Here is a short-form spec for an initial product, a replacement for the existing stock rectifier/regulator. I have included few of the technical considerations which have driven this specification, even though they might be helpful for those who wish to suggest or contemplate alternative systems. This is for clarity; the considerations and choices are open for discussion.
I would like to keep this thread about features, rationale, and related issues. I do not mean to shutdown discussion about why this performance is possible or impossible. I just don't want to mix such technical exchange with the product definition process. (This is just a request, not a futile grasp for power!) Thanks in advance for assistance with determining features.
An Intelligent Power Management System for V-Stroms, Design Spec
The R/R unit is replaced with 2-3 physical modules, described as follows.
Physical Aspects, Placement and Interconnection
The "Vital Power Module" (VPM) mounts where the old R/R was, and has a slightly larger area heatsink, shaped to fit in the space vacated by the V-Strom stock R/R. Cables and connections are:
1. (Input) recepticle for 3-phase magneto power
Connects to 3-wire stator cable plug.
2. (Output) plug for output B+ and return
Connects to 4-wire fused battery cable recepticle.
3. (BiDir) varying "high" voltage ("VHV") output and I2C communication bus
Connects to the "Auxillary Power Module" via a cable.
4. (BiDir) varying "high" voltage output and I2C communication bus
Connects to a future "Boost Power Module" via a cable.
5. (Output) Generation subsystem status cable
Connects to a tri-color LED
mounted somewhere visible to rider.
The "Auxillary Power Module" (APM) is mounted inside the fairing, on the left or right side, to the steel tubing which is part of the frame, (where there is airflow when the bike is moving). Cables and connections are:
1. (BiDir) varying "high" voltage input and I2C communication bus
Connects to the "Vital Power Module" via a cable.
2. (Output) 12V headlight power cable
Connects to fusebox via 2 plugs replacing both headlight fuses.
3. (Output) 12V custom power recepticle
Connects to moderate power loads not present on a stock bike.
4. (Input) a plug for an optional push button switch input
Connects to an optional push button mounted wherever customer likes.
Sometime not long after the VPM and APM have been developed, a "Boost Power Module" (BPM) will exist which can be mounted similarly to the APM except on the opposite (right or left) side of the fairing. Cables and connections are:
1. (BiDir) varying "high" voltage input and I2C communication bus
Connects to the "Vital Power Module" via a cable bussed also to the APM.
2. (Output) 12V custom power terminal block
Connects to higher power loads not present on a stock bike.
Functional Partitioning and Capability
The VPM is able to supply 150 Watts steadily to the bike DC bus, more than enough to supply the engine's loads (pump, fan, ignition), operate signal and running lights, and recharge the battery after engine starts. It normally does not supply enough power to the B+ DC bus to additionally operate the headlights or heavy custom loads (such as heated gear). It will readily handle several added low-power consumer electronics loads (such as a GPS or phone charger.) It will recharge the battery and supply the loads it has at 250 Watts until it thermal monitoring system requires output to be trimmed back to the 150W level. (In cold weather at highway speed, when combined with the APM output as it powers only high or low beam headlights, this will make 500W available to power the bike and custom loads.)
The VPM is responsible for optimizing the voltage level of the VHV DC bus to maximize available power when load shedding is in effect or nearly so, or to minimize stator heating stress when no load shedding is close to necessary. It effects this control by commanding the APM (and BPM if installed) whether to shed (or how much to reduce) their loads and by varying the battery recharge rate when it needs charging.
The VPM is responsible for monitoring the battery charge state, getting it charged if possible, and avoiding overcharge. It will have a strapping option to manage a LiFePo4 battery instead of a conventional lead-acid battery. (End-of-charge voltage and voltage versus temperature vary with chemistry.)
The VPM will drive a tri-color LED to indicate conditions likely to be of interest to a non-technical rider (who may be far from home). These conditions will be encoded as follows:
a. Starting: blipping red/green/amber cycle, at crankshaft turn rate
b. Idling, if battery discharging: repeating red/amber/green/blue slide
c. Idling, if battery recharging: repeating blue/green/amber/red slide
d. Idling, if battery charged: repeating amber/orange/red slide
e. Running, some loads shed, battery not depleting: green with amber blips
f. Running, no loads shed, battery not depleting: steady green
g. Running, battery charged but depleting: red/amber/green slide
h. Running, battery mid-charge but depleting: amber/green/blue slide
i. Battery depleting, nearly discharged: green/blue slide, lingering blue
j. Subsystem failure detected: blinking red (conveying a failure code)
Other useful indications may be added over time. This scheme needs more work. As a routing convenience, this indicator might move to the APM.
The APM receives power via the VHV bus from the VPM and communicates with it to effect the system behaviors described next.
The APM can supply 250 Watts total to the headlights, its custom power recepticle, and (when those do not need that much power) to the B+ DC bus (under control of the VPM).
The APM may, as necessary to avoid battery depletion, shed any load connected to its custom power recepticle by turning it off. It will, when possible without depleting the battery, turn the recepticle back on. Load shedding is under the control of the VPM; the APM just effectuates it. This shedding will definitely occur when ignition is on before starting and during starting.
Before and during starting, the APM will depower the headlights. (This provides most of the benefit of a headlight relay.)
The APM headlight output will be current limited to protect against momentary high current faults which can occur during incandescent lamp failure. It may pulse such a fault if it persists, to promote clearing it and allowing the other headlight filaments to be repowered. Such pulse currents would be drawn from the battery (from the fuse block connection).
When the headlight fuse block outputs are first powered by the APM, the power level will be brought up over a 100-200 millisecond interval to avoid having to supply incandescent inrush current and to prolong lamp life. Headlight power will be supplied at 12.5 Volts, regardless of battery level, unless the VPM calls for headlight load shedding, in which case the power will be supplied at 9 to 12.5 Volts. (This will happen only when idling for several minutes, when there is not enough power available from the stator to run the engine and headlights at full voltage without depleting the battery.) Should the bike be idling so slowly and for so long that this moderate load shedding is not sufficient to avoid depleting the battery, the headlight voltage will be reduced as necessary to keep the battery from being fully discharged.
The APM will provide a secondary "remote voltage sense" through its fuseblock connection to the B+ DC bus, to help the VPM manage battery charge state accurately without error due to load-driven I*R drops. (This function will be interleaved with providing power through that connection.)
The APM will have a strapping option to make the optional push button command toggling of headlight modulation. If the switch closure is prolonged, it will be interpreted as a modulation enable, to be ended when the switch reopens.
The Boost Power Module (BPM) will be an optional add-on (when it exists). It is not necessary for stock bikes having less than 250 Watts of custom loads. It is intended for heavy added power loads, such as fully heated clothing, perhaps for more than one person. (The BPM is agnostic as to what the custom load is, as long as it is well behaved and does not draw more than 250W.)
The BPM receives power via the VHV bus from the VPM and communicates with it to effect the system behaviors described next.
The BPM can supply 250 Watts to its custom power terminal block when engine speed is in the cruising range, above about 4000 RPM.
The BPM may, as necessary to avoid battery depletion, shed any load connected to its custom power terminal block by turning it off. It will, when possible without depleting the battery, turn the recepticle back on. Load shedding is under the control of the VPM; the APM just effectuates it. This shedding will definitely occur when ignition is on before starting and during starting. It is also likely to occur when engine speed is below about 4000 RPM. The BPM's custom load has the lowest priority during load shedding.
The BPM will detect current overload faults at its custom load terminal block and respond by turning it off for that session, until the engine stops. The fault will be signaled as an error code to the tri-color LED.
The VPM and APM together will likely cost about $140 retail.
The VPM and APM individually (as spares) will cost a little more.
The BPM will likely cost about $110 retail.
Neither of these figures is a commitment and may change.
The VPM+APM will comprise a 500 Watt DC power source for V-Stroms which substantially reduces thermal stress in the magneto stator, while providing intelligent power management to avoid problems associated with power usage near the limit of available power. Bonus features, such as elimination of start switch metal migration, headlight modulation, and battery status indication, should help justify the system's cost increment over simpler, more power limited rectifier/regulator solutions.
The VPM+APM+BPM will comprise a 750 Watt DC power source for V-Stroms under cruising conditions, while gracefully falling back to VPM+APM performance at engine speeds too low to permit 815 Watts to be drawn from the magneto. This power delivery will occur with stator winding temperature rise held to 2/3 of what occurs with a shunt or fully loaded series R/R.