Braking Question(s)

[lolelectronics]

Hey gang. Longtime lurker here,

I've been chugging around town on my board without any real problems, but I'm eager to get some second opinions on improved braking power (without having to add mechanical brakes). There are some pretty wicked hills around my city, and going down them can be hit or miss as to whether the ESC will just give out on motor braking entirely, which is a dangerous scare to say the least. (I'm using the Hobbywing 150A EZRUN, with 50-75% braking. I've alternated between the two values, but I can't remember what it's set at now. I've tried 25%, but that wasn't enough to slow me down on hills).

I've spent a few days searching every keyphrase I can think of that relates to braking, but I'm not sure I've found the kind of information I'm looking for. I have, however, read posts where some others had the same problem with their ESC failing due to too much downhill braking. What exactly is happening there? Does anyone have an ESC that DOESNT fail on them regardless of how much downhill braking you throw at it, and/or what's your setup like?

I'm currently rolling with a single 63mm motor, but I'm considering adding a second one in a diagonal setup after reading recommendations that dual motors provide better braking power. I'm thinking 2x turnigy 190kv's on a 6s 10Ah battery. I like everything about my Hobbywing ESC except for this braking issue. Do I need to get different ESCs? Will two motors make a noticeable difference?

Thanks—I appreciate any advice you can throw at me.

 

[onloop]

Two motors makes your brakes twice as good. The gearing ratio will also affect the strength of your brakes. More reduction equals less brake force being transferred to the wheel.

There are also other variables that alter brake performance.
- rider weight
- wheel size

 

[torqueboards]

I would try a higher percentage for your brakes. I ride in San Francisco and I've tried a single motor and brakes definetly aren't that great because of the steep incline. Although, they work dual motors is definetly much better. If I had mechanical brakes sure it wouldn't be an issue.

I would recommend a dual motor setup and/or you can do what beto_pty has done on this forum and setup a band brake on a servo. You can still control it by your controller. I imagine it works really well.

 

[lolelectronics]

Excellent. I appreciate the responses! I'll definitely go the dual motor route, then.

I would try a higher percentage for your brakes. I ride in San Francisco and I've tried a single motor and brakes definetly aren't that great because of the steep incline.

I've had brakes fail at all levels: 50, 75 and 100%. The longer I brake on a steep incline the more likely it is to cut out on me. The past few times it's happened, I've checked to see if the ESC or motor was unusually hot and as far as I can tell, neither were. I'd still love to know what causes this failure and/or if it doesn't happen on some other ESCs or if it happens to everybody.

I would recommend a dual motor setup and/or you can do what beto_pty has done on this forum and setup a band brake on a servo. You can still control it by your controller. I imagine it works really well.

I had disc brakes on my board in the past, but I removed them until I have more time to rework how they attach. I had a twig get caught in one of the calipers which not only ground me to a halt but also ground the wheel flat from locking up. Once I can build a decent guard piece I'll probably put them back on, they were great.

 

[made_in_the_alps_legacy]

problem with their ESC failing due to too much downhill braking. What exactly is happening there? Does anyone have an ESC that DOESNT fail on them regardless of how much downhill braking you throw at it, and/or what's your setup like?.

hummm... weird... living in the alps, I can brake 7kms long with -500m denivelation, 1WD, Hobbywing 150A ESC, I faced heat built up and brought the ESC fan back only for this reason, I never had ESC cut-off during downhill, maybe thanks to my 5.5" wheels ?
Are you sure it's not the "high temp" cut off protection kikcking in ?

 

[lolelectronics]

hummm... weird... living in the alps, I can brake 7kms long with -500m denivelation, 1WD, Hobbywing 150A ESC, I faced heat built up and brought the ESC fan back only for this reason, I never had ESC cut-off during downhill, maybe thanks to my 5.5" wheels ?
Are you sure it's not the "high temp" cut off protection kikcking in ?

That's a good question. My board is in a state of disarray at the moment, but I want to say that I tested it with the high temp cutoff option turned off, too, and had the same results. I can't say for sure, though. I need to get this guy back together so I can find out.

 

[made_in_the_alps_legacy]

OK i think onloop's comment regarding wheel size above is a signifiant factor,
meaning for a given braking force, motor has to provide much more torque when wheels are smaller