Disappointing torque and speed

ESK8 Electronics
1

Hi guys. Just finishing up my build. Had a few test rides. I have:

Turning sk3-6354 motor 260kv 8s3p (hodgepodge of free 18650 batteries) Entertion VESC fw 2.18 Sparkless 120a on/off switch Torqueboards mini 2.4 Ghz remote controller Enertion trucks and pulley 83mm wheels

The problem is I can’t get the torque everyone talks about, nor the top end. I can get up to about 15 mph. This seems very low. One calculator said I should get up to 33 mph (no load). With load, I should be north of 25 mph.

I’ll post my VESC settings when I can, but anything I should zoom in on? I’d like to enjoy it without investing more $$$ at this time.

I know the batteries could be questionable. If I replace them, what should I consider for about 10-12 mile range in an 8s set up?

2

What is your gearing?

3

Also http://calc.esk8.it Calculate estimated speed

4

You should all ready be around the 10 mile mark with the 8s3p. I’m sure the torque has to do with either the battery no supplying enough amps or some VESC settings are wrong.

5

Yeah 8s3p is not going to get you enough power. Figure you are going to get a max of 5 amps per cell, at 8s3p that is less than 500 watts.

6

I kinda semi disagree I’m running a 6s lipo and I got more than enough torque. Don’t get me wrong it’s not a smooth start but I can go up some long steep hills.

But I’m sure you know a bit more about eboads then me… just my opinion

Edit: unless lipo’s are different then liion

7

Maybe switching to lipos would be the easy way to go or add to the current pack

8

Sounds like OP is using recycled li-ion 18650’s, do you have any experience with these?

1 Like
9

I have only used lipo so far. I think the batteries ‘life’ has expired, not the 8s part

10

Think the root cuase is right here

2 Likes
11

Well even fresh 5amp max cells will feel sluggish at 8s3p…8s10p is a completely different story. :grin:

12

chaka is saying that the 18650’s have way too low of a discharge rate because they’re most likely laptop batteries. Low discharge rate leads to underwhelming wattage.

13

Okay, I’ll say your right. You have more experience, I was just providing another opinion.

Edit: I didn’t know there was any difference between lipo and liion, with the discharge! Learn something new everyday.

14

I wanted to provide a complete picture with full disclosure. That’s why I mentioned the mix of li-ion batteries. However, the same lot supplied batteries to a different custom 6s2p using an RC ESC. It is torquey and faaaast.

When I can, I’ll post BLDC tools screens. I’m hoping some adjustments can help.

15

If I do replace the batteries, any suggestions on a lipo for the same 8s set up? I’ve invested in a 33.6 charger and understand my motor can’t go to 10s due to high kv?

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2x 4s lipo in series.

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Here are my current VESC settings

BLDC_Tool2.png1547×817 108 KB
BLDC_Tool3.png1547×817 97.8 KB
BLDC_Tool66.png1547×817 116 KB

18

What about mAh? 5000, 8000, 10,000? How about two of these?

ZIPPY Flightmax 8000mAh 4S1P 30C http://www.hobbyking.com/hobbyking/store/__16226__ZIPPY_Flightmax_8000mAh_4S1P_30C.html

1 Like
19

The more the mAh the more the range, but also the more the price. They would work! I would have some VESC experts look at ur settings. Also if u go with the batteries don’t forget a balance charger.

20

Also crank up your maximum input voltage to 53V