Alternator, DC Motor, Battery - Remote Control Lawn Mower DIY

In this video we look at how to correctly size an alternator. I also mention the characteristics of electric motors and batteries.
See also my other videos:
• RC Lawn Mower Build Tips
If you have any questions about the diy lawnmower or suggestions for the topic of the next video, please send me email on: [e-mail]
Chapters:
00:00 Intro
00:10 Basic Information
00:24 Electric Motor
00:48 Batteries
01:13 Alternator
01:31 Alternator Sizing
04:43 Outro

[@Rambleon444]

Thank you, from California. Also, the amount of amps you need depends on how hard you are working on the motors. Many variables are at play for how many amps you use... the vehicle's weight, the drag of the drive line including tracks, terrain, how fast you go, how much stopping and going, amount of turning, how hot the motors get...

[@Me-qc2ud]

Really good information. Thanks for taking the time to explain it

[@kmonnier]

Great video, thank you for explaining the math behind the process

[@MatthewHanson1]

I have to say you did a great job narrating that video and explained it very well. I drive around a bunch. And one of the places I drive around is a Ryobi r&D lab. They are developing self guided electric mower. That should be pretty cool. But yours is cooler with those tracks. Peace out and have a great day!.

[@gregorkobetic]

Thank you for kind comment. I try to encourage people to take on a similar project. Have a nice day!

[@ajaxmuchacha3758]

Thank you for the great content! Can I ask how you went about sizing the alternator? I have a fairly flat yard, so thinking of two 200w motors. Wanted to now what size alternator you recommend to maintain 100% battery charge?

[@gregorkobetic]

Hi, 24V 55A alternator are available for good price. You have to dimension alternator with extra power, becouse motors take more current then declared if they stall. If you can get 12v motors you can get 12v alternator for lower price. But remember less voltage take more current for the same amount of power.

[@crikson76]

Legenda!👍

[@gregorkobetic]

Tnx! :)

[@ronzika335]

Thanks for posting. Is there a risk of overcharging?

[@gregorkobetic]

If you use lead acid batteries then there is no risk. If you look at the table on my batteries you will see the term "floating use", where the voltage is exactly the charging voltage of alternator. "Floating use" means the voltage that keeps the battery at 100% capacity.

[@ronzika335]

To clarify, is it proper to send the alternator voltage full time to the 2 lead acid batteries? That would be ideal because of the simplicity. This video was very helpful. Especially the discussion on pulley diameter ratios. Thanks

[@gregorkobetic]

@@ronzika335 yes, it is ok to connect alternator directly to lead-acid batteries. Thanks for nice comment.

[@francmastnak740]

Odlična prezentacija a imam za sebe eno vprašanje.Imam 4 motorje 24v 300w altenator 110a in 2 akumulatorja 12v zaporedno vezana vsak po 100ah.Ali bo to zadovoljivo.Hvala za odgovor

[@gregorkobetic]

Živjo! Seveda, imate še precej rezerve. Bencinski motor bo dovolj močan?

[@francmastnak740]

Mislim da 16konjev 432ccm

[@gregorkobetic]

Super, tole bo konkreten stroj. Se priporočam za kakšno fotografijo. Srečno!

[@alex4l3x65]

I am currently using an alternator 24v 35A. The ratio is 2:1. The engine has 5.5 HP and struggles when the two electric motors use Full Power. Can i reduce the load on the gasoline engine when use a 1,5:1 or 1:1 ratio on the alternator?

[@gregorkobetic]

Hi! You will not get enought power from alternator and batteries will have to compensate the difference in power. Maybe batteries will discharge eventualy. Is there any chance you can reduce speed of your mower with gear? What is max speed of your mower?

[@alex4l3x65]

The Motors are gear reduced to 75 r/min with 250w and ned about 16A on Full Power. The Mower has about 80/85 kg and runs about 2.6km/h. There are only steep slopes on my property, so the mower almost always needs full power.

[@gregorkobetic]

You have good design. It's hard to give a good suggestion. Try to do something so that the gasoline engine doesn't struggle to cut grass, in terms of easier ejection of grass (increase the opening), replace the blades with flatter blades (less lift) maybe.

[@alex4l3x65]

Thank you for your answers.
I think I'll try to modify the carburetor and the intake system a little to squeeze more power out of the engine.
PS your Mower is awesome👍🏻

[@gregorkobetic]

@@alex4l3x65 you are welcome! Thanks!

[@diegoContodo]

Hi friend, why you need an extra alternator if the mower motor comes with one?

[@gregorkobetic]

Some gasoline engines have generator for charging batteries for electric starter and to power lights, etc... however this power is in range of about 100W. My motors together need about 700W

[@diegoContodo]

@@gregorkobetic Thank you! Has the alternator some rpm works limit? I mean, my alternator has a 2.3in pulley while the gasoline engine crankshaft has a 6.3in pulley, witch means that, when the gasoline engine be working on 3000 rpm, the alternator will on 8700 rpm

[@gregorkobetic]

@@diegoContodo my alternator can go over 10000, I can remember exact number. I think you are in safe range. But anyway check datasheet of your alternator 😉

[@turtlewax2]

Can you help me please

[@gregorkobetic]

Yes of course. How can I help you?

[@turtlewax2]

@gregorkobetic7513 I have a Daredevil Mower and it moves very slow

[@turtlewax2]

@@gregorkobetic I am not 100 percent knowledgeable about this subject

[@gregorkobetic]

@@turtlewax2 uff its difficult to say anything without debugging electronics. If motors have torque, but are running slow, maybe there is something you can do on your remote control transmitter. If you provide me more information we can figure it out perhaps. Write me on [e-mail]

[@turtlewax2]

I tried to email you