Drive System Advice

[maddox10]

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.

[typhoon_driver]

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.

[cjsowry]

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

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!!!

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!!

[typhoon_driver]

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.

[Chez]

@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?

[typhoon_driver]

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.

[maddox10]

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.

[teamshock]

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.

[typhoon_driver]

What speedo did you use Will?

[teamshock]

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