The Sparrow's 12 Vdc voltage drops out a lot under load, due to poor wiring:
- cheapo fuse box
- wires are too small
Corbin tried to improve the situation by increasing the DC-DC converter voltage, from 12 V to 13.5 V, and even 15 V!
That made things worse, not better: for a given power, a higher voltage means lower current.
The result is that, for example, when opening the left window, the voltage at the right window dropped from 13 V to 10 V!
I restored the original 12 V output on the DC-DC converter, beefed up the ground and positive wires, and used a new, separate fuse, between the DC-DC converter and the ignition key.
- I removed the resistors on the DC-DC converter that were used to increase the output voltage from 12 V to 13.5 V
- I fed the ignition switch directly from the DC-DC converter, through its own 30 A fuse on a wire mounted fuse holder (instead of feeding it from the 30 A fuse in the fuse box)
- I used 8 AWG wire in crucial portions of the 12 V dc wiring (I could only get black wire, so I used yellow and green colored tape to clarify that the wires were +12 V and ground respectively)
- Negative: from the start point ground in the motor controller compartment, to the DC-DC converter, to the green wire that was formerly connected to the DC-DC converter (as close as possible to the 14 AWG common ground bus green wire), and to the green ground wire under the dashboard under the radio.
- Positive: from the DC-DC converter, to the yellow wire that was formerly connected to the DC-DC converter (as close as possible to the fuse box), to the ignition switch white/red wire through a 30 A fuse
Connections to 12 V DC-DC converter
Connections to star ground in motor compartment
Connections to ignition switch
Now, when opening the left window, the voltage at the right window drops only 0.5 V.