The Elec-Trak E15 Electric Tractor and PV System

This is our project to recondition an E15 Elec-Trak electric tractor.  The aim is to get the  Elec-Trak  into good enough shape for lawn mowing and snow throwing tasks as well as (hopefully) to integrate the tractor with our existing grid-tied PV system so that we can use the Elec-Trak for power during emergencies and keep it charged with our PV array.

The Elec-Trak dressed for the snow

This has been a fascinating project and I can highly recommend it.

One thing I want to make clear is that I'm no expert on Elec-Traks or on restoring them.  If any of you old hand Elec-Trak folks see any oversights or dumb mistakes, please let me know.

There is a section for comments and questions here...

I'd especially like to thank Mark Frerking  who not only wrote the article below for Build-It-Solar on the Elec-Track, but also found the Elec-Track that I ended up buying, and has also been a great source of information on rebuild -- Thank you Mark!!

I bought the E15 used from Joe in Colorado Springs and hauled it all the way up to Bozeman in a small trailer behind our Honda Pilot.  I'd like to thank Joe and son for being patient and very helpful through working out the pick up logistics, the loading, and passing on a lot of useful information about this E15.

What's an Elec-Track?

In a nutshell, the Elec-Trak tractor was a GE product in the 70's.  The Elec-Traks were a series of electric tractors and riding mowers that use an onboard bank of lead acid batteries to power the tractor and also to power a large array of accessories that GE offered.  There were something of the order of 30,000 of these tractors made by GE and the companies that GE sold the operation to.  The machines are very functional and very durable.  The Elec-Trak has developed a devoted set of followers and there are probably thousands of them running and being restored -- this is pretty impressive given that the last new one left the factory in  early 80's.  There is also an active Elec-Track online owners club and a couple of good places to get parts from. 

If you are interested in learning more about the Elec-Track, here are a few good sources of info:

An Elec-Trak description and history from Mark...

- The Elec-Trak Owners Club Online Forum...

- George's most excellent My Elec-Traks site...

- The Solar Electric Tractor and Mower section of Build-It-Solar...

I particularly like George's site -- he has an incredible collection of beautifully restored Elec-Traks.    There is also a lot of very good Elec Trak reference material on the site, including many of the original manuals.  Note also the solar electric array on the Elec-Trak barn roof!

Elec Trak E20
Mark's beautifully restored E20
E20 with Front-end Loader
One of George's many restored Elec Traks

Goals for our Elec-Trak Project

The three main goals I have for the project are:

1 - Mow the Lawn and Blow the Snow

The immediate aim is to get the tractor back into condition to mow our much too large lawn (about an acre), and also to do some of the snow plowing chores in the winter.  The tractor came with a mower deck, a front mount blade, and a 42 inch snow blower as attachments.  Until recently, the tractor was being used, so I'm starting from a pretty good base.

When I got the Elec Trak, the battery pack had about had it, and there is quite a bit of rust to clean up, and a few things to fix.  But, I had the advantage of starting with an Elec Trak that had until recently been used. 

Here are the details on putting a bit more life in my E15:

- Cleaning up the rust, painting, ...

- A new set of batteries and cables...

- Fixing a few things...

- The new charger/inverter... 

- The snow blower and mower deck...

One reason we would like to move to a solar electric mowing and snow blowing solution is that gasoline powered mowers are surprisingly heavy polluters.  They do not have catalytic converters and their emissions of unburned hydrocarbons, oxides of nitrogen, particulate matter, and carbon monoxide are quite high.  So, switching to solar electricity  for mowing and plowing has more of an impact on air pollution than you might think.   The pollution estimates vary, and will be coming down some as new EPA regulations go into effect, but any way you slice it, mowers are a large source of pollution.

2 - The New Charger/Inverter  (and Solar Charging the Elec-Trak)

My initial goal was to have a dedicated solar array and charge controller to charge the Elec-Trak batteries.  This seemed like a nice clean solution, but the more I thought about it, the more it appeared to make more sense to just charge the Elec-Trak from grid power and to expand my existing grid tied PV array to cover the extra Elec-Trak energy usage.  This way the PV panels can be active all the time, instead of dedicating PV panels to the Elec-Trak that would only be used a small part of the time.  We have been planning to expand the PV array anyway, so this just makes the expansion a bit larger. 

Details on the new charger/inverter...


The charger/inverter charging the Elec-Track from 120VAC.
Elec-Track portable power 
The same charger/inverter mounted to the Elec-Trak
and providing 120VAC out in the field.

So, to charge the Elec-Trak battery pack, what I did (instead of a solar charging setup) was to buy a combination charger and inverter from Tripplite.  The charger part of this heavy duty unit  will charge the 36 volt Elec-Track battery pack from a 120VAC outlet.   Or, out in the field, the inverter part will provide 120 VAC for tools etc from the battery pack.   It will also provide some power for the house in power outages (see below).  

Normally, the charger/inverter lives in the garage next to the Elec-Trak parking spot, and charges the Elec-Trak after use using a disconnectable cable.  When power is needed out in the field, the charger/inverter mounts to the back of the Elec-Track (as in the right picture) and comes along to provide 120VAC from the battery pack.   

This worked out particularly well in that the charger that comes with the Elec-Trak was missing on mine.

Details on the charger/inverter...

3 - Integrate With Current Grid-Tied PV System for Emergency Power

We currently have a grid-tied PV system that works well and that helps us offset some of our electricity consumption.  But, as with all grid-tied systems that do not have battery backup, when the grid power goes down, our grid-tied PV system also goes down -- so, no power from PV in power outages.

My aim for an extended power outage is to use the Elec-Trak battery pack with the new Tripplite charger/inverter to supply power to the house,

To recharge the Elec-Trak battery pack, I am using am reconnecting some of the PV modules in our grid tied system to feed a regular PV system charge controller to charge the Elec-Trak battery pack during the day.   After the power outage, the PV modules are restored to the normal grid-tied configuraiton.

The battery pack will supply about 5 KWH of usable stored energy, and this is  enough to supply a few key loads via extension cords for an extended power outage.  The loads include fridge, a few efficient lights, the furnace, and a few other odds and ends like a laptop and small TV.    To charge the Elec Track battery pack, six of the PV panels in our existing grid tied PV array are reconnected to feed an Xantrex MPPT charge controller.  This provides enough power to fully recharge the Elec Trak pack on a sunny day, and to provide a good charge even on a not so sunny day.

Back when we put in the original PV system, I thought about putting in a grid-tied with battery backup, but the added cost of the fancier inverter and a battery pack plus the long term cost of maintaining and replacing a battery pack just seemed not to be worth it.  This is especially true given that our power is reliable, and the battery pack would just be sitting there doing nothing 99.9% of the time.   Putting the Elec-Trak battery pack into service for backup power is really appealing to me in that its a battery pack that is already earning its keep with lawn chores, and this is a chance to let it take on another job without adding more battery pack expense and maintenance. 

Details the emergency power scheme and the first test results here...


Elec Trak ready to be charged by PV
elec trak pv charge controller
The Xantrex Charge Controller
and fused disconnect below.

Its cloudy, but still getting
286 watts of charge. 
Sunny conditions charge
should be over 1200 watts.
elec trak emergency solar charging
The charge controller, cables, etc.
ready to go back to the barn
where they live between
power outages.

Comments, Questions?

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December 13, 2011