H-bridges

Question

Good day folks! Anyone have recommendations for an alternative to the BV-4113 Motor Controller? Looks like my Dogbot (dog baby sitter bot) requires more power than the BV-4113 can deliver. Oddly enough the Tank's motors in its original form only pulled 1Amp, but when connected to the BV-4113 they now pull 2 Amps, which causes the motor controller to shutdown to prevent overloading. If I connect the motors directly to the 7.2 Vdc battery, they run smoothly and as fast as before.

Thanks for you recommendations! AND DJ, thanks for creating a very cool product !

DJ Sures · Answer

thanx dude Are you providing direct power from the battery to the HBridge Motor Supply? I use the BV for my omnibots, and they draw a lot of juice. I wonder why yours is so power hungry

jstarne1 · Answer

@ DJ Why not hook motor controller to a relay so your getting juice straight from the battery and low load on motor controller. You can get solid state relays that are super fast too.

Dave L · Answer

DJ, I do run the battery straight to the Motor Controller. I suspect its because the tank tracks are fairly heavy as they are metal tracks. Jstarne1, I prefer the kiss method. The more complex the project, the more things to troubleshoot later!

jstarne1 · Answer

I only suggest a relay because it completely prevents risk of damage due.to stalling and reduces running temprature of a h bridge. If you ever fins you need to draw more amps I don't.see.why a.relay wouldn't work. @dj do you agree with this , usingbh bridge to trigger relay if your motors draw more that h bridge rating?

Dave L · Answer

I found that replacing the 7.2 battery with a 9.6 made all the difference in the world. It dropped the current back to 1 amp, but did cause the BV-4113 to get hot real quick, so I will need to rig a heat sink. @Dj, I didn't notice the VR on the EZB getting hot, is there any issue using 9.6 vdc to drive it?

jstarne1 · Answer

Voltage regs getting hot when you pass up 6 volts is normal you really need to attach a large heatsink and fan. Also be sure to use good thermal paste like arctic silver 5 for CPUs. The heatsinks that fit two regulators well are basically gpu heatsinks https://www.ebay.com/itm/Very-Small-Unbranded-Aluminum-Heat-Sink-and-Fan-Screws-1-3-4-inches-center-/370581010535?pt=LH_DefaultDomain_0&hash=item5648597867

smoketester · Answer

I'm going experiment with an Adafruit motor shield along the way to my first big robotics project (a Hearoid). Like DJ's Omnibot it's fairly heavy and I expect to have some cooling issues. Not the most elegant arrangement but its what I have on hand and that fits the budget for now. Just read the following and I'm reconsidering the motorshield idea. Ok. The L298 was designed for low current / high voltage (up to 46V) stepper motors. It can also drive 2 DC motors. The Arduino motor sheild includes some additional logic making it easier to drive DC motors. This does not mean it cannot drive stepper motors, only that the code will be different. From my personal experience the L298 is a poor choice for robots unless you need high voltage and low current. Although it can handle 2A per channel it needs a huge heatsink to do so for any length of time. This is because it has a relatively high voltage drop. Every robot I made using this chip (Pictomatix, Mr. Tidy are 2) suffered from poor torque due to the high internal resistance of the chip and overheating. You are better off stacking some L293D's in parallel. I just pulled the base from my Hearoid and am ready to start testing just how many amps the stock DC motors with gearing (assumption) are pulling.

PhG · Answer

Hi DJ, In this clip on YouTube : https://www.youtube.com/watch?v=gxrjo9Z6wkY&feature=g-all-u&context=G200c88dFAAAAAAAAAAA you are using a 4 Amps H-Bridge. This one really looks interesting. I can't find it in your store here. There's a lighter H-bridge (sold out) but I want the heavier thing. Suggestions where to order/buy ? Thnxs and keep up the good work, PhG

jstarne1 · Answer

They are on eBay , 4a max 2amp continous is what I was seeing.

Dave L · Answer

Well I added a heatsink and fan, seems to keep the chip cool, but the bot still has problem running when there's a load. If it's resting on a lift (off the tracks) the tanks run fine. As soon as I set it on the floor, the tank can run forward and back with no problems, but it stalls when trying to turn left or right. I am assuming that the controller cannot handle the load of the one stopped track when turning.

jstarne1 · Answer

Yes amps will spike on a heavy tread vehicle as one tread makes tons of drag. Are you using variable speeds? There are a few solutions to reduce a stall spike. First is when turning power the other tread in reverse direction. This literally cuts amp load in half and reduces that dead weight drag of one track not moving. This will give you a solid left right forward back. It's only tricky when moving forward and turning which requires you to have the tread on opposite side your turning to moving faster than the inside tread. This will definitely draw more current than just the simple forward backwards and rotation left and right because speeds must vary for each tread and slower treads create drag. Most robot owners do not use variable speed forward moving turns for this reason. If you want to have arcing turns using variable speed you need a motor controller that will handle at least twice your right and left turning current draw.

Dave L · Answer

Originally the tank motors only pulled 1 amp. I was hoping that by removing the turret and using less wieght, they would pull less current. Not so much! So it looks like I will be buying another controller. How are the Sabertooth's working these days with the EZB?

jstarne1 · Answer

They work , so does hb25 from paralax. Both heavy duty controllers.. both are more money but that's the price of stuff working right? Lol

jstarne1 · Answer

https://www.robotshop.com/sabertooth-2x5a-rc-driver.html?utm_source=google&utm_medium=base&utm_campaign=jos  5amps continually. 10amps max for each motor. If the h bridge I bought from dj can't cut it this is what I will buy. Runs 6-12v

jstarne1 · Answer

Here is a cheaper option , just as effective , May seem overkill but you wont have power issues with a 10a h bridge , here is a company I've bought stuff from and controller is half the cost , direct signals from ezb and easy to wire up labeled barrier strip on the oth https://www.ebay.com/itm/150754427920?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 er end.

bret.tallent · Answer

Nice Option. Thanks.

Dave L · Answer

Yes, thanks for the info.

jstarne1 · Answer

No problem guys

jstarne1 · Answer

Why not switch your base to a rad 2.0 base , much less current draw , a little wider but overall about the same internal room , they are cheap I even have a spare one laying around. Or you could find one on eBay. Your treads are close together and I imagine they would scratch up a hardwood or kitchen floor. Rad are rubber tracks.

RichiesRC · Answer

@Dave L Hi Dave, Came across this site: HERE and they have some serious high power motor controllers, not cheap but have some serious grunt. The other option might be to upgrade to brushless motors and use brushless speed controllers. can be got fearly cheap and a massive range available from 1 amp up to 200 amps and at up to 37 volts and some even higher. I'm not sure if they would work with the EZ-B but I can't see why not as they all use a the same kind signal just like servos. They may need slight mods as many come with a built in BEC to power the radio gear.(you just cut one wire). Some have forward and reverse options and heap of other programmable options. I have one here that I ordered by mistake with out a BEC Programmable Continuously current: 60A Input voltage: Ni-Mh 6-16 cells, Li-Poly 2-5 cells BEC current: no Weight: 35g Size: 58mm long x 35mm wide x 12mm thick plus wires Price:around $15.00 + shipping  Rich

kkeast · Answer

@RichiesRC, Is that a bi direction ESC? $15 bucks is a very good price. v/r Kevin

RichiesRC · Answer

@kkeast Kevin I'm not sure if that one is as I can't remember and will plug it in and check for you. But I know you can get them and they are still not very expensive. That one is really for a model plane you really need a car or boat one. You can also get a program card for most of them that makes programming heaps easier but the card I have is for another brand of ESC's that I use in my helicopters. also have a boat one(water cooled) 200amps, pretty sure that one has reverse. Rich

jstarne1 · Answer

I have brushless controllers but e They have safety features that make you do things like full throttling from controller till you hear beeps then throttled back. Blah blah blah. Is there ways to turn those features off? I have two brand New axi motors2814 10th I believe ,

RichiesRC · Answer

@jstarne1 That is why I have a program card so you can program it without all those annoying beeps, it has a menu and a digital read out. Can't stand trying to program them via the beeps. But you must get the right card for your ESC as the card below won't work with that 60 amp ESC. Rich

PhG · Answer

@RichiesRC

Have a look at this thread from a little while ago.

You can hook up brushed motors in combination with RC controllers to the EZ-B. Works perfectly but depending on load and power consumption the controllers produce some heat. So a heat sink might be a good idea. The Graupner controllers are well suited for a heatsink because they have a metal body with good mounting possibilities.

https://synthiam.com/Community/Questions/373

PhG

Dave L

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