The specifications of DC motor should be as similar as it can get to 11HP ICE engine,

That would be one approach. But you could do better by determining the actual power requirements or duty cycle needed for the machine and design the electric propulsion system around that.

Another method is to search this forum, the web and the EValbum to see what others have done for similar conversions.

 

I have been searching on EV album for over a week... And the Motenergy motor is the best I could find.

So I just decided to give it a try on forum if someone of the older and more experienced members could deliver fast solution.

By the Motenergy motor I have problems with relatively high voltage (48V) and high constant current (200A) because I want to install the Winstons LiFePo4 batteries with relatively low constant current and low voltage. After all I am rebuilding a garden machine not a car, so the budget limit is 2000$. So that’s why I can't afford to buy 2600 AH batteries, but just 500AH - 600AH it would be more than enough.

I am also interested in Kokam Lithium Polymer batteries, which would deliver enough current and voltage. But here is the problem of expensive battery controller. Maybe the solution would be Mini BMS, but as I said the Kokam Batteries are Lithium Polymer and the Mini BMS is intended for LiFePo4 batteries. Maybe someone had tried to use Mini BMS on Kokam batteries and would share the experience.

Regards

 

Hi proton,

Here are some more comments from me.

So I just decided to give it a try on forum if someone of the older and more experienced members could deliver fast solution.

I think using this forum is a wise decision on your part, however beware of fast solutions

so the budget limit is 2000$

On the surface that appears to be enough to build a very nice project. But making hasty decisions and buying components before you have a well thought plan can eat a couple thousand in a hurry.

I have been searching on EV album for over a week...

Yard machines and specialty EVs are difficult search items. We have been trying to get the forum admin to start a section or sub-forum for such. You can find a number of examples linked on this thread http://www.diyelectriccar.com/forums/showthread.php/express-your-interest-non-road-going-54835.html

And the Motenergy motor is the best I could find.

I am not saying that particular motor won't work for you, but it may not be your best bang for the buck. It is basically a redesign of the Briggs & Stratton Etek motor from 10 or 15 years ago. You can imagine what B&S had in mind when they spent a ton of money and introduced the Etek. Well, that didn't work out so well for them and they ceased production after a short time, really none of the Etek motors found application on commercial lawn equipment or otherwise and I bet B&S lost a bundle. Don't make the same mistake

By the Motenergy motor I have problems with relatively high voltage (48V) and high constant current (200A)

I think 48V is an excellent choice for vehicles of this nature. And your "constant current" statement leads me to believe you have a misconception about the way electric motors operate. A "constant current" would require a constant load, which is an unlikely situation.

because I want to install the Winstons LiFePo4 batteries with relatively low constant current and low voltage. After all I am rebuilding a garden machine not a car, so the budget limit is 2000$. So that’s why I can't afford to buy 2600 AH batteries, but just 500AH - 600AH it would be more than enough.

2600 Ah at 48V = 125 kWh That would be enough energy to mow a golf course When you put cells in series to make a battery, the charge (Ah) doesn't add. Even though you're not building an EV car, look over the EVInformation section here and see how energy usage and range are figured. This can be adapted to your machine and you can get a better idea of how to size your battery.

I am also interested in Kokam Lithium Polymer batteries, which would deliver enough current and voltage. But here is the problem of expensive battery controller. Maybe the solution would be Mini BMS, but as I said the Kokam Batteries are Lithium Polymer and the Mini BMS is intended for LiFePo4 batteries. Maybe someone had tried to use Mini BMS on Kokam batteries and would share the experience.

I use Kokam on my eTractor. Just for example, it was originally equipped with a 10 hp gas engine. I have an old floor sweeper electric motor powering it. I got the motor for free. It needed some TLC. It was originally rated at 3/4 hp. I run it at 48V and use an inexpensive Curtis controller. Been working for like 15 years. I do not mow with it, but do occasionally use it hard.

Stick around and read up on things. These smaller EV projects are great ways to get acquainted with the EV conversion process.

Regards,

major

 

Thanks Major.

Due to my inexperience’s with LiFePo4 batteries, I have decided to buy 4x 12V batteries VARTA Professional AGM 85Ah (deep cycle), which are relatively cheap and can be bought in local stores.

http://www.varta-automotive.hu/uploads/tx_sbdownloader/Folder_Caravan_UK.pdf

What do you think? Do I need BMS for these batteries?

Regards

 

Due to my inexperience’s with LiFePo4 batteries, I have decided to buy 4x 12V batteries VARTA Professional AGM 85Ah (deep cycle), which are relatively cheap and can be bought in local stores.

http://www.varta-automotive.hu/uploads/tx_sbdownloader/Folder_Caravan_UK.pdf

What do you think? Do I need BMS for these batteries?

Hi pro,

This probably belongs in the battery section. And like your question on the motor, my answer is similar. Research before you buy.

That does appear to be a nice battery. And first off, BMS is used for cell monitoring and/or management. With those 6 cell Pb-Acid batteries you cannot access individual cells, so a true BMS cannot be used. You said you were doing a 48V system, so 4 batteries in series. If you charge at 48V, you will want to occasionally check the balance between the 4 batteries, maybe 1 or 2 times a season. Then individually charge at 12V if they drift. But BMS, no.

Also, back to your application, which I do not understand. In previous posts you talk about 200A continuous. At 200A, those 85Ah batteries will run for about 12 minutes. Is that going to be long enough for your intended use? Are you really going to pull 200A continuous? Again, you need to define what you are doing before you start buying.

Regards,

major