Motor Controller For 24v Dc Motor

 
#1

I've been reading up and not quite sure which is correct for me, sabertooth, kangaroo, hbridges, and that easily work with the ez-b. It seems there are a lot of post, but refer to other posts and each has a different way of working but seem to have a few buts. If you have this then use this and now I'm unsure. My original thought was a sabertooth.

I have 2 24v dc motors 8.9amp

My battery is two 18v in parallel getting 8ah

I am looking for speed control, I'm going to use the moble app, but might want to switch to a game remote.

Is the sabertooth the correct and easiest way to connect to the ez-b? I was at the Robotshop looking and there are a lot of choices.
http://www.robotshop.com/en/medium-power-motor-controllers.html

Thanks

#2

@kashyyyk,

The hbridges only supports up to 2.5Amp.
Saberthooth's are a good board pending how much you want to spend, if your motors Are 8.6 A each you would need the 2x25 saberthooth it supports 25Amps.

If your total motors only use 8.6Amp then the 2x12amp sabertooth will work.

You might need a larger amp hour battery to power the motors though.

I haven't played with the Kangaroo so don't have a good answer. I do know the kangaroo is an ad on board.

You can do speed ramping in ezb software as many examples out there.

#3

Ok thanks, i'll focus on reading up on only the sabertooth.

The battery should be ok, it will only move just showing lt off to friends, it will mostly just sit and run lights and scripts and the battery will handle that easily.

#4

I think the sabertooth is the easiest to configure because it's only one wire to the ezb for signal. Most hbridges will require minimum of 4 wires without speed control and 6 with speed control.

The downfall to sabertooth is the price. You can find affordable hbridges for your amp requirements on eBay for cheap... but it will use more I/o.

I damaged a sabertooth once by connecting it backward. It was a silly mistake, but costly.

IMO, if you can afford sabertooth, go for it because it's a well known and proven peice of hardware. Just be careful like all electronics and do not release the magic smoke!

#5

Thanks, I'll watch out!

I do want simple, i did see I'll have to read up on the regenerative function it does and how to protect against it.

#6

I’m ready to get my sabertooth. I want to be able to push the droid around when powered off. Can I use a couple of the automotive 5 pin bosh relay between the sabertooth and motors? So when I have power the relays close completing the circuit and when I turn off power the circuit opens.

#7

@kashyyyk The relays would work but... Can't you just put 2 toggle switches on the + side of the motors? On... when you want to run it... Off... when you want to push it... would be much cheaper and simpler..

#8

It would, but that one time I forget to switch them, I'd be kicking myself. This way it is automatic.

#9

merne gave you some incorrect info 2 months ago. When you're looking at the amp rating of a Sabertooth it's listed as "amps per motor channel". So a Sabertooth 2x25 can handle two motors that can draw up to 25 amps each. Also a 2x25 ST will handle to to 50 peak amps (per motor channel) for a short time. This means that if you have a motor that draws near 25 amps under constant load but when it starts up it will draw up to (for example) 40 amps for a second or two then this ST will handle the extra load .

So, if you're in your build if you're still using two motors that will draw 8.9 amps each then you can save lots of money and get a Sabertooth 2x12 for about $80 USD. Compared to the $125 of the other mentioned ST model that's a $45 USD savings! The ST 2x12 will handle up to 25 amps peak load. Winky

The 2x12 Sabertooth also comes in a RC model for $65 UDS. You can use a RC controller either model though. However this RC model has less advanced features. You'll have to decide if this one is right for you. Smile

I think the relay is an excellent idea to isolate the regen power of the ST from your battery when powered off. I built a TIP transistor switch that the EZB would switch on at power up to close the power circuit between my power supply and the a ST 2x12 I had. I then upgraded to the 2x32 because it has a voltage clamp feature that keeps the regen voltage from backfeeding into a PS and I scraped the TIP transistor switch.

If you haven't bought one yet and If you're interested I have 3 brand new and unused Sabertooth 2x12 controllers. I'll sell one or more for $50 each plus shipping. Just let me know. Winky If you want, I'll through in the EZB activated home made TIP switch I made (I actually have two) for free but I think it will only handle about 5 amps. It may be rated for more amps but I can't remember what I used. It's been years. *eek*

#10

Why not go for the easiest sollution...
Install esc's. They come for brushless or brushed motors, cheap, high performance and compact.

Here's a small overview:


Hobbyking - Esc's

Good luck,