what hbridge will work

Hello all. I just connected my wiper motors (2) to my Moto monster and after a very short time of testing using the SMC3 utils, my motors would not work. It seems as tho my monster board is fried, not good. Question is what H-bridge should I be using for driving up to four(4) wiper motors? my power supply puts out 12vdc @ 7 amps. The motors are good because when I connect them to the PS, they work well. As of now I am on hold.
Thanks Terry W.

Hi Terry, If 7 amps total output for your power supply is not a typo, your first issue is probably not having enough power available! At 12v you need a minimum of 1 amp for each 12 watts of motor power. So, for example, one 180-watt motor needs 180 divided by 12 = 15 amps per motor. Four of them will require 60 amps minimum. 7 amps will only run one 84 watt motor at best! I say minimum and at best because motors draw even more current as they approach stall speed. Since simulator motors are constantly changing directions, they are often running close to stall speed where they require the most power to operate. The motors may work when you hook them up directly to your power supply because they quickly come up to speed where they require less power to continue running.

If you have a good car battery you can use, I would try that instead of your power supply for testing purposes. You may have fired your boards already though by under powering them while applying to large of a load!

Hi Terry. First check the bridge w/o the motors connected. you have a power meter, so use it for that. Furthermore you "screwed" your boards onto a plate and fixed them with nuts. These nuts are really big and can damage the traces respectively producing a short circuit. If so, the board is definitely damaged. If all is fine, have a look to the correct wirings. At least I would not use the soldered (with the monster moto delivered) standard pins. Try to connect the 12v electrical wire directly to the board by soldering them to get the best current flow.

As others have pointed out something doesn't seem right here. The Monster Moto boards shouldn't fail with a wiper motor and 7A PSU unless something is wired incorrectly.

As @bsft always reminds people wiper motors need the earth disconnected from the case to avoid short circuits... have you done this or isolated the motors some other way?

If you can't determine what caused the H-Bridges to fail then you may find any replacement will have the same end result. The moto monster drivers chips are pretty rugged. Have you tried powering them up again, sometimes they shutdown to protect themselves and need the power cycled to run again.

OK,at this point I am 99.9 percent sure that my controller board is fried. I was looking for the thread that bsfs posted on how to disconnect earth ground from wiper motors w/pictures but some how I have lost the note. I can tell you this, there are three sets of brushes and I think that I need to remove one but not sure which one? and that could be why this happened. It seems that if I decide to run four(4) wiper motors that I will need to use at a mim. two(2) monster boards. Is that correct? On my proto platform I was using three (3) motors very small amperage and two of them were connected to one terminal with one of the motors having the wires reversed for opposite movement. Only two motors were controlled with a pot. That worked quite well.

Each Sparkfun Monster Moto supports up to two motors (Dual H-Bridge). According to this using four motors you need two h-bridges.

for four motors you need at least two moto monster or if you want more power for your motors you can use one moto monster per motor as @Pit has wired them for his sim.
in your other thread @bsft and me have suggested you this and this for motors isolating.
if you have to remove one brush remove the one which is wired to the low speed contact

@insanegr , thanks for providing those links

Thank both of you for responding so quickly. Here is what I am dealing with. in the picture, #1-ground,#2-low speed and #3-high speed. I get a reading on the multimeter (buzzer) from case to contact on all 3 contacts. I think the reading is there because of the armature? From looking at the brush holder on back side there is no way they could be shorted and they are not, I checked that. Thanks again
Terry W.

While I’m not an expert at removing earth ground from wiper motors (I don’t use them myself), it appears that the board the holds the brushes is grounding the case when you put screws in it to hold it into position. You can either try to insulate the screws so they don’t make contact with the copper on the board, or better, just remove the copper around the portion where the screws come into contact with it. I don’t know if there is another grounding point other than that but there could be. Use the ohms setting on your tester and connect it between the negative motor terminal and the case to see if that opens the circuit. Don’t be concerned with connecting the slow speed terminal and brush. All you need to use is fast since you will be controlling the speed with a controller. Maybe someone with actual wiper experience will chime in too if there is more you should know.

Hi Terry,
I hope it will be solution how to separate ground from wiper motor body . Just you need cut wires off from brushes and connect it straight to power wires . And use only high speed brushes , low speed brush should be disconnected .

that means that your motor is not ground isolated and you have to isolate them.
when motors are isolated we get reading only between contacts or wires them self s and not between body and contacts or wires.
@auryza post explains what to do
but you can also cut and solder a wire only to the ground
get rid of the low speed brush (if you want, doesn't harm anything if you don't)
and keep the high speed as it is
less job to do
hope i helped

Thanks all, I did isolate the ground on all my motors. They should all work ok, but now I need to purchase a new Dual H-Bridge controller board. If I were to purchase this on http://www.aliexpress.com/store/pro...mart-Car-Strong-Braking/325585_709407235.html. how would I go about connecting it to my Arduino board? I don't understand the pin out from the moto monster to this one? Thanks again
Terry W.

Blazin H
Thanks for the reply. Here is the power supply I am using. Is it too small?

Terry, figure out how many amps you will need under full load (reversing) and then double it.....and then add 10%

Seriously, either use a 12v car or marine battery or get a couple server power supplies at 45+ amps. That power supply you have is good for bench testing circuits but not not for motion platforms.

I think you mean you need a driver board, the Arduino works as the controller

If you want cheap and strong bridges try the Monster Moto from Sparkfun. Please have a look at the very first posting here, or you need more power so you can use the Monster h-bridges as a single bridge which doubles the power, more information at http://www.xsimulator.net/community...cts-as-a-single-motor-driver-more-power.5482/. You will find any Monster Sparkfun Samples at Aliexpress for less than 20.- bucks. Generally I would only buy what was successfully tested here. Some of the bridges like the one described in your posting do not match the specifications, 50A would be nice but they will never survive only for seconds if you are pushing them to the limit.

Ok that's what I needed to know. I will shop for a bigger PS.
Terry W.

The Monster Moto is what I have now and it did not hold up to one motor however I think my problem was the power supply, too small. What I am hoping to do is operate four (4) wiper motors using only two pots to control them. Do you think a monster moto will work for that?
Terry W.

Hi Terry, I seriously doubt the moto monster failed from lack of power. Mine, until recently, performed great and you know how much power my rig sucks down. The failure was my fault, I allowed them to get plugged with lacquer dust. Combine that with high heat....yep....a little fire resulted. I have two but I pulled the other one off and switched to Pololu 755s which I had started to collect for my 6DoF but I am going to use three Moto Monsters on my 6DoF rig (which will pull even higher amps).

Looks like Historiker is actually Johnny on the spot and beat me to the answer! Thanks!