I need an automatic way to recharge my boat battery, and don't have power down at the dock. Self starting generators are super expensive, and I had a spare alternator for my Mercedes. Decided to try and make my own after a near-sinking incident when the bilge pump killed the battery. Unit is small and cool enough to be mounted in the engine compartment to run the 1500W stereo all day as well, after I find a way to vent the exhaust.
Bosch AL0789X 150A Alternator
Search "mercedes (320,430,500) alternator" on eBay. Other alternators may fit if they have the same mount points and pulley dimensions. The 115A Mercedes alternator should fit, but I haven't tested.
Wingsmoto 49cc Electric Start Engine
These are common Chinese 49cc engines, available from several suppliers under various brands.
ANNIMOS 20KG RC Servo
Other servos should work, but code will have to be adjusted for their response curves.
K&N 62-1360 Vent Air Filter
1/4" Aluminum Plate
For the base plate to bolt the mounts to. Wood may work if you don't plan on using it anywhere wet.
to make the servo to throttle linkage
Nuts and Bolts
+ 2x M5 washers forgot in that order.
Control board will be posted on OSHPark with DigiKey or Mouser cart when it's finalized, and source code on Github.
Only the engine/alternator mounts and coupler are necessary if you just want a 12v generator without self starting. The engines are available in electric+pull start or pull start only. Tune the throttle manually for your load level. That's how I'm running it at the moment, but with a servo tester to manually control throttle.
Base plate is not meant to be printed. I cut mine with my waterjet. Print a single layer on your aluminum to use as a drilling template.
Printed at 270C on 110C Garolite bed, with enclosure heated to 70C to prevent warping.
0.4mm nozzle, 0.2mm layers, 5 shells, 7 top/bottom layers
Other materials may work, but need to withstand somewhat high temperatures. Remember that the structural parts are transferring up to 2100W of energy. Of coarse, PEEK, Ultem, or DMLS would be even better if you have a machine that can print those things. I'm working on modifying my printer.