Which rating motor controller and charger should I use?

Jorge P · 2017-10-26 07:38

Hi all, I've come accross a problem of selecting a motor controller to use for some mobility based motors. I need a controller with dual motor control that will power two 275 Watt (Continuous) and 1000 watt peek current at 22.5 Volts for each motor. I will be using 2x12volt or 4x12volt deep cycle/gell/sla batteries wired for 24 volts. The motors are from a Mid Wheel Drive powerchair that is sitting in the corner decommissioned due to parts availability and a broken hand controller. The base is about 250 to 300 lbs and is steel framework, awesome for a big bot. I will, of course, be using a propeller for controlling the motor controller but want to keep the option open for Radio Control available. The motors are labeled DRVASMB1905 and DRVASMB1906 (Pride Mobility 6000z Power Chair). The controller from the chair is not an option, but I can open it to see the goodies it contains for possible parts.

When I look at the motor controllers available, I see 30Amp, 60Amp, 120 Amp, etc... but I don't want to play it too safe and buy anything overkill for these motors, on the other hand I don't want to burn up $1000 worth of motor either, and that's each new

I have a budget of no more than $500 for the controller. Would it be less expensive to build one, if so any recomendations?

I also have to choose or build a charge controller to be capable of charging the batteries while the device is still functional. I intend to try making it a tracked bot to plow snow from the walkway and driveway using GPS/BTLE or other devisable means, maybe a drink fetcher too

I am currently looking at the motor controllers from http://www.ionmc.com but want to hear some feedback from others who may have used these types of motors, or can help me choose based on the rated wattage listed above.

BTW: these motors have brakes that need to be powered by 24 volts to let the motor spin, it can be removed but would prefer to keep brake system intact.

Thanks
Jorge P.

DrPop · 2017-10-26 15:41

Hi Jorge, sounds like a neat project getting off the ground!
275W at 24V is ~ 11.5A.
1000W at 24V is not quite 42A.

So it depends on how hard you're going to stall the motors. Ideally you would look for something with at least a small buffer over your 11.5A normal load, so on the lower cost end, 12 to 15A on each motor would probably work.
The only possible issue here is the stall on these motors is 4x what the normal run load is. So to get a motor controller that can handle the stall load, you might have to bump up to 25A controllers or something in that range.
I've noticed a rough correlation, for example, a 3A controller will have about a 5A peak rating. That's why you might have to go up to a 25 or possibly even 30A controller to get roughly 42A peak for that "just in case" scenario.

tonyp12 · 2017-10-26 16:19

Maybe this one could work: I can't tell if reversible.
https://www.banggood.com/9-50V-40A-DC-Motor-Speed-Control-PWM-HHO-RC-Controller-12V-24V-48V-2000W-MAX-p-1096519.html?rmmds=detail-left-hotproducts

Pretty sure the manual controller could be replaced with pwm R/C analog signal from a Prop Pin, if above 3.3V driver you would need to a buffer ic in between.
But also look at versions that does intend to be used with digital inputs from a MCU.

Jorge P · 2017-10-26 21:42

Thanks for the rapid responses, I will be using this motor controller due to its ability to use the DOUT pins to dissengage the motor brakes as pointed out by ION staff in an email, and it has a professional looking case design, they also stated that the metal base of my mounting surface would be an induction heat sink. It is a 60A dual controller which is slightly more than I need but not overkill. In a month or two I will have pictures and the project set up with progress and goals of the bot so the community can follow along.

Attached is a photo of the powerchair in its current state. The chair part will be removed. This is an older Pride Mobility Quantum 6000 that is no longer serviceable.

tyvm
Jorge

DrPop · 2017-10-26 21:50

Yeah, 60A per channel, that's about double what you need, so lots of safety factor built in there. Will be cool to see what you build on such a beefy platform! :cool:

lardom · 2017-10-27 13:35

I don't see a way for you to connect your micro to the MCP263 Dual 60A. I only see a couple of ways to connect it directly to your computer. One of your requirements is mobility. Take a look at this.

Jorge P · 2017-10-27 19:08

lardom wrote: »

I don't see a way for you to connect your micro to the MCP263 Dual 60A. I only see a couple of ways to connect it directly to your computer.

The DB15 Connector is configurable through the PC and it supports I2C/CAN/RC/PC/Analog/Pulse/UART RS232/UART TTL. It's in the datasheet page 4. I did indeed look at that controller you linked, a while ago. The cost is less expensive, however the case would bring the cost up a bit and require special consideration to seal it from the weather while allowing airflow. The MCP263 is mostly enclosed making it much simpler for me, I can use an off the shelf case to seal it from a more harsh environment. The original controller is actually 100 Amp and costs ~$1,200 and is not weather proof. This will be used in dirty/wet/damp winter/blizzard conditions for extended periods.

lardom wrote: »

One of your requirements is mobility.

It will not be used, any longer, as a mobility device, nor can I claim it can do so (incase someone is injured while using it as such). There are laws in place that would require me to have all sorts of certifications and testing to make a true Mobility Aid, which will exceed my expertise by a long shot and increase costs significantly.

For this particular chair here is the rundown of the parts and costs for certified "Mobility Aid" replacement parts currently available that are outragousely expensive due to its "Mobility Aid Certification".

I will give a full rundown on the entire project, in a month or two, as I get more parts to show what I am doing. The base is just the beginning steps that can hopefully be suitable for any similar Power Chair in mid wheel drive configuration that has been decommissioned. These are quite expensive devices capable of a total load of 1000lb loads, the base weighs approximately 250 to 300 lbs with the batteries installed. Everything I make for this will be "Open Source" and "Open Hardware" with exception to parts I have to order like specific controllers, unless they are labeled as such.

Which rating motor controller and charger should I use?

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