5S or 4S

[tom255]

I bought BK9920 and 9XL motor. I thought before that i build Savage but i got good ofer for my Savage and sold it and bought HB LSP. So i need ur suggestion.

I thought to use 8000mah lipo 4S but i think how it perform on LSP i want archive at least 35-40 mph for my local track its enough.
2 options what u prefer? Honestly i want use 4S its cheaper and lighter

1. 4S2P 8000mah lipo gear higher 9XL to archive 35-40
2. 5S2P 8000mah lipo gear normal 9XL to archive 35-40

I want to know which option more harmful in thermaling spot, i suggest with lower voltage its draw more amps its means more heat on motor

What you think can i use 1st its cheaper for me becouse i want to use spare Lipo so it makes more than $100 difference if i take additional warranty.

I run a 9xl on 5s 4000's in my converted LSP pro. I am very happy with the speed and torque. I am actually going to get a 4s 8000 and a Neu 1512 soon, 5s is a little much for the track IMO...

I race and bash, so if you race I would get 4s, if you bash I would get 5s.

Bye :018:

Also my 9xl is geared 15/46 for 5s; a 9xl with 4s I would gear it 18/46 or so...

[hyperasus]

If you have a choice, the higher the voltage the better. I'd got with 5s.

[Mike.L]

Originally Posted by hyperasus

If you have a choice, the higher the voltage the better. I'd got with 5s.

For the track....?you dont want to mutch power for a track trust me. 4s sould be tight.

[hyperasus]

Even so. Woudn't it be better to go higher cell and lower kv motor? Same power with better runtimes and cooler ecs and motor.

[pinolelst]

Originally Posted by hyperasus

Even so. Woudn't it be better to go higher cell and lower kv motor? Same power with better runtimes and cooler ecs and motor.

weight might be a factor...
pinolelst

[starscream]

With the 9920 and 9XL,
Personally,
I would gear down a touch and run 5S.

[tom255]

Need to find Gold SPOT.
I know in my track 40+mph its realy usless
What u all think if i gear it same high as 4S but use 5S battery with reduced trottle travel, lets tell ~ to 80%, i mean in that case if i want to use 4S and 5S without messing with gears. If i will buy 4S and spare pack 5S
Can i get more runtime from 5S againtst 4S without thermal issue?
Realy i dont want to use any vents or something, its looks so ugly and 1 more moving element and weak point.
Why i am asking becouse i dont have any experince with brushless conversion and its my first build. Theory is one but practice can be other.
I am educated in electricity so i know what is this, its not new to me.
And i want to be sure with battery choise, because if i order Lipos from here and they are not cheap, import taxes and VAT add more 25% to battery.

cemetery gates u have similar setup what i want to build what is ur ESC and what runtime u get from yours 5S 4000 lipos? any temperatures will be helpful to understand which temperatures i can expect.

Here I am first guy who wants to build BL Tryggy my mates laught on me. I want kick some nitro asses. And my goal is not to do pit stops and win a time in outlaw calss so why i want to use high Ah battery.

[crazyjr]

I would think it would be better to gear for the speed you want on 5s, instead of running set speed for 4s and adding a cell and trimming down to 80%. the added gear would cause strain in the system and without full power to accelerate could cause overheat. Part throttle is the worst enemy of a brushless system and overgearing makes it worse. I'm still learning but i do know, from brushed racing, that you can't up the power and stick with the gearing from the lower power, bad things happen, trust me

as far as batteries i'd go with the maxamps 8000 because its not about the time its about the deliveryand with bigger density of power the better the batteries will handle the load, Besides 2 2s 2p batteries are lighter than 12 cells, by about 100 grams (maxamps 2s2p 8000 mah lipo, 370g. 6 cell NIMH 4400 maxamps pack 420g)

[hyperasus]

crazyjr is right. Running at part throttle is a very bad idea. 4s really isn't very much for a full size monster truck. In fact. If you have not bought the batteries yet....maybe even consider 6s. If you ran on 4000mah 5s or 6s you would be keeping weight down and efficiency up. Voltage is your friend and it will provide outstanding nitro slaying torque with very low temps and long runtimes. If you was trying to run a Mamba Max ecs then you are stuck with 4s. But with 9920... go for the gold man. Buy 2 4000mah 3s and a very low kv motor. Thats what I'd do anyways.

Another thing. I am just thinking outloud here so someone feel free to correct me if its a bad idea... It sounds like what you want is just enough speed but with very good runtimes. What about going 6s and an L sized can? On 6s it would still run very cool, provide plenty of power for the speeds you want, and provide much better runtimes then an XL motor.

[tom255]

I wrote before that i bought 9XL combo for Savage but plans is changed and bought HB LSP. Now i thinking...
And i thin i will stick for start on my 9XL
I still think L cans more for Buggy
Maybe go for A123 in 5S2P.
Main thing with lipos i dont like is, that they not last long, so many % of fail in my opinion. Even if u behave with them with care
So if i will buy lipo i am want for sure buy additional warranty but on fail returnig battery and replacing procedure realy complicated (u need to proov that u returning product under warranty they take again some money about 5% from paperwork) otherwise customs will shave me again 25% lipo cost. Redicilous.
But with A123 i can rebuild packs easier and replace damaged cells by self buying those from net even with price $16,5 per cell.
Anyway i have little bit time to think.
But couple thins i learned that u still recommend to go higher voltage i will gett better rinetimes becouse motor work more efficent.
And reduce throtle travel is bad idea (probably realy hard for ESC).

Thanks for suggestion

[tom255]

Hyperasus if i will buy 4000mah 3S lipos 10C and go in series like 6S keep in mind to gear it to 35-40mph
is 40Amps enough for 9XL? Or i should to buy higher Discharge rate battery
Can i expect any LVC?
Or Heat issues on 9XL and ESC
Damn i wish to see grpahs, what is difference between 5S and 6S

[neweuser]

Well, I run 4s in my maxx and it's fine. But I use a different motor. 5s is about the limit for the 9920. Personally, unless you have a long straight away on the track, doing more than 35 is pretty much useless. And yes, you would need an LVC, Mike sells the li saver for cars which is good. You could go with the A123 cells if it's better for you. Also, I would think 6s is going to be some weight...my 5s is pretty heavy, but they are also 8000mah.

[Serum]

Runtime on 5S would increase if geared for the same speed, go for 5S if you can swing it, and for the need for speed moments, you can gear her up a bit..

[luvsrc]

Dont worry too much about weight issues for the heavier the truck gives you more traction especially with brushless system due to instant power,it will dig in better in the ground.I just ordered 2 3s maxamps 8000mah, Iwill use it for bashing and racing for my e revo, my system is Hacker 9XL and MGM 24 160 controller.I used my 4s lipo on my track with my 9 XL, but I could have bought the 5s lipo which I think will be the sweet spot vs the 6 s lipo but i like power and speed for bashing, I just need to practise to drive it in our track for 6s lipo will be much harder to control, It is a matter of practise and throttle control and adjusting /tuning your truck. Remember Practise/Repetition is the Mother of all skills:027: