mah and runtime for racing 1/8 Buggy?
 

Looking for info on what kind of racing run time people who are racing brushless 1/8 buggys get allong with their setup info. I am converting one right now and am trying to decide how big of a battery I should plan for needing in the battery tray.

The local track runs 20 minute mains on 1/8 buggies. Any idea what kind of battery size I would need to get through a 20 miute race?

Im going to be running a Maxtrix w a Mamba maxx on 4 or 5s. I have options as far as motors go so I can pretty much set it up for whatever KV in need. I have a 1700 kv, 2000kv and 2200kv motors.

Also, what kind of speeds should I be targeting for a rather large track. (250ft x 125ft) and a smaller indoor track (125 x 65)

Edit: Correction... Local track runs 15 minute mains, not 20.

The place I race at also has 15 minute 1/8 buggy mains. I was able to go the distance with my Enerland / Poly RC 5000mAH 4S Li-Po. That is on a Neu 1512 2.5D and a Mamba Max ESC. When I charged up the battery about a week later, I put less than 4AH back in (3700mAH if I remember correctly).

I like the single battery setup to try and keep things light. Of course dual 8AH Maxamps is a great deal, but you do pay a penalty in weight.

The track I go to is a bit on the small side and with my original setup of about 39MPH top speed, I never maxed it out. I think I am about 35MPH right now and that is still plenty for the track. It doesn't seem like over 40MPH does much good unless you have extremely long straight-aways.

Matt

I'm also planning on running a single pack. I have an enerland 4350mah 5s pack that I was planning on running. According to my estimates I figured that that should be just about enough, but wasn't sure. I am going to buy a 2nd pack and was thinking that I would go w/ the 5000mah, but didn't want to take the extra weight if I didnt need to.

I am guessing that the 5s pack I have will be more voltage than I really need, but I am going to be running a slightly lower kv motor than you so the speeds should be around the same as yours. Maybe slightly higher.

Sounds like the 4350mah will be really close. I guess I'll have to take it out for a practice run and time it to see how long it runs before I buy another pack.

You may consider like a 6000 mah pack. That may get you in the area you need.

Unless your system is much less efficient than mine, you should have no problem making the 15 minutes.

You 5S pack has more energy storage than my 4S pack.

3.7V/cell *4 = 14.8V, 14.8V * 5AH = 74 Watt Hours
3,7V/cell *5 = 18.5, 18.5 * 4.35AH = 80.5 Watt Hours

For the comparison to work, you need to have the same amount of power draw. Since you are using a lower KV motor, that seems reasonable as long as it is geared right.

Matt

Edit: Oh ya, that is where I saw the picture of the big 5s Enerland cell...... in your 1/8 Buggy w/ a Outrunner Motor thread. I love my Enerland 4S pack. They just get warm after 15 minutes of racing.

That makes sense to me. I think I will be OK with this also, but I'm still gonna take it out for a couple test packs before buying another pack, just to make sure. Just a little to close for me to be comfortable without real world testing.

Yea, that outrunner is just an experiment. Not sure how its gonna work. Ita a 2093kv motor, but that is an unloaded value so I am estimating it will be more like 1800 or so loaded. Plus its a much smaller motor than the Nue 1512. If the outrunner doesnt work out, I have a Neu 1515-2.5D that will be going in. Thats a 1700kv motor. but slightly longer than your 1512. Im estimating that either of these will have me right around 40-43. Probably a little hot for a indoor track, but it will be perfect for the outdoor track in the spring.

That sounds like a fairly large track so your runtime will be significantly less than a smaller track. You'll most likely have to test your buggy with the 4350mah 5s pack to see how long you can run before it dumps.
I agree with CC, 5000Ah may get you through 15 minutes on a short track but you'll most likely need at least 6Ah for a large track.

Keep us updated as I am very interested in your results.

Thanks

BTW
What kind of buggies are you guys running?

I'm doing a Cen Matrix. Have an Ofna MBX converted, but its not race worthy. Thing breaks every time it runs. Thats why I went w/ the Matrix. Its the beafyest buggy Ive seen.:dft009:

[So you mean the average amp draw over a timed race will be higher on a large track vs a small track? Not sure I understand why. I am thinking that the highest amp draw is the first few seconds after hitting the throttle. And then under hard braking. I would think that there would be more frequent throttle stabbing and hard braking on a small track vs a large track.

What am I missing?