3s vs 6s Battery Capacity

[Eshubert]

I'm totally new to this. I have a Kraton 6s i run with a 15T pinion. I have four 3s 5000mAh 50C Spektrum batteries that work great and last about 15 min on 6s. The LVC kicks in on average cell V of 3.7-3.8V.

I of course want to lengthen the time of my runs. I'm looking for bigger batteries and better manufacturers.

Who are the best manufacturers of batteries? I see SMC, Turnigy, and gensacearespammers are pretty popular. Who do you guys like?

Why is it so hard to find a 6s battery at 10,000mAh and so easy to find 3s at 5,000mAh. Are 2 3s batteries at 5,000mAh equivalent to 1 6s battery at 10,000mAh? Is a single 6s battery going to last longer than 2 3s batteries on a run?

And just to add another layer what are your thoughts on hardcase vs softcase? is softcase just out of the question for bashing?

 

[ph47mf]

I run softcase in my 4s and it works, just make sure you strap it in nice and tight with no room for movement, my friend who was a bit careless last time we went out and his lipo was all puffed up. If the option is there, hardcase would be better.

 

[fpvmiller]

It's not hard to find 6s 10000mah lipos. It's just hard to find them in high C ratings.

When you series two 3s lipos you don't gain capacity you gain voltage. If you parallel two lipos together you gain capacity and remain at the same voltage.

 

[CrashBoom]

Generally speaking, it's better to get several lower capacity batteries and swap them. The weight of large batteries can causing handling problems and swapping batteries gives your electronics a chance to cool down.

When you run 2x3S batteries you are running them in series, so the voltage is additive but capacity is constant. 2x3s @ 5000mah are equivalent to 1x6s @ 5000mah.

Most of my batteries are soft case. Hard case might prevent minor punctures, but the walls are generally not very thick.

 

[Overpowerrc]

Running parallel 3s 5000mah would give you 3s 10000mah so there no easy way to get the best of both

 

[Eshubert]

Generally speaking, it's better to get several lower capacity batteries and swap them. The weight of large batteries can causing handling problems and swapping batteries gives your electronics a chance to cool down.

When you run 2x3S batteries you are running them in series, so the voltage is additive but capacity is constant. 2x3s @ 5000mah are equivalent to 1x6s @ 5000mah.

Most of my batteries are soft case. Hard case might prevent minor punctures, but the walls are generally not very thick.

Don't you mean the 2x3s in series @ 5000mAh is equivalent to 1x6s @ 10,000mAh?

 

[chevys10zr2003]

Don't you mean the 2x3s in series @ 5000mAh is equivalent to 1x6s @ 10,000mAh?

No. If you run (2) 3s, 5,000 mah batteries in series, it is the same as running (1) 6s, 5,000 mah battery. If you run (2) 3s, 5,000 mah batteries in parallel it is the same (1) 3s, 10,000 mah battery. Neither scenario will double the voltage AND double the capacity.

 

[CrashBoom]

Don't you mean the 2x3s in series @ 5000mAh is equivalent to 1x6s @ 10,000mAh?

I do not. In series, voltage adds up but capacity does not.

 

[Eshubert]

No. If you run (2) 3s, 5,000 mah batteries in series, it is the same as running (1) 6s, 5,000 mah battery. If you run (2) 3s, 5,000 mah batteries in parallel it is the same (1) 3s, 10,000 mah battery. Neither scenario will double the voltage AND double the capacity.

Thank you for this. I hate to admit I'm an electrical engineer and I wasn't thinking about this right. It's all about Watt Hours when it comes to batteries. 11.1V (3S) * 5000mAh * 2 = 22.2V (6S) * 5000mAh = 111Wh

Any feedback on which battery manufacturers you like the most?

I do not. In series, voltage adds up but capacity does not.

Got it. Which battery manufacturers do you like the most?

 

[CrashBoom]

Which battery manufacturers do you like the most?

Lately I've been buying China Hobby Line, but I also have HRB, SMC, Ovonic and Goldbat. I do think the China Hobby Line batteries have the most punch and I'll most likely be sticking with those going forward. That being said, I wouldn't classify the other brands I own as overtly "bad".

 

[TooTall]

Lately I've been buying China Hobby Line, but I also have HRB, SMC, Ovonic and Goldbat. I do think the China Hobby Line batteries have the most punch and I'll most likely be sticking with those going forward. That being said, I wouldn't classify the other brands I own as overtly "bad".

CHL are very good batts and reasonably priced.

 

[jkflow]

Hate to bust everyone's enthusiasm in this thread, it's all good info but won't get you a second longer runtime based on your problem.
You are not hitting LVC at 3.8V, you are simply overheating the ESC. If you can cycle power and run again you have a thermal problem.

Gear down or increase your cooling capacity on your ESC, drive slower and less acceleration.

If you are fairly new to this, check your bearings and anything potentially binding in your drive train, you should not have any grinding in the bearings.
That is the most common issue.

LVC hits around 3.3V and will damage your Lipo's i.e. you never want to hit LVC. LVC does not neceassrily allow for a reset or will quickly activate again, that is how you know if its a thermal issue or LVC.

Note: If your ESC overheats my guess is that you are getting critical on the motor. You never want to go beyond ~ 180F or you will destroy it rather quickly.

get yourself a cheap temp gun for checks in the field until you are comfortable.

 

[Eshubert]

@jkflow

What size pinion are you running on your kraton 6s? I have a temp gun and i'll check it out next time it does this. Are there any different flashes or beeps for LVC cutoff vs overheating on the BLX185?

you are correct. 1st time it did this, i turned it off and back on again and was able to get a few more minutes of run time. next time i just stopped and put it on the charger to check the voltages. i'll go double check the drive train too.

 

[Knxwledge]

Lately I've been buying China Hobby Line, but I also have HRB, SMC, Ovonic and Goldbat. I do think the China Hobby Line batteries have the most punch and I'll most likely be sticking with those going forward. That being said, I wouldn't classify the other brands I own as overtly "bad".

Which one are you running? The Black Series or the G Plus?

 

[CrashBoom]

Which one are you running? The Black Series or the G Plus?

G Plus. I have a 2x3s 70C pair and a 1x6s 55C.

 

[Knxwledge]

G Plus. I have a 2x3s 70C pair and a 1x6s 55C.

Thanks. I noticed that the max charge rate is 5C. Are those safe?

 

[CrashBoom]

Thanks. I noticed that the max charge rate is 5C. Are those safe?

I always charge at 1C regardless of the manufacturer rates, so I can't say. Better safe than sorry.

 

[jkflow]

@Eshubert Kraton on grass here in Florida is a 13T event for 'high speed' bashing, with jumps and cooldowns I can do 15T on 6S.
I switched over to a Max6/4985 combo but I get about the same speed performance before that one overheats.

Experimenting now with better ESC fans but had no chance of trying due to weather. My bash spot is currently under water due to the tropical storm, should be better later in the week.

 

[rflx]

Hate to bust everyone's enthusiasm in this thread, it's all good info but won't get you a second longer runtime based on your problem.
You are not hitting LVC at 3.8V, you are simply overheating the ESC. If you can cycle power and run again you have a thermal problem.

Gear down or increase your cooling capacity on your ESC, drive slower and less acceleration.

If you are fairly new to this, check your bearings and anything potentially binding in your drive train, you should not have any grinding in the bearings.
That is the most common issue.

LVC hits around 3.3V and will damage your Lipo's i.e. you never want to hit LVC. LVC does not neceassrily allow for a reset or will quickly activate again, that is how you know if its a thermal issue or LVC.

Note: If your ESC overheats my guess is that you are getting critical on the motor. You never want to go beyond ~ 180F or you will destroy it rather quickly.

get yourself a cheap temp gun for checks in the field until you are comfortable.

If I hit LVC on the BLX ESC, go home and connect the charger, then the Cells will be at 3.7 to 3.8 Volts. For my Max8 (set to high LVC) it's something like 3.65V. I'm sure I would get lower readings if I tested the voltage right after removing the pack, but still. It might be a problem with some ESCs, but in general hitting LVC should not damage Lipos.

I agree that being able to drive for multiple minutes after turning the ESC back on is a little strange. But that also shouldn't work if the ESC is too hot, right?

 

[Eshubert]

If I hit LVC on the BLX ESC, go home and connect the charger, then the Cells will be at 3.7 to 3.8 Volts. For my Max8 (set to high LVC) it's something like 3.65V. I'm sure I would get lower readings if I tested the voltage right after removing the pack, but still. It might be a problem with some ESCs, but in general hitting LVC should not damage Lipos.

I agree that being able to drive for multiple minutes after turning the ESC back on is a little strange. But that also shouldn't work if the ESC is too hot, right?

I'm reading more about this and it could be heat or voltage droop. I wish the ESC was smarter and would tell me somehow. The voltage droop at high current could be triggering the LVC cut off. Then you turn it off and on again and the battery is fine until it hits the cutoff again. I would rather be safe than sorry so i'll look into adding fans to the motor and going to a lower pinion. I'd love the batteries to last forever but it seems like LVC in the 3.4-3.8V range is pretty normal and maybe this ESC is just cutting out at 3.7-3.8V. i'll try experimenting with 50% throttle run until ESC shuts off and see if the cells go lower in voltage.