Battery Sound Off! Everyone please post what batteries and charger you use.
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Jjlackner
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That's a lot if wasted money! What do you recommend? I'm waiting for the dura 245 dual charger and 3s 35c 5000mah lipo package...it's on back order. Would you cancel the order! Thanks.
Aboulafia
Member
A small reminder about ohms rules P=U.I
The problem you will have it is a Duratrax 245, that it's not powerfull enough to charge your two batteries @ 1C. It can deliver only 40 W per channel and for your's 5 Ah 3s battery you need a minimum of 63 W per channel @1C (4.2v x 3(s) x 5 A)
I'm not sure there is a lot of charger on the market able to handle 100 W per channel (confortable) and probably it will be a better choice to buy 2 charger that works simultaneously. My Ultramat (90 W) can just handle my Hobbystar 3s 7600 mAh that needs 83 w of power @ 1C.
If you want to charge two batteries with one charger, you will need to find a big DC charger like this : http://www.progressiverc.com/icharger-308duo.html but I'd rather buy two 106B @ 89 us$ each. If one failed, I can continue charging with the other one, the time to fix it ;-) (this is an example, i do not work for iCharger)
An other point to verify, it is that often, the manufacturer do not give the maximum power of the charger on AC but when it's pluged in DC.
I think, is you limit your batterie pack to 3s and be sure you'll nerver climb to 4,5,6s, you can do the job with a 90 W-10 A Ac charger like a Ultramat 16s (that do a good job)
This is the minimum. A 80 W (common) is already not enough for my 3s 7600 mAh pack.
And were talking about charging your lipo @ "only" 1C. For 2C rate is the double.
Fortunately, I red on the website of the manufacter Panasonic, that the optimal charging rate to get the maximum of cycle on a Lipo is around 0.7/0.8 C. It is the charging rate they use go give the cycle life of a battery Less than that it is not so good. I gess it's the same rules in other brands.
I leave this open door for the pro of lipo to give me some explanations about that.
For the batteries itself, it's difficult to make recommandations. For my Nero, I want 3s hardcase. I found the Hobbystar 3s 7600 mAh 75c @ around 65 us$ each. They last around 45/50 mn hard driving on the heavy Nero. They fit perfectly on the Nero battery case.
They have plenty of power, but they are TOO NEW (few cycles) to recommand it.
My other pack (gens-ace-r-spam) looks good but same thing. The 2s 6500mAh pack @ 50c last around 30 mn hard driving on the Nero and around 50/60 mn on my buggy Cobra (on track condition, not often full throttle)
Next year I could express you my opinion about these batteries.
Regards.
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Jjlackner
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Thanks so much...now I'm confused. I am a total newbie to rc and lipo at the least is very confusing. I am considering cancelling my order. Do you recommend any sites or forums I can look at to better understand lipos and charging them? Thank you for your help.
Aboulafia
Member
There is many site what can give you information about battery. You can begin by here :
- https://rogershobbycenter.com/lipoguide/ it's well explained, simple and enough for rc user.
- http://batteryuniversity.com/learn/ probably one of the most complete site on general battery (not only lipo)
I didn't keep the link to Panasonic, but it's not so much interresting for rc users, it's about satellite inboard lipo etc
With the first link is really enough informations for rc users after it's only if you want to improve your culture.
Enjoy !
- https://rogershobbycenter.com/lipoguide/ it's well explained, simple and enough for rc user.
- http://batteryuniversity.com/learn/ probably one of the most complete site on general battery (not only lipo)
I didn't keep the link to Panasonic, but it's not so much interresting for rc users, it's about satellite inboard lipo etc
With the first link is really enough informations for rc users after it's only if you want to improve your culture.
Enjoy !
Jjlackner
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I really appreciate your help for a new rc guy. I was wondering if there is any pros or cons between 2s1p and 2s2p packs? Same for 3s? Your thoughts? Thanks a lot!
Aboulafia
Member
and to help you on the choice of your battery remember that :
U=R.I and P=U.I ( P Watt, U volt, I Amp)
If the power of your bushless motor is 2000 W for example, if you run on 4s (3.7 x 4 = 14.8v) it can demand 135 A on your battery. If nobody lies ;-p if you have a lipo 4s 5000 mAh 30C looks good.
5000 mAh x 50c = 150 000 mAh = 150 A
For the same motor and on 6s now (3.7 x 6 = 22.2 v) you 'only' need 2000 W / 22.2v = 90 A.
That means that if you have the same capability battery 5000 mAh (4s and 6s), you can run 2,22mn (2 mn 12s) on 4S and 3,33mn (3mn 18s) on 6S on full load→ 50 % more time.
This not a scoop, your voltage is 50% higher and probably the weight of your 6s battery will be around 50% more. (a little less)
But remember that, for the same motor your C rating decrease if the voltage increase. and your 6s battery need only to be a 6s 5000 mAh @ 20C
5000 mAh x 20c = 100 000 mAh = 100 A (for 90 A power on the same motor)
But as I said, this is true if nobody lies and manufacturer always lies a little (a little ? not sure) and if you find a 30 C lipo by calculation it's certainly better to increase a little the discharge rating to 35C but not to 100C lipo, you'll waste your money for nothing.
Off course i gave this values only for example. You never drew so mutch power for long time. But probably on big 1/8 Monster, the motor power schould be between 2000W/ 3000 W and believe me, this a lot on this low voltage.
Enjoy !
And I want to apologize to the autor of the thread to have a little overflowed the main subject.
U=R.I and P=U.I ( P Watt, U volt, I Amp)
If the power of your bushless motor is 2000 W for example, if you run on 4s (3.7 x 4 = 14.8v) it can demand 135 A on your battery. If nobody lies ;-p if you have a lipo 4s 5000 mAh 30C looks good.
5000 mAh x 50c = 150 000 mAh = 150 A
For the same motor and on 6s now (3.7 x 6 = 22.2 v) you 'only' need 2000 W / 22.2v = 90 A.
That means that if you have the same capability battery 5000 mAh (4s and 6s), you can run 2,22mn (2 mn 12s) on 4S and 3,33mn (3mn 18s) on 6S on full load→ 50 % more time.
This not a scoop, your voltage is 50% higher and probably the weight of your 6s battery will be around 50% more. (a little less)
But remember that, for the same motor your C rating decrease if the voltage increase. and your 6s battery need only to be a 6s 5000 mAh @ 20C
5000 mAh x 20c = 100 000 mAh = 100 A (for 90 A power on the same motor)
But as I said, this is true if nobody lies and manufacturer always lies a little (a little ? not sure) and if you find a 30 C lipo by calculation it's certainly better to increase a little the discharge rating to 35C but not to 100C lipo, you'll waste your money for nothing.
Off course i gave this values only for example. You never drew so mutch power for long time. But probably on big 1/8 Monster, the motor power schould be between 2000W/ 3000 W and believe me, this a lot on this low voltage.
Enjoy !
And I want to apologize to the autor of the thread to have a little overflowed the main subject.
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Dopeman
Active Member
All of that stuff is way above my pay grade. I know that I am a noob and I bought the Nero / Duratrax package from tower. I run them in my Senton and my Nero. Probably about a dozen charges so far with no issues. I plug them both in and charge them simultaneously. Take about an hour and 15 min or so. No problems thus far.
Jjlackner
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Thanks so much...very confusing to say the least.
Also, please accept my apologies for changing subject in this thread.
Drpoomanchu
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I also have the Duratrax 3s 5000mah 35c kit with 245 charger. Been great so far. About 6 cycles no issues. Not bad for 199.99 imo
Erex
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I was lucky enough to get one. My 5600 have been on back order for 3 weeks
338federal
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I don't have any arrma rc cars. But thinking to buy a big rock. Lipos i drive is efi 5000mah 3s or gens-ace-r-spam 5300mah 2s. But if i get this truck so gens-ace-r-spam 3s lipos. I can charge with 5C charge. Charger is massive revolectrix DPL8 2844w of charge power. It takes 15min to charge the lipos.
338federal
Member
On the lipos i had. Charge Rate: 1-3C Recommended, 5C Max. Home i charge with 1-3C and field 5C charge. 40amps on both channels.
The efi lipos are 1C max. My thunder power lipo up to 12C charge. There 12C maybe but i charge max 5C here to. I don't have time to wait many hours to lipos get fullcharge. With 3 lipos i can fly constantly with no brake all day long.
Great thread here guys.
Im a noob and was just about to pull the trigger on a kraton and 2 batteries of the exact spec Arrma recommends.
But upon reading the great info here, feeling like I shouldn't follow their spec and should consider their numbers as bare minimums.
Would you all agree?
My goal is to maximize power and runtime.
So with that, should i focus on gettting the highest mah, volt and C as possible?
Also, is there any reason to get a single 6s battery vs 2 @3s?
Thanks in advance.
Im a noob and was just about to pull the trigger on a kraton and 2 batteries of the exact spec Arrma recommends.
But upon reading the great info here, feeling like I shouldn't follow their spec and should consider their numbers as bare minimums.
Would you all agree?
My goal is to maximize power and runtime.
So with that, should i focus on gettting the highest mah, volt and C as possible?
Also, is there any reason to get a single 6s battery vs 2 @3s?
Thanks in advance.
calabiyau
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slpcrf450x
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Yes, Arrma states that those are minimum battery specs.
A high C rating is good but don't get caught up only looking at really high C rated packs that are really expensive. Arrma says 35C minimum so just find something higher than that that is still a good value.
The voltage will be the same for all packs for however many cells you are running. 3.7V per cell is how they are listed, or 4.2V per cell at full charge.
Your run time will be dependent on the mAh of the battery. For example I have a pair of 5200 mAh 3s batteries that get decent run time, but my 7200 mAh 3s SMC batteries seem to last forever! The only down side to the bigger packs is more weight if you are doing a lot of jumps.
I have been very impressed with my SMC batteries and would buy them again. I think they are excellent value for the money. I think they don't exaggerate their ratings either. My charger shows how many mAh has been out into the batteries as it charges. From a full discharge my Power Hobby 5200mAh always take right around 5000mAh of charge. My SMC 7200mAh batteries take 7500-7800mAh of charge.
Good description but there are a small mistake,
you calculated with 30c and written 50c. I think the 30 keeps from the calculation before.
5A x 50C = 250A
5A x 30C = 150A
Conclusion: Maximal mA and highes C-rate you can get with the voltage you need.
But don´t forget, if increasing the voltage -> the Amps also will increasing! (U x I = P)
The other way: calculate or measure the amps of the complete system on full force.
If you have the result, for example 180A, choose the right type of Lipo....
Do you agree @Aboulafia?
