Limitless 3 Amps vs 84 grams

[Danyrc]

I have three high flow fans (two on the motor, one on the ESC) installed on my Limitless. Between all they roughly draw around 3 Amps of current. When running 6s I have two options for give them power, first one is using a DC buck converter (capable of supplying 4A) that weights 52g, second option is using a dedicated 3s lipo weighing 136g. What do you think would be a better option for speedruns, loosing 3A from your main pack or adding 84g of weight to your rig? Which option would you choose and why?

 

[Edough13]

I'd use the separate pack 84g is nothing that's going to make a huge difference. I just added 42g with going all Basherqueen CF over stock plastic and aluminum and I doubt it's going to effect anything at all. As it is these cars power to weight ratio is way off as they are so light for the amount of power.

 

[LibertyMKiii]

There is a balance between preventative aids and ultimate performance/weight/power considerations.

First you may consider that the worlds fastest do not run a fan on the motor at all. They all mention that during the 8 second run the motor performs fine and only saturates/heat soaks the motor after the run. (you can see this on your ESC data logs also)

With that said damage could occur and we don't all have the budget to replace motors and ESCs often like Raz.

My preference would be a dedicated small separate LiPo for simplicity and less failure points. Because it wouldn't need high amperage maybe you could find a lighter battery that is Lithium ion or another option?

 

[ABabyEater]

I'd run an extra lipo. Looking at switching up my layout to run a lipo for all receiver and servo power as well

 

[Danyrc]

Thanks all for your responses. Here you have both contenders

 

[K-BASH]

My opinion is with a car that has a power to weight ratio close to 1 horsepower per pound.a few extra grams on keeping system safe on a warmer than normal day is worth it.id make a decision on ambit temp an on how hot of a setup id be running that day,I'd have temp gun in one hand and pulled trigger in other,
I'd setup for both options

My opinion is with a car that has a power to weight ratio close to 1 horsepower per pound.a few extra grams on keeping system safe on a warmer than normal day is worth it.id make a decision on ambit temp an on how hot of a setup id be running that day,I'd have temp gun in one hand and pulled trigger in other,
I'd setup for both options

 

[rotauq]

If it needs that much cooling, your pushing it too hard
I am in luck that the XLX2 doesn't need improved cooling at all. I do run a 1A fan on the motor at only 5v via the receiver. But it's merely there to cool down the motor between runs than to cool it on the run.

A very small (drone) ubec can deliver up to 5A (5v-12v) with less than 10grams. I do use them for leds and such. I mostly start with an external battery and end up using a ubec on the main leads so (so equal drain on both batteries in my case) If a few amps is hurting your top speed, you are running the wrong battery/ies

 

[Danyrc]

If it needs that much cooling, your pushing it too hard
I am in luck that the XLX2 doesn't need improved cooling at all. I do run a 1A fan on the motor at only 5v via the receiver. But it's merely there to cool down the motor between runs than to cool it on the run.

A very small (drone) ubec can deliver up to 5A (5v-12v) with less than 10grams. I do use them for leds and such. I mostly start with an external battery and end up using a ubec on the main leads so (so equal drain on both batteries in my case) If a few amps is hurting your top speed, you are running the wrong battery/ies

Thanks @rotauq . Actually the car is not running hot at all is just that those are the fans I made and installed since the beginning and as @LibertyMKiii said I prefer to be cautious and be on the safe zone having an over exaggerated cooling system than having to buy another Castle combo.
Being an absolute illiterate about electronic and electricity, that DC buck converter was the only one I could find capable of delivering more than 3A at 12V, I tried other less heavier than this one but even though they were rated at 3A, all of them failed to give that current. Could you please give me a link of one of those drone ubecs?

 

[rotauq]

Thanks @rotauq . Actually the car is not running hot at all is just that those are the fans I made and installed since the beginning and as @LibertyMKiii said I prefer to be cautious and be on the safe zone having an over exaggerated cooling system than having to buy another Castle combo.
Being an absolute illiterate about electronic and electricity, that DC buck converter was the only one I could find capable of delivering more than 3A at 12V, I tried other less heavier than this one but even though they were rated at 3A, all of them failed to give that current. Could you please give me a link of one of those drone ubecs?

Couldn't find the exact 5A one i am using, but here is a 8S 12v 3A version. At 0.8gr and weight concerns you could also fit two of these in there.
The golden rule here is, the fancier they look the crappier they are. You really just want the ones with just solder points, no cables attached.

I would say, save weight with one fan less on the motor (obviously measure temps for a bit). Any fan pulling 1A is a ridiculous (good) fan already. Running 2 is overkill unless they are cheap 0.2A fans

 

[Danyrc]

Couldn't find the exact 5A one i am using, but here is a 8S 12v 3A version. At 0.8gr and weight concerns you could also fit two of these in there.
The golden rule here is, the fancier they look the crappier they are. You really just want the ones with just solder points, no cables attached.

I would say, save weight with one fan less on the motor (obviously measure temps for a bit). Any fan pulling 1A is a ridiculous (good) fan already. Running 2 is overkill unless they are cheap 0.2A fans

Thank you. These are the fans I'm using, Sunon fan they actually draw 0.9A but can give a flow of 31.3CFM. Lol, I know they are overkill

 

[rotauq]

Thank you. These are the fans I'm using, Sunon fan they actually draw 0.9A but can give a flow of 31.3CFM. Lol, I know they are overkill

Lol, 3x 31CFM in that tiny limitless body. Where does all that air come from and go?

I am running a single Delta PFB0412EHN 22CFM at my motor. And it doesn't get hot at all. Even after 2x 500A+ pulls i never measured more than 60C (@20C ambient temperature)