Drive System Advice

Hi,


My proposed drive system, but before I pull the trigger, I've probably
overlooked something. So was hoping for some advice before hand.


Motors
-> Electric E scooter 36 volt 1000 watt Motor chain drive Quantity: 2
Attachment 6523


ESC
-> RageBridge 2 or Sabertooth Dual 32A Motor Controller Quantity: 1


Wheels
-> 10" Yellow Puncture Burst Proof Solid Rubber Sack Truck Trolley Wheel & Axle Quantity: 4
Link


Tx & Rx
-> HobbyKing HK6S 2.4Ghz FHSS 6Ch Tx & Rx (White) (Mode 1) Quantity: 1
Link


Batteries
-> Turnigy nano-tech 5000mah 5S 35~70C Lipo Pack Quantity: 2
Link


Charger
-> Turnigy TQ4 4x6S Lithium Polymer Battery Pack Charger Quantity: 1
Link




I'm aware chains and sprockets will be needed, but I was hoping to sort
this out little later down the line.

Initially I was thinking of 4 motors, but then i would also need 2 ESC, so i thought I would start with two motors and see how it goes.

A couple of points, a single ragebridge might not be super happy, using one per scooter motor would be better. As a general rule, stay away from sabertooth escs. They are fragile as shit and will most likely break as soon as they see combat.

Another point is that you have two 5s batteries, presumably to give 10s for the scooter motors... ragebridges are 8s max.

Scooter motors and robot power vypers are a proven combination though so you may want to look into those as an alternative.

Thanks for the feedback Harry. I'll check out the Vypers. :)

@Harry, I thought the Rage Bridge 2 input range was 8v - 40v? If only 8s can be supplied how would that work with 36v motors?

Motors can be undervolted as well as overvolted. Since 8S is ~30V it wouldn't be too drastic a reduction.

A 1000W 36V rated motor would be a 620W motor on 30V, still useable for a heavyweight drive, but on the low end.

A hard limit is 40v. Listed as 12-30v nominal. Fully charged 8s is 33.6v. Fully charged 10s is 42v.

42 > 40

Pop. Unhappy ragebridge.

You can get 24v 800w scooter motors if you look around, those on 6, 7 or 8s would work :)

The 24V 800W motors are 1.2 Kw on 30V, so that could work.

Or just run the 24v motors on 6s with a ragebridge.

Cool that clears that up :) Are the Turnigy nano-tech lipo's a good option, the 4s on hobby king get hammered a bit in the reviews. I'm not that good with battery brands, any recommendations?

Turnigy nanotechs are not bad, but not very long lived in our application. They get puffy after a few hard uses.

We prefer de Zippy's from HK.

Had very good experiences with optipower lipos. Get a nice discount off the list price with FRA membership.

Yes those were the ones in PP3D when we were welding ourselves in the arena and the packs were fine. Charged up no bother at all and all balanced fine.

Quote:

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Originally Posted by harry hills

A hard limit is 40v. Listed as 12-30v nominal. Fully charged 8s is 33.6v. Fully charged 10s is 42v.

42 > 40

Pop. Unhappy ragebridge.

You can get 24v 800w scooter motors if you look around, those on 6, 7 or 8s would work :)

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What? Why does the voltage go so high when fully charged??

Ragebridge is on order and I have a 36v motor next to me!! :( Luckily just the one!

So best to go with a 24v 800w, overvolt it on 30v(8s) and get more watts compared to a '36v 1000w motor' running on 36v(10s)...??

I'm so confused!!! :rofl:

Suppose it'll work out cheaper, less powerful batteries. Glad I saw this now, before I bought the second 36v motor and/or my ragebridge blew up!!

I would recommend buying the 24v 800w motors and running them on 6s or just over 25v. You won't be stressing the motors or the motor controller and with a first robot, getting it running is the biggest challenge. It certainly won't be underpowered running two 800w motors on the drive.

@typhoon_driver, using two 24v 800w motors with 6s would it still be better to have one Ragebridge per motor? Or would one be fine running both?

I imagine a single rage bridge should be able to handle that. Just don't adjust the current limiting settings on it (we never touched ours and it was fine) and give it a test when you have the machine together for the first time. Give it a short burst of driving around nice and slowly. Stop and touch the heat sink to see if it's getting hot. Then slowly speed up until you are hammering the hell out of it.

Also make sure you gear the robot for a sensible top speed.

I agree with Gary, if you don't overdo in speed , the ragebridge 2 will do the task.

Just to give a comparisation, Bullfrog uses 2 24V 1.2Kw Iskra on 37V( theoretical power 2x2.85Kw) 2x5S 8000mAh Zippy LiPo) and an old Robotpower Sidewinder (2x80A channels), but with a 20-1 gearratio on 280mm wheels.
Top speed isn't blistering, but due the big gearratio, we get there very fast,giving it the impression of great top speed.

The 24v, 800w scooter motors work well on 6s. We used them with a 4:1 chain reduction on 160mm wheels with no problems and the speed was pretty good.

What speedo did you use Will?

We used a Wotty for s2 but we're changing to a Roboteq Ax2850 as the Wotty is going back into Maelstrom.

I'm big wotty fan. Ironside runs 2, one for wheels and one on the weapon motors.

The wottys are good but they are rather bulky. I couldn't believe how small the ragebridges were. I'm also impressed by the size of the vex victor BBs.

That Optipower discount is very tempting...

Great information shared on this thread, really useful, I've ordered all my parts and they are slowly arriving now.

Wondered if you guys could offer me any advice with R/C Systems, the one I mentioned originally in this thread is a cheap one £25 on hobbyking, but what should I be looking for when purchasing a R/C System to work with my RageBridge? Any recommendations at differing price ranges?