# LiPo eTractor



## major (Apr 4, 2008)

Well, here it is. A $3000 battery in a $30 EV. Yeah, it is a lawn tractor. And a crappy one at that. But I got a real nice battery. A 14 cell, 40 Ahr Kokam LiPo. Notice the CellLog8s. Intend to get real world data. Scraped up two bales of cut grass and had only 14 mV cell drift


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## Woodsmith (Jun 5, 2008)

Nice cost ratio!

Nice tractor too. There are a few trator threads now, maybe we should have a subsection on tractor conversions.

I reckon many converters are spending more on LiFeP04 then the donor was worth. I know I am. My donor MR2 was only £300 and I recovered that cost by selling off ICE parts!


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## major (Apr 4, 2008)

Woodsmith said:


> Nice cost ratio!
> 
> Nice tractor too.


Figures you'd like it  Wheelies are a lot more spectacular since I dropped 100 pounds of lead in the front


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## MN Driver (Sep 29, 2009)

Scratches head, $3000 for 14 40Ah LiPo cells 2,072Wh $1.447/kwh :-O

I realize those were a few years back when they were purchased and I know a little of the story about why you have them.

What I would do for a similar pack using LiPos, since I can't source them the same way as you did.
I'd work with 6s packs of 5Ah parallel them as 9 packs in parallel to get 45Ah and two strings to get 12s and then work with that voltage to build a system of roughly the same capacity. I'm not sure what other options there are for decent Lithium Cobalt at a good price.
1,998Wh for $857.34 plus the pain in the ass of terminating all the bullet connectors and soldering the balance leads appropriately, but maybe a little less than working with pouch Kokams.
111Wh 6s 5Ah packs for $47.63 $.429/Wh Considering the $.35/Wh cost of LiFePO4, the gap is only a 22.5% premium now but for cells that can push 25c continuous and 35c burst. ...if only they had ones that could take 5C charging without doubling the cost and I'd be all set to build a prototype I'd like to build.


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## Peter S (Mar 5, 2009)

Nice !! I have just orded 20 TS90ah for my lamnmower,and all this money just becaus I hate my B/S dripping oil on the floor


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## Jan (Oct 5, 2009)

Major, that looks like Victor's Battery pack. How on earth...?


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## major (Apr 4, 2008)

MN Driver said:


> Scratches head, $3000 for 14 40Ah LiPo cells 2,072Wh $1.447/kwh


Hey MN,

I think you have a decimal error 

And I was able to salvage some cells and parts from a messy situation. So aside from some small parts, battery was at no cost to me, just a lot of time spent bringing cells back from death. But my lab tests showed they actually have full capacity. No idea of how long they will live.

Now to get my charger working out in the barn. In the lab, I found that my old 48V, 17A PbA charger did a nice job. Shuts off at just about 4.0 V/c. I can watch it with the CellLogers.

After that, I am thinking of paint job. Not that it needs it 

Hey, on my budget, you take what you can get 

major


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## major (Apr 4, 2008)

There's more about the battery on this thread. 
http://www.diyelectriccar.com/forums/showthread.php/lithium-battery-monitor-39708p2.html


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## JRP3 (Mar 7, 2008)

Sweet! Do you have fuses on your Cell log leads?


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## major (Apr 4, 2008)

JRP3 said:


> Sweet! Do you have fuses on your Cell log leads?


No, I live dangerously  I use the proper (JST) plug and carefully route the leads and wrap them in nylon spiral. They are fixed in place and not messed with after installed. Not recommending my method, but works for me. I've got it on 4 different batteries now, without problems. I move the CellLog from one battery to another by unplugging it without disturbing the leads. 

major


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## major (Apr 4, 2008)

Hi Guys,

I just made new CellLog connectors for the eTractor. While down in the FrakenbasementLab, I made a few extra. If anybody is interested, $15 including S&H, $25 for 2. Proper JST plug and pins. 9 colors, 22 GA, stranded tinned wire, 300V, 90/105 degree C, 30-36 inches long. I used a JST crimp tool. Contact me PM.

I'm not going into this business. Just thought I might help a couple guys out and recover some cost of the mile of wire I had to buy to get 9 colors 

Regards,

major


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## major (Apr 4, 2008)

major said:


> Now to get my charger working out in the barn. In the lab, I found that my old 48V, 17A PbA charger did a nice job. Shuts off at just about 4.0 V/c. I can watch it with the CellLogers.
> 
> After that, I am thinking of paint job. Not that it needs it


Hey,

Got my charger aworkin'  Seems to work real good. Stops at just about 4.0 V/c. It weighs like a 100#. So ain't goin' onboard.

Since I changed from PbA to LiPo, a lot less weight up front. So the steering works a lot easier and better. I used it for about half an hour at yard work. Didn't drain the Battery very far at all. Did a road test. About 10A in 2nd, guess about 8 mph. 17A in 3rd, maybe 15 mph. On the grass, it pulls about 18-20A in 2nd. Pulling the grass sweeper, maybe up to 25A.

With the 40 Ahr LiPo, I am wondering if I can get like 2 to 3 hours on this puppy. With the PbA batteries, I'd have to recharge after like 15 to 20 minutes 

Notice the Red Green mounting of the CellLog8sers. I was going to run new leads and Velcro to the dash, but decided I would tear it down and give it a paint job. Maybe start that this week. Then a pic of it in the barn stall.

Oh, cell drift up to 60 mV.

major


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## ElectriCar (Jun 15, 2008)

Oops. Got sidetracked checking out the tractor.


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