EcoRider - riding mower electric conversion

[Daox]

More updates. I'm rebuilding the deck to hopefully lower the amperage draw it takes to spin the blades up.

EcoRider - riding mower electric conversion - Page 7 - EcoRenovator

[Daox]

Test number two went went off last night. I lowered the voltage and only used two batteries instead of three. Oddly enough, my amperage was lower than with three batteries (which is opposite of what it should have been). My guess is that the lower motor rpm really helped out. At 36 volts (3 batteries) the motor spins 1.5 times as fast as 24 volts (2 batteries) since rpm is proportional to voltage. At 24 volts, my motor rpm is much more in line with what was intended for the mower. The result was driving around still took 20-25A, but the mowing deck only took another 25A! This is HALF the amperage of the last test. It seems that the deck rebuild and proper pulley sizing really works out well. I am very excited about this!

The next step is to procure some actual deep cycle batteries. My power died off insanely fast because I just used two semi-dead staring batteries. One trip around the house and they were already puking on me. The local battery store has some group 24 deep cycles for $70 which seems pretty reasonable. I'll have to look into what else they have too. I might want to go with something larger. I'd ideally like a 1 hr run time. At 50A, I would get about 40 minutes of run time since you don't want to cycle batteries beyond 50% to retain good life. The alternative is to go back to 36 volts, but resize my pulleys. This theoretically would drop my amperage down to ~33A. This would (again theoretically) give me right around an hour of run time and maybe a bit more because of the peukert effect. So, 36 volts is looking like the way to go.

[solarguy]

Group 24, aka golf cart batteries, should be perfect for this application. I'm not totally convinced that $70 is a fantastic price. Call a golf cart place just for comparison.

Good progress.

Please carry on.

troy

[Daox]

Well, I re-ran my numbers and it looks like I need at least a 190Ah battery if I am going to be able to mow for an hour straight without recharging. I got some tips from the local EV guys that helped out here. My estimates were quite optimistic. So, I think I will be looking at going to use 8Vs or 6Vs so I can get some more Ahs.

[rainyday]

Have fun making your lawn mower electric powered. Sounds pretty ambitious. I guess if a golf cart can do, why not a lawn mower?

[Daox]

Its up and running with batteries from Ben Nelson. I got a video over on ecorenovator.

EcoRider - riding lawn mower electric conversion - Page 10 - EcoRenovator

[bennelson]

I got my batteries back from you and heard a rumor you got some new ones!

Where's the update!? You gotta let us know!

[Daox]

I did get new ones! They just came in on Friday and I just picked them up yesterday morning actually. I'll post updates when I have actually done some work.

I ended up going with an AGM 150Ah group 31 battery. They were surprisingly well priced at $93. I bought them from a fork lift repair shop up in Cedarburg which is just a few miles north of me.

They should give me enough run time to do at least half the lawn at once with charge to spare. I decided against going all out and trying for the 1hr run time simply because I never once cut the entire lawn at one time this year. The field is always dry and I end up mowing it once ever three or so times I mow around the house.

[Daox]

Looks like its time for the monthly update of this thread. For those who would like to catch up quickly, I have actually written a blog series that sums it up fairly quickly.

EcoRider blog series

More in depth info is available in the build thread on ecorenovator. Or, you can ask questions here.

I also recently made an evalbum page for the mower too.



Okay, on to the updates!

At the end of last month I picked up the batteries that I'll be using on the mower. They are group 31, 150Ah flooded batteries. I picked them up from a local fork lift repair place. They did blow the budget for the project kinda as they are new. But, with the life I expect out of them, I'm not going to worry about it. I couldn't find any good sources for used batteries at the time.





Last weekend I started the battery racks. I went with two in the back for traction, but one in the front to keep some reasonable distribution of weight (no wheelies!). The rear rack is all done, but the front one still needs to be made. I like how the rear rack will give me very easy access to the batteries for checking the water level. The one up front won't be quite as easy to check since it'll be under the hood.







I'm really looking to get this thing running soon as I need to cut the grass before the snow starts to stick. My in laws recently took back the push mower we had borrowed from them so I have no way of mowing right now.

However, I'm also a bit excited to see the snow fly so I can get a chance to try out this attachment I got a few weeks back.

[bennelson]

Tim,

I think I may actually have THE EXACT SAME snowblower attachment.
We should do an EV SnowBlower work-day sometime.

It might be possible to pull the drive pulley off the blower and mount a direct-drive motor directly in it's place. We would have to see how many amps that pulls for if it is practical or not!