Battery Choices

The prototype Coot was not altogether perfect. Let me tell you about my first ride with Molt in April 1973. After towing it to the airport and unfolding the wings, he had to remove the battery and its box from under the front deck hatch, just to adjust the chain on the electric gear retraction motor.   After that he had to reinstall the battery and hook up the cables again before he could start the engine.   However, there was poor electrical contact, so the starter wouldn't engage.   The battery had to be fiddled with again.   This didn't enhance my confidence as a potential Coot-builder.

 The problem was that Molt had put the battery in the wrong place. Not only was it extremely inconvenient to have to remove the battery and its box and cables every time he wanted to check the finicky gear drive chain, but the same issue applied every time he wanted to bleed the brakes or check any of the instruments. Also, the length of the cable from the battery to the engine starter was unnecessarily long, adding extra weight and voltage drop.   It would have been far better to balance the aircraft properly through engine location than have to rely on balancing the plane by putting the battery so far forward.   The right place for the battery is in the baggage area, perhaps behind the passenger seat (to partially balance the pilot when flying solo) with nice short leads to pylon-mounted relay switches and to the engine starter.


Another battery question might be: what type would be best for a Coot?   Some builders invest many dollars in a fancy aircraft battery, such as a Gill.   Others choose to have a 24-volt system, so they install two massive Die-Hards.   The weight of these systems varies a lot, and can range up to 100 pounds.   I prefer to save both weight and money by purchasing a little tractor (U1AHP) battery every 3 years or so from Batteries Plus. They weigh only 18 pounds and cost ~$25.   It's hard to beat lightness and low cost. When I used to park Harvey outside, a flexible solar panel kept him charged, but now that he's inside, I just give the battery a slow charge every 6 months or so.   Of course, Harvey doesn't need his battery very much, just for engine starts and for the radio during takeoff and landing.


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