PD or Iota for my upgrade?

westend wrote:
Would it be possible to add additional CRC on a separate board to increase capacitance? You seem knowledgable on a component level so this would be an easy upgrade. Without knowing the circuit, it would seem to be doable if inrush current could be handled. Thermistors?

I noticed that the board has room for three large input capacitors, and that's what's shown in the patents. There are only two on there - the third space is there, but it's empty. I suspect cost cutting and "good enough" is the reason, although perhaps they found better/larger caps. It's one area I'm looking at - but I may add the last cap. Yes, there are some other options for PF correction, if I decide I need them.

In addition to PF correction (which is the hardest thing to do IMHO), I'll be looking at installing remote voltage sensing (if I decide that the drop over my 1/0 cables and shunt is too much).

I'll also look at doing temp compensation, which can be integrated into the remote voltage sensing. You basically tell the 3846 chip that you want lower voltage when hot and higher voltage when cold.

There's a simple circuit they use to control output voltage. They've got a jumper for gel batteries to lower voltage, and several resistors in a controllable voltage divider (controlled by the microcontroller), all of which affect the voltage at a single pin on the UC3846 to tell it what the output voltage should be - normal boost or float. With a temp sensor at the battery and remote voltage sensing, those voltages can also be modified to produce whatever voltage is desired.

Edit: The gel cell jumper can optionally be used to reduce output voltage for very hot conditions without any modification, and might allow an add-on temp compensator for up to 0.4 volts decrease of the output voltage.

I don't have immediate plans for any of this, I'll be waiting through the warranty period, but it's nice to know I have the option to make those changes and the information needed to make most repairs after the warranty is over. Until then, I'll live with the manual control the PD gives you.

I know many will say why bother - buy something that has the features you want - PF correction, remote temp or voltage sensing, etc., but the devil I know is far better for me than the one I don't, particularly when I have his reins in my hand in the form of a circuit diagram and pushbutton manual control over the mode output voltage. :)