Is the last 20-50% of your battery pretty useless? Or have you just kept the thing fully charged all the time?
I’ve been thinking a bit lately how a battery for a race build would play out. Hypothetically, say 10 laps on a .5mi track, routinely pulling many amps. By the easy numbers, 9ah should get you around 5mi @ 40-50wh/mi avg (yeah, I know that’s unlikely in this setting); but at what point in the cycle does pulling 150amps from your battery cause it to hit cutoff voltage? If you are able to limit your draw somehow to just above cutoff, how much do you have to sacrifice, and how early in the battery cycle do you have to do it?
Have you looked into lipos at all for their much higher discharge rates? They tend to experience much less sag because of this. Comparing 12S 18ah li-ions(30Q)/60c lipos/100c graphene lipos, I expect there would be a pretty significant reduction in sag at each step.
I don’t have enough data to know if this even backs up what I said, but as an example, I only see 2v of sag @ 44v (<50% battery) pulling around 90A on my 12S 18ah 60c lipo setup.
What @ryend is saying Is that you won’t brake the world record with li-ons
The amount of extra amps you have to draw to get from 50-80mph is a massive amount where you won’t be able to get there because your battery voltage will practically instantly hit voltage cutoff
On the other hand if you could draw more amps (lipos) then your voltage decrease is going to be much slower
@professor_shartsis would you like to do some explaining here (you are limited to 500 words)
Well I know that on a 12s4p 30q I can pull almost 100A and that will sag a full 50.4v pack down to 39v in approximately 4 seconds (no exaggeration). At this point the vesc starts to limit power to manage the battery levels.
@mackann currently has 12s6p 30q so I would assume pulling 150A would have exactly the same effect.
Any bottlenecking the delivery system from source to load is a mistake.
Pinging your watt ceiling is a mistake
Anything but the correct gearing for your target speed is a mistake.
Plastic gears may work on your Barbie Lambo but in no way should be on a phorarri.
Taking an untested rig into the unknown is a mistake and is also negligible.
Iv been wrong before. But im here to walk and talk about this. . #vid&radar
Love Moe,[quote=“Trampa, post:156, topic:17722”]
We do not want our gear to be used at such speeds
[/quote]
Smart, however
Would like to see @Trampa with a vested interest in short track. Both dirt and street. A great platform for truck and teck development.
my only comment is be careful how quickly you release the throttle at the end because the wind force at those speeds might be enough to literally blow you off your board with a sudden removal of all vehicle thrust.
About the gears you are wrong. Its one motor steel gear and the plastic, however very strong one. Its been rided on high performance board for a year now without any visible wear.
But im not gonna argue against you because I know you are the best on this.
Il just order a speed gun and we will se what happens.
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