Amp draw and small batteries

[beomagi]

Hi all. I've been digging around and noticed a lot of crawlers use small packs - even small 2/3a nimh cells normally found on 1/18 scale RCs.

Are crawler/scale packs normally small because they don't really draw a lot of amps? Anyone ever plotted amp draw over a session of crawling? What sort of runtime do you get with these small packs (1000-2000mah)?

[SilmarilS]

1 to 10 amps draw is pretty common on a crawler.. some spikes around 20A with very good motors.

So a small 1000mAh with 20C is adequate.

[JohnRobHolmes]

I typically get an hour or better on a 8mph scx10 and 1300mah 3s. If I drive like an asshole with a fast brushless system that clocks 20mph, 30 minutes.


The highest peak I have logged in a crawler is 85 amps in a bind. On the average, it is just a few amps. In fact, most of the energy in a crawling speed rig goes to the servo and not the motor.

[axial 4x4 crawler]

On my custom crawler, I use a 1,300mah 3s lipo and no I haven't ran it yet but I can estimate it to have at least an hour or so..maybe more. Now on my other rigs, like a 5000mah 2s or whatever..hell I get a very long run time depending on the rig and the set-up.

[Docwolf]

I get like 5 hours on my 3s 5000mah with a 35t motor.

[beomagi]

Thanks Silmarils, John, axial4x4, Doc.

I generally use the axles to make higher speed buggies, not crawlers, so I can use this as an estimate. I have been thinking about going with a legitimate crawler on some bully axles I picked up though. I found some interesting batteries while digging around, and was wondering if they would work.

These are quite recent - "sony vtc5" and appear to be a hit in the electronic cigarette community, and I've seen them popping up on e-bike/e-scooter areas too.

Here's the first hit off amazon for it - Amazon.com: Sony 18650 30a Vtc5 2600mah Us18650vtc5 Two High Drain Batteries: Home Improvement

It's an 18650 (think small a123 cell) with LiMn chemistry. 2600mAh, and capable of 30 amps. Given the size and weight, I'm thinking it should be pretty good for a crawler. I picked up 4 to test in an rc18t build I did years ago. Figure I can try it out on larger scale if it works well.

Size comparison (mm):
18650 - 18*65
2/3A - 16.8*28.7
2s 2/3A - 16.8*57.4
SC - 23.1*43.2