1. I'll have to check on the MOSFETs, but I don't recall them being anything particularly special.
2. Runtime on the LiPo has been super. I think it is realistic to count on a full day of nerf on one battery. But I havn't yet tested that. I did do a half day with no issues though.
3. This is a huge question. One that I'm in the process of answering for myself, but I'll try to condence it and give you something usable.
I should have had a better overall plan and goal. Because I didn't yet know what I wanted, I tried a lot of things that didn't pan out well. For instance, I should have skipped right over the 7-seg displays and gone straight for OLED. Another major issue I wish I had seen in advance is EMI from the Motors and main power lines.
I have already purchased MOFSETs as per advice from the britnerf forums, from the Managing Director of Blastersmiths UK, the IRFZ44N.
I have also ordered a well-supported OLED right off the bat, no mucking about with the bulky segmented display and driver chips. I'm going to be doing the SMG mod to shorten the barrel and have a relocated battery box, but I will be either putting in a pair of 130 or keeping the stock motors, just with 18AWG wiring for power supply systems. I am not doing anything to make sure it passes the Toruk test, as I am not a competitive Nerfer.
Here's an enhancement for you - https://code.google....SecretVoltmeterIf you use the right Atmega chip, then you can find out what the internal voltage is, and from that, you can work out what the current charge state of your LiPo is, without needing additional circuitry. Personally, I will be powering my nano from the JST balance plug, full voltage, onto the unregulated power pin.
Thanks for mentioning the EMI. I will make sure to put a ferrite ring around the Arduino power supply. Sure, I'll be feeding it from the unregulated supply pins,
I suspect that once I get this all prototyped and working on the Nano, I will do the same, and do my own PCB, and use the correct Atmega SMD to get the pack size down.