swollen with the time)... I will buy 40C next time just to be on the safe side...

lipo batteries cat get to 140* without issues and if they are getting swollen, it is a good chance you are over discharging them...
I have used 12c packs in my ERevo and the only issue I've had with them is when I over discharged two different packs and they puffed some