# Conversion of Snapper Rear Engine Rider with 56V EGO Lithium batteries



## piotrsko (Dec 9, 2007)

You would be better off finding a partial electric car pack from a leaf, volt, whatever. Cheap and easy is a used brushed motor about 48 volts perhaps from an electric forklift.


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## merkurmaniac (Dec 25, 2016)

I am giving up on the idea of the 56V Home Depot EGO batteries and I am sort of homing in on this plan:

Manta II 10 hp DC electric motor 12 24 48 Etek / Motenergy Permanent Magnet 
http://www.ebay.com/itm/Manta-II-10-hp-DC-electric-motor-12-24-48-Etek-Motenergy-Permanent-Magnet-USED-/331610128568

And to power it, using a 48V Module from a used Chevy Bolt. I know that I will need a contactor, and a large fuse, some safety disconnects, and the like. A couple questions about the lithium battery though:

What is the simplest way to charge it ? I will have days of time to recharge it, so speed is not a big issue. I am guessing that a BMS would help maintain the life of the battery, but I also am guessing that if I had none, it would probably still be fine, as long as the charger was at least a little sophisticated.

Also, I imagine that with the 4hp motor, it may draw 100 amps (and maybe up to 300 per the motor) but unlikely. At that rate, I would think that the battery will need no cooling and should last a very long time. I would mow for maybe an hour or so, max, each week.

Also, if this battery would be very oversized, is it worth investigating any NiMH options (like from a prius) or would any vehicles besides the Volt yield a 48V battery that might be lighter and smaller, and obviously less cap[acity, but maybe still enough.

Piotrsko, I have read a bunch of your Chevy Volt battery stuff. Complicated, but very interesting.

TIA, Richard


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## stifflkd (Feb 3, 2013)

I have converted a 48" commercial walk behind to electric a few years ago. Best to go Li ion. Lead acids are too heavy and lack the capacity.
Try this guy (Nick)

http://evbatterycenter.com/HAC4/ind...ashop&view=category&layout=listing&Itemid=680

I have no affiliation but he can offer a package of Leaf batteries with BMS either as a DIY or package. Don't leave off the BMS. Even with a smart charger the BMS will balance/bleed the individual cells.

As for a motor take a look at the Motenergy ME1004. It uses a 1" shaft that is standard on most lawn tractors so you should be able to use the same pulley. The motor also spins at 3600 rpm @ 48V which matches closely to the originl ICE specs. Add a simple contactor and you should be good to go.

Assume you'll be drawing 100-120 A on average with rider, blades engaged and moving at a comfortable speed to determine your run time.


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## merkurmaniac (Dec 25, 2016)

O.K., so now I am proceeding with the plan. I have bought the Motenergy ME-1004 motor and also a 48V module from a Chevy Volt. It is supposed to be from a 2016 model year car with 7,000 miles on the clock. Its supposed to come with the original BMW wiring on it. So far, I am in about $1,000 and don't want to screw this thing up.

Two items on the shopping list then, are a contactor and a charger. 

I'll also need a set of guages. I was considering this:

https://www.amazon.com/gp/product/B01JOUZELG/ref=s9_acsd_simh_hd_bw_b1402d_c_x_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-3&pf_rd_r=HZ65HCX69Y6E6ZY0YXE4&pf_rd_t=101&pf_rd_p=47595890-73ad-5d76-bb3a-a9a9c076405f&pf_rd_i=15729811 but it only has a 100amp shunt. I don't expect that the motor will be pulling a whole lot more than that, as I have no hydrostatic transmission on this mower. I have just belts and a friction disc type variable speed transmission. Will the 100amp limit on the shunt mean that it'll burn out if I exceed that, or is that likely a continuous duty rating ?

For a charger, the battery seller suggests limiting the voltage to 49.5V to help the battery life. I DO expect that my entire system will be grossly oversized, in terms of battery capacity. Run time to mow my lawn will be only about 20-30 minutes a week. Was considering a mechanical timer in addition to any electronic timer, e.g. have a 6 hour mechanical limit, that would not let the battery charge longer, but that's the mechanical engineer in me, thinking of a mechanical timer in addition to a limit on the electrical side on the charger.


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## merkurmaniac (Dec 25, 2016)

I posted an update to this thread, but I think it required moderator approval. Perhaps because it had a link to an electronic circuit board on amazon ?

This is a test post, then, of sorts.


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## merkurmaniac (Dec 25, 2016)

Here is the update then, it looked like that last post went fine, so I'll update again. I didn't want to type a bunch and have it go into the ether for ever.

I have been doing a ton of reading, and some buying. I have bought a ME-1004 electric motor that I plan to run at 48V without a controller. The mower that I will use is a rear engine snapper. It has a continuously variable friction disc transmission, so no hydrostatic drive to consume power. Sitting at idle, I expect that it will consume very little power, as it will just be spinning some pullies, and not much else. 

The battery that I chose is a 48V module of a Chevy Volt battery pack. I think that it should have tons of extra capacity. The battery arrives tomorrow and is from a 2016 Volt with 7,000 miles. I am thinking of running without a BMW, for the time being. I plan to slowly charge it, like maybe at 600watts. It'll run about 20 -30 minutes, then have a week off to charge.

I am leaning towards a meanwell RSP-500-48 power supply and a DROK CCCV charge controller device that I saw a guy using on youtube.

I am trying to figure out what kinds of other devices I'll need to safely control the mower. I think that I will need a contactor, and I'll likely retain the 12V battery to power it. It seems like a big pain, perhaps I'll have a transformer to let down 48V to power the contactor, since my current 12V battery is failing and it seems like a waste to buy another, just to have it close the contactor.


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## dh1 (Dec 21, 2015)

You could use a 48volt contactor and a manual battery disconnect with a fuse just for safety.


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## Duncan (Dec 8, 2008)

Hi
One of the nice things about the Volt battery is that it has quite a linear charge/voltage graph

This means that you can charge and discharge to a voltage and be quite safe
(Most other lithium ion chemistries are effectively flat on the charge voltage graph so that you need to track charge to see where you are)

I'm charging my pack to 4.05v and discharging to 3.5v
For your "48v" pack that would be 48.6v to 42v

For your use you could be more conservative

This means that all that you need is something to switch your charger off at that voltage

And a voltmeter so that you can stop before you go too low

As far as balancing is concerned I an very very bad to my pack and it is still staying balanced!

About half way down page 48 of this thread is a really easy and neat way to check your batteries balance

http://www.diyelectriccar.com/forums/showthread.php/2012-chevy-volt-battery-93101p48.html


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## merkurmaniac (Dec 25, 2016)

One thing that I am considering, is having the original metal snapper ignition lock, operate the contactor. It had a run position, and a start position. I think that I'll just use it for the run position, to power or kill the system. What concerns me is that the key may then have 48V going thru it. Is this dangerous or painful to a wet/sweaty users hand ? 

I have now bought a big manual disconnect, the "big red button". So I'll have that. Also a fuse, the contactor, and I imagine a shunt for an ammeter too.


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## dh1 (Dec 21, 2015)

You might find 1 side of the key switch is connected to the tractors frame.


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## merkurmaniac (Dec 25, 2016)

I have uploaded the tractor wiring diagram. It appears to me that the ignition switch has 3 positions.

OFF = circuit "M the ignition ground is connected with the BODY and with an engine ground. This grounds out the ignition and kills a running engine. I got that much.

RUN= nothing connected or explicitly disconnected

START=Power to solenoid to crank the starter motor.

===================================
For my "modern" usage, I'd like the key to close the contactor. I'd like the seat switch (NC when off seat) to be a permissive that must be met for the contactor to close. So, to me, with a mechanical engineer brain, I'd think of it like in the OFF position, some device is grounded, and in the RUN position, that device is no longer grounded. I have a bunch of standard automotive relays that have NormallyClosed and NormallyOpen pins on them... Is a creative arrangement of relays what I am looking for ? I am not sure how to control this circuit ...


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