skerry1

iTrader: (74)

I've tried doing the research but I still don't understand completely this lipo situation.

My main concern is run time, consistency and power. I guess that's everybody though. I'm going with the Mamba V3/2200kv combo. It can use up to 6s so my question is this. What value is there in 6s over 4s? How does the discharge rate effect it? Everybody says to stay over 25c but nobody really says why. So I guess what I want to know is if I have a 6s 5000mah battery with 25c and a 4s 5000mah battery with 30c, what differences would I see??

Thanks in Advance
Stephen

pirape

I cant really help you there but all I can say is that even with 4s setup you will see a huge differance of power compaired to nitro...

with 6s it will just tear

Edumakated

iTrader: (19)

The first rule you need to know when going to electric 1/8th is that Voltage * Motor KV = RPM. Understanding this basic math helps you pick the most appropriate battery for your situation. So in your situation, 4s (14.8 volts) * 2200kv = 32,560 rpms.

Most nitro engines put out RPMs in the mid 35,000 rpm range. Ironically, this is also the sweet spot for brushless motors as well in terms of runtime, power, and efficiency. So your gearing is generally the same as a nitro and depending on your track, you might gear up 1 or 2 teeth on the pinion.

When picking your setup, you generally want to pick a combo that puts you in the 28-34,000 rpm range for the best run time.

When choosing 4s, 5s, or 6s you need to pick the appropriate KV motor to get the benefits of the higher voltage. As voltage increases, the required amps to generate the same power goes down which means you run more efficient and do not need as much MAH to generate the same run time.

Generally, 4s batteries are mated with 1700 - 2200kv motors. 5s with 1400 - 2000kv and 6s with 1350 - 1550kv motors. All of these generate roughly the same RPMs.

The higher voltage setups tend to put less stress on the electronics and batteries and usually have cooler running systems as they don't require as much amps to generate the power. Amps = Heat (wasted energy).

In terms of run time, typically the following are good for 15-18 minutes when mated with the motors in the KV range presented above:

4s 5000 = 14.8 * 5000 = 74,000
5s 4000 = 18.5 * 4000 = 74,000
6s 3300 = 22.2 * 3300 = 73,260

As you can see from the math, each of these batteries have the same available power and run time but the the MAH required as voltage goes up decreases.

So, you can run 6s with the 2200 kv motor but you will not get very long run time because you will be turning RPMs at nearly 60,000 and the car will be stupid fast. If you are bashing, this is fine for speed runs, but if you plan to go to the track or run off road, you want to pick the right kv motor and voltage.

skerry1

iTrader: (74)

Thanks man, that was a big help. I was getting so frustrated, you def helped out. If you or anyone could help me with one more thing. So I don't need as much power, I could prob go with less motor but the combo is so much more price efficient that I can't see spending $70 for less motor when hopefully as I learn I will be able to use the 2200 more to it's potential. Would getting a lower cell battery back off some of the power and give me higher run times? Perhaps going to a 3s or even 2s would work?

Edumakated

iTrader: (19)

No, that isn't a good idea. Remember, the lower the voltage, the harder the battery has to work to supply the needed power. This creates heat (amps). You can get away with 3s in some situations, but anything less than 4s isn't recommended for 8th scale.

My personally opinion is to buy the right setup the first time. The 2200 combo isn't bad, but you will probably be better served with an 1800-2000kv motor. You will get better run time. Both Tekin and Castle offer an 1800 and 2000kv motor.

Are you racing? What car? How long are your A main's typically?

skerry1

iTrader: (74)

Yes I'm racing, they usually run AA or AAA mains at 10 minutes. I'm running an O'Donnell Z01B

rcgod

iTrader: (33)

Just get a 4500-5000 mah 4s battery and run the 2200 kv
motor. If you only run 10 minute races it will be fine.

rcmike

iTrader: (40)

What c rating would you recommend for this 14.8v with the castle 2200kv motor ? To help de-tune this set-up could you turn down the punch in the esc ? the batteries would be 5000mh, thanks

YDBD

iTrader: (3)

At least a 20c 5000mah continuous, but remember C rating is not standard and sometimes used for marketing.

Many guys have had good luck with Turnigy and Zippy Lipos. I run trak power 5000 mah 20c+ and ACE POW 5300mah 30c+.

I would set your punch to about 50-70%, the 2200 is very torquey...

Rampokker

iTrader: (9)

The 2200kv castle motor is definitely a handfull in a buggy. Heaps of fun though! I'm running one in my xray xb8ec (which isn't one of the lightest buggies around) and on a 4s lipo I get around 17 min on a small to medium sized track. And I'm geared the same on top end as the nitro buggies.

When I started out I ran turnigy 20C 5000mah batteries, and then later changed to 30C 5000mah ones. The 30C batteries ended up being a bit cooler than the 20C ones after a race. So my personal recommendation would be to go with 30C at least.

You can turn the punch control down on the esc, and it does work pretty good. Only thing is that if you turn it down too much, it gets difficult to correct the car in the air.

Knowing what I know now, I think an 1800kv motor would be better for runtimes. But price wise the 2200 combo just made more sense. And with some throttle control, it's a good combo to run when you don't need more than 15min runtimes.

rcmike

iTrader: (40)

Thanks everyone !

prdmetalworks

Dont mean to hyjack, but I have a similar question & it sounds like you guys know what you are talking about. I am going to be running an RC8Te on a med / large track with about a 40 -42 second lap time. It seems most of the elec. truggy guys are having a hard time making a 15 minute main. I don't know what mah their packs are, but every one of them is running a 2000kv Tekin with an RX8 and 4S packs.
I was going to go with this setup until I starting reading all the threads in this forum, now I'm thinking 1550kv on 6S? I'm pretty sure this will give me a longer & cooler run, but how will it compare to the speed & power of the 2000 / 4S setups. I have driven a couple of these trucks & it seems like the torque & speed is perfectly suited to the track, so I would like it to be pretty close in comparison - just want more run time, as it seems the guys that do make the 15 are taking it easy for the last 5 minutes.
If I do go with 6S, what mah?

bohdi

iTrader: (12)

I ran the RC8T on 1550 and 5s. I could do 15 minutes easliy. I burned 3800mah in a 15 minute main and I have a 5000mah batt. I a pretty sure I could do 16 but I would never run a battery past 80%
16/50 geared

Edumakated

iTrader: (19)

If you are running 15 minute mains with a truggy, you definitely want to go 5s or 6s. I have run both in my truggy and 15 minutes is easy. Truggies burn way more juice typically than a buggy, so making 15 on 4s is going to be challenge unless you run at least a 6000mah pak.

You can make 15 minutes on a 5s 5000 pack with enough room for a minute or two or warm up laps. I make 15 easily with a 6s/1350 in my truggy with a 4000mah pack. Typically only burn about 3000-3300.

Both are 5s/1550 and 6s/1350 are going to have the same speed roughly as a 4s/2000-2200 setup. Remember Voltgage X Motor KV = RPM

prdmetalworks

Thanks guys, I think I will go 1350kv on 6S