“The lump” – Engineering Prototype Preliminary Evaluation
In the fall of 1997 I got my first GPS receiver, an Eagle Lorance, for around $130 which was well within my toy budget and became hooked. I soon realized that it was an ideal accessory for off-road use on my Kawasaki KLX300 while exploring trails and riding dual sport events. Shown is a picture of my KLX at a ride last year in GA. Note the Garmin III in the homemade handle bar mount.
With the acquisition of a ’96 BMX GS R1100 in the spring of 2000. For this bike my homemade kludge simply would not do. So a Touratech mount was purchased – fine German craftsmanship to match the bike. In fact the mount looks like a very expensive prototype made in a fully equipped model shop so at $89 I consider it a bargain.
After using a GPS receiver for a number of years several problems became apparent:
To address the problems noted above it is apparent that an accessory power module was needed that had the following features:
After studying a number of different power source options it was decided that perhaps simplest was best. Two basic design architectures were considered:
Initial investigations into a single cell system showed that the voltage multiplier circuitry would be two expensive and inefficient to justify the lower cost of the Nicad cells. Therefore it a multi-cell system was selected.
For the Garmin III eight to ten cells are needed. Prototype 1 uses 10 cells and the planned prototype 2 will use eight cells. The 10 cell model gives about 70 minutes of battery backup when fully charged. The eight cell model will obviously be provide less backup time but will have the advantage of smaller size and lower cost.
The pictures below show Lump1 installed on my KLX300. Note that the view is looking straight down with the headlight assembly’s upper restraint removed and folded forward. The Lump consists of a cutoff Garmin power connector to a heat shrink package that houses the welded Nicad cells, bridge rectifier, zener and series resistor. The ends of the package are folded over to provide some “spring” tension so that the tie wraps don’t become loose.
The blue crimp go to the headlight wires but in this case I already had a power module in place so I connected to those wires which go to the headlight connection.
View from the Pilot’s seat: