DR10 Battery Sizing; Is My Logic Way Off?

[morrisey0]

I am getting around to ordering final components for my DR10 kit, and I am on batteries now. Is this modern age of 6000mah+ lipos, it seems like a lot of people are running this type of 2S in their no prep cars. But when I think of 1:1 drag cars, those guys run fuel cells big enough to get them to the end of the track and back, like 2-3 gallon tanks. So if weight is so critical, am I wrong to think about looking at low mah, high C packs? Like 1000 - 2000mah? Just from quick looking, 1500 2S's are in the ballpark of 1/3 the weight of a 5000 (3oz vs 9oz). Of course for testing purposing and running for S&Gs, a big pack will probably be in the car, but for actual racing, I am thinking about just having multiple low mah packs on hand, and swapping out after every one or two races. Heck, my race day probably won't be more than 1-2 races for awhile anyway.

EDIT: Sorry, wrong board. I can't see a way to delete it though. Please feel free to move or delete. I would if I knew how.

[juicedcoupe]

Are the really high C rated packs available in lower mah?

I see 4000 mah packs at 220C. I don't see anything like that in smaller packs.

Just thinking that the smaller cells may not be able to move that much current.



Can't compare to a fuel cell in a car. They can have a -12 outlet on the tank, regardless if it's one gallon or thirty.

[coxbros1]

above statement is accurate on the -12 line....i have tried a 1500mah 3s in a RJSpeed rail with blistering results....too much power in fact....it got sideways halfway thru a speed run and slammed into a curb destroying the car...only parts i still have left are the battery and wing, so my opinion about u trying the smaller packs seems ok...but i am not a rc no/prep racer. i am sure "kidagain can shed some light on the subject

[RC10th]

Weight = traction but at what point does it become counter productive. Also higher Mah and C rating means a higher voltage during discharge. I'm sure those guys have done extensive testing.

[coxbros1]

i concur with RC10th....whatever is in their cars now are the fastest...period!

[Basher67]

First, you have to understand the "c rating" is BS. It is a made up advertised rating. No prep drag cars are a much different animal than a promod. You're trying to send what is essentially a 5lb. short course truck down the track. It takes a ton of current. I have seen all types of batteries show their shortcomings. I run a Reedy zapper 6100 mah shorty. This battery is only "rated" at 85c. I'm running a Tekin Rx8 and a 2.5t dragmaster motor. I pull a ton of current out of that battery, as you can imagine. I keep careful watch over the stability of the current draw with the data logging in the esc. You need a good amount of mah and low internal resistance to get a battery that will consistently perform in a no prep car. I've been happy with my Reedy, but the next battery I will be buying is an SMC drag specific battery. Very high quality battery and can't beat the price. Battery weight is a consideration, but should not be the deciding factor.

[morrisey0]

All great tips and advice. I thank you guys! I'll start off with my already-owned 5000mah cells, and work up from there. Thanks again!

[Basher67]

what esc/motor are you going to start with?

[morrisey0]

what esc/motor are you going to start with?

Right now I have a Hobbywing EZRun 3660 4000kv with XR10 Pro 160a. Just a starter kit.

[KidAgain]

iP 6200 shorty 2s 120c HV charged to 8.44v or Maxamps 4750 shorty 175c 2s is what I run in my outlaw car and both work great...........

[GoMachV]

If the C ratings are to be trusted, and using some numbers posted above, that means the 6200 (6.2a) at 120c would be capable of a 744a discharge rate. The 4750 (4.75a) at 175c would be capable of a 831a discharge rate. This season we ran gens ace redline shortys which are 6000mah (6a) at 130a, which equates to 780a discharge. All in the same ball park.

As you can see, the capacity of the pack means a lot when you are looking at how it relates to the C rating. Say you had a 100c pack but it was only a 2000mah, your down to a 200a discharge capability. Take your 5000mah pack, I’d guess a 85c rating, making it around 425a discharge.

Again, this only works if the manufacturers numbers can be trusted- and they can’t. Yours will be fine for learning with that combo I’m sure, but when you are ready to step up just buy a quality pack with a name brand.

[KidAgain]

If the C ratings are to be trusted, and using some numbers posted above, that means the 6200 (6.2a) at 120c would be capable of a 744a discharge rate. The 4750 (4.75a) at 175c would be capable of a 831a discharge rate. This season we ran gens ace redline shortys which are 6000mah (6a) at 130a, which equates to 780a discharge. All in the same ball park.

As you can see, the capacity of the pack means a lot when you are looking at how it relates to the C rating. Say you had a 100c pack but it was only a 2000mah, your down to a 200a discharge capability. Take your 5000mah pack, I’d guess a 85c rating, making it around 425a discharge.

Again, this only works if the manufacturers numbers can be trusted- and they can’t. Yours will be fine for learning with that combo I’m sure, but when you are ready to step up just buy a quality pack with a name brand.

Nice breakdown bud thanks.........................