Imagine:   Totally pollution-free transport.
We've had so many people call to discuss charging their Gorillas on alternative energy systems, that we've decided to put this webpage together to answer many of the questions.

There are dozens of Gorilla owners on solar, and a few on hydro and wind power. 
A few brag that they have never plugged their Gorilla into "the Grid."

 Sun Bathe, Sun Fed - feels good !

Charge your Gorilla from Solar/Hydro/Wind Charge directly from alternative energy systems, for pollution free transport. Click on picture to see the Solar Charging Port Look closely -  next to the 110-v electrical plug. "Anderson" quick disconnect for solar, hydro, or wind charging of electric vehicles. Only $49. (installed, with in-line fuse, and mating connector w/6' of extra cable)

Adventures with a Solar Powered Lawn Tractor by Christopher Zach compliments Home Power 4-page feature article in Home Power Magazine Issue 96, Aug.-Sept. 2003 available at www.HomePower.com

 

TABLE OF CONTENTS FOR TOPICS BELOW: Difference between Power and Energy ? How much power does it take to run a Gorilla ? How much energy does the Gorilla carry ? Energy per mile of travel ? Expected Gorilla range ?  Do the math.  It's not rocket science. What to expect from your solar system ? Taking efficiencies into account (a.k.a. inefficiencies). Wind and Hydro Systems ? What is an Anderson Connector ? Misc. Topics (charge regulators, power-point tracking, lightning arrestors)

"From batteries at 50% discharge, it takes 1.28 KWh and 5 hours to recharge and equalize." graph and data compliments of Dave Brown, 24-volt Gorilla owner in Wisconsin

Difference between Power and Energy ?
 

Power - is the rate of doing some useful work, like "powering" a car on a level road, or up a hill. It takes power (about 60 horsepower for a normal car)  to propel it up a 6% grade at 40 mph. (variables include:  weight of the car, grade, speed, rolling resistance, drivetrain efficiency, etc, etc.) Power is an instantaneous measurement.  It takes so much power, at one instant in time. Less of a grade, less instantaneous horsepower required.           More speed = more horsepower required. Watts are the electrical units or measurement of power. Seems so simple:  Power = volts X amperes  equals so many watts               Again, an instantaneous measurement.

A SUV uses more power sitting at a traffic light, than a Gorilla uses at top speed.       Watts

Energy -  The amount of power expended over a period of time. If it took one hour to climb that grade using 60 horsepower, we could say we used 60 horsepower-hours.  (60 hp X 1 hr) Watt-hours are the electrical unit or measurement of energy. A 100-watt light bulb, used for one hour, uses 100 watts X 1 hour = 100 watt-hours         or  divide by 1000  = .1 kiloWatt-hours  $    Your utility company charges   $ from under a nickel, to over 15 cents per kilowatt-hour.   In Southern California, at 12.8 cents/kilowatt hour - That 100 watt light bulb (.1kW), used for 1 hour, would require  .1 kilowatt-hour of electricity, costing about 1.28 cents. Used for one day:   (.1kw X 24 hours X .128cents/kw-hr) about 31 cents. That's $9.22 per month for a single 100 watt bulb.  Ouch!     "Bubba Junior, turn off that light."

F.Y.I. 60 horsepower-hours = 44.7 kiloWatt-hours   We buy electricity by the kilowatt-hour because watt-hours are such a small unit of measurement (to people that don't make their own energy). Washington State has very low electricity rates because they have lots of low cost hydro power. Hawaii and Maine have high rates because they buy or import most of their power; (or coal, oil, and natural gas)   "A million$ here, a million$ there, pretty soon we're talking real money"

How much power does it take to run a Gorilla ?
 

The e-ATV 24 volt  utility Gorilla, pulls about 40 amps from the batteries on level ground, at the top speed of 13 to 14 mph. Power =     volts  X    amps Power = 24 volts X 40 amps             or       960 watts  (remember ? - instantaneous) To do this for one hour ? 960 watt-hours  .96 kW-hours    ~ 1 kW-hr. for each hour of driving	F.Y.I. 746 watts = 1 horsepower   The e-ATV 24 uses about 960 watts 746 watts/hp =1.29 horsepower at top speed.
Our faster Gorilla, the e-ATV 36, pulls about 50 amps at the ~19 mph top speed.  More speed = more power	You can do the math.

How much energy  -  per mile of driving ?
 

Simply, divide         the energy usage per hour                               by the miles traveled in one hour at 13 miles/hour .96 kW-hrs    equals    .074 kW-hrs       or     74 Watt-hrs    13 miles                         mile                              mile (That's 46 Watt-hrs/kilometer.)

The Gorilla is very efficient. 2 or 3 times that of a golf cart, 4 or 5 times that of most electric utility vehicles. Warning:  Rolling resistance is a range killer.   Off-roading can use 3, 4, even 5 times the energy.

How much energy does the Gorilla carry ?
 

FACT:  The Gorilla e-ATV 24 uses three T-875 eight-volt golf cart batteries, in series, to supply 24 volts. AMP-HOUR ratings are not very useful to EV people who normally draw massive amps.  ( fortunately?/unfortunately?)  for short periods.    How much energy will our batteries hold (or supply)? This is not a simple question, because the potential supply varies with demand (amp draw from the batteries). That chemical reaction is less efficient at high amp draws. Also explains the problems with low temps. Below:  we will use the manufacturer's advertised reserve capacity to calculate ENERGY CAPACITY:

Amp-hour rating of batteries Battery manufacturers use a 20-hour test to get amp-hour ratings. a very optimistic way of advertising The T-875 is rated at 150 amp-hours.* Divide 150 by 20 hours to calculate that this battery will supply 7.5 amps. for 20 hours, or 1200 minutes. 7.5 amps X 8 volts ? that's a 60 watt draw for 20 hours; or 1.2kW-hr.

"As advertised"  RESERVE CAPACITY (data published by battery companies): *Trojan Battery Co.  **US Battery Mfg. Co. The 8-volt, T-875 battery will supply: 75 amps  for     85 minutes** 56 amps  for   117 minutes* 25 amps  for   325 minutes** 7.5 amps for 1200 minutes*  (from amp-hour rating, upper right ) ---->                                                            Energy Capacity Remember we're looking for kW-hrs.  (How much energy can we carry with us in our batteries ?) kW-hrs = amps X volts X hours (25 amps X 8 volts X 325 minutes/60min/hr)/1000 = 1.083 kW-hr (56 amps X 8 volts X 117 minutes/60min/hr)/1000 =  .874 kW-hr (75 amps X 8 volts X  85 minutes/60min/hr)/1000 =   .85 kW-hr.*                                                                                               *seems very optimistic 3 Batteries on-board - remember ? So, multiply by three to find that we're carrying about 2.5 to 3 kW-hours of energy with us. At 12.8 cents / kW-hr.  that's about 38 cents worth of "the juice."

Reserve capacity: Battery manufactures test to see how long a battery will provide a certain number of amps (before falling below 1.75 volts per cell - which is considered 80% discharged). "Batteries are the Achilles' Tendon of electric vehicles."                    A. Harry Gorilla "If we put as much emphasis into battery development as we put into the lunar mission, or our present pre-occupation with fuel cells and hyperogen, we'd all be driving zero pollution electrics by the end of the decade."                    A. Harry Gorilla

Calculated range ?  Do the math. 
It's not rocket science.

We'd like to have reserve capacity minutes at 40 amps draw.    (see data from the battery manufacturers in section above) If you try to graph these data points, you'll quickly see that  you'll get a curved line.  It is very difficult to estimate (interpolate) points between these amp draws. Let's just average between the 25 and 56 amp draws as an estimate for a 40 amp draw:               = ~221 minutes Overly optimistic ?  Would you believe 200 minutes ?       200 minutes         =    3.33 hours run time.        60 minutes/hour  3.33 hours at 14 mph, yields a calculated range of 47 miles. Sound optimistic ? We agree !  This is under ideal conditions. Accelerating, stop and go, turns, hills, rough terrain, rolling resistance, load, cold outside, old batteries, new batteries, alignment, etc. etc. We've gotten over 40 miles on a Gorilla, we advertise "up to 35" and we start asking questions, when potential customers start talking about anything over 20. In battery technology, this line is called "Peukert's Curve" It is possible to graph this as a straight line on logarithmic paper. Get Smart !     DISTANCE = RATE x TIME   Convert .62 miles = 1 kilometer or 1.61 kilometer = 1 mile

What to expect from your solar system ?
 

Lets look at a pair of 80 watt, 12 volt panels to charge your Gorilla. Total watts available:  2 X 80 = 160 watts Now, lets assume that you can get the near 160 watts from your near peak sun hours of about 5 hours per day: 160 watts X 5 hours = 800 watt-hours  (.8 kW/hrs)                Divide:     800 watt-hours                              74 watt-hours/mile                                  Yields 10.8 miles  calculated range/day

Two 12-volt panels in series, provide 24 volts.       74 watt-hours/mile (energy use per mile of driving from above) Not Bad ! Further than I want to go.

Taking efficiencies into account (a.k.a. inefficiencies)
 

Hypes & inefficiencies & realities:
1.  Do 80 watt panels output 80 watts ?	Expect maybe 80% of that an average relatively clear day ?
2.  Panel output varies with angle of the sun, humidity, temperature, etc.	Maybe 5 hours per day. More in summer, less in winter. Can be enhanced by tracking.
3.  Temperature ?	Yes, output drops if the panels are in hot sun like Arizona.  They prefer cool. Some newer panels claim to have made improvements in this area.
3.  Clouds kill the output ?	Maybe only 50% Snow really does a job on 'em though.  snowjob ?
4.  Low voltage means lots of line losses ?	True.  Use bigger wire than necessary, and short runs.
5.  There's inefficiencies involved with charging batteries ?	True.  In tests of DC input vs. DC output we've gotten as high as 90% with healthy batteries.
6.  The bottom line ?	On an average clear day, with at least seasonal tracking, you can probably obtain about 70% efficiency (for ~5 hours ?).

Wind and Hydro Systems ?
 

Hydro: The first time someone called to discuss charging a Gorilla on hydro, I asked; "how many watts are we talking about ?" He replied; "about 50" I laughed ------------------------------------------------------------>   He replied; "THAT'S 24 HOURS PER DAY" 50 watts x 24 hours:  that's 1200 watt-hrs. per day "Not Bad !"	I said: "50 watts - that's like - (chuckle/snort) spittin' in a lake."   some hydro systems run 24 hours per day, 365 days per year
Wind:	Some people have more wind than they need. Why is it so windy in California ? Because LA sucks, and San Francisco blows . (erase before publishing)

What is an Anderson Connector ?
 

Looks much different, but Anderson connectors are used like a plug and receptacle for any electrical appliance. They are designed to carry lots of amps. Anderson connectors are available in 350, 175, 120, and 50 ampere ratings.  The 50 amp size is ideal for quickly making a connection for solar charging the Gorilla. We don't like to hear about Gorilla's battery pack being charged with more than 20 amps These connectors are made from polycarbonate plastic - so tough, that you can drive over them.  The electrical contacts are so thick, that they will last years of making and breaking.

Originally designed for disconnecting the charger on electric forklifts, or to quickly "swap-out" the one large battery on-board. (the 350 amp. size) 50 amp Anderson connectors

Misc. Topics (charge regulators, power-point tracking, lightning arrestors)
coming soon