Testing the mower proved to be more difficult then I had anticipated. Wouldn't you know it, the only time I have ever been excited about mowing the lawn and it rained for a week straight? I did manage to get some tests done in my garage and even mowed a little grass when the rain let up.

Reserve capacity test:

I bought the Sun Xtender deep-cycle PVX-420T over two years ago and have never used it. The manufacture recommends running this test if the battery has gone unused for over 6 months. This test is used to insure the battery is capable of providing the necessary capacity to perform properly. After the battery is fully charged (12.7V) you are suppose to discharge the battery at 25 Amps in till the voltage reads 10.5. Luckily the mower pulls 25 Amps when running (not cutting). So I turned it on and timed how long it took to go from 12.7V to 10.5V. This ended up taking well over an hour. The PVX-420T was rated to do this in 61 minutes. So the battery past this test with flying colors. If it would have taken 49 minutes or less the manufacture recommends replacing the battery.

Fifteen minute mow test:

I was anxious to get out and try the mower so during a break form the rain I did just that. The wet grass didn't provide ideal mowing conditions but I will take what I can get at this point. I measured the battery voltage to be 12.5 (about 90% capacity) prior to mowing. I had the mower deck set to the second to highest position and the grass was moderately long and wet. I watched the ammeter while mowing and it was pretty consistently pulling 45-60 amps. I mowed for about fifteen minutes (about 1/3 of my yard) and when I finished the battery voltage read 12.25 (about 60% capacity). Not bad considering the grass was wet. I figure that in ideal conditions (moderately long dry grass) the mower should pull between 40 and 50 amps. At that amperage the 40 amp-hour battery should last about an hour before becoming completely discharged. Completely discharging the battery is not good for it so I will only run the mower for 45 minutes which is about how long it takes to mow my lawn. This should leave the battery at about 11.75 (about 30% capacity).

Testing the charging station:

Once again the rainy weather did not provide the ideal conditions for testing the solar panel charging station. Therefore, I had to use a battery charger to recharge the battery to a safe level. I used the 2 amp setting on the charger. This gives the battery 2 amps at a constant voltage in until it reaches about 80% (12.4V) capacity. It then starts to vary the voltage and this is not good for the battery. At this point I take the battery off the charger and plug it into the solar charging station. In a full winters day sun it raised the battery from 12.4V (80%) to 12.5V (90%) so I know its working. I plan on using the charging station at greater lengths when the weather allows me to do so.

Over all I really enjoyed completing this project. It was a lot of hard work but most things worth doing are. In retrospect there are only a few things I would change. First, I would find a mower that could be easily disassembled or at least able to be disassembled. This would save time and labor on the fabricating portion of this project. Next I would invest in a larger solar panel, at least 50 Watts this would allow the battery to be charged quicker and require less sun between mows. I would have also use a breaker rather then the switch I installed or mount a fuse between the battery and motor. This would help to make the system safer and protect the motor if the amperage rose to an unsafe level. Besides that the mower runs great and I'm looking forward to quiet pollution free mowing from here on out.

If you have any questions feel free to e-mail me at createfreedumb@hotmail.com

Jeremy James