Bobcat Lawn Mower (project in progress)

[ebizzle]

Hello Everyone I'm another new user who may have bitten off more than I can chew...

I'm trying to build a big electric lawnmower, the goal is to use mower commercially and cut down on noise and pollution in the neighborhood.

The setup so far is a ME1302 I bought on facebook (thanks @kinkkink ) and 4x 12v LiFePO4 100Ah Batteries in series for a 52v pack. I had SendCutSend make me a motor adapter plate and it fits like a glove in the same spot as the original 14HP Gas Motor.

I got a Sabvoton SVMC72200 controller from a buddy with a Surron Bike, but it turns out that controller uses hall effect sensors and wont be able to read the Sine/Cosine Encoder on the motor.

It looks like the SEVCON Gen4 is the go-to controller for these motors, so I reached out to ThunderStruck EV to get a one and it turns out the programming is a complex process. According to them there are timing differences from motor to motor and I'd need to send them my motor so they can program the SEVCON. Mailing this motor to california (and back to the east coast) is probably going to be another couple hundred bucks, so I'm considering just buying the SEVCON programmer and trying to DIY it. All I need it to do is spin the motor ~3000RPM and not overdraw the batteries.

seems like my options are
A: Ship the motor to California, buy a new SEVCON and have thunderstruck program it and make a harness. $$$
B: Buy a SEVCON controller and programmer and try to DIY it
C: Put magnets on the motor pulley and try to rig up some goofy hall-effect setup for the Sabvoton controller
D: start over and use a DC Golf cart motor and a cheaper curtis DC Controller

Any input would be appreciated.

 

[amberwolf]

I'm pretty sure it would be worth the money to ship it to them to set it up; given the issues people have had trying to setup Sevcons on their own. (costs too much for the adapter and software or I would have some experience with that on the one I have here).

But another option is to install hall sensors into the motor, or to use the controller in sensorless mode. If it doesn't have a sensorless mode, there are controllers that do.

As long as there's no significant load on the motor during startup, sensorless usually works well. Sensors (3-phase UVW hall, SIN/COS encoder, etc) are usually needed for low-speed high-load startup operations,etc.; my guess is they won't be required for your usage.

 

[nicobie]

Where are you planning to put the 4 lead acid batteries on the mower?

 

[PaPaSteve]

To help with your decision do a search on this site for : help with Sevcon controller programming.
Sevcon was used in the early Zero motorcycles so perhaps checking some of their forums might yield some info.

Fight Systems in Carlisle, PA may be of some value to your project.
At least they may be a drive away instead of shipping.

 

[ebizzle]

Where are you planning to put the 4 lead acid batteries on the mower?

Those are actually Lithium batteries, they're only about 20lbs a piece. I made a battery tray out of angle iron today, theyll sit about 4 inches above the mower deck. more pictures soon.

Thank you AmberWolf for mentioning sensorless controllers. I purchased a Kelly 300A sensorless controller today. The motor is mostly going to be spinning at a constant high RPM, so sacrificing low speed control and responsiveness is perfectly fine. Maybe rushing to buy another cheap chinese controller is a bad idea, but it's about 1/8 the cost of buying a sevcon so I'm willing to try it.

Thanks papasteve for letting me know about the Zero Motorcycles and the Sevcon distributor on the east coast.

 

[PaPaSteve]

Glad I could offer some help
It will be interesting to see your final results

 

[Chalo]

Can you get a sensorless controller beefy enough for your application and that motor? That's what I'd try first. I don't think you need all 15kW for a mower, but de gustibus non est disputandum.

 

[Hillhater]

I'm trying to build a big electric lawnmower, the goal is to use mower commercially and cut down on noise and pollution in the neighborhood.

“Commercial use”.. suggests a lot of use ?.
you are using <5.0 kWh of battery on a 10+ kW motor, …but even if you only use 5kWh on average,….you can expect short working days !
what are you planing to recharge with ( charging time ??)
In my experience, most of the noise from this type of rotary mower actually comes from the blade rotation .