- Regulator ramps up slowly
- Will auto-size, including re-triggering when the RPMS have changed substantially
- Regulators to Voltage, Amp, and/or Watts as configured.
- AND - key here: Exits Acceptance phase when the battery is actually FULL as indicated by Amps, not time...
ASCII communications is working well, I added a "RTS;" string to indicate the regulator is resetting either due to a recoverable fault, or in response to a change to the regulator EEPROM saved configurations.
Two areas not tested / fully debugged:
- Dual regulator synchronization and communication.
- Temperature probes - I am not happy with the assemble method for these NTC probes.
- Bluetooth - More thought need to be put into the initialization of this device.
I also am not happy with some of the hardware design elements, specifically the following subsections will need to be looked at more closely:
- Use of Zener Diodes for clamping input voltages (as opposed to discrete Diodes). They show an impedance that impacts high impedance lines (ala the NTC probes)
- VBat pre-scaler - Also an impedance issue on both the INA-220's and the raw Atmel A/D.
- Amps pre-scaler - Already noted, the INA-220's have a max voltage limit of 28v, so will need to use gnd based shunt, or do some pre-conditioning for allow for a high amp shunt.
- Switching power regulator. I am getting issues with I2C noise and faults whenever I start the main engine, and am thinking it might be related noise coming in via the Enable line.
- FET Driver; The current chip is working well, but will be a bit stressed when doing Equalization on 48v systems.
I have ideas for each of these:
- Return to clamping diodes instead of zeners - might have to use SMT parts due to PCB space though . . .
- There is an improved version of the INA220 called an INA226 with higher Vmax and better resolution on sampling. I MIGHT be able to get away using resistor dividers using it, but in worst case will need to add perhaps an op-amp pre-scaler. In any case, I am thinking of abandoning the switching ckt for the prescaler, as well as the RAW A/D sampling and just go with a fixed ckt to cover the whole voltage range.
- Already looking at adding an AD8217 as a level shifter for the Amps shunt.
- Need to scope the power-supply ckt, but one improvement idea I have is to use the Enable pin as a true Enable driving say a FET and relocate the LM5008's power source to the Alternator Alt+ line. I figure with the heavy cables this will be much cleaner - and I can apply effective filtering to the Enable line driving the FET much easier and at lower cost than trying to filter out Enable based noise feeding the switching supply directly.
- Will look at other FET drivers - am going to have to break down and add an external charge pump though :-(
I also need to consider to keep the largely through-hole PCB design, or give up and switch over the SMT parts. I am finding the Through-hole parts harder to locate, some parts not even available anymore, and at times more costly... Have been looking at toaster-over and electric fry-pan approaches to reflowing small batch SMT boards :-)
OK, will likely lose internet connection for a few weeks - but this code-drop will give some hope to those who case!