Last night (after sunset) we were able to breach the harbor mouth under new power.
In the pics you can see the vintage Minn Kota that powered V1. Tiny motor, tiny prop. Next to that is a big upgrade courteously of a Masterguide bow mount.
(note: I apologize for the pictures. My Nexus 5X is finally giving up the ghost after a very hard life. It was an excellent phone.)
Both of those motors are 12V rated… but obviously the one on the right is capable of putting on a better performance.
We picked up a bow mount Masterguide (remote control steering and all) for $26 at the Fleamarket. It had a bad steering gear box and trouble with the PCB board.
No problem… all we wanted was the lower unit. We disassembled it, along with the vintage Minn Kota, and put something new together. The Minn Kota donated only the mounting hardware. Control is handled by a 300A AXE controller.
This is a progress pic (of course that stuff needs to be ocean resistant…) but in it you can see the basic layout:
Battery: 6S 6P 35C Hobby King packs. This works out to 22.2V @ 18Ah so capable of 20KW burst and almost 1kA.
Controller: AXE 300A controller capable of 16V to 60V… so Ebike battery compatible.
Throttle: Zero pulldown 5K Magura. Note that you need to configure this to run 5K to 0K (to avoid WOT on a disconnected throttle) and be sure to enable the interlock on startup (wont run until it sees 0% on the throttle). Take your time with the Magura and make sure you get a clean 5Kohms to 0ohms… they can be calibrated and many people change the output range to match a standard 1.2V to 4.2V hall throttle.
Wiring: Coming out of the lower unit were 4 wires… the heavy RED and BLACK are direct motor connections. The Green and Blue can be ignored as they go to a mosfet pack that we wont be using. (The AXE controller handles all our PWM needs)
We connectorized everything up with Anderson PP45’s in parallel (2P can handle 100A continuous into 10AWG) and SB120’s… which are rated for 240A @ 600V. Balance taps are paralleled at the cell level using MethTek parallel boards. Currently there is no BMS in the system, we are working on that.
As a rule of thumb… doubling voltage quadruples power. In this case we doubled voltage and sized up the prop considerably… leading to a huge performance increase. The speed and acceleration is night and day. We will grab some GoPro video some time this week.
V3 will be a Gen 4 Sevcon along with a 75-7… but that adds all sorts of complexity that we are not in a position to tackle yet. Prop angle, waterproofing, steering….