Tonight I added my 3s lipo pack successfully with the lifepo4 main pack. It rides nearly as fast as the straight 48v 5ah lipo, but not quite since it pulls 3amps less due to the lifepo4 BMS limiting to 21.5amps. It needs more refinement with attaching it, but this little frame bag is working.
I also added a precharge resistor to prevent the spark upon connecting to the controller.
My MW clone PS unit pushes 11.4amps at 54volts, so I need to file down the shunt to get it near 5-7amps.
It's going to be nice to have those extra 200watts, up to 1000w now. It should also take some stress off the likepo4 pack as long as I keep my speed about the same as before (aside from those keys spots where I will need it).
Now the decision is: do I buy just one more 3s pack so I can get full range on the lifepo4, or do I also get 2 more 5s packs so I have the option of 48v 10ah as well?
Even with keeping the controller amps limited to below the lifepo4 BMS amp limit, the lipo stick I added in series still pumps more than it's share of amps. I did 5.5 miles today, 125 wh total, but it only took 32 minutes to recharge the lifepo4 - which would mean that I only used about 60-70 wh from it, instead of the estimate 102 wh share. This makes sense of course, because the lipo 3s pack was drained about 70% even though only 2.5ah were used. Result: I would likely need to parallel 3 of these 3s packs to provide enough run time (15ah) to match the 11ah of the lifepo4. I have one 3s pack in the mail coming, so two will probably not last that much, I lowered the controller amp setting to 21amps to help even things out.
1/21 update: Today I parked at a bike rack at a new Staples building and there was a power outlet right there! I couldn't resist since I had my lipo charger in my backpack, hooked it up for 10 minutes of 25watt charging LOL. It's nice to know there's another location I can lock up and charge at. (It's even hidden due to the bike rack being in this recessed section of the front wall of the building.
I weighed my bike today, with the additional lipo, spare tube parts, and ulock - came out to 57lbs. My next roadie build will likely come out to 28lbs
I'm going to have a q100 with either 10 or 13s 5ah of lipo, and hope that it does okay on 20amp limit with careful usage. 800watts to the wheel plus my 1800w on a 28lb bike should result in acceleration that is impressive. Aiming for 0-20mph in 1.5 seconds. Will be a steel fork with torque arms to be safe. I have no idea how these q100's perform, so it will be interesting. I do know it's a 4lb motor, that's why I got it!